RAYMOND WILLIAMSON 49 now in a situation where she did not have hair and could not 6. Mavrokokki T, Cheng A, Stein B, Goss A. Nature and Frequency of wear a partial denture. Figure 1 shows the patient’s clinical Bisphosphonate-Associated Osteonecrosis of the Jaws in Australia. J Oral picture just after sequestration of the buccal plate overlying Maxillofac Surg 2007; 65:415-23. the right maxillary canine. Figure 2 shows the patient’s x-ray 7. Mehrota B, Ruggiero S. Bisphosphate Complications including prior to debridement surgery. Figure 3 shows anterior maxilla Osteonecrosis of the Jaw. Am Soc of Hematol 2006; 1:356-60. eight months post debridement. This patient was now able to 8. Lacy M, Dispenzier A, Gertz M, et al. Mayo Clinic Consensus wear a partial denture over the surgical site. In addition she Statement for the use of bisphosphonates in Multiple Myeloma. Mayo Clin had purchased a wig and the difference in her self-esteem Proc 2006;81:1047-1053. was very gratifying to see. One should never lose sight of 9. Thakkar S, Isada C, Smith J et al. Jaw complications associated with having empathy for one’s patients. bisphosphonates use in patients with plasma cell dyscrasias. Med Oncol 2006; 23:51-6. CONCLUSION 10. Williamson RA. Surgical management of bisphosphonate induced osteonecrosis of the jaws. Int J OMS 2009 (Dec) in press. Bisphosphonates are an important part of the 11. Pautke C, Kesting M, Hoelzle F, Steiner T, Deppe H, Bauer F, chemotherapeutic treatment for patients being treated for Loeffelbein D, Martens H, Wolff K-D and Kolk A. Bisphosphonate bone related cancers. Complications, such as ONJ related osteoporosis therapy and jaw osteonecrosis. J Cranio-Maxfac Surg 2008 to bisphosphonate use, are low, but patients should be (Sept); 36: S34. monitored regularly by their treating physician and dentist so that the complications are recognized early and managed, Address for correspondence: with prevention being the key. Oral Surgery Department School of Dentistry REFERENCES University of Western Australia 17 Monash Ave 1. Durie BG, Katz M, Crowley J. Osteonecrosis of the jaw and NEDLANDS WA 6009 bisphosphonates. N Engl J Med 2005;353:99–102. [email protected] 2. Wang J, Goodger NM, Pogrel MA. Osteonecrosis of the jaws associated with cancer chemotherapy. J Oral Maxillofac Surg 2003;61:1104-7. 3. Pogrel MA. Bisphosphonates and bone necrosis. J Oral Maxillofac Surg 2004; 62:391-2. 4. Marx RE. Pamidronate (Aredia) and Zoledronate (Zometa) induced avascular necrosis of the jaws: a growing epidemic. J Oral Maxillofac Surg 2003; 61:1115-7. 5. Carter GD, Goss AN. Bisphosphonates and avascular necrosis of the jaws. Aust Dent J 2003; 48:268.
Ann Roy Australas Coll Dent Surg 2010;20:50-51 THE USE OF VIRTUAL REALITY TOOLS IN SURGICAL EDUCATION Andrew Smith, BDS, MDSc, FDSRCS, FDSRCPS, FRACDS(OMS)* Andrew Smith is the Winthrop Professor of Dentistry, Head of the School of Dentistry and Director of the Oral Health Centre of Western Australia at the University of Western Australia ABSTRACT Advances in computing, specifically those used for simulation and games technology has allowed for exciting developments in dental and surgical education. At the same time concerns are being raised that students with relatively little training, practise to improve their skill on patients with all of the inherent risks that may occur. Simulation in dentistry has been practised for many years and so the concept is not new to the profession. New tools have been developed that both enhance teaching and learning and are also useful for assessment of students and trainees. The challenge of virtual and simulated reality tools is to have the required fidelity to improve teaching and learning outcomes over the currently utilized methodology. INTRODUCTION to align their course with what simulation offers. This is particularly the case in consideration of the balance between Simulation has long been used in dentistry but in the last the consumer’s need and the manufacturer’s intent. From decade or so issues of patient safety, regulatory requirements, the consumer aspect there is the ‘must have features’, the patient shortage, the need to teach communication, to achieve ‘want to have features’ and then the ‘alternative features’, competency and to show leadership and most importantly the ‘don’t need features’ and finally the ‘manufacturer wants the educational requirement for an evidence and validation you to have features’! of the process has occurred. In simulation, quality is the ability to immerse the student Prevailing trends in simulation are those of a huge and does not relate to the fidelity of the simulator. It is critical demand for simulation but limited supply of infrastructure. that the Infrastructure has to meet its designed function and The challenges to simulation development include a lack of that the simulation facility has to do what it is designed to do. a plan, failure to train instructors, problems with scenario development, engagement with the faculty and, of course, DISCUSSION funding. Why do we need simulation and virtual reality for dental and oral surgery? There has been availability of human jaw Funding organizations require a return on investment in bones and teeth, but this is less so now for a variety of ethical simulation. There is scrutiny of cost, systems testing/human and infection control issues. Dentistry has many years of factors, orientation, retention of skills, economic efficiency experience in simulation from old-fashioned phantom head and compliance with regulatory requirements. Simulation mannequins though OSSIM† to DentSim.‡ must provide effective competency training, team and There is however no really good animal or simulation communication skills and may be valuable in the teaching of model for dento-alveolar surgery. In designing a good tool it unusual and critical events. is required to maximize the real drilling and instrumentation experience. The tool needs to instil the initial learning of In the development of simulation tools there are threats; surgical anatomy, and to relate this to planning and drilling these include, unused or underutilized equipment, design techniques. In terms of teaching and learning a virtual reality failures in the facility and audiovisual components. In system has to have the haptic of the differences between addition, inadequate training and funding for training often results in under use of the equipment. Most simulation tools TABLE 1 are designed to develop competency but rapidly can become Dreyfus - Competencies a summative assessment tool. Expert: Has an intuitive understanding of the situation and zooms in on the If one accepts that the role of simulation is to achieve central aspects competence then the Dreyfus competency pyramid, is worth examining (Table 1). This puts competency at the level of Knowledgeable practitioner: Sees the situation as a whole and acts from the practitioner, but not of the expert. Concern is raised that personal conviction competency therefore, is a lowest common denominator and that excellence loses out. The contrary argument is that the Practitioner: Acting consciously from long term goals and plans level of the competency bar for the practitioner can be set at a very high level. Experienced Beginner: Incorporates aspects of the situation The other major criticism pointed at simulation is that Novice: Rule based behaviour, strongly limited and inflexible simulation sometimes seems to drive the curriculum whereas it really must be the other way around. Course leaders need * Presented at the Twentieth Convocation of the Royal Australasian College † A-Dec, 2601 Crestview Drive, Newberg, Oregon 97132 USA. of Dental Surgeons, Perth, Western Australia. March 2010 ‡ Image Navigation Ltd., Moshav Ora 106 Jerusalem, Israel 90880.
ANDREW SMITH 51 the hardness of tooth and bone. Further developments of the use of educational measuring tools is part of the ongoing an oral surgery model by adding modules for endodontics, experimentation. The educational strengths of the system are periodontics and implant dentistry is also a consideration in being analysed and it is recognized that in some areas the making the development multidisciplinary within dentistry. reality of the simulation is rather less important than was first Teaching staff shortages are a constant problem and so thought. It has been shown that trainees very actively engage remote mentoring can resolve some of these issues. in learning and develop perceptual skills more rapidly than with conventional learning method. The advantages of virtual reality training are that there is a freedom to fail, which is possible on a cadaver CONCLUSION model but unethical on a live human. It is possible for the student to practise until competency standards are met. The Despite all of the advantages of patient safety, training simulations are standardized and repeatable. As there are quality and the possibilities of surgeon credentialling minimal occupational health and safety risks, the system has should virtual reality surgical training be implemeted, when greater availability and access than a conventional simulator it usually involves significant financial investment and laboratory. Machinery being available twenty four hours training of teaching staff in new skills? In terms of some a day allows greater flexibility in rostering students and surgical skills systems, for example, those for laparoscopy consequently less need to buy as many workstations. and anastomosis, there is significant evidence to show that there is a quantitative gain in the speed and quality of skill The development of a dento-alveolar surgical simulation acquisition. For the jaw and third molar model the jury is still system was an initiative of a multidisciplinary team from the deciding upon its verdict. University of Melbourne§ and facilitated by cooperation with a commercial venture Forrslund Systems|| from Stockholm, REFERENCES Sweden. Initial experiments were undertaken in Melbourne and Sweden and further development is now underway at the 1. Dreyfus H L and Dreyfus S E Mind over Machine: the power of human University of Western Australia. intuition and expertise in the era of the computer. Oxford; Basil Blackwell. 1986. Clinical data from computerized tomography scans of jaw bones and teeth were obtained. Digital segmentation of Address for correspondence: anatomy into ‛objects’ was performed and the objects were School of Dentistry given properties such as colour or texture. This together Oral Health Centre of WA with a two handed force feedback probe gives a haptic, three 17 Monash Avenue dimensional virtual reality tool. Clever technology is not the NEDLANDS WA 6009 Australia be all and end all of this. The tool has to be shown to be at [email protected] least equivalent to conventional teaching methodology and § MUVES, Room N721, Faculty IT Unit, Faculty MDHS,The University of Melbourne, Victoria 3010, Australia. || Forsslund Systems AB, Folkskolegatan 3 4tr, 117 35 Stockholm, Sweden.
Ann Roy Australas Coll Dent Surg 2010;20:52-55 RIDGE PRESERVATION: DOES IT ACTUALLY WORK? Ivan Darby, BDS, PhD, FRACDS(Perio), DGDPRCSEng, FADI* Associate Professor Darby is Head of Periodontics in the Melbourne Dental School, the University of Melbourne. ABSTRACT Post-extraction the alveolus undergoes modelling which reduces height and width. This may present a problem for subsequent crown and bridge or implant therapy. Ridge preservation is the use of grafts and/or membranes to try to minimize the loss of the alveolar ridge. Extraction sockets have been filled with autogenous, allogenic and alloplastic materials. Membranes or soft tissue were used to contain the graft. More recently biodegradable sponges and materials coated in growth factors have been tested. Studies have primarily looked at either maintenance of vertical and horizontal dimensions or the healing of the socket and how much of the graft material is incorporated into the newly formed bone. Irrespective of method or materials, there seems to be some maintenance of the alveolus. Bone fill seems to occur in preserved extraction sockets, but in most cases with a high percentage of residual graft particles. In general, there is a lack of evidence to show that ridge preservation aids in correct 3-D implant placement, maintains hard and soft tissue volume over a prolonged period of time or for success and survival of implants placed into ridge preserved sockets. Still the most effective way to maintain ridge volume is to keep the natural tooth. Key words: Extraction sockets, bone grafts, membranes, implants, ridge preservation INTRODUCTION loss heal more quickly as the reduced level of the alveolar ridge means less infill is required. Bone does not regenerate The outcome of implant dentistry is no longer measured to a level coronal to the horizontal level of the bone crest or by survival, but success, which is a measure of biological or to the level of the neighbouring teeth i.e., 100% socket fill technical complications. Success can also mean the implant is does not occur. in the optimal position for restoration. The loss of bone post- extraction may leave an inadequate bone volume for correct Schropp et al.1 studied the effect of a single tooth 3-D implant placement. Ridge preservation is the attempt to extraction of premolar or molar teeth on bone healing minimize the loss either by use of a particular technique or and soft tissue changes using clinical and radiographic by grafting materials placed in the socket. It has commonly measurements as well as digital subtraction radiography. been used to facilitate implant placement, but is it effective? They showed that major changes take place in the 12 months following an extraction with an average of 50% reduction in Healing of Extraction Sockets the width of the alveolar ridge. Two thirds of this reduction occurred within the first three months. This loss averaged Healing of an extraction socket is characterized by between 5 and 7 mm and was similar at all sites in the internal changes that lead to formation of bone within the mouth. Importantly, most of the subjects did not wear a socket, and external changes that lead to loss of alveolar denture after extraction. Immediately after tooth extraction ridge width and height.1 the width of the ridge was an average of 12 mm (8.6 -16.5 mm) and 12 months later 5.9 mm (2.7 - 12.2 mm). Given When a tooth is removed, there is haemorrhage followed that a standard body implant requires a minimum of 6 to 7 by formation of a blood clot that fills the entire socket.2 The mm of bone dimension, many of these sites would not be concomitant inflammatory reaction stimulates recruitment of suitable for implant placement. The authors conclude it cells to form granulation tissue. Within 48 to 72 hours the clot would be advantageous if this loss of bone dimension could starts to break down as granulation tissue begins to infiltrate be prevented. the clot especially at the base and periphery of the socket. By four days, the epithelium proliferates along the socket A recent study by Araujo and Lindhe3 showed that in the periphery and immature connective tissue is apparent. After first eight weeks following extraction in a dog model there is seven days, the granulation tissue has completely infiltrated marked osteoclastic activity resulting in the resorption of the and replaced the clot. At this stage, osteoid is evident at the facial and lingual crestal walls. They noted that the reduction base of the socket as uncalcified bone spicules. Over the next of height was more pronounced at the facial wall and was two to three weeks (three to four weeks after extraction) this accompanied by a horizontal loss on both facial and lingual begins to mineralize from the base of the socket coronally. walls. Bone dehiscences or fenestrations present at time of This is accompanied by continued re-epithelialization which extraction, particularly in the facial or lingual walls, are most completely covers the socket by six weeks post-extraction. likely to be filled by fibrous reparative tissue, which may Further infill of bone takes place with maximum radiographic occupy considerable space in the socket itself. density at around 100 days. Ridge preservation A number of factors may affect the healing of sockets.1 The size of the socket is important with wider sockets Ridge preservation is defined as any procedure undertaken requiring more time to bridge the defect compared with to minimize bone loss due to extraction and to maximize narrower sockets. The sockets of teeth with horizontal bone bone formation within the socket. Many techniques use the principles of guided tissue/bone regeneration. * Presented at the Twentieth Convocation of the Royal Australasian College of Dental Surgeons, Perth, Western Australia. March 2010
IVAN DARBY 53 Methods and Materials Sponges made of polylactic/polyglycolic acid or collagen have been placed in extraction sockets to preserve Currently, the most effective method of maintaining the ridge.7,8 The collagen sponges also acted as a carrier for alveolar width and height is the presence of a tooth. growth factors.7. Therefore, if possible, the tooth to be extracted should be retained for as long as possible and extracted in keeping with In addition to the great variation in the materials used, the timing of the implant placement. Pain and infection may there is not surprisingly great variation in the methods used. require immediate removal of a tooth. These involved a combination of bone grafts, membranes and soft tissue coverage and are shown in Table 2. The use of techniques that minimize the amount of trauma occurring during an extraction should be used. These include Figure 3 shows the sequence of ridge preservation in a severing the periodontal fibres by periotomes or luxators and lower premolar site and subsequent re-entry at eight months. gentle lifting of the tooth from the socket by forceps (Fig. 1). Multi-rooted teeth can be sectioned and the individual roots Outcomes of ridge preservation elevated out (Fig. 2). Raising a flap will increase the loss of Many of the studies investigating ridge preservation have buccal alveolar bone. looked at bone formation or dimensional changes. In general, ridge preservation procedures are effective in limiting Some papers have suggested debriding the socket or horizontal and vertical ridge changes.5 There is no evidence perforating the cortical plates to induce more bleeding.4. To to support the superiority of one technique over another. date neither has been shown to be more effective than letting Deproteinized bovine bone mineral (DBBM) does seem to the socket heal normally. Removal of chronically inflamed be a more reliable material than demineralized freeze-dried tissue and foreign bodies is still necessary. Fig. 2. – Sectioning of a molar tooth for elevation of each root in order to Soft tissue coverage of the socket has been proposed minimize bone damage upon extraction. (Photograph courtesy of Dr Robert for optimum healing and aesthetics.4 However, there is no De Poi). evidence that soft tissue coverage alone is beneficial. It can be difficult to mobilize sufficient tissue, especially at posterior sites, to cover an extraction socket and may result is soft tissue or aesthetic complications. In any event the socket will epithelialize in six to eight weeks. At this time point there should be sufficient of the socket left to ridge preserve, although there is no evidence for the outcome of this in the literature. The materials used for ridge preservation are those that have been used for guided bone regeneration or guided tissue regeneration and reflect what is available commercially. Table 1 shows the range of bone graft materials and types of membranes that have been reported in clinical studies.5,6 For a full list of the authors readers are referred to Darby et al.5 AB Fig. 1. – Use of a periotome to sever the periodontal fibres around a central CD incisor. (Photograph courtesy of Dr Robert De Poi). Fig. 3. – Ridge preservation of a lower premolar. A) shows the extraction socket, B) DBBM in place, C) coverage of the particulate graft by a collagen membrane and D) re-entry at eight months prior to implant placement. (Photographs courtesy of Dr Fiona Little).
54 RIDGE PRESERVATION: DOES IT ACTUALLY WORK? TABLE 1. 94% survival three to seven years post-placement and Norton The different types of bone graft materials and membranes that have been and Wilson14 89% 18 months post-placement. The longest follow-up period has been by Sclar.8 He used the Bio-Col reported in the dental literature in ridge preservation studies. technique, where DBBM is placed into the socket, a collagen plug is placed on top and is loosely sutured into position with Bone graft materials Types of membranes the epithelium allowed to grow over the plug. He reported a 94% survival rate in 248 ridge-preserved sites in his private Demineralized freeze-dried bone Expanded polytetrafluoroethylene practice over six to 73 months. allograft Collagen Deproteinized bovine bone mineral Polylactic/Polyglycolic Acid CONCLUSION Titanium Autologous bone Acellular dermal matrix graft The recent 4th ITI consensus conference concluded that Bioactive Glass “ridge preservation procedures result in greater orofacial Hydroxyapatite dimension of bone than when no ridge preservation Calcium sulphate procedures are performed”.15 These authors suggested that Solvent-preserved cancellous graft when an implant is to be delayed for more than a two to three Biocoral months post-extraction then ridge preservation procedures Irradiated cancellous allograft should be considered for maintaining as much bone volume Solvent-dehydrated allograft as possible. Whilst there is no firm evidence of ridge preservation on implant success, it would seem appropriate TABLE 2. to use these procedures. However, the best ridge preservation The various combinations of materials and soft tissue manipulation method is to keep the natural tooth for as long as possible. reported in ridge preservation. REFERENCES Bone graft material, membrane and soft tissue advancement 1. Schropp L, Wenzel A, Kostopoulos L, Karring T. Bone healing changes Bone graft material and soft tissue advancement and soft tissue contour changes following single-tooth extraction: A clinical Membrane and soft tissue advancement and radiographic 12-month prospective study. Int J Periodontics Restorative Bone graft material alone Dent 2003; 23: 313-23. Membrane alone Bone graft material and collagen wound dressing 2. Amler MH. Histological and histochemical investigation of human Sponge alveolar socket healing in undisturbed extraction wounds. J Am Dent Ass1960 61 31-4. bone allograft (DFDBA) or autologous particulate grafts. The use of membranes required soft tissue coverage to maximize 3. Araujo MG, Lindhe J. Dimensional ridge alterations following tooth outcomes. Exposure of expanded polytetrafluoroethylene extraction. An experimental study in the dog. J Clin Periodontol 2005 32 (ePTFE) membranes was common and resulted in a much 212-8. reduced bone infill and dimensional stability. The exposure of collagen membranes was less frequent and less detrimental. 4. Darby IB, Chen S, De Poi R. Ridge preservation: What is it and when Given the diversity of soft tissue closure and concomitant should it be considered? Aust Dent J 2008; 53: 11-21. procedures, it would appear that ridge preservation can be successful even if primary closure is not achieved. However, 5. Darby IB, Chen ST, Buser D. Ridge preservation techniques for implant it is recommended when a particulate graft is used to hold dentistry. Int J Oral Maxillofac Implants 2009; 24(Supp): 260-71. it in place. There seems to be no difference with tooth type, position or reason for extraction in the outcome, and the 6. Lee DW, Pi SH, Lee SK, Kim EC. Comparative histomorphometric use of antibiotics cannot be supported or denied given the analysis of extraction sockets healing implanted with bovine xenografts, heterogeneity of the available literature. irriadiated cancellous allografts, and solvent-dehydrated allografts. Int J Oral Maxillofac Implants 2009; 24: 609-15. The amount of bone formed at ridge preserved sites varies between techniques, materials and timing of sampling. 7. Fiorellini J, Howell T, Cochran D, Malmquist J, Lilly L, Spagnoli D, Irrespective of graft material, some bone is formed and varied Toljanic J, Jones A, Nevins M. Randomised study evaluating recombinant between 18 and 64%.9-12 The longer the sampling time after human bone morphogenetic protein-2 for extraction socket augmentation. J the ridge preservation procedure the more bone there was Periodontol 2005;76:605-13. at the site. When materials with a slower substitution rate are used, residual particles are to be expected at the time of 8. Sclar A. Ridge preservation for optimum esthetics and function. The implant placement. The effect of the residual graft material Bio-Col technique. Compend Dent Ed 1999; 6: 3-11. on osseointegration and survival/success outcomes of the implant therapy is unknown. 9. Froum S, Cho S-C, Rosenberg E, Rohrer M, Tarnow D. Histological comparison of healing extraction sockets implanted with bioactive glass Very few papers have reported the effect of ridge or demineralized freeze-dried bone allograft: A pilot study. J Periodontol preservation on facilitating implant placement. Many 2002;73:94-102. mention that implants were placed, but often implants could be placed in untreated control sites. An interesting finding by 10. Tal H. Autogenous masticatory mucosal grafts in extraction socket Sandor et al.13 and Fiorellini et al.7 was that ridge preserved seal procedures: a comparison between sockets grafted with demineralized sites required much less grafting than untreated sites at the freeze-dried bone and deproteinized bovine bone mineral. Clin Oral Impl time of implant placement. Res 1999;10:289-96. The longevity of the grafted sites and the implants placed 11. Vance GS, Greenwell H, Miller RL, Hill M, Johnston H, Scheetz JP. at these sites has been poorly reported. The majority of the Comparison of an allograft in an experimental putty carrier and a bovine- literature does not report on implant survival and the grafted derived xenograft used in ridge preservation: a clinical and histologic study sites are only followed until they are biopsied at time of in humans. Int J Oral Maxillofac Implants 2004;19:491-7. implant placement. Sandor et al.13 showed approximately 12. Artzi Z, Tal H, Dayan D. Porous Bovine Bone Mineral in Healing of Human Extraction Sockets. Part 1: Histomorphometric Evaluations at 9 months. J Periodontol 2000;71:1015-23. 13. Sàndor GK, Kainulainen VT, Queiroz JO, Carmichael RP, Oikarinen KS. Preservation of ridge dimensions following grafting with coral granules of 48 post-traumatic and post-extraction dento-alveolar defects. Dent Traumatol 2003;19:221-7.
IVAN DARBY 55 14. Norton M, Wilson J. Dental implant placed in extraction sites implanted Address for correspondence: with bioactive glass: Human histology and clinical outcome. Int J Oral 720 Swanston Street, Maxillofac Implants 2002;17:249-57. Parkville, VIC, 3010, Australia. [email protected] 15. Chen ST, Beagle J, Jensen S, Chiapasco M, Darby IB. Consensus statements and recommended clinical procedures regarding surgical techniques. Int J Oral Maxillofac Implants 2009;24(Supp): 272-8.
Ann Roy Australas Coll Dent Surg 2010;20:56-58 NOVEL APPROACHES IN 3-DIMENSIONAL FACIAL PROFILING TO ESTABLISH FACIAL AESTHETIC OBJECTIVES IN THE TREATMENT OF FACIAL DYSMORPHOLOGIES Peter Claes, Ph D, M Eng* Mark Walters, M Sc John Clement, BDS, LDS RCS, Dip For Odont, PhD Peter Claes is at the Melbourne Dental School of the University of Melbourne. Mark Walters is in the Maxillo-Facial Unit of the Princess Margaret Hospital for Children in Perth Western Australia. John Clement is the Professor and Inaugural Chair of Forensic Odontology at the University of Melbourne. ABSTRACT When confronted with facial dysmorphologies, three-dimensional (3D) facial harmony is preferably assessed with regard to normality. This, however, presents two major challenges. The first challenge is to define normality. What makes non-dysmorphic faces appear normal? The second challenge is to situate the craniofacial dysmorphology with respect to normality. What makes the dysmorphic face not appear to be normal? To tackle these challenges, a novel approach based on a Face Space is proposed. In essence, faces are represented as points in a High-dimensional space, the dimensions of which capture important sources of allowed facial variation within a normal population. To establish an aesthetic objective of a given dysmorphic face, the novel concept of the “normal equivalent” of that face via robust projection into the Face Space is proposed. This technique is demonstrated on an artificial example in which smiling whilst showing teeth is considered a surrogate for facial dysmorphology.. INTRODUCTION when viewed in a standing upright position. Alternatively, the advent of 3D surface scanners, being able to capture The aim of multidisciplinary treatment of facial the facial profile with a high accuracy and quality, gives the dysmorphology is to achieve pleasing aesthetics with a possibility to scan a person in an upright position, without functional dentition and airway. Conventional planning being harmful. These types of 3D scanners are rapidly prioritizes dental alveolar and skeletal discrepancies. Facial being introduced into clinical practice and allow for the profile outcomes are most certainly considered but difficult construction of reference facial databases in order to define to predict. More recently there has been a shift in philosophy normality. in the treating of facial dysmorphologies where facial profile is the priority with functional requirements of the airway and Simple measurements, indices and ratios measured on dental occlusal relationship considered secondary. This has normative reference data have been used successfully to been referred to as FAB; Face-Airway-Bite. characterize specific aspects of craniofacial shape and have been used until now. However, these measurements often Criteria for treatment objectives for the dentition and fail to represent complete three-dimensional morphology of airway are well established but for facial aesthetics are the head. When specific measurements are used individually, more problematic. Facial aesthetics has been described by they oversimplify and when they are used collectively, they a set of facial proportions that was first described by the are difficult to interpret.3-5 Greek sculptors and now known as the Lysippan Canon of Proportion. These were modified by the renaissance artisans Because no objective standard for three-dimensional as a set of neoclassical canons that are with some modification facial shape has been satisfactorily defined, outcome the benchmark in facial aesthetic reconstruction today. planning and analysis of facial dysmorphology still relies on subjective visual judgment today.6 A first attempt to The treatment objectives for reconstructive surgical standardize complete 3D shape is the use of archetypes.7 procedures are to achieve normality.1-3 This indirectly poses the problem of defining normality first, which can only be Archetypes are averaged or generic facial profiles achieved based on proper normative reference data. Coming constructed from a dataset and where first used in for the from a clinical background the most commonly known diagnosis of syndrome faces.8,9 Very recently archetypes imaging device for this purpose is a Computer Tomography from normative data were used as references for the (CT) scanner. A disadvantage however, is the level of treatment assessment of dysmorphologies.6,10 However, irradiation absorbed by the subject during CT scanning, there is some evidence that these generic heads are not well limiting the reference database to patient data and incomplete represented in the population. That is, an averaged face does head scans or deceased subject data. Furthermore, CT images not equate to a typical face. The average face is too perfect are acquired of subjects in a horizontal, supine position. As and, as such, appears to be artificial. The means to establish a result, due to gravitational forces, facial shapes extracted a patient specific typical or normalized reference would be from CT images will differ from the typical facial shape more desirable. * Presented at the Twentieth Convocation of the Royal Australasian College In this paper a novel approach to establish facial of Dental Surgeons, Perth, Western Australia. March 2010 aesthetic objectives or standards in the treatment of facial
PETER CLAES, MARK WALTERS, JOHN CLEMENT 57 dysmorphologies in a patient specific way is proposed. The faces are represented as a single point in a high-dimensional concept of an archetype is extended into a Face-Space (FS) in 12000 x 3) coordinate system or Face-Space. The next step which faces are represented as points in a High-dimensional is centring the data around the average which is equivalent space, the dimensions of which capture important sources to translating the origin of the Face-Space to the centre of of allowed facial variation within a normal population. To the point cloud formed by all the faces. Finally, a probability establish an aesthetic objective of a given face, the novel distribution is associated to the Face-Space by fitting a concept of the normal equivalent (NE) of that face via robust multivariate normal distribution to the point cloud using projection of the face into the Face-Space is proposed. The PCA. This results in a correlation ranked set of principal Face-Space can be considered as an objective standard for components (PCs) modelling the inter-subject variance and normal 3D facial shape and in conjunction with the normal covariance. The most prominent spread of variation within equivalent provides a means to objectively plan and assess the dataset is always extracted by the first PC, and the the treatment of facial dysmorphologies. second widest variation by the second PC, etc. This type of variations extracted is entirely dependent on the distribution MATERIALS AND METHODS of the dataset being studied and hence in this study will only model variation of non-dysmorphic facial profiles. Normative Data acquisition This normative Face-Space contains a more complete Ethics approval for the project The Characterisation description of the underlying data then what has been of 3-Dimensional Facial Profile in Young Adult Western known previously. Besides the creation of just an average Australians was granted from the Princess Margaret Hospital reference face, variation present in the normative population for Children (PMH) ethics committee (PMHEC 1443/EP) is modelled as well using the set of principal components. in Perth, W.A. 3D surface scans of healthy young people Hence, the Face-Space describes typical and the limits of between the ages of 5 and 25 were collected using a 3dMD differences within the normative population and therefore facial scanning system. Facial data that were collected were defines normality for complete 3D facial shapes. represented as a complete surface. Shape data consisted of a dense number of points each with its own x, y and z component Normal Equivalent construction in 3D space. This collection of 3D points can exist as a point cloud or wireframe. To enable the standardization of shape Assessment of a facial profile with atypical or dysmorphic represented by point clouds a method11 that automatically parts is done via a robust projection of that face into the achieves anatomical correspondence between faces was Face-Space. During the projection, the dysmorphic parts of employed because of the impracticality of indicating the face can be isolated and colour coded images/maps can thousands of corresponding points manually. be generated that assist the treating clinician in defining the problem. These maps depict confidence limits, representing Normative Face-Space construction the belief that local facial features and parts are within normal allowed variation or not. By removing regions of the face The result is a normative database in which every facial considered as dysmorphic the remaining components can be surface is represented by the same number of points (12000) mapped to the normative face space to provide a complete with the same connectivity, such that for every point on facial map that is within prescribed normative limits. This one facial surface the corresponding point on every other generates a normalized facial profile which is termed the facial surface is known. This enables the creation of facial normal equivalent (NE) of the dysmorphic face. This NE archetypes and the statistical analysis of 3D facial shapes in can be considered a patient specific typical or normalized a Face-Space. By averaging densely corresponding points reference to compare or assess the dismorphic face against. for all faces an average face is constructed. Additionally, using the knowledge of the densely corresponding points, Fig. 1 – An artificial example: expression as dysmorphic surrogate to illustrate the proposed approach. From left to right, the original surrogate example, the Normal Equivalent after projection of the surrogate into the normative Face-Space and the confidence map (using a gray-coloured confidence range from 0 (black) to 1 (white)).
58 THREE DIMENSIONAL FACIAL PROFILING RESULTS a normalized facial profile could be generated, called the normal equivalent of a given dysmorphic face. This NE Four hundred faces from WA have been processed, with can be considered a patient specific normalized reference ages ranging from 5 to 25 years, into a normative Face- to assess the dismorphic face against. This technique was Space. All faces were scanned without an exaggerated smile demonstrated on an artificial example in which smiling showing the teeth. In order to illustrate the technique an whilst showing teeth is considered a surrogate for facial artificial example was constructed and scanned as a single dysmorphology. The results were very promising. In order to face with an exaggerated smile whilst showing the teeth. illustrate the value in clinical practice the application of this With regard to the normative model this exaggerated smile technique on real clinical cases is planned. is considered atypical and hence is used as a surrogate for facial dysmorphology. ACKNOWLEDGMENTS The result is depicted in Fig. 1. From left to right the The authors would like to thank Miranda Norquay from original surrogate scan, the Normal Equivalent after the Princess Margaret Hospital for Children (PMH) in Perth, projection of the scan into the normative Face-Space and WA for providing the high quality 3D Scans. The data the confidence map are shown. The Normal Equivalent have been used to generate the results. This work was also still strongly resembles the original surrogate scan (patient supported by the Australian Research Council (ARC) grant specific) but is now within normal allowed variation. Indeed, DP0772650. the exaggerated smile that made the surrogate scan atypical to the normative database is reduced up to a point where the REFERENCES teeth are not shown anymore. The remaining smile is possible within the variation of the normal population encoded in the 1. Farkas LG, Anthropometry of the head and face in medicine. 1981, normative Face-Space. The confidence map nicely depicts New York: Elsevier. the areas of the original surrogate that are atypical (black) and typical (white) according to normality. This map is very 2. Panchal J, Marsh JL, Park TS, Kaufman P, Pilgram T, Huang SH. useful in defining the problem and can assist the treating Sagittal craniosynostosis outcome assessment for two methods and timings clinician during assessment. The map shows that the areas intervention. Plast Reconst Surg 1999;103:1574-84. of the mouth where the teeth are shown are indeed atypical as expected. Furthermore, it also shows that other areas, like 3. Vannier MW, Marsh JL. Three-dimensional imaging, surgical planning, the chin and cheeks, are strongly affected by the exaggerated and image-guided therapy. Radiol Clin North Am 1996;34:545-63. smile and became atypical as well. When examining the person in question it is indeed so that these areas changed 4. Landes CA, Bitsakis J, Diehl T, Bitter K. Introduction of a three- a lot when showing the teeth and that these results are very dimensional anthropometry of the viscerocranium: Part i. Measurement of plausible and promising. craniofacial development and establishment of standard values and growth functions. J Craniomaxillofac Surg 2002;30:18-24. CONCLUSION 5. Farkas LG, Deutsch CK. Anthropometric determination of craniofacial When confronted with facial dysmorphologies, morphology. Am J Med Genet 1996;65:1-4. 3-dimensional (3D) facial harmony is preferably assessed with regard to normality. Because no objective standard for 6. Marcus JR, Domeshek LF, Loyd AM, Schoenleber JM, Das RR, normal three-dimensional facial shape has been satisfactorily Nightingale RW, Mukundan S. Use of three-dimensional, normative defined so far, outcome planning and analysis of facial database of pediatric craniofacial morphology for modern anthropometric dysmorphology still relies on subjective visual judgment. analysis. Plast Reconst Surg 2009;124:2076-84. Simple measurements taken on normative reference data have been used successfully in the past but failed to represent 7. Thomas CDL, Claes P, Shaweesh AI, Clement JG, Three-dimensional complete three-dimensional morphology of the head. The use facial shape archetypes for identification and diagnosis, in 1st International of archetypes presented a promising alternative. However, Symposium on biological shape analysis. 2009: Tsukuba, Japan. there is some evidence that these generic faces are not well represented in the population and the means to establish a 8. Shaweesh AIM, Thomas CDL, Bankier A, Clement JG. Delineation of patient specific typical or normalized reference would be facial archetypes by facial averaging. Ann Roy Australas Coll Dent Surg more desirable. 2004;17:73-9. A novel approach to establish facial aesthetic objectives 9. Shaweesh AIM, Clement JG, Thomas CDL, Bankier A. Construction or standards in the treatment of facial dysmorphologies in a and use of facial archetypes in anthropology and syndrome diagnosis. patient specific way is proposed. The concept of Archetypes Forensic Sci Int 2006;159:175-85. was extended into a Face-Space (FS) which besides an average also captured important sources of allowed facial 10. Terajima M, Nakasima A, Aoki Y, Goto TK, Tokumori K, Mori N, variation within a normal population. Using the Face-Space Hoshino Y.A3-dimensional method for analyzing the morphology of patients with maxillofacial deformities. Am J Orthod Dentofac 2009;136:857-67. 11. Claes P, A robust statistical surface registration framework using implicit function representations: Application in craniofacial reconstruction, in Faculteit ingenieurswetenschappen, department Elektrotechniek, afdeling PSI. 2007, K.U.Leuven, Belgium: Leuven. ISBN 978-90-5682-809-7. Address for correspondence: Melbourne Dental School 4th Floor, 720 Swanston Street Carlton, Victoria 3053 [email protected]
Ann Roy Australas Coll Dent Surg 2010;20:59-63 ASPECTS OF WEAR AND TEAR OF TOOTH STRUCTURE Bill Kahler, BDSc (Qld), FRACDS, MScDent (Syd), DClinDent (Adel), PhD (Syd), MRACDS (Endo), FICD* Dr Kahler maintains a full time specialist private practice restricted to Endodontics in Brisbane, Australia. He also acts as Endodontic Co-ordinator at the Dental School of the University of Queensland. ABSTRACT Lifestyle factors and the increased longevity of the dentition due to greater life expectancy have resulted in greater wear and tear (cracking) of teeth. Often there exists interplay between damage and repair. An understanding of these mechanisms of damage and repair will assist the clinician in correct diagnosis and treatment planning. Preventive strategies as well as interdisciplinary measures are required for optimal outcomes. However, are some of our restorative interventions causing further damage to tooth structure? INTRODUCTION of intratubular dentine (sclerosis) or pulpal reparative dentine beneath the lesions of tooth wear was shown.1 The Lifestyle factors and the increased longevity of the premise is that patent tubules are required to transmit the dentition due to greater life expectancy as well as a desire of stimuli to pulpal neurons and dentine experienced via the patients to retain their dentition have resulted in greater wear hydrodynamic mechanism.6 Conversely, tubules narrowed and tear (cracking) of teeth. Teeth are subject to a variety by intratubular dentine, obliterated by sclerosis or closed of processes of tooth wear that include etching, attrition, by reparative dentine on the pulpal wall to form dead tracts abrasion, erosion, and more controversially stress-corrosion will not transmit pain stimuli. As the lesions of tooth wear (abfraction). Teeth may also crack (tear) as a consequence progress episodes of dentinal sensitivity, or lack thereof, may of parafunctional forces and prior restorative work that has occur as repair takes place beneath the lesion through the the potential to introduce micro-cracks that can propagate formation of sclerotic dentine. to initiate tooth fracture. It is the objective of this article primarily within the framework of the author’s research to Beneath the amelo-dentinal junction (ADJ) are great outline the mechanisms of this damage and demonstrable numbers of fine, terminal branches of odontoblastic tubules repair that may occur in dentine which is a biological (Fig. 1). The odontoblasts are not receptor cells capable response by the pulp and an intrinsic quality within dentine. of transmitting signals to nerve fibres. Nerve endings are However, are some of our restorative interventions causing present only in the tubules of the deepest dentine, of the further damage to tooth structure? Fig. 1. – A schematic diagram illustrating odontoblasts within patent TOOTH WEAR dentinal tubules which branch finely beneath the amelo-dentinal junction. The tubules increase in diameter the nearer they are to the pulp. Patent Teeth are subjected to wear processes due to longer tubules leak dentinal fluid on surfaces denuded of enamel. This activates retention of the dentition, parafunctional habits and dietary dentinal sensitivity by hydrodynamic stimulation of nerve endings in the effects from consumption of acidic drinks and wine. Tooth pulp. a) exposed dentinal tubules; b) dentinal fluid leaking; c) dentinal fluid wear is shaped by interactions between acid wear, erosion, movement; d) subodontoblastic nerve plexus and reparative dentine (brown). attrition, abrasion and dentinal slerosis.1 It is generally accepted that non carious cervical lesions (NCCLs) occur on surfaces exposed to brushing. However, studies have shown that factors other than dentifrice-abrasivity play important roles in the formation of these lesions.2 Clinical observations still favour the possibility that excessive oral hygiene practices, such as brushing and flossing, produce cervical lesions by abrasion.3 The tooth surfaces on which NCCLs develop have been shown to be those least protected by serous saliva from the major salivary glands.4 It may be that dentinal tubules opened up by erosion are initially repaired by salivary pellicle or by mineral deposits from either the saliva or the odontoblasts as intratubular dentine. Areas of dentine in cervical erosions which are sensitive, display patent dental tubules. Teeth without symptoms exhibit occluded tubules.5 In a recent scanning electron microscopic (SEM) study that examined the patency of tubules, the formation * Presented at the Twentieth Convocation of the Royal Australasian College of Dental Surgeons, Perth, Western Australia. March 2010
60 ASPECTS OF WEAR AND TEAR OF TOOTH STRUCTURE predentine and within the subodontoblastic neural plexus of not sensitive. However, the most important biological reason the pulp.6 However, odontoblastic processes are bathed in a why superficial tubules and their narrow branches do not tissue fluid which fills the dentinal tubules and their branches spill dentinal fluid, is that dentinal tubules beneath attrition up to the ADJ. It is currently believed that rapid movements wear facets are occluded by the process of dentinal sclerosis.9 of this fluid are sensed as pain by nerve endings in the pulp.6 This ‘hydrodynamic’ theory holds that an the outward flow When enamel is removed by wear, the underlying of dentinal fluid occurs when the tubules are opened. This dentinal tubules become filled with an amorphous calcified stimulates mechanoreceptors, the nerve endings in the pulp, tissue called intratubular dentine which is secreted by that give rise to dentine sensitivity. However, the rate of fluid the odontoblasts.10 Initially, the diameters of tubules are flow within open tubules depends on their width.7 Terminal narrowed by the build-up of this material within their walls. branches of tubules near the ADJ, have smaller widths than Subsequently, the odontoblastic processes retract, leaving the tubules within the deeper dentine and predentine.8 As behind tubules virtually occluded by intratubular dentine tubule diameters double, a 16-fold increase in fluid flow (Fig. 2). Dentine so modified is called sclerotic dentine (Fig. occurs, because fluid-flow depends on the fourth power of 3). Sclerotic dentine can extend within the tooth crowns from the radius of the tubule.7 This may be one reason why the the ADJ to the pulp. Thus, dentinal sensitivity is repaired and dentine just below the ADJ, when first exposed by attrition is symptoms are relieved by closing of the narrow, superficial tubules by intratubular dentine. Tracts of sclerotic dentinal Fig. 2. – A schematic diagram illustrating that odontoblasts deposit tubules are formed beneath wear facets.11 Reparative dentine intratubular dentine in response to noxious stimuli. By narrowing tubule seals not only sclerotic dentine from the pulpal surface but diameters, the hydrodynamic mechanism of dentinal sensitivity is disrupted. also empty tubules of “dead tracts”.1 As the nerves and Tracts of tubules filled with intratubular dentine are sclerotic and insensitive. mechanoreceptors in the pulp become isolated from the worn dentine surface, they no longer react to stimuli on wear Reparative dentine seals sclerotic dentine on the pulpal wall (brown). facets. Fig. 3. – SEM image of the surface of sclerotic dentine. Most tubules are As acid exposure to teeth is considered a primary factor obliterated. Residual tubules are part of a dead tract. Bar = 10 μm in the development of NCCls any comprehensive treatment plan needs to address both dietary modification to decrease the acid exposure and wear and the reasons for the lack of salivary protection.1 While palliative measures are often employed, the dentine beneath NCCLs is sclerotic and therefore poses challenges for restoring these lesions for sclerotic dentine does not respond to etching or to bonding in the same manner as normal dentine. Current dentine bonding techniques rely on the formation of a hybrid layer enhanced by the demineralization of the dentine to form micro-porosities that allow penetration of the bonding agents.12 It is difficult to achieve sufficient demineralization of sclerotic dentine to attain optimal bonding through resin tags.13 Debonding, marginal leakage and loss of cervical restorations may then occur as a consequence.14 Other studies suggest that NCCL restorations fail as a result of the flexure of the tooth from excessive occlusal stress transferred to the cervical area.15 When bruxism is postulated to be the primary cause of NCCLs located at the cemento-enamel junctions (CEJ) and that tensile stresses are thought to be responsible for breakdown of cervical tooth structure, then clinicians will seek mechanical and technical solutions rather than adopt preventive strategies to arrest acid wear. Thus, the clinical diagnosis, conservation and restoration of non-carious cervical lesions should take into account the protective properties of serous saliva on the surfaces of acid wear, abrasion and of the extent of sclerotic dentine beneath NCCLs. CRACKED TEETH (TEARING) A cracked tooth is a frequent dental complaint with patients seeking treatment often presenting with a protracted history of pain of varying intensity.16 While intermittent pain on biting and thermal sensitivity are the most consistent complaints associated with these teeth, cracks in teeth may result in a wide range of symptoms from occasional
BILL KAHLER 61 ab c Fig. 4. – a. Optical micrograph of the crack tip illustrating its discontinuous nature (arrows). Many small micro-cracks coalesce resulting in a continuous crack b. Optical micrograph illustrating the discontinuous nature of the crack tip with the formation of ligaments that bridge across it (arrows). Many of these ligaments formed as a result of the micro-cracks that developed parallel to the main crack. c. Optical micrograph illustrating the formation of major ligaments bridging across the crack tip (arrows). (Reprinted with permission from Elsevier). discomfort to severe and prolonged pain. Symptoms are toughening mechanisms, such as micro-cracking (Fig. 4a, 4b), often dependent on the depth and direction of the crack occurring ahead of the crack tip and ligament development and the tissues involved. Cracks in teeth can occur in both (Fig. 4b, 4c) behind the tip. These ligaments across the crack horizontal and vertical directions and may involve enamel, tip greatly contribute to the greater toughness of dentine as the dentine, pulp and/or the periodontium.16 Cracks in posterior closure forces generated reduce the magnitude of the stress teeth often originate from an internal line angle at the floor of at the crack tip. This mechanism is primarily responsible for a restoration and often involving a marginal ridge extending the high toughness of fibre-reinforced materials. In addition, in a mesio-distal direction.17 Vertical root fractures are dilatancy about the crack tip was observed as indicated by longitudinally orientated fractures of the root that extend the fluid ingress and egress (Fig. 5).21 The size of this zone from the root canal into the periodontium.16 appeared to be much larger than the narrow zone of micro- cracking about the crack tip. During loading, a region of Clinicians regard unsupported enamel as a brittle hydrostatic tension and superimposed shear stresses develop structure as it is the underlying dentine that gives structural about the crack tip. These stresses are able to induce dilation strength to tooth structure. Dentine is a highly mineralized of a region about the crack tip in a similar manner to the tissue, which forms the bulk of the tooth. It is a hydrated development of a plastic zone about the crack tip of a metal. compound that contains fluid filled tubules surrounded The major difference being that dentine, particularly the by highly mineralized peritubular dentine embedded in more collagenous intertubular region, contains many fine intratubular matrix. Hydroxyapatite crystals, the main tubules connected to the main tubules. Fluid is able to inorganic material, provide strength, while collagen fibrils migrate into the structure to accommodate both the dilation provide toughness.18 Dentine is able to resist fracture as the ahead of the crack tip and the relaxation of this region behind orientation of collagen fibrils counter the directional effect the crack tip. Energy is consumed by both the inflow and of the dentinal tubules, thereby exhibiting crack stopping egress of fluid from this region. The collagen within this behaviour.19 Also, Pashley (1990) has suggested that the region is also able to extend when moist to accommodate fluid filled dentinal tubules could function to hydraulically such dilation and shear strains. These observations of fluid transfer and dissipate the occlusal forces applied to teeth.20 flow about the tip of a crack on loading and unloading From the perspective of theoretical mechanics, the structural support the hydrodynamic theory of dentinal sensitivity.6 stability of dentine is a function of mineralization and of Figure 6 is a schematic diagram summarizing the toughening moisture content. mechanisms considered to be operating during the fracture of dentine.21 Fracture of dentine is a function of crack initiation and crack propagation. Kahler et al. demonstrated that dentine Clinically, the significance of this work is the importance possessed fracture-toughening mechanisms that impede in maintaining the dentine during cavity preparation. Dentine crack propagation.20 This study clearly demonstrates the should be retained for the structural strength that it provides presence of micro-cracking for the first time in dentine (Fig. the tooth and its ability to resist fracture propagation. 4 - 7). Crack growth resistance of a material is a consequence Excessive removal of dentine cannot be recommended and of intrinsic micro-structural damage mechanisms operating this is in accord with the principles of minimally-invasive ahead of the crack tip, and extrinsic crack tip shielding dentistry. Despite the fracture-toughening mechanisms mechanisms that operate behind the crack tip. Intrinsic observed in dentine, recent research indicates that the mechanisms are an inherent property of the material that trend to place resin composites in posterior teeth may be control crack initiation. Extrinsic mechanisms, which include introducing further damage to tooth structure. A recent crack deflection, inelastic or dilated zones that surround the study has demonstrated substantial interfacial failure of the crack wake, and bridge formation (ligament toughening) enamel-resin composite bond and cracking in the enamel between the crack surfaces acting in the crack wake, are adjacent to the interface (Fig. 7, 8).21 The author proposed responsible for resistance-curve behaviour (R-curve).21 simple analytical models that may allow further research to reduce the deleterious effects of polymerization shrinkage In this study, the optical observations reveal fracture mechanisms of dentine that show a number of extrinsic
62 ASPECTS OF WEAR AND TEAR OF TOOTH STRUCTURE Fig. 5. – Optical micrograph illustrating the development of water droplets Fig. 7. – A representative occlusal cavity restored with resin composite. just behind the crack tip formed moments after the crack arrested following Black arrows indicate the presence of a “white line” and cracking in the enamel. The white arrow shows a gap or failure of the adhesive bond at the crack extension. (Reprinted with permission from Elsevier). tooth-restoration interface. stress that introduce damage as a consequence of restorative intervention.22-25 Despite the considerable improvements in 6. Brännström M, Lindén LÅ, Åström A. The hydrodynamics of the the development of resin composites the concept of ‘total dentinal tubule and of the pulp fluid. Caries Res 1967;1:310-317. etch and total seal’ is not a paradigm that can be reliably achieved. 7. Pashley DH. Dentin permeability, dentin sensitivity, and treatment through tubule occlusion. J Endod 1986;12:465-74. ACKNOWLEDGMENTS 8. Dourda AO, Moule AJ, Young WG. A morphometric analysis of the The author gratefully acknowledges the assistance of cross-sectional area of dentine occupied by dentinal tubules in human third Professors Michael Swain and William Young for their molar teeth. Inter Endo J 1994;27:184-9. assistance and guidance in the relevant studies. 9. Dowell P, Addy M. Dentine hypersensitivity: a review of aetiology, Figures 4a, 4b, 4c, 5 and 6 have been reprinted from symptoms, and theories of pain production. J Clin Periodontol 1983;10:341- Kahler B, Swain MV, Moule A. Fracture-toughening 50. mechanisms responsible for differences in work to fracture of hydrated and dehydrated dentine. Journal of Biomechanics 10. Holland GR. The odontoblast process: form and function. J Dent Res 2003;36:229-37, with permission from Elsevier. 1985;64:499-514. REFERENCES 11. Pindborg JJ. Pathology of the Dental Hard Tissues. Munksgaard: Copenhagen 1970; 345-6. 1. Daley TJ, Harbrow DJ, Kahler B, Young WG. The cervical wedge- shaped lesion in teeth: a light and electron microscopic study. Aust Dent J 12. Nakabayashi N, Kojima K, Masuhara E. The promotion of adhesion 2009;54:212-9. by infiltration of monomers into tooth substrates. J Biomed Mater Res 1982;16:265-3. 2. Volpe AR, Mooney R, Zumbrunnen S, Stahl D, Goldman HM. A long term clinical study evaluating the effect of two dentrifices on oral tissues. J 13. Van Meerbeek B, Braem M, Lambrechts P, Vanherle G. Morphological Periodontol 1975;46:113-8. characterization of the interface between resin and sclerotic dentine. J Dent 1994;22:141-146. 3. Levitch LC, Bader JD, Shugars DA, Heymann HO. Non-carious cervical lesions. J Dent 1994.22;195-207. 14. Hörsted-Bindslev P, Knudsen J, Baelum V. 3-year clinical evaluation of modified Gluma adhesive systems in cervical abrasion/erosion lesions. Am J 4. Young WG, Khan F. Sites of dental erosion are saliva-dependent. J Dent 1996;9:22-6. Oral Rehab 2002;29:35-43. 5. Brannstrom M, Garberoglio R. Occlusion of dentinal tubules under superficial attrited dentine. Swed Dent J.1980:4:87-91. Fig. 6. – Schematic illustration of the toughening mechanisms operating Fig. 8. – Cracking in the enamel is evident in a horizontal section from this during the fracture of hydrated dentine. Note the extensive ligament tooth restored with Z100 employing an incremental placement technique. formation bridging the crack and the visco-elastic/plastic energy dissipation Some interfacial fracture of the resin/enamel interface is evident as well as cracking in the adjacent enamel. Small voids are evident in the composite zone about the crack tip. (Reprinted with permission from Elsevier). resin.
BILL KAHLER 63 15. Grippo JO, Simring M. Dental “erosion”revisited. J Am Dent Assoc 23. Kahler B, Kotousov A, Swain MV. On the design of dental resin-based 1995;126:619-20. composites: A micromechanical approach. Acta Biomaterialia 2008;4:165- 72. 16. Kahler W. The cracked tooth conundrum: Terminology, classification, 24. Kahler B, Kotousov A, Borkowski K. Effect of material properties on diagnosis, and management. Am J Dent 2008;21:275-82. stresses at the restoration-dentin interface of composite restorations during polymerization. Dent Mater 2006;22:942-7. 17. Kahler B, Kotousov A, Melkoumian N. On material choice and fracture 25. Borkowski K, Kotousov A, Kahler B. Effect of material properties of susceptibility of restored teeth: An asymptotic stress analysis approach. composite restoration on the strength of the restoration-dentine interface Dent Mater 2006;22:1109-14. due to polymerization shrinkage, thermal and occlusal loading. Med Eng Phys 2007;29:671-6. 18. Marshall, G.W. Dentin microstructure and characterisation. Quintessence International 1993; 606-17. Address for correspondence: University of Queensland Dental School 19. Renson, C.E., Boyde, A., Jones, S.J.,. Scanning electron microscopy 200 Turbot Street of human dentine specimens fractured in bend and torsion tests. Arch Oral Brisbane 4000 Biol 1974;19:447-54. [email protected] 20. Pashley, D.H., 1990. Dentin permeability. In: Experimental Endodontics. Ed. Spångberg LSW.CRS Press Inc, Boca Raton., 19-49. 21. Kahler B, Swain MV, Moule A. Fracture-toughening mechanisms responsible for differences in work to fracture of hydrated and dehydrated dentine. J Biomechan 2003;36:229-37. 22. Kahler B. Stresses created at the interface of composite resin and tooth structure: Simple analytical modelling and experimental observations. PhD thesis; University of Sydney, 2009.
Ann Roy Australas Coll Dent Surg 2010;20:64-65 GENERAL WELL-BEING IN THE NEW DECADE – IMPORTANT CONSIDERATIONS Simon B. Dimmitt, MB BS, BMedSc(Hons), FRACP, FCSANZ* Dr Dimmitt is Clinical Professor of Medicine in the School of Medicine and Clinical Pharmacology of the University of Western Australia. ABSTRACT Chronic diseases have created a growing burden of ill-health as populations age, become more obese and as survival with many conditions improves. Cardiovascular disease, cancer and anxiety/depression merit priority by being common and treatable. Genomics aid diagnosis and understanding but have limited impact on management. Early diagnosis requires comprehensive annual clinical reviews, in which dental practitioners have an important role. Relevant imaging can be helpful. Useful early interventions include tactical lifestyle measures, weight control, appropriate supplements and low dose pharmacotherapy. Well-being requires avoidance of major illness and but with sufficient investment and focus, has rendered preservation of optimal health. Chronic systemic diseases HIV disease manageable. Timely vaccination lessens and are on the increase,1 as we age, become more obese2 and as often prevents a range of serious viral infections, well effective treatments increase survival. Disease management demonstrated with influenza, hepatitis B and childhood is enhanced by early diagnosis of treatable conditions exanthemata. Early appropriate use of antibiotics can be life with strategic screening. Numerically, the major disease saving in acute bacterial infection. Peri-operative topical areas which reduce quality of life and cause disability antiseptics and antibiotics have substantially reduced wound are cardiovascular, cancer, musculoskeletal disease and infection morbidity.3 depression. All gingival and dental infections are increased in Coronary and hypertensive heart disease become diabetes, meriting more aggressive surveillance and symptomatic in the second half of life, cause considerable management. There is a substantial association between morbidity and account for almost half of deaths. Strokes periodontal and coronary disease4 but this may be largely mainly occur after age 60, cause major disability, contribute related to associated obesity and less healthy lifestyle. The substantially to dementia and account for more than 10% of most sensitive marker of systemic inflammation, C-reactive deaths. protein, predicts coronary events but this relationship has not been shown to be independent of obesity, diabetes, More than one half of us will develop cancer, usually hypertension and hypercholesterolaemia. later in life but sometimes tragically earlier. Prevention and early diagnosis are priorities. Reduction in sun, tobacco Genomics have better defined most diseases and and alcohol exposure are fundamental in prevention. Skin, dominate contemporary clinical research. Although heredity colorectal, breast and prostate cancer, the commonest contributes substantially to all diseases, family history and malignancies, are mostly sporadic and this has spawned genetic testing have to date only had a limited role in clinical increasingly effective diagnostic screening, based on various practice. The main clinical application has been precise early forms of cross-sectional imaging or digital photography diagnosis or exclusion of genetic disease in the relatives of which can be archived and compared. patients presenting with confirmed disease. The accuracy of predicting cancer risk with genetic testing is improving Symptoms related to mental health occur in about one but clinical application is limited to high-risk kindreds. third of us, mildly in many more, often from early in life. Personalised genome analysis5 based healthcare in routine Depression often emerges in mid-life and is expected to clinical practice appears some way off. account for more disability than any other illness later this century. Overlap with more identifiable and treatable anxiety Annual clinical reviews are fundamental for individual disorders is considerable. These degrade sleep and quality of health inventory but are not routinely funded, except life, impede healthy lifestyle and contribute to psychosomatic in the context of insurance. Compliance with recurrent symptomatology and hypertension. examinations can be problematic because of cost and because many individuals find detailed and predictive Alcohol and other substances give acute stress and clinical consultations confronting. other symptom relief but over time reduce quality of life, exacerbate mood and fatigue disorders and contribute to Dentists are in a strategic position because clinical practice violence and motor vehicle accidents. is based on regular clinical reviews. As well as surveillance for oral pathology, the dentist has the opportunity to conduct Intercurrent infections take an enormous toll across all something of a systemic inventory, in particular related to ages. Antiviral drug development has proven problematic planned dental procedures. Collaboration with general practice and referral to medical specialists can significantly * Presented at the Twentieth Convocation of the Royal Australasian College enhance patient care. of Dental Surgeons, Perth, Western Australia. March 2010
SIMON DIMMITT 65 In terms of prevention and management, healthy lifestyle daily. Outcomes are superior when thiazide diuretics13 measures are fundamental. Most importantly, these include and digoxin14 are used at lower doses. Higher doses of modest portion nutrition with as much food variety as atorvastatin than 10 mg daily, not necessary in patients who possible. Regular modest exercise improves energy and achieve weight loss, are of marginal additional benefit but well-being but has a limited impact on weight. Adequate are associated with a marked increase in the incidence of leisure time with family and friends and sensible working side effects.15 hours and structure are priorities. Combinations of drugs acting through different More than two thirds of western populations are physiological mechanisms are increasingly used in complex overweight or obese. Obesity is associated with fatigue and chronic diseases like hypertension, type 2 diabetes mellitus daytime somnolence.6 There are complex relationships of and rheumatoid arthritis. Additive efficacy enables lowering obesity with anxiety and mood disorders.7 Weight reduction individual drug doses, with the dividend of fewer side effects, thereby may improve these and quality of life. which are usually not additive. These are the principles of polypill16 pharmacotherapy and multi-centre trials have Weight reduction with bariatric surgery can lower mortality begun to confirm clinical utility. 40%.8 The almost 60% reduction in coronary mortality is due to the greater than 60% reductions in hyperlipidaemia, Regular medical surveillance, precision diagnostics, hypertension, type 2 diabetes and obstructive sleep apnoea.9 healthy lifestyle, tactical nutrition supplements and strategic Cancer mortality was reduced almost 60%.8 Weight loss by pharmacotherapy are all priorities for optimal long term dietary discretion should confer pro rata benefits. Statistical health and well-being. modelling from published trials data suggests that as little as 1 kg weight loss is associated with a 3-5% reduction in REFERENCES coronary risk in high risk individuals. Pharmacotherapy may facilitate weight loss. 1 Editorial. Tackling the burden of chronic diseases in the USA. Lancet 2008;373:185. There is abundant evidence for benefits from ω-3 marine oil supplements, probably because most of us normally 2 Haslam DW, James WPT. Obesity. Lancet 2005;366:1197-209. consume insufficient fish. There is robust evidence that ω-3 marine oil supplementation reduces blood pressure, 3 Healy B, Freedman A. ABC of wound healig. Infections Br Med J thrombotic events10 and depression.11 2006;332:838-41. It may be prudent for many to take a comprehensive 4 Spahr A, Klein E, Khuseeyinova N, et al. Periodontal infections and vitamin and mineral supplement to make up for incidental coronary heart disease. Arch Intern Med 2006;166:554-9. unanticipated dietary deficiencies. This is clinically warranted during weight loss programs, pregnancy and 5 Edelma E, Eng C. A practical guide to interprestation and clinical in rehabilitating alcoholics but is likely to have broader application of personal genomic sceening. Br Med J 2009;339:1136-40. applicability, especially with chronic disease. 6 Vgontzas AN, Bixler EO, Tan T-L, Kantner D, Martin LF, Kales A. Long-term pharmacotherapy has been shown in Obesity without sleep apnoea is associated with daytime sleepiness. Arch hypertension to consistently reduce cardiovascular diseases, Intern Med 1998;158:1333-7. so called primary prevention. There is an increasing role for long term drug therapy in the management of established 7 Atlantis E, Goldney RD, Wittert GA. Obesity and depression or anxiety. chronic diseases, so called secondary prevention. Indications Br Med J 2009;339:871-2. supported by extensive clinical trials work include warfarin following venous thrombo-embolism, statin cholesterol- 8 Adams TD, Gress RE, Smith SC, et al. Long-term mortality after lowering drugs in atheroma, anti-platelet drugs in arterial gastric bypass surgery. N Engl J Med 2007;357:753-61. diseases, immune suppression in auto-immune diseases like rheumatoid arthritis and spondylo-arthropathies and 9 Buchwald H, Avidor Y, Braunwald E, et al. Bariatric surgery. A remission-maintaining hormonal and cytotoxic treatments systematic review and meta-analysis. JAMA 2004;292:1724- 37. in malignant diseases. Net benefits of long term drug treatment in appropriately selected patients are unequivocal. 10 Kris-Etherton PM, Harris WS, Appel LJ. Fish consumption, fish oil, These trials have provided a basis for calculation of cost- omega-3 fatty acids, and cardiovascular disease. Arterioscler Thromb Vasc effectiveness. Multi-national clinical guidelines increasingly Biol 2003;23:e20-30. reflect published data rather than simply committee consensus. 11 Parker G, Gibson NA, Brotchie H, Heruc G, Rees A-M, Hadzi-Pavlovic D. Omega l-3 fatty acids and mood disorders. Am J Psych 2006;163:969-78. Drug therapy carries the risk of side effects and adverse drug reactions. These may at the least reduce quality of life 12 Campbell CL, Smyth S, Montelescot G, Steinhubl SR. Aspirin dose for and at worst may threaten life. Most drug effects are dose- the prevention of cardiovascular disease. JAMA 2007;297:2018-24. related and some research is now focussed on establishing least necessary dose. Aspirin is now routinely recommended 13 Psaty BM, Smith NL, Siscovick DS, et al. Health outcomes associated as an antithrombotic in arterial disease at 75 mg daily,12 with antihypertensive therapies used as first-line agents. A systematic having been formerly employed at doses of over 600 mg review and meta-analysis. JAMA 1997; 277:739-45. 14 Rathore SS, Curtis JP, Wang Y, Bristow MR, Krumholz HM. Association of serum digoxin concentration and outcomes in patients with heart failure. JAMA 2003; 289: 871-8. 15 Dimmitt SB, Stampfer HG. Low drug doses may improve outcomes in chronic disease. Med J Aust 2009;191:511-3. 16 Law MR, Wald NJ, Morris JK, Jordan RE. Value of low dose combination treatment with blood pressure lowering drugs: analysis of 354 randomised trials. Br Med J 2003;326:1427-34. Address for correspondence School of Medicine and Pharmacology University of Western Australia Suite 304, 25 McCourt Street Subiaco Western Australia 6008 [email protected]
Ann Roy Australas Coll Dent Surg 2010;20:66-70 IT AND SECURITY CONSIDERATIONS FOR ONLINE CLINICAL RECORDS Patricia A.H. Williams, BSc (Hons), M Comp Sc, Grad Cert Ed, PhD Dr Trish Williams is Senior Lecturer in the SECAU Security Research Centre and School of Computer and Security Science at Edith Cowan University in Western Australia. ABSTRACT E-health and the national electronic medical record are on our doorstep. As an integral part of the healthcare system, dentistry needs to get on board with this national initiative. How prepared is the dental profession for this? How can a culture of online clinical records be promoted and what protocols and infrastructure exist for this to occur? The lack of government restriction means that dentistry should be taking full advantage of what is possible. The benefits and barriers to adoption of online records will be presented to provide a frame of reference for the next major shift in electronic communication. INTRODUCTION patient records, with test results and radiography available at the point of care. Thus an integration of multiple sources of The increasing use of information systems and networks, patient and support information and guidelines is required. together with converging technologies, has created a radical In addition, such integration will better inform patients about shift in how we access and use information. Information is their own health information. From a national perspective now a resource and our dependence on it is unmistakable. understanding the aggregation of data is essential to support Access is through fixed, wireless and mobile technologies, the society in which we live. This includes aspects from and our interconnectedness via the Internet surpasses national assessing health care system costs to inform policy making, and international boundaries. Importantly, it supports our to the national security issues of bioterrorism detection critical infrastructure, functions and services. There is little which relies on the aggregation of data in real time.3 argument that information systems can garner significant cost savings and strategic advantage for any information Increasingly all health practitioners are being encouraged dependent organization. This cost saving is principally in to use information technology to make their businesses the timely delivery and storage of information for legitimate more efficient and accountable. This impetus for adoption purposes or use by the organization. It creates an opportunity of information technology comes from several vectors. for great benefits in sharing information. Unfortunately, it Primarily this comes from Government to meet national also creates vulnerabilities by increasing exposure to security policy and regulation. The goal of which is a comprehensive threats. To keep up we need to develop new ways of using patient health record. The secondary driver is closer to home the technologies and new ways of thinking and interacting such as health practice administrators and managers to with the technologies.1 It has and will continue to change improve operational excellence and cost savings. our environment and the way we live and work. The result of this trend is that health providers are availing themselves The cornerstone of the e-health innovation in Australia of broadband technologies and information systems. Yet, is the Healthcare Identifiers Bill presented to the Australian healthcare adoption of these technical innovations has Federal Parliament in February 2010.4 This legislation sets moved slowly worldwide.2 In 2009 it was quoted that whilst the foundation for the integration of patient information medicine has only 10% electronic records, dentistry has a across primarily the public health system. In Australia mere 2%. the majority of dental services are privately funded regardless of dental insurance cover. Public services exist This paper aims to raise awareness of the possibilities that for concession card holders but are run by the State and the electronic environment and its associated technologies Territory governments and not federally.5 Unfortunately, the can bring. It includes the current drivers for change and the provision to include allied health, which includes dentistry, numerous benefits that dentistry can realize. Further, it raises is noticeable by its absence in the current e-health initiative. the issues the dental profession needs to be aware of in order The Australian Dental Association (ADA)6 highlighted the to create a frame of reference for understanding the changes issue of inclusivity in the e-health program which is based that have occurred and will occur in the future. on participation agreements by dental practitioners with an existing commonwealth recognized Health Provider NATIONAL E-HEALTH INITIATIVE Organization. Further, the AHA cites the issue of many dental practitioners still being paper-based, and therefore There is a need to establish a national health information non e-health prepared. This is potentially a major obstacle infrastructure to address both individual patient health and to the creation of a national e-health system without national health concerns. From the patient perspective government financial incentives for adoption and education. improving patient safety and health care quality through The general practice health practitioner cohort has been reducing errors, occurrences of interactions and allergies etc. provided with the Practice Incentive Program to modernize are highly desirable. This is only achieved through complete their practices by installing medical information systems and adopting electronic clinical records and e-prescribing.7 * Presented at the Twentieth Convocation of the Royal Australasian College It is inconceivable to have a national e-health record of Dental Surgeons, Perth, Western Australia. March 2010
PATRICIA WILLIAMS 67 without dentistry, as it would be deficient without pharmacy, richer computing environment, both visual and predictive. laboratory results and other branches of allied health care. At a patient level this is a potential that general medicine can only dream about. To date, the inclusion of visual So how does dentistry fit into this? There has been representations rather than true images has meant programs national and state condemnation of the quality of dental were of limited use. However, technical advances mean that record keeping. For instance, the Dental Board of Western the ability to image data will radically change the future Australia (2008)8 in its annual report cited poor record of digital charting. Another aspect of dental informatics is keeping as disappointing with the occurrence ranging from dental decision support, particularly for dental training. Such carelessness to incompetence. The majority of dental services systems can provide support which can use evidence based in Australia are not driven or overseen by the Government. approaches.11 The advancement of dental informatics will Currently, Medicare funding is only available for dental harness the benefits of electronic systems whilst exploring services to those with chronic conditions and complex care new opportunities. needs (with referral by the GP) capped over a two year period and some specifically funded programs such the Teen With dental informatics as a discipline base, it is important Dental Plan.9 Regardless of the position of the government to appreciate the wide range of benefits it can provide. of the day, the dental profession needs to take advantage of the positive impact that the electronic environment can have BENEFITS on the business capacity and the quality of patient care. There are many advantages in creating an electronic DENTAL INFORMATICS environment around dental practice. As Fig. 1 indicates this can be viewed as a continuum of the opportunities created The development and adaptation of technology into by technology. the dental arena needs to be both planned and appropriate. The term dental informatics (similar to medical and health The benefits are located across a spectrum from basic informatics) covers a myriad of facets of the use of computers to highly sophisticated, both in the types of technology and technology in healthcare. It is not solely about electronic employed and the benefits that these bring. charting and records: it is about electronic health records and decision making tools together with data analysis. The major At level A there are immediate benefits in electronic issue that this new discipline has to address is the adoption administration in single data collection points and of the technology and its integration into workflow.10 Like management of multiple sites. Billing and business programs many applications of computing, the initial road has been can result in improved control of cash flow. problematic with user issues being a major stumbling block.11 As is the case with medical informatics, dental informatics is At level B a reduction in overheads commences. This a technological venture with a scientific basis that is situated includes lower advertising costs by using email and text predominantly in the domain of informatics rather than in messaging, lower printing costs, appointments, recalls, clinical dentistry. Unfortunately too it is similarly, still, ill- missed appointments, electronic claims which also improve defined.12 cash flow and improve financial management. Arguably, the application of computing in dentistry is At level C we begin to see advances in both practice broader than electronic records. It is about applying scientific management and clinical capabilities. From a management development to medical and dental techniques which has perspective, the protection of information and data loss from always been complex. Yet in dentistry it has significant fire, theft and natural disaster can be minimized. Electronic potential in the use of artificial intelligence techniques in a records of all types reduce storage space, improve the security of records and facilitate multiple concurrent accesses. The question that needs to be at the forefront of decisions at this Fig.1. – Continuum of opportunities derived from technology
68 IT AND SECURITY CONSIDERATIONS FOR ONLINE CLINICAL RECORDS level is how much is your data worth to your practice and using dental records where dental records are illegible; what would be the impact of its temporary loss or permanent where there is a lack of adequate charting; lack of uniformity destuction? in charting; changes in dentition; where inadequate dental radiograph exist or through human error.19 Similarly after From a clinical perspective, automatic recalls and major disasters, such as Hurricane Katrina, where records improved proactive preventive services can be utilized. are destroyed, a national health database can benefit those Electronic records are reproducible, searchable, accessible, who are displaced. legible, can be sorted and allow single data entry for multiple uses e.g., clinical charting and financial management. Ultimately, the integration of patient clinical data, Paper records are usually written in chronological order, so charting, images and x-rays allows proper recording of recording information electronically can facilitate a more information and retrieval from the same user interface. logical format. Viewing of information in different formats We then have the technical knowledge and data to support such as chart, graphs, and colour coding is easily achieved advancements of dental techniques and procedures using the electronically, making the information more useful and easier accumulation of health information.20 Yet, whilst all these to access. Importantly, the general health status and health opportunities are possible there are also factors holding back information on a patient, particularly in complex cases, can the development and adoption of this electronic revolution. be automatically linked to medical references and associated support information. Lastly, it provides a complete and BARRIERS accurate record to support patient treatment and fulfils the legal documentation should it be required. The obstacles to the adoption and effective use of electronic records can be roughly categorized into privacy At level D the exciting opportunities begin. Digital issues, technical security and human factors. radiography and photography has significant cost and time savings in addition to the health benefits for the patient in Privacy and confidentiality concerns are regularly less radiation. It allows for instantaneous viewing of images raised as the predominant obstacles to the implementation with greater accuracy. It provides the ability to investigate of electronic solutions and to sharing information. This is further in real-time, thus providing for better and more a valid concern. However, with the appropriate security immediate diagnosis. It also facilitates remote consultations controls in place the benefits far outweigh the risks. Part which are a radical shift for the practice of dentistry.13 In of this equation is deciding the level of risk the practice is addition, since patient education is an important part of prepared live with. This is done inherently with the paper- dentistry using 3-D imagery can enhance motivation and based record as risks to privacy and confidentiality are the understanding by patients.14 Research into the content of same risks. The same laws apply: there are no separate laws dental records has revealed that more work needs to done for electronic information. on the specification and standardization of what is included in the dental records since this is not consistent in either Another key concern has been the safety and security the paper or electronic record.15 One often forgotten benefit of records, particularly in the event of a catastrophic event. at this level is that it is easier to have a proper protocol in Data protection has been an obstacle in adopting electronic place and for it to be followed consistently electronically, systems – yet this is essentially a myth. The choice of system as it allows for organization of apparent disorganized and to meet the needs and philosophy of the practice is important disparate information. and this requires planning. The protection that you afford the systems you put in place form part of this choice. In At level E the initiation of a World Wide Web presence reality the use of electronic records in which the appropriate significantly assists in advertising and patient services integration of systems, redundancy and storage is used makes location, as 60% of people look for people, business and such records more secure and more accessible.20-22 services via the Web. It also provides another avenue for advertising. Some of the more common technical security concerns include: At level F there is enhanced inter and intra-practice communication due to the integration of technology • Broadband connection which allows fast access and with work flow and this also makes remote consultations searching for information, yet the same facilities assist possible.16 unauthorized access to information for malicious purposes or financial gain; At level G there is unlimited potential! Educational opportunities proliferate with the use of electronic records • Traditional malware – viruses and worms; systems, particularly in the area of dental training.17 More importantly, the rapid advances in dental techniques and • Mobile devices such as flash technology (USB and thumb procedures come from the accumulation and analysis of drives, iPods, PDAs) which make it easier to copy and walk patient data, which is difficult to collate when in paper form. away with information and thus can be more easily stolen; Indeed large scale collection of data on the oral health of Australians is currently not possible.18 In addition to these • The potential for application flaws is real security threat as general areas, activities such as forensic identification using dental software is specialized and the developers’ main focus dental records (disaster victim identification) can be vastly is on functionality and not security. Such flaws may result improved. There are significant problems in identification in exploits that could allow escalation of privileges either within the database or the underlying operating system. The challenge between functionality and security is not new one and will continue to be a tussle for the foreseeable future;
PATRICIA WILLIAMS 69 • Insecure disposal of storage and back up media.23 The neither time nor resources to allocate to this task. Further, discipline of digital forensics allows for retrieval of data as technology becomes more commonplace and more from even wiped disks. If as researchers we can do this, so electronic health records are utilized, implementation of can the criminals; and the integrity of the information as even basic security measures can be problematic for those alteration of information appears to be easier and less easily whose core business is not security. detectable raises concern. Finally, a reactive obstacle is the transition from The human aspect is where most security fails. It is the paper to the electronic setting which is not necessarily a human facet of implementation and day to day security smooth transition; neither is it an automatic one. Change procedures that are at risk. This is not surprising since management should be carefully considered both from an security is not a dental practice‘s core business, but if we operational and workflow perspective as well as from the are to protect the electronic systems that we depend upon, human psychological viewpoint. Often the psychological it needs to be an essential element of routine activity. The barrier is to adopting a new method of doing a task rather successful introduction of technology, its integration into than the use of the technology itself. It is not necessarily a workflow, and realizing its benefits can be dependent more complex process that needs to be adopted but rather upon staff training – an oft ill-considered and unaddressed just a different way of doing things.25 component of technology acceptance.24 Ultimately the best protection, in conjunction with the Human threats come from both internal and external technical solutions, is the creation of a culture of security. sources. Internally these include practice staff and authorized The human element is still the real variable in the security third party service provider. Externally these range from equation. recreational hackers to organized criminal networks. The technical focus for many years has been on protecting a WHERE TO FROM HERE? network from the outside and the security controls available for this are robust. The use of firewalls and intrusion As e-heath advances, electronic health records will become detection systems are commonplace (although not always the standard for care, and may even become mandatory. This installed to their maximum protective capacity). There is demand will come from governments, insurance companies, no shortage of advice on the technical aspects of protecting and patients. The USA already has legislation for this to be electronic information. Yet the potentially most harmful in effect by 2015 and chartless records will not be a choice.13 security incidents can occur from within the practice by At present many computer applications are only at the “edge people who have legitimate access to information. Incidents of what is possible computationally”.11 Increased utilization may be accidental or malicious, but all types are potentially will have dental images and analytical tools as their basis. more harmful as authorized access raises less concern and What is needed is a longer term view, despite possible short incident alarm. The legitimate user is called the insider threat term costs. The most important reflection should be how the and is often less seriously considered particularly in trusting, electronic environment can help to improve the quality of health oriented environments.2 care for your patients in a more efficient manner. Electronic health records can provide greater protection and better use ‘Trust’ is an inherent characteristic of health service of patient information and thus improve the quality of patient providers; however. it also contributes to a more insecure care. environment. Research into a similar environment (Australian General Practice) indicates that the Embrace the opportunities presented to you in the implementation of security is poorly applied due to a lack networked age and do not be apprehensive. The advances and of knowledge and a complex working environment. The changes will happen with or without individual practitioner factors that contribute to ineffective information security are participation. Now is the time to make the mental shift and related to trust, capability, costs, time, lack of knowledge, come along for the journey. and attitude, together with deficiencies in knowledge of legal requirements, use of technology, and awareness of insecurity REFERENCES impacts. 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Dental key factors in healthcare and therefore require more specific Economics 2009;99:24-7. protection. Further, the general nature of standards means that the application of them to a specific context requires 4. Australian Government, eHealth: Healthcare Identifiers Service, http:// time and resources to develop. Typical health practices have www.health.gov.au/internet/main/publishing.nsf/Content/pacd-ehealth- consultation, 2010. 5. National Advisory Committee on Oral Health. Australia’s National Oral Health Plan 2004 - 2013. Australian Health Ministers’ Conference. 2004 6. Australian Dental Association, Submission to the Department of Health and Ageing on Healthcare identifiers and privacy: Discussion paper on proposals for legislative support, http://www.health.gov.au/internet/main/ publishing.nsf/Content/eHealth-038/$FILE/038_Australian%20Dental%20 Association_14-08-09.pdf, 2009.
70 IT AND SECURITY CONSIDERATIONS FOR ONLINE CLINICAL RECORDS 7. Medicare Australia. Practice Incentives Program (PIP), http://www. 19. Integrated Publishing. Dental Technical Volume 1 – Dentist training medicareaustralia.gov.au/provider/incentives/pip/index.jsp, Dec 2009. manual for military dentists. No date. 20. Kahn E, Benjamin S. Computerized charting and the electronic health 8. Dental Board of Western Australia. Annual Report. http://www. record. Dental Economics 2002;92:60-9. dentalboard.wa.gov.au 2008. 21. Alsobrook SC. Security in dental office computing. Dental Assistant Mar 2003;72:10-2, 14. 9. Dept of Health and Ageing. Dental Health: Dental services under 22. Williams PAH. When trust defies common security sense. Health Medicare, http://www.health.gov.au/internet/main/publishing.nsf/Content/ Informatics Journal 2008;14:211-21. Dental+Care+Services, Oct 2009. 23. Valli C. IT Sharps: Disposing of your IT medical waste. In: Arabnia HR, Aissi s, eds. Proceedings of the 2007 International Conference on 10. Koch S. Designing Clinically Useful Systems: Examples from Security & Management. USA: CSREA Press, 2007. Medicine and Dentistry. Journal of Dental Research: Dental Informatics & 24. Benjamin SD. The time for enhanced technology is now! Dental Dental Research 2003;17:65-68. Economics 2009;99:46-8. 25. Wagner I, Ireland R, Eaton K. Digital clinical records and 11. Reynolds PA, Harper J & Dunne S. Better informed in clinical practice administration in primary dental care. British Dental Journal practice – a brief overview of dental informatics. British Dental Journal Apr 2008;204:387-95. 2008;204:313-7. Address for correspondence: 12. Shahar Y. Medical informatics: between science and engineering, SECAU - Security Research Centre between academia and industry. Methods of Information In Medicine School of Computer and Security Science 2002;41,1: 8-11. Edith Cowan University 270 Joondalup Drive 13. Dykstra B. Are you sure? Dental Economics 2008;98:134-7. Joondalup Western Australia 6027 14. Crews M. Motivating Your Patients with Technology. Oral Health [email protected] 2008;98:59-60,62. 15. Schleyer T, Spallek H,Hernández PA. Qualitative Investigation of the Content of Dental Paper-based and Computer-based Patient Record Formats. Journal of the American Medical Informatics Association 2007;14:515-26. 16. Lowe E, Rego N. Modern technology for lab communications. Dental Economics 2009;99:81-2. 17. Atkinson JC, Zeller GG, Shah C. Electronic patient records for dental school clinics: more than paperless systems. J Dent Educ. May 2002;66:634- 642. 18. Spencer J, Harford J. Symposium: Is it Time for a Universal Dental Scheme in Australia?-Inequality in oral health in Australia. Australian Review of Public Affairs Oct 2007.
Ann Roy Australas Coll Dent Surg 2010;20:71-74 REPAIR OF CRITICAL SIZE DEFECTS IN THE RABBIT CALVARIUM WITH THE USE OF A NOVEL SCAFFOLD MATERIAL Jocelyn M Shand, MDSc, MBBS, BDS, FRACDS(OMS), FDSRCS* Andrew A Heggie, MBBS, MDSc, BDSc, FRACDS (OMS), FFDRCS, FACOMS Jason Portnof, DMD, MD Dr Shand is in private oral and maxillofacial practice in Melbourne and is a consultant in the Oral and Maxillofacial Section at the Royal Children’s Hospital of Melbourne. Dr Heggie is Head of the Oral and Maxillofacial Section at the Royal Children’s Hospital of Melbourne and Dr Portnof is a Research Fellow in the Unit. ABSTRACT A number of materials have been implanted into skull defects to determine if improved healing outcomes can be achieved. In some instances, packing or implanting bone-inducing alloplasts into a standardized skull defect results in better healing than an untreated defect. AlloDerm® is a skin derived acellular collagen membrane and has characteristics that are known to be effective in promoting bone growth. It has not been previously investigated for use in cranial bone healing. The aim of the investigation was to determine if implanting this novel scaffold into skull defects will improve the quality of bone repair. Six rabbits received AlloDerm grafts into critical-sized calvarial defects. The rabbits were sacrificed at two months and the specimens examined histologically and radiographically. At the time of sacrifice, it was found that while bony growth had commenced at the margins of the defect and as isolated islands within the graft, there did not appear to be a major benefit in using the material described. INTRODUCTION do not integrate well and do not remodel over time. Advances in the development of materials with osteoconductive The management of large bony defects in the skeleton is and osteoinductive properties have occurred but relative an ongoing challenge for the surgeon due to the volume and to autografts there are still disadvantages.9 Salyer and co- contour of the deficit requiring repair. This is of particular workers studied demineralized, perforated, allogeneic importance in the paediatric patient with craniofacial bone implants in craniofacial surgery with good results anomalies as the primary malformation is often complex and and concluded that the effectiveness and safety of bone must be addressed with a series of interventions spanning implants is largely determined by the type and quality of from infancy until adulthood. Skull defects may result processing. Seventy-two patients underwent grafting with from congenital conditions, such as cutis aplasia, and post- allogeneic grafts prepared with the protocol of the Pacific traumatic or post-surgical conditions and infection. Current Tissue Bank (Los Angeles, USA) and were followed for approaches for the reconstruction of bony defects include up to two years clinically with a good outcome.10 The same autogenous and vascularized grafts, allografts, alloplasts group published the results of cranioplasty in the canine and distraction techniques.1-4 Repair of large calvarial skull using demineralized perforated bone.11 They confirmed defects in young children poses a significant challenge due that demineralized perforated bone matrix implants were to the limitations of the autogenous bone volume available. well accepted into 10 x 15 mm calvarial defects with Calvarial bone cannot be readily split for reconstructive use little tissue reaction and minimal osteoclastic activity at until approximately 8 years of age. The treatment of hard three months post-implantation. This study suggested that tissue defects may add significantly to the costs of health demineralized bone matrix implants have an osteoinductive care worldwide due to the need for follow-up surgery in capacity and found no statistical significant difference in the many cases.5 outcome of the formation of new bone following insertion of demineralized perforated bone matrix implants of tibial Autogenous bone grafting remains the current gold donor site versus calvarial donor site origin. standard for the reconstruction of bony defects in the craniofacial skeleton. However, autogenous grafts can Shand and co-workers investigated the incorporation of be limited by the shape and volume of donor bone, donor fresh frozen irradiated (FFI) membranous allogeneic bone site morbidity, and the outcome may be compromised by grafts into critical-sized calvarial defects in the rabbit.12 unpredictable resorption and/or remodelling. A range of Radiographic, histological, and fluorescent microscopic materials of both synthetic and biological origin has been analysis of specimens revealed that FFI membranous grafts used in the reconstruction of skull defects.1-3,6-8 Traditional were well incorporated into rabbit calvarial defects. After biocompatible materials include hydroxyapatite bone 12 months revitalization of the entire graft was incomplete, substitutes and alloplasts such as porous polyethylene however, neovascularization, bone marrow regeneration, (Medpor)† and titanium mesh. While the biocompatible and new bone formation was evident throughout the materials generally provide greater structural support, they † Porex Corp., Georgia, USA * Presented at the Twentieth Convocation of the Royal Australasian College of Dental Surgeons, Perth, Western Australia. March 2010
72 REPAIR OF CRITICAL SIZE DEFECTS IN THE RABBIT CALVARIUM grafts. Ascherman et al. examined the use of quick-setting A hydroxyapatite (HA) cement‡ and absorbable plates§ in 10-mm-diameter cranial bone defects in rabbits.6 They B demonstrated growth of new bone into the HA cement was found along the periphery in all specimens at six months. Fig. 1 – A. Rabbit calvarium with dura exposed following removal of critical sized bone flap. B. AlloDerm graft positioned in the calvarial In another study calcium phosphate cement and osteotomy defect. autogenous calvarial graft was compared in 8-mm-diameter bone defects in rabbit calvaria.8 This group demonstrated removed from the dura and AlloDerm grafts were shaped that new bone formed in both groups and regeneration and placed into the defects and the wounds closed with 4/0 increased with time. However significantly more new vicryl sutures (Fig. 1B). Amoxycillin was administered for bone formed in the autogenous bone graft than formed in 5-days post-operatively. The rabbits were sacrificed at eight the calcium phosphate cement group. Calcium phosphate weeks using intravenous thiopentone. The calvarium was cement showed results at six weeks that presented similar to resected en bloc. Plain skull radiographs were taken at the autogenous bone at three weeks. time of surgery and at the time of sacrifice, together with computed tomography (CT) scans following sacrifice. The There has been a need to develop accessible, widely specimens were then divided into eight coronal sections applicable alternatives to the current bone replacement and examined radiographically and histologically. The strategies. Tissue engineering using stem cells, scaffolds specimens were decalcified, processed, embedded in paraffin and nutrients are under development but there is, as yet, no before sectioning and staining with haematoxylin-eosin suitable formula for predictable graft construction.5,13-15 and Masson’s trichrome. A point counting morphometry technique was used to estimate the relative volume of new A number of acellular dermal grafts with a regenerative bone within the grafts.22 tissue matrix have been developed. One of these,AlloDerm®,|| has been used for a range of procedures including abdominal RESULTS wall repair, breast reconstruction and other reconstructive All of the rabbits recovered following surgery. approaches.16 Studies have reported favourable outcomes in Macroscopically, there was no evidence of infection nor loss primary palate repair and in palatal fistula repair,17,18 A small of graft material. Plain radiographs and 3-dimensional CT number of recent papers has reported on the promising results with the use of AlloDerm in the reconstruction of bone defects including post-mastoidectomy wounds, periodontal alveolar defects, nasal deformities, and anterior and middle cranial fossa defects.19-21 AlloDerm consists of a dense network of extracellular matrix fibrils made up of collagens, elastin, fibronectin and a complex array of endogenous dermal proteins. AlloDerm has inductive properties due to stem cell populations that target the graft material, deposit in the graft and adhere to the matrix. These cells then differentiate into tissue specific cell types and a new matrix is formed in the graft material. While these reports are promising, the outcome of acellular dermal grafts in cranial defects has yet to be determined. It was the aim of this investigation to conduct a pilot study to evaluate the effect of AlloDerm on bone regeneration in critical-sized calvarial defects in the rabbit. METHODS AND MATERIALS The study was approved by the Ethics Committee of The Royal Children’s Hospital of Melbourne. Six adult New Zealand white rabbits (Oryctolagus cuniculus) were given an endotracheal general anaesthetic. The scalp was shaved, prepared with Betadine and infiltrated with local anaesthetic (bupivocaine HCl 0.5%, adrenaline 1:200,000) and a midline incision was made from the fronto-nasal to the occiptal regions, the pericranial tissues were elevated and the calvarium exposed and a critical sized defect outlined (Fig. 1A). A 15 mm circular osteotomy was performed with a surgical drill. The full thickness calvarial bone flaps were ‡ Mimix, Biomet Microfixation, Jacksonville, Florida, USA § Lactosorb, Biomet Microfixation, Jacksonville, Florida, USA || LifeCell Corporation, Branchburg, New Jersey, USA
JOCELYN SHAND, ANDREW HEGGIE, JASON PORTNOF 73 TABLE 1 Point counting morphometry results for each specimen Magnification Ratio Percentage (new bone/total bone area) 39% 26% X5 841/2142 29% X5 565/2142 28% X5 626/2142 23% X 10 593/2142 21% X 10 490/2142 X 10 459/2142 Fig. 2. – Dorso-ventral radiograph of calvarium at two months. The point counting morphometry technique demonstrated variable new bone formation within the grafts between 26 to Fig. 3. – CT scan of calvarium at two months demonstrating bone ingrowth 39%, with a mean of 31% (Table 1). at margins and islands of bone within the graft. DISCUSSION scanning demonstrated the deposition of new bone along the periphery and limited areas of osteoid within the graft site The reconstruction of skull defects has been investigated (Fig. 2, 3) for many years, yet the ideal graft or material has yet to be developed.23-25 In the authors’ pilot study, using acellular Histological examination revealed collagen fibres and dermal matrix, rabbits were sacrificed at two months after fibroblasts and some bony in-growth at the periphery of the graft placement. Pripatnanont and co-workers reported that defects and islands of osteoid within the AlloDerm. However rabbits are often utilized in calvarial bone regeneration this bone regeneration was partial (Fig. 4 A, B, C). The studies because rabbit physiological bone healing is similar osteoid formation within the grafts tended to be close to the to that of humans and the rate of healing is approximately dural surface or at the margins adjacent to the calvarial bone. three times that of humans. Hence, from a physiologically perspective eight weeks in the rabbit may be compared with six to eight months in humans.22 In a study using different proportions of autogenous bone (AB) and deproteinized bovine bone (DBB) (Bio- Oss, Geistlich pharma AG, Switzerland) to repair 10 x 10 mm calvarial defects in rabbits, new bone formation was assessed.22 It was determined through histomorphometric and radiographic analysis that autogenous bone chips presented more bone formation at eight weeks. However this was not statistically significant. It was also determined that the composite grafts in the proportion 1:2 (AB:DBB) generated significantly higher bone content than the 1:4 group. Biologic bone tissue engineering, including the use of recombinant human BMP-2 (bone morphogenetic protein), has expanded the field of bone reconstruction. BMP-2 is a purified, isolated osteogenic biomaterial that serves as a chemical messenger to induce bone formation. While demineralized bone matrix products theoretically inherently contain some BMPs, the synthetic, recombinant BMPs are A BC Fig. 4. – Histological examination of grafts after harvest. A Two month specimen demonstrating the AlloDerm graft and calvarial margin (Haematoxylin / eosin x 5). B AlloDerm graft at two months showing bone formation at the margins and islands of osteoid in the graft (Haematoxylin / eosin x 5). C AlloDerm graft and calvarial margin demonstrating bone ingrowth and bone regeneration within the graft (Masson’s trichrome x 5).
74 REPAIR OF CRITICAL SIZE DEFECTS IN THE RABBIT CALVARIUM provided in much higher concentrations. Por et al. described 8. Cavalcanti SC, Pereira CL, Mazzonetto R, de Moraes M, Moreira RW. the combination of recombinant human bone morphogenetic Histological and histomorphometric analyses of calcium phosphate cement protein 2 (rhBMP2) and struts of either metal or resorbable in rabbit calvaria. J Craniomaxillofac Surg 2008;36:354-9. plates.23 The results of this study confirmed that complete bony regeneration occurred in the rhBMP2 groups only. 9. Rose FR, Oreffo RO. Bone tissue engineering:Hope vs Hype. Biochem Biophys Res Commun 2002;22:292:1-7. The use of composite allogeneic and alloplastic bone substitutes including demineralized bone matrix (DBM) 10. Salyer KE, Gendler E, Menendez JL, Simon TR, Kelly KM, Bardach J. putty, calcium phosphate cement, and native partially Demineralized perforated bone implants in craniofacial surgery. J Craniofac purified bone morphogenetic protein (BMP) to close 15 mm Surg 1992;3:55-62 diameter parietal bone defects in rabbits was also studied.7 It was demonstrated that the unfilled (control) defects, defects 11. Salyer KE, Bardach J, Squier CA, Gendler E, Kelly KM. Cranioplasty covered with resorbable (LactoSorb) membrane, and those in the growing canine skull using demineralized perforated bone. Plast filled with calcium phosphate cement alone all healed with Reconstr Surg 1995;96:770-9. a fibrous scar. In contrast, defects reconstructed with DBM putty in combination with resorbable membrane and calcium 12. Shand JM, Heggie AAC, Holmes AD, Holmes W. Allogeneic bone phosphate in combination with BMP healed with bone grafting of calvarial defects:an experimental study in the rabbit. Int J Oral bridging the entire defect at 12 weeks. Maxillofac Surg 2002;31 :525-31. The present study recorded that acellular dermal grafts 13. Yu D, Li Q, Mu X, Chang T, Xiong Z. Bone regeneration of critical did not make an appreciable difference to bone healing over calvarial defect in goat model by PLGA/TCP/rhBMP-2 scaffolds prepared the experimental period, but research is ongoing by many by low-temperature rapid-prototyping technology. Int J Oral Maxillofac groups worldwide to promote bone growth and repair. The Surg 2008;37:929-34. era of transplantation of autogenous tissues to skeletal defects is likely to be replaced by tissue regeneration techniques in 14. Greenwald JA, Mehrara BJ, Spector JA, Warren SM, Fagenholz PJ, the near future. Smith LE, Bouletreau PJ, Crisera FE, Ueno H, Longaker MT. In vivo modulation of FGF biological activity alters cranial suture fate. Am J Pathol CONCLUSION 2001;158 :441-52. In this pilot study examining acellular dermal grafts within 15. Mooney MP, Losken HW, Moursi AM, Shand JM, Cooper GM, Curry calvarial defects and utilizing 3D computed tomography, C, Ho L, Burrows AM, Stelnicki EJ, Losee JE, Opperman LA, Siegel plain radiographs and histological examination new bone MI. Postoperative anti-Tgf-beta2 antibody therapy improves intracranial was evident at the graft-calvarial margin and within the volume and craniofacial growth in craniosynostotic rabbits. J Craniofac implanted AlloDerm graft. In conclusion, within AlloDerm Surg 2007;18:336-46. grafts in critical sized calvarial defects bone regeneration was demonstrated at eight weeks but was limited. 16. Eppley BL. Experimental assessment of the revascularization of acellular human dermis for soft-tissue augmentation. Plast Reconstr Surg ACKNOWLEDGMENTS 2001;107:757-62. The authors would like to thank the Australia and New 17. Steele MH, Seagle MB. Palatal fistula repair using acellular dermal Zealand Association of Oral and Maxillofacial Surgeons matrix:the University of Florida experience. Ann Plast Surg 2006;56:50-3. Education and Research Foundation and the Melbourne Research Unit for Facial Disorders, University of Melbourne, 18. Clark JM, Saffold SH. Decellularised dermal grafting in cleft palate for their support. Dr. Portnof was also supported by the repair. Arch Facial Plast Surg 2003;5:40-4. Stryker ANZAOMS Fellowship at the Royal Children’s Hospital of Melbourne. 19. Weber PC et al. Use of AlloDerm in the neurotologic setting. Am J Otolaryngol 2002;23:148 - 52. REFERENCES 20. Caffesse RG et al. Regeneration of hard and soft tissue periodontal 1. Clark JM, Saffold SH, Israel JM. Decellularized dermal grafting in cleft defects. Am J Dent 2002;15:339-45. palate repair. Arch Facial Plast Surg 2003;5:40-4. 21. Lorenz RR et al. Endoscopic reconstruction of anterior and middle 2. Eppley BL, Pietrzak WS, Blanton MW. Allograft and alloplastic bone cranial fossa defects using acellular dermal grafts. Layngoscope substitutes:a review of science and technology for the craniomaxillofacial 2003;113:496-501. surgeon. J Craniofac Surg 2005;16:981-9. 22. Pripatnanont P, Nuntanaranont T, Vongvatcharanon S. Proportion of 3. Kao ST, Scott DD. A review of bone substitutes. Oral Maxillofac Surg deproteinized bovine bone and autogenous bone affects bone formation Clin N Am 2007;19:513-21. in the treatment of calvarial defects in rabbits. Int J Oral Maxillofac Surg 2009;38:356-62. 4. Shand JM, Heggie AA. The use of bone grafts and substitutes in the craniomaxillofacial region. Ann R Australas Coll Dent Surg 1998;14:125- 23. Por YC, Barceló CR, Salyer KE, Genecov DG, Troxel K, Gendler E, 30. Elsalanty ME, Opperman LA. Bone generation in the reconstruction of a critical size calvarial defect in an experimental model. J Craniofac Surg 5. Snowden CB, Miller TR, Jensen AF, Lawrence BA. Costs of medically 2008;19:383-92. treated craniofacial conditions. Public Health Rep 2003;118:10-7. 24. Jensen J, Kragshov J, Wenzel A, Sindet-Pedersen S. In vitro analysis 6. Ascherman JA, Foo R, Nanda D, Parisien M. Reconstruction of cranial of the accuracy of subtraction radiography and computed tomography bone defects using a quick-setting hydroxyapatite cement and absorbable scanning for determination of bone graft volume. J Oral Maxillofac Surg plates. J Craniofac Surg 2008;19 :1131-5. 1998;56:743-8. 7. Haddad AJ, Peel SA, Clokie CM, Sándor GK. Closure of rabbit 25. Hopper RA, Zhang JR, Fourasier VL, Morova-Protzner I, Protzner calvarial critical-sized defects using protective composite allogeneic and KF, Pang CY, Forrest CR. Effect of isolation of periosteum and dura on alloplastic bone substitutes. J Craniofac Surg 2006;17:926-34. the healing of rabbit calvarial inlay bone grafts. Plast Reconstr Surg. 2001;107:454-62. Address for correspondence: Oral and Maxillofacial Surgery Unit Department of Plastic and Maxillofacial Surgery, The Royal Children’s Hospital, Flemington Road, Parkville, Melbourne, Victoria 3052,
Ann Roy Australas Coll Dent Surg 2010;20:75-78 UNDERSTANDING ADHESIVE DENTISTRY Michael Burrow BDS, MDS, PhD, MEd, FICD* Michael Burrow is Professor in Restorative Dentistry and Clinical Dean at the Melbourne Dental School of the University of Melbourne. ABSTRACT This review paper firstly provides an outline of the development of resin-based adhesives. A simple classification method is described based on whether an acid etching agent requiring a washing and drying step is used. These systems are called etch and rinse systems. The other adhesives that do not have the washing and drying steps are referred to as self-etching adhesives. The advantages and disadvantages of these groups of adhesives are discussed. Methods of adhering to the tooth surface are provided, especially where the resin-based adhesive reliability is difficult to control. INTRODUCTION the introduction of Bis-glycidyl dimethacrylate (Bis- GMA) by Bowen in 1962, which revolutionized the tooth- The surgical treatment of dental caries and restoration coloured restorations. This resin remains one of the common replacement remains a major part of the time to treat patients matrix resin components for current resin composite filling in any modern dental practice. Philosophically, it has been materials. a long-standing aim for all of us to retain as much tooth structure as possible. Even in the times of GV Black, one of About the same time as Bowen developed Bis-GMA, his treatment tenets was to retain tooth structure. In recent Masuhara was investigating the use of tri-n-butyl borane times, the introduction of Minimal Intervention or Minimally (TBB) as a co-catalyst to facilitate bonding to dentine. Invasive Dentistry (MID) has moved the philosophy the next This system was incorporated into the product marketed as step along to avoid surgical treatment of caries lesions or at Palakav.‡ Work continued on researching various materials least to keep cavity preparations as small as possible. in an attempt to form a stable bond and one strong enough to hold a restoration in place as well as to counteract forces MID has been achieved due to the development of from polymerization shrinkage. adhesive restorative materials. The two broad groups of adhesives are the resin-based materials and polyalkenoate In 1965, Bowen introduced N-phenyl-glycine and acid-based cements. This paper will concentrate on the resin- glycidyl methacrylate (NPG-GMA) used in Cervident, but based materials. the clinical ‘success’ was short-lived.4 It was not until 1979 when Fusayama and his group published the paper ‘Non- A BRIEF HISTORY pressure adhesion of a new adhesive restorative resin’ in the Journal of Dental Research that a new era of adhesive The quest to develop a resin-based adhesive is not new. dentistry commenced.5 This work was criticized due the use Buonocore is a name synonymous with the development of phosphoric acid on the dentine, which was believed at that of the acid-etch technique in 1955 with the classic paper time to cause damage to the pulp (Fig.1). titled ‘A simple method of increasing the adhesion of acrylic filling materials to enamel surfaces’.1 However, the work At about the same time Nakabayashi published his 1982 of Oskar Haggar predates Buonocore’s work when, in 1949, paper describing the layer forming a new type of dentine he developed a glycerolphosphoric acid dimethacrylate that was made up of dentinal collagen and resin from the adhesive, Sevriton Cavity Seal,† an adhesive intended for TBB, 4-methacryloyloxyethyl trimellitic acid anhydride use with Sevriton filling material. This material is, in part, a (4-META), polymethylmethacrylate-based adhesive, Super precursor to the modern day phosphate ester type adhesives. Bond.||This became to be known as the ‘Hybrid Layer‘ and Although not well known, Kramer and McClean identified, has been the subject of intensive research that continues even using light microscopy, the penetration of this adhesive into now. the surface of dentine.2 It could be said this was the first time a hybrid layer was identified and predates Nakabayashi’s At about the same time Nakabayashi published his work landmark paper of 19823 by 30 years. However, the first in English, 3M introduced the first version of Scotchbond§ attempts at bonding to dentine were not successful. It took to Australia. Scotchbond was a two-part adhesive mixed another 20 or so years before researchers again revisited then placed on the cavity surface which yhen penetrated the idea of attempting to bond to dentine using resin- the dentine smear layer forming a weak bond after enamel based materials. During this period however, the acid-etch etching. Acid etching of the dentine remained contentious technique for bonding to enamel became well established for even up to the early 1990s. During this time the explosion anterior tooth-coloured restorations. of dentine bonding systems began with such systems as The next step forward in resin-based restorations was † De Trey/Amalgamated Dental, UK. ‡ Kulzer GmbH, Germany * Presented at the Twentieth Convocation of the Royal Australasian College || Sun Medical, Japan of Dental Surgeons, Perth, Western Australia. March 2010 § 3M, MN, USA
76 UNDERSTANDING ADHESIVE DENTISTRY Fig. 1. – Phosphoric acid-etched dentine surface showing the collagen fibre TYPES OF ADHESIVE SYSTEMS network remaining after the hydroxyapatite has been lost. It is this layer that must be infiltrated by resin to form a good hybrid layer. Resin-based adhesive systems can be divided into two broad groups. The first type of adhesive is one that uses an GLUMA¶ which used glutaraldehyde and 2- hydroxyethyl etching agent such as phosphoric acid on the enamel and methacrylate (HEMA) to bond to dentine in conjunction dentine surface and is rinsed off with an air-water spray. with the mild etching of EDTA. This system showed some These systems are called ‘etch-and-rinse’ systems. The other promise clinically. The use of HEMA in adhesive systems broad group of systems that do not have a rinse step can be from this point became virtually universal due to its ability called ‘self-etch systems’. Within these two broad groups to bond in a moist environment such as cut dentine due to its the adhesives can further subdivided by the number of steps hydrophilic nature. used to complete the adhesion process. The time of greatest advance in dentine bonding came Etch and rinse systems: during the 1990s. Dentine etching methods were changed with the introduction of maleic acid or weaker concentrations Three-step – these systems use a separate etch, priming of phosphoric acid, the introduction of various priming agent and resin adhesive. The priming agent is usually a agents, and later the combination of the priming agents and solution of HEMA in a solvent such as water, ethanol or adhesives. However, the weaker acid etch based systems did acetone. Its purpose is to make the etched dentine surface not last long due to the etched enamel surface being quite more receptive to the application of the hydrophobic bonding difficult to detect and thus lost popularity with practitioners. resin, which is the third step. At the same time, Kanca described the wet bonding technique, which changed the way bonding was approached, Two-step - these systems have a separate etch and then although it failed to simplify the bonding method.6 the priming and bonding steps are combined into a single procedure. These systems require the use of the very In 1993, the concept of using an acidic resin to etch technique sensitive ‘wet bonding’ method. Most of these the enamel and dentine surface was introduced in Japan by systems have a volatile solvent of either ethanol or acetone the Kuraray Company. This concept has now been widely to aid diffusion of the primer-adhesive solution into the adopted by manufacturers as an alternative method to the etched dentine surface. traditional use of phosphoric acid to etch the enamel and dentine simultaneously. This method has now been extended Self-etch systems: to the point where manufacturers have combined all of the tooth surface treatment steps into one to achieve adhesive to Two-step – these systems have an etch and priming step enamel and dentine. Unfortunately, the rapid succession of where an acidic resin solubilizes the smear layer and etches new adhesives and techniques has led to most practitioners the underlying enamel and dentine while it simultaneously either being confused or unsure of which is the ‘best’ resin- primes the tooth surface in readiness for the adhesive. The based adhesive to use clinically. excess self-etching primer is blown off and with this much of the dissolved smear layer is also blown out of the cavity. The To answer this question it is necessary to take a step adhesive is then applied and usually air-thinned. back and analyse what occurs when various adhesives interact with the tooth surface. The concept of generations One-step – this group is the newest and simplest of of adhesives has also served to confuse practitioners even the resin-based adhesive systems. The etch, prime and further as there is not a true chronology of the so-called adhesion steps are combined into a single process. These generations of adhesives as they have been developed. The systems are either two-bottle or one-bottle solutions. The simplest way of classifying resin-based adhesives is to follow smear layer is again solubilized but remains on the tooth the classification proposed by Van Meerbeek’s group.7 surface. These systems often contain more water than other adhesive systems; this is to help maintain the low pH needed ¶ Bayer Dental, Germany for etching the tooth surface. However, a drawback is the ‘all-in-one’ adhesives can dissociate more easily as well as incorporating of water into the bond layer. Each of the two broad groups of resin-based bonding systems have advantages and disadvantages in their use. The etch and rinse systems have been available for the longest period of time and current clinical evidence indicates the three-step etch and rinse systems show reliable long-term results.8 The disadvantage of these systems is that the stripping of almost all the hydroxyapatite from the dentinal collagen means that complete envelopment of the collagen fibrils is almost impossible and will then create a location for the bond to deteriorate over time. When the hydroxyapatite is completely removed from the dentine surface, the remaining collagen fibre network tends to collapse and shrink after the washing and drying step. With the 3-step systems, the primer, presumably due to its very low viscosity and ability to wet the collagen fibre network is able to infiltrate the
MICHAEL BURROW 77 Fig. 2. – Phosphoric acid etched enamel – note the typical etch pattern. the non-fluoridated tooth enamel did bond more strongly.10 However, there was no difference in the dentine bond Fig. 3. – Enamel surface etched with SE Primer (Kuraray). The surface of strengths. For the scenario where enamel is either uncut the enamel is not as clearly etched as with the phosphoric acid. However, the and retains the fluoride rich layer, or enamel is the major surface is roughened, but the current thinking is that a chemical bond is also source of retention e.g., resin veneer, then phosphoric acid established with this surface. etching of the enamel should eliminate this problem. Clinical evidence is showing that the 2-step self etch systems are collapsed collagen, restore its shape to almost the original performing well and little different from the 3-step etch and form allowing penetration of the adhesive in the third step rinse systems.9 The evidence for the 1-step self etch systems of the bonding process. This same bonding process is more is still limited, although promising outcomes are slowly difficult for the 2-step etch and rinse materials. Hence the appearing for this group of adhesives.11,12 A point of note is need for the ‘wet bonding’ technique that is achieved by that some of the new 1-step self etch systems are marketed leaving water between the collagen fibrils after the etching, as a single bottle solutions. These systems seem to dissociate washing and drying steps. The tooth surface has to be left more easily after being applied to the tooth surface. To with enough moisture such that collagen fibril shrinkage avoid this, it is essential to follow exactly the application does not occur. However, the method is extremely difficult time recommended by the manufacturer and only dispense to consistently achieve, therefore the technique sensitivity of the adhesive immediately prior to application to the tooth this bonding method is very high and consistent bonding is surface to prevent evaporation of the solvent. difficult to achieve. The bonding mechanism of most systems, either etch The self-etch systems have been shown to be less and rinse or self etch systems has been shown to be micro- technique sensitive than the etch and rinse systems.9 mechanical with the bond enveloping collagen fibres and This was shown when novices in bonding were able to hydroxyapatite crystals to form a hybrid layer. However, achieve outcomes in a laboratory bond test not dissimilar recent evidence by Yoshida and his co-workers has shown to experienced researchers. However, questions have been that monomers such as 10-MDP and 4-META are able to raised about the ability of the systems that use a milder pH form a salt with hydroxyapatite.13,14 The work has shown, self-etching solution (around pH 2) to adequately etch enamel in the case of 10-MDP, that a relatively insoluble salt can that has developed in a fluoridated water supply environment. be formed with hydroxyapatite. However, in the case of (Fig. 2 and 3) A comparison of teeth that developed in either 4-META, the salt is soluble. Nevertheless, this evidence a fluoridated or non-fluoridated environment showed that is a clue as to why some of the self etch adhesive systems that contain these monomers show good bond strengths even though the hybrid is much thinner than the etch and rinse systems. These systems are also showing good clinical durability, again supposedly due to the chemical adhesion to tooth structure. The clinical study over 10 years using Clearfil SE Bond** by Akimoto has shown excellent outcomes.15 It is possible other monomers can also achieve a chemical bond, but evidence of this is still lacking. When bonding to tooth structure it is not a ‘one method fits all’ situation, this is perhaps the greatest misconception by practitioners. The adhesion of different systems, be they etch and rinse or self etch will vary depending on the location of the tooth because the deeper the dentine in the cavity, the greater its surface wetness. The etching process removes smear plugs producing an inherently wetter surface, therefore those systems that do not bond well in a wetter environment should not be used. In this case, systems that do not disrupt the smear plugs are likely to be more reliable on deep dentine. When unsure of the bond reliability of a resin-based adhesive, then a glass ionomer lining is a sound alternative since these materials will adhere to ‘wet’ dentine. Bonding to caries-affected dentine is a contentious issue (Fig. 4 and 5). It is known that the caries-affected dentine is less permeable to fluid movement along the dentinal tubules due to occlusion with whitlockite crystals.16,17 However, caries affected dentine is also inherently wetter and contains slightly less hydroxyapatite. Bonding to this substrate is **Kuraray, Japan
78 UNDERSTANDING ADHESIVE DENTISTRY Fig. 4. – ‘Normal’ dentine surface after etching with phosphoric acid. Note the porosities on the surface that must be infiltrated by resin to form a bond.. Fig. 5. – Acid etched dentine surface after caries removal with Carisolv® Fig. 6. – Top – prepared enamel and dentine surface. Middle - Enamel/ leaving the affected dentine in place. Note the difference in appearance dentine surface where the self etching primer has not worked correctly on compared with normal dentine. The depth of demineralization is greater and the dentine. Lower – note the patch appearance of the dentine indicating the fibre network more open. This tissue is inherently wetter thus making the self-etching primer should be re-applied. bonding a little more technique sensitive. possibly more of a problem for the etch and rinse systems as the etching process tends to remove a greater amount of hydroxyapatite crystals, and to a greater depth, than ‘normal’ dentine. This therefore makes adhesive resin infiltration more difficult to achieve. The alternatives are either a self etch system or glass ionomer cement. In the case of restoring a carious proximal cavity, the next question that should be asked in the clinical decision process is where is the proximal margin located? A proximal cavity where the gingival margin of the proximal box approximates the gingival tissues or is as far down as root surface dentine, then bonding of resin based systems becomes much more unpredictable. The most reliable material of choice is a glass ionomer cement using the laminate method (sandwich technique). Ideally a conventional high strength glass ionomer cement should be placed to a thickness of approximately 2 mm along the gingival floor of the proximal box. Once set, the resin-based adhesive can be simply bonded to the GIC surface. The work by Zhang and others has shown that a good bond strength can be achieved with most self etch systems to conventional glass ionomer cements.18 The bond between the GIC and resin composite was marginally better for the self etch systems compared with the etch and rinse system. It is
MICHAEL BURROW 79 believed the etching, washing and drying steps for the etch 4. Bowen RL. Adhesive bonding of various materials to hard tooth tissues. and rinse adhesive caused enough crazing of the GIC surface II. Bonding to dentine promoted by a surface-active co-monomer. J Dent such that it was more likely to fail cohesively compared with Res 1965;44:895-902. the milder etching of the self etch systems tested. Should a GIC-resin laminate method be employed, it is essential to 5. Fusayama T, Nakamura M, Kurosaki N, Iwaku M. Non-pressure monitor the GIC base. If a patient’s oral hygiene is poor in adhesion of a new adhesive restorative resin. J Dent Res 1979;58:1364-70. this region there is the potential for dissolution of the GIC,19 which can be overcome by coating the GIC with either a 6. Kanca J3rd, Resin bonding to wet substrate. 1. Bonding to dentin proprietary coating or with the resin adhesive. Alternatively, Quintessence Int 1992;23:39-41. a resin-modified glass ionomer cement adhesive could be used to bond to a deep proximal cavity. The only problem 7. Van Meerbeek B, De Munck J, Yoshida Y, Inoue S, Vargas M, Vijay P here is the potential problems with the light curing of the et al., Buonocore memorial lecture: adhesion to enamel and dentin: current adhesive. status and future challeneges, Oper Dent 2003;28:215-35. Finally, one of the difficult aspects of resin adhesion 8. Peumans M, Kanumilli P, De Munck J, Van Landuyt K, Lambrechts is to know when the adhesive is working properly. Apart P, Van Meerbeek B. Clinical effectiveness of contemporary adhesives: a from following the application instructions, it is important systematic review of current clinical trials. Dent Mater 2005;21:864-81. to look for a change in appearance of the bonded surface. Usually a well bonded surface will have an ‘oily/glossy’ 9. Sano H, Kanemura N, Burrow MF, Inai N, Yamada T, Tagami J. Effect appearance on the dentine (Fig. 6). The only systems where of operator variability on dentin adhesion: students vs. dentists. Dent Mater this tends to vary are the single step self etch systems that J 1998;17:51-8. require very strong air blasting after application. The dentine surface after application of these systems tends to have a 10. Shida K, Kitasako Y, Burrow MF, Tagami J. Micro-shear bond strengths matt and occasionally tacky appearance. It is important to and etching efficacy of a two-step self-etching adhesive system to fluorosed use magnification to view the bonded surface. If the surface and non-fluorosed enamel. Eur J Oral Sci. 2009;117:182-6. change is not apparent, then reapplication of the either the self-etching primer in the 2-step or adhesive in the 1-step self 11. Kubo S, Yokota H, Yokota H, Hayashi Y Two-year clinical evaluation etch systems should occur. Similarly for the etch and rinse of one-step self-etch systems in non-carious cervical lesions. J Dent. systems, reapplication of the bond is possible before curing. 2009;37:149-55. This should improve the reliability of the bond. 12. Van Landuyt KL, Peumans M, Fieuws S, De Munck J, Cardoso MV, Adhesive dentistry allows us to conserve tooth structure Ermis RB, Lambrechts P, Van Meerbeek B. A randomized controlled clinical in a way never before possible. This will allow patients to trial of a HEMA-free all-in-one adhesive in non-carious cervical lesions at retain teeth for longer. But, adhesive dentistry has brought 1 year. J Dent. 2008;36:847-55. with it a new level of complexity that means practitioners must consider the benefits and disadvantages of the 13. Yoshida Y, Nakagane K, Fukuda R, Nakayama Y, Okazaki M, restoration placement process and be willing to modify Shintani H et al., Comparative study on adhesive performance of functional techniques as necessary. This is quite different from the monomers. J Dent Res 2004;83:454-8. almost ‘universal’ method that has been used for amalgam when restoring posterior teeth based around the outdated 14. Yoshida Y, Van Meerbeek B, Nakayama Y, Snauwaert J, Hellemans L, Black’s cavity form. Lambrechts P et al. Evidence of chemical bonding at biomaterial-hard tissue interfaces. J Dent Res 2000;79:709-14. REFERENCES 15. Akimoto N, Takamizu M, Momoi Y. 10-year clinical evaluation of a 1. Söderholm K-J, Dental Adhesives…How it all started and later evolved. self-etching adhesive system. Oper Dent 2007;32:3-10. J Adhesiv Dent 2007;9:231-40. 16. Tagami, J, Hosoda H, Burrow MF, Nakajima M. Effect of Aging and 2. Kramer IRH, McLean JW, The response of the human pulp to self- Caries on Dentin Permeability. Proceedings of the Finnish Dental Society, polymerising acrylic. Br Dent J 1952;93:150-3. 1992;88 (suppl 1):149-54. 3. Nakabayashi N, Kojima K, Masuhara E, The promotion of adhesion 17. Banomyong D, Palamara JE, Messer HH, Burrow MF. Fluid flow by the infiltration of monomers into tooth substrates. J Biomed Mater Res after resin-composite restoration in extracted carious teeth. Eur J Oral Sci 1982;16:265-73. 2009;117(3):334-42. 18. Zhang Y, Burrow MF and Palamara J. Bonding glass ionomer cements using resin-based adhesives. IADR ANZ Division, Pan Pacific Federation Meeting, Wuhan, China 2009. 19. Scholtanus JD, Huysmans MC. Clinical failure of class-II restorations of a highly viscous glass-ionomer material over a 6-year period: a retrospective study. J Dent 2007;35:156-62. Address for correspondence: Melbourne Dental School 720 Swanston Street Carlton Victoria 3010 [email protected]
Ann Roy Australas Coll Dent Surg 2010;20:80-81 THE MISSING LINK IN MINIMAL INTERVENTION DENTISTRY: EFFECTIVE CARIES CONTROL Hien Ngo, BDS, MDS, PhD* Professor Hien Ngo is Chair of the General Dental Practice discipline at the School of Dentistry at the University of Queensland. In the later part of the 19th century, there was no clear state. The microbial metabolic activity in a biofilm is distinction between carious process and the lesion, so the continuous and result in pH fluctuations. The earliest term caries was used to refer to the cavity which can be clinically visible outcome of this process is a white spot found on tooth surfaces. It was in this setting that Dr Miller lesion, which is formed on a tooth surface where a biofilm is (1890) introduced the chemo-parasitic theory of caries, allowed to stagnate over time and the pH fluctuation leads to which stated that caries only develops in the presence of a cumulative net loss of calcium and phosphate. acids which are produced by bacteria living mainly in saliva. It was one of his contemporary colleagues, Dr Black, who When this is not rectified over a long period of time, observed the association between the accumulation of plaque the biofilm is transformed and its composition and activity and the development of cavities, this is the first association will assume the pathological level as its new natural state. between dental biofilm and caries. This observation led to Therefore the ultimate clinical outcome, in the control of the universal acceptance of the extension for prevention caries, is changing the ecological balance to bring the dental principle, which required the extension of the boundaries of a biofilm back to its natural and healthy state. cavity preparation out to self cleansing areas. Until recently, there was no real appreciation of the evolutionary nature of This latest theory combined the key elements of the dental biofilm, its sophisticated structure and physiology and earlier two and it adds the patient to the caries equation. It is its important role in maintaining oral and general health. the patient who has control over the oral environment, which in turn has great influence on the biofilm. This theory can be It was not until Dr Keyes (1960) had completed his used to explain the clinical case of a patient who has a high series of experiments on germ free rodents that the role of number of mutans streptococci but does not develop caries fermentable carbohydrate was fully understood, the mutans lesions. Some of the possible reasons are: streptococci was identified as the most cariogenic group of bacteria and the transmissibility of caries from animal to The structure of the dental biofilm is such that saliva and animal was established. This work led to the specific plaque fluoride can easily penetrate and reach the tooth biofilm fluid hypothesis which was proposed by Dr Loesche (1986) and it interface. was then that the mutans stretoccoci and a very small number of other species were identified as the main pathogens. The The enamel chemistry makes it more acid resistance. attempts to develop vaccine and gene therapy were based on the belief that caries can be controlled by targeting those There is also an abundance of lactate consuming species. species. This concept is universally accepted and is still taught in many dental schools, even though there is now There are ammonia producing bacteria to neutralize considerable doubt about its validity. It is now accepted that acidity in biofilm fluid. the relationship between mutans streptococci and the caries process is weak. There are individuals who have a high Caries is a chronic, life style and biofilm associated count of mutans streptoccoci who do not go on to develop disease. Biofilms that colonize the oral cavity are highly caries lesions but more importantly, the reverse is also true, complex and their role in health and disease is now much where caries lesions can form in individuals who do not better understood. It can be argued that a biofilm, in adults, is have detectable levels of mutans streptococci. A high level unique to the individual because its composition and activity of mutans streptococci only reflects the breaking down of the are heavily influenced by nutritional and physical conditions homeostasis of the biofilm. Its validity as a diagnostic tool of the oral cavity and of different sites in the mouth. is being questioned so it should only be used to monitor the results of the prescribed treatment. Saliva plays a vital role in maintaining homeostasis in dental biofilms. Demineralization and remineralization The understanding of the caries process has changed a take place at the tooth-biofilm interface and can be great deal in recent years so this led to the development of heavily influence when healthy saliva gains access to this the ecological plaque hypothesis, which was proposed by interface. Healthy saliva is supersaturated with respect to Professor Marsh in 1994. It states that changes in the oral hydroxyapatite so it has a general protective effect; it is environment can drive the balance of the resident microflora, also a very effective buffer and can neutralize acidity in the creating a shift from its original healthy state to a pathogenic biofilm fluid. When the biofilm is allowed to grow too thick then the protective effect of saliva is diminished as it can’t * Presented at the Twentieth Convocation of the Royal Australasian College reach the interface. of Dental Surgeons, Perth, Western Australia. March 2010 As the understanding of the caries process has changed substantially, it is important to move from the simple Venn diagram (Fig. 1), which only illustrates the multi-factorial nature of the caries process, to a more clinically relevant model (Fig. 2).
HIEN NGO 81 Fig. 1. − The multifactorial nature of the caries process. This model illustrates clearly the primary factors which can significantly modify the metabolic cycle in the dental biofilm: Diet. Fluoride in the dental biofilm fluid. Fluoride strengthening effect on dental hard tissues. Saliva. It clearly identifies the three areas which dentists need to work on in attempting to control the caries process: Tooth: manage and repair any defects. Oral environment: changing the primary factors with the ultimate aim of reversing a cariogenic biofilm back to its healthy natural state. Educate and motivate the patient to gain cooperation and compliance in making changes to the primary factors. The dentist, therefore has three distinct roles to play. First, as a physician to diagnose and prescribe treatment. Second, as a counsellor to educate, motivate the patient and assist the patient in understanding and managing the caries process. Third, as a surgeon to manage and repair defects on tooth surfaces. Recognizing that the caries process had many similar features with a chronic and life style associated disease like diabetes, To conclude this article here is a quote from Sir William Osler (1849-1919) “a good physician treats the disease while a great physician treats the patient who has the disease”. Fig. 2. − Schematic illustration of the contributing factors of the caries Address for correspondence: process. 200 Turbot Street Brisbane Queensland The success of a treatment plan relies on patient Australia 4000 cooperation and that depends on the development of a good [email protected] understanding of the interaction among the contributing factors that lead to the acceleration of the carious process.
Ann Roy Australas Coll Dent Surg 2010;20:82-85 OSSEOINTEGRATION – THE INFLUENCE OF IMPLANT SURFACE Saso Ivanovski. BDSc, BDentSt, MDSc (Perio), PhD* Saso Ivanovski is Professor of Periodontology at the School of Dentistry and Oral Health, Griffith University, Gold Coast, Australia. ABSTRACT The modification of implant surfaces from the original machined to ‘micro-rough’, and more recently ‘bioactive’, surfaces has been proposed to improve clinical outcomes. This review outlines the evidence for the superior performance of modified implant surfaces. Pre-clinical trials consistently show that modified implant surfaces are more osteogenic and improve the degree of osseointegration. Clinically, there is a clear trend for improved clinical success with ‘micro-rough’ compared with machined implants. This is particularly the case in compromised sites, such as the posterior maxilla, and compromised patients, such as smokers. Furthermore, ‘micro-rough’ implant surfaces perform better in augmented sites, and facilitate the more predictable use of short implants, thus reducing the need for more invasive augmentation procedures. ‘Micro-rough’ implants have been associated with an increased susceptibility to peri-implantitis, but these findings relate to a surface that is no longer manufactured. Newly developed ‘bioactive’ surfaces have only been evaluated in a limited number of clinical studies. INTRODUCTION they have a small degree of roughness which is essential for osseointegration. Dental implants manufactured from titanium have become a well established treatment modality for the 2. Second generation ‘micro-rough’ surfaces with increased replacement of missing teeth. The clinical procedures using microscale roughness developed in the 1990s. These surfaces dental implants are well documented, with good long term are commonly referred to as being ‘rough’, although they success rates reported in healthy patients and in favourable vary in the degree of roughness between manufacturers. anatomical positions.1 However, with increased clinical use Common clinically utilized ‘micro-rough’ implants include: and greater acceptance and popularity of implants, there are greater demands placed on implant systems from both a. SLA (sand blasted, large grit, acid etched) surface.† clinicians and patients. In particular, there is demand for implant placement in sites where the quality and/or quantity b. Double acid etched (DAE) surface.‡ of bone is less than ideal due to either local or systemic factors. Furthermore, there is a demand for accelerating c. Titanium oxide (TiO2) blasted surface.§ the treatment process in order to obtain restoration in the d. Anodic oxidization of machined surface.|| quickest possible time. 3. Third generation ‘bioactive’ surfaces which aim to Due to these increasing demands, there are continuing actively promote bone deposition on the implant surface efforts to enhance the rate and amount of osseointegration. and hence further enhance osseointegration via nanoscale or One parameter which could influence the success rate of chemical modification of existing ‘micro-rough’ implants. implants is the alteration of the surface topography by These surfaces have identical microscale topography as their increasing the roughness of the implant surface. Indeed, predecessors and commonly used examples include: the use of microscale, and more recently nanoscale, modifications of implant surfaces has been proposed as a. Modified SLA surface. (SLAactive).† Chemical one of the key factors in increasing the clinical success modification of the SLA surface manufactured with the aim rate of implants, especially in areas of compromised bone of minimizing surface contamination and transported in quantity and quality. This review will explore the evidence saline in order to maintain the contaminant-free surface. that surface modification affects osseointegration. Emphasis will be placed on studies utilizing common commercially b. TiO2 blasted surface modified by the incorporation of available implant surfaces. fluoride ions.¶ COMMERCIALLY AVAILABLE IMPLANT c. Nanometer scale discrete crystalline deposition (DCD) CaP surface.** DAE surface modified by precipitation of SURFACES: CaP molecules aimed to achieve roughness at the nanoscale level. Commercially available implant surfaces can broadly be divided into three categories: PRE-CLINICAL STUDIES 1. First generation machined titanium surface representing In Vitro Cell Culture Studies the original dental implant surface developed in the 1960s by Professor P-I Brånemark. These implants are also known In vitro studies utilizing cell culture models have as turned or smooth surface implants, although in reality been useful in determining the effect of different implant * Presented at the Twentieth Convocation of the Royal Australasian College † Straumann, Switzerland. of Dental Surgeons, Perth, Western Australia. March 2010 ‡ Osseotite, Biomet 3i, USA. §TiOblast, AstraTech, Sweden. ||TiUnite, Nobel Biocare, Sweden. ¶ Osseospeed, AstraTech, Sweden. ** Nanotite, 3i Biomet, USA.
SASO IVANOVSKI 83 surfaces on cell function. In particular, the effect of surface implants, with implant success of up to 99% reported at 15 modification on osteoblast function has been extensively years follow up.1 However, poorer results were obtained in studied. It has been demonstrated that micro-roughness compromised sites (e.g., posterior maxilla) and patients (e.g., can enhance osteoblast function when compared with smokers). Anecdotal evidence suggests that the development machined implant surfaces.2 In response to smooth surfaces, of modified implant surfaces has coincided with several osteoblasts attach and proliferate, but exhibit relatively low significant developments in implant dentistry which may expression of differentiation markers, whereas, when grown be related to enhanced osseointegration, such as decreased on rough surfaces, osteoblast proliferation is reduced and healing times, improved success of augmentation procedures, differentiation is enhanced, leading to a microenvironment and increased success in compromised sites and patients. conducive to bone formation.2 It is noteworthy that there are a large number of studies which document the clinical performance of first generation New generation ‘bioactive’ implant surfaces have also machined and the various second generation ‘micro-rough’ been shown to further enhance osteoblast function compared implants, but there are relatively few studies which report on with ‘micro-rough’ surfaces. It has been shown that both the newly developed third generation ‘bioactive’ implants. the modified SLA and titanium oxide blasted surfaces can enhance osteoblast differentiation.3 Most clinical trials are either retrospective or prospective cohort studies, and there are few randomized controlled In Vivo Pre-clinical Trials clinical trials that directly compare the relative performance of different implant surfaces. In a systematic review of the Animal studies have shown that ‘micro-rough’ surface few available controlled randomized clinical trials, most of titanium implants results in superior bone to implant which involve a small numbers of patients, it has been shown contact compared with machined implants,4 as well as that there is a clear trend towards a higher risk for implant superior torque removal values.5 Histological analysis failure in implants with machined surfaces compared with of the sequential healing events associated with ‘micro- ‘micro-rough’ surface implants.12 rough’ surface titanium implants has shown that initial bone formation around these implants occurs not only at the In the absence of large randomized controlled clinical exposed bone wall of the surgically created implant recipient trials, a review of cohort studies incorporating large numbers site, as is the case with machined surface implants, but also of cases is necessary in order to ascertain the relative along the ‘osteophylic’ implant surface.6 Furthermore, it has performance of ‘micro-rough’ and machined implants. A been demonstrated that there is a higher level of organization recent review13 undertook a comprehensive assessment of in the wound and greater bone-implant contact during the 1- to 15-year survival rates of fixed implant rehabilitations early healing associated with ‘micro-rough’ compared with in the edentulous maxilla incorporating 32 studies, including machined surfaces.7 1,320 patients and 8,376 implants. Implants with micro- rough surfaces showed a statistically higher survival rate More recently, it has been demonstrated that nanoscale than machined implants at all intervals (1, 3, 5, 10 and 15 and chemical modifications of implant surfaces provide year time points). additional benefits in terms of ossiontegration, compared with ‘micro-rough’ surfaces. Indeed, surfaces with the same Short Implants ‘micro-scale’ topography, but with additional nanoscale modifications have been shown to promote superior It is well established that tooth loss leads to resorption osseointegration in vivo, as measured by increased bone- of the associated alveolar bone. This presents a clinical implant contact, especially during the early stages of challenge, especially in the posterior regions where healing. More specifically, it has been demonstrated that anatomical constraints in the form of the maxillary sinus and the chemically modified SLA surface promoted enhanced the inferior alveolar canal limit the height of bone available bone apposition during the early stages of osseointegration for implant placement. Although augmentation procedures compared with the SLA surface.8 Fluoride ion incorporation are available, it has been shown that vertical augnmentation into the TiO2 blasted surface has also been shown to is unpredicatable, and that implant survival is higher when improve bone-implant contact during the early phases of short implants are used then when vertical augmentation is oseeointegration,9 and result in enhanced removal torque utilized.14 Furthermore, the use of short implants also has values.10 Similarly, the nanoscale modified DAE surface has the advantage of lower patient morbidity and less technique also been show to result in improved bone-implant contact sensitivity than augmentation procedures. in human studies,11 and superior removal torque values in animal studies.10 Therefore, the relative clinical success of short implants with machined and ‘micro-rough’ surfaces is an important In general, second and third generation implant surfaces clinical consideration which has been studied in several appear to promote increased bone-implant contact, especially clinical trials. Feldman et al.15 compared a large number during the early stages of wound healing, thus suggesting of machined (2294) and ‘micro-rough’ DAE (2597) short that these implants would perform better than machined (10 mm or less) implants and found that the difference in implants, especially in compromised sites and patients. cumulative survival rates between short- and standard-length implants was greater for machined-surfaced implants than CLINICAL TRIALS for DAE implants. For DAE implants the overall difference in survival rates between standard and short implants was It is important to note that excellent long term results have 0.7%, which was not statistically significant. However, there been reported with the original first generation machined
84 OSSEOINTEGRATION – THE INFLUENCE OF IMPLANT SURFACE was a 2.2% difference in 5-year survival rates between the be noted that this meta-analysis was carried out on studies machined-surfaced short- and the standard-length implants. with relatively low numbers of participants and implants. For these implants, a 7.1% difference was observed in the Of particular note is a split-mouth study19 including 26 posterior maxilla and an 8.5% difference in the anterior patients in which peri-implantitis affected seven implants maxilla. These findings were supported by a another study in five patients, all having a rough titanium plasma sprayed which investigated 96 short (6-8.5 mm) implants placed in (TPS) surface and none of the contralateral implants with the posterior maxillas of 85 patients.16 The implants had a a machined surface. The implants with the TPS surface are machined (54) or a ‘micro-rough’ oxidized (42) surface and no longer commercially available, and an increased risk for were followed for two years. Of the five implants that failed, peri-implantitis has not been reported for currently available four had a machined surface, and one had an oxidized surface. ‘micro-rough’ implants. Therefore, there is clear evidence that short implants with a ‘micro-rough’ surface perform better than their machined In terms of treating peri-implantitis, the ultimate goal is counterparts, especially in compromised sites, such as the to regenerate the lost bone and achieve re-osseointegration to posterior maxilla. the previously contaminated implant surface. In this regard, better outcomes have been reported with ‘micro-rough’ Smoking compared with machined implant surfaces, although there is variability in the performance of different ‘micro-rough’ Smoking is recognized as a potential risk factor for implants.20 implant failure. Balshe et al.17 compared the long-term survival rates of machined (2182 implants in 593 patients) Third generation ‘bioactive’ surfaces and ‘micro-rough’ (2425 implants in 905 patients) surface implants among smokers and non-smokers. Among the It is important to note that the vast majority of clinical ‘micro-rough’ surface implants, smoking was not identified data showing an improved clinical performance associated as being associated with implant failure. In contrast, smoking with modified implant surfaces relates to the comparison was associated with implant failure among the group with of second generation ‘micro-rough’ and first generation machined surface implants (HR = 3.1; 95% CI = 1.6 to 5.9; machined implants, and there is little clinical evidence P < .001). Furthermore, implant anatomic location was not for additional clinical benefits of using third generation associated with implant survival among patients with ‘micro- ‘bioactive’ surfaces, which have only recently been rough’ surface implants and among non-smokers with introduced. Since these ‘bioactive’ surfaces are largely machined surface implants. However, anatomic location modifications of well-documented ‘micro-rough’ surfaces affected the implant survival among smokers with machined and their superiority has been demonstrated in pre-clinical surface implants (P = .004). In particular, implant survival trials, it may be assumed that they will have superior was the poorest for machined implants placed in posterior clinical performance. However, such assumptions should maxillary sites of smokers. be made with caution, and considering that ‘micro-rough’ surfaces perform well in most clinical scenarios, the use of Augmented sites new generation ‘bio-active’ implants should be evidence- based and take into account cost-benefit considerations for In their review of studies involving fixed implant individual patients. reconstructions of the maxilla, Lambert et al.13 found that machined implants placed in augmented bone had a SUMMARY AND CONCLUSIONS statistically significant lower survival rate, unlike ‘micro- rough’ surface implants, for which no statistical difference Modifications of the original machined titanium between augmented and non-augmented bone survival rates implant surface have been carried out in order to enhance was found. Machined implants showed a stable survival rate osseointegration and provide a clinical benefit for the only when placed in native bone. When machined implants patient. The following conclusions can be reached following were placed in augmented bone, the survival rate decreased assessment of the relative performance of modified implant significantly at each study endpoint (1, 3, 5, 10 and 15 years). surfaces: In relation to sinus augmentation procedures, superior 1. Pre-clinical in vitro cell culture studies and in vivo performance has been associated with ‘micro-rough’ histomorhometric analysis of bone to implant contact compared with machined implants in a recent systematic consistently show that modified implant surfaces are more review.18 A meta-analysis showed that the mean survival rate osteogenic and improve the degree of osseointegration, of ‘micro-rough’ implants was 96.7% (for 2,544 patients especially in the early stages of bone wound healing. and 8,303 implants placed) compared with 86.3% machined 2. The majority of clinical trials report on machined surface implants (for 950 patients and 3,346 implants placed). and ‘micro-rough’ implants, with relatively few studies evaluating the use of newly developed ‘bioactive’ implant Peri-implantitis surfaces. 3. There is a clear trend for improved clinical success when Perimplantitis is an inflammatory disease leading to using ‘micro-rough’ implants, particularly in compromised bone loss around implants, which has a similar aetiology and sites, such as the posterior maxilla, and compromised pathogenesis to periodontitis. A meta-analysis has found a patients, such as smokers. greater incidence of peri-implantitis around implants with 4. ‘Micro-rough’ implants perform better in augmented ‘micro-rough’ surfaces when compared with implants with sites. machined surfaces over a 3-year period.12 However, it should
SASO IVANOVSKI 85 5. The use of short implants is more predictable with 11. Orsini G, piattelli M, Scarano A, Petrone G, Kenealy J, Piattelli A, ‘micro-rough’ than machined surface implants. Caputi S. Randomized, controlled histologic and histomorphometric 6. There is evidence that ‘micro-rough’ implants are more evaluation of implants with nanometer-scale calcium phosphate added to susceptible to peri-implantitis, but these findings relate the dual acid-etched surface in the human posterior maxilla. J Periodontol to a surface that is no longer manufactured, with no such 2007;78:209-218. susceptibility being found in relation to currently available surfaces. 12. Esposito M, Murray-Curtis L, Grusovin MG, Coulthard P, Worthington 7. In terms of osseointegration to a previously diseased HV. Interventions for replacing missing teeth: different types of dental implant surface, ‘micro-rough’ implants perform better than implants. Cochrane Database Syst Rev 2007;4:CD003815. machined implants. 13. Lambert FE, Weber HP, Susarla SM, Belser UC, Gallucci GO. REFERENCES Descriptive analysis of implant and prosthodontic survival rates with fixed implant-supported rehabilitations in the edentulous maxilla. J Periodontol 1. Lindquist LW, Carlsson GE, Jemt T. A prospective 15-year follow-up 2009;80:1220-30. study of mandibular fixed prostheses supported by osseointegrated implants. Clinical results and marginal bone loss. Clin Oral Implants Res 1996;7:329- 14. Esposito M, Grusovin MG, Felice P, Karatzopoulos G, Worthington 36. HV, Coulthard P. Interventions for replacing missing teeth: horizontal and vertical bone augmentation techniques for dental implant treatment. 2. Bachle M, Kohal RJ. A systematic review of the influence of different Cochrane Database Syst Rev 2009;4:CD003607. titanium surfaces on proliferation, differentiation and protein synthesis of osteoblast-like MG63 cells. Clin Oral Impl Res 2004;15:683-692. 15. Feldman S, Boitel N, Weng D, Kohles SS, Stach RM. Five-year survival distributions of short-length (10 mm or less) machined-surfaced 3. Masaki C, Schneider GB, Zaharias R, Seabold D, Stanford C. Effects of and Osseotite implants. Clin Implant Dent Relat Res 2004;6:16-23. implant surface microtopography on osteoblast gene expression. Clin Oral Implants Res 2005;16:650-656. 16. Renouard F, Nisand D. Short implants in the severely resorbed maxilla: a 2-year retrospective clinical study. Clin Implant Dent Relat 4. Buser D, Schenk RK, Steinemann S, Fiorellini JP, Fox CH, Stich Res.2005;7:S104-10. H. Influence of surface characteristics on bone integration of titanium implants. A histomorphometric study in miniature pigs. J Biomed Mater 17. Balshe AA, Eckert SE, Koka S, Assad DA, Weaver AL. The effects of Res 1991;25:889-902. smoking on the survival of smooth- and rough-surface dental implants. Int J Oral Maxillofac Implants 2008;23:1117-22. 5. Buser D, Nydegger T, Hirt,HP, Cochran DL, Nolte LP (1998). Removal torque values of titanium implants in the maxilla of miniature pigs. Int J 18. Del Fabbro M, Rosano G, Taschieri S. Implant survival rates after Oral Maxillofac Implants 1998;13:611-619. maxillary sinus augmentation. Eur J Oral Sci 2008;116:497-506. 6. Berglundh T, Abrahamsson I, Lang NP, Lindhe J (2003). De novo 19. Astrand P, Engquist B, Anzén B, Bergendal T, Hallman M, Karlsson U, alveolar bone formation adjacent to endosseous implants. Clin Oral Kvint S, Lysell L, Rundcrantz T. Nonsubmerged and submerged implants in Implants Res 2003;14:251-62. the treatment of the partially edentulous maxilla. Clin Implant Dent Relat Res 2002;4:115-27. 7. Abrahamsson I, Berglundh T, Linder E, Lang NP, Lindhe J. Early bone formation adjacent to rough and turned endosseous implant surfaces. Clin 20. Renvert S, Polyzois I, Maguire R. Re-osseointegration on previously Oral Implants Res 2004;15:381-92. contaminated surfaces: a systematic review. Clin Oral Implants Res 2009;20:216-27. 8. Buser D, Broggini N, Wieland M, Schenk,RK, Denzer AJ, Cochran DL, Hoffmann B, Lussi A, Steinemann S. Enhanced bone apposition to a Address for correspondnence: chemically modified SLA titanium surface. J Dent Res 2004;83:529 – 533. School of Dentistry and Oral Health Gold Coast Campus 9. Berglundh T, Abrahamsson I, Albouy JP, Lindhe J. Bone healing at Griffith University implants with a fluoride-modified surface: an experimental study in dogs. Queensland 4222 Clin Oral Implants Res 2007;18:147-52. Australia. s.ivanovski@griffith.edu.au 10. Meirelles L, Currie F, Jacobsson M, Albrektsson T, Wennerberg A. The effect of chemical and nanotopographical modifications on the early stages of osseointegration. Int J Oral Maxillofac Implants 2008;23:641-7.
Ann Roy Australas Coll Dent Surg 2010;20:86-87 UNDERSTANDING RISK FOR PERIODONTAL DISEASE Mary Patricia Cullinan, BDS, MSc, FADI* Gregory John Seymour AM, BDS, MDSc, PhD, FRCPath, FFOP(RCPA), FRACDS(Perio), FADI, FICD, FPFA, FRSNZ Mary Cullinan is Associate Professor in the Discipline of Periodontics, Department of Oral Sciences and Sir John Walsh Research Institute, University of Otago, Dunedin, New Zealand. Gregory Seymour is Dean and Professor of Periodontics, Faculty of Dentistry, University of Otago, Dunedin, New Zealand. ABSTRACT An ability to identify individuals at risk for progressive periodontal disease would enable targeted prevention and treatment, thus reducing the economic burden on society. The importance of the interplay between microbial, genetic and environmental factors in risk assessment is recognized and the relative contributions of various risk factors has been determined. However, newer technologies will enable more accurate individual risk profiling in the future. INTRODUCTION Many of these studies have been cross-sectional and have looked at polymorphisms in isolation without taking into It is generally believed that risk for periodontal disease account other risk factors. A longitudinal study design is the result of the interaction between bacterial, genetic enabled determination of the relative contributions of and environmental factors. While genetics may place us at specific IL-1 and IL-10 gene polymorphisms, smoking, age risk for certain diseases, whether we develop these diseases and presence of Porphyromonas gingivalis.2,3 It was shown and at what age will be determined by our environment and that IL-1 genotype alone had no significant effect on disease behavioural choices. progression; however, it did have significant interactive effects with other risk factors. For example, IL-1 genotype Many years of research have increased our understanding positive (IL-1α+4845T/IL-1β+3954T) individuals who of the pathogenesis of chronic periodontitis. Microbial, smoked could be expected to have 70% more disease than genetic and environmental risk factors have been identified IL-1 genotype negative smokers. Likewise, IL-1 genotype yet the ability to identify individuals who are at risk of positive individuals with Porphyromonas gingivalis in their disease or disease progression has proven elusive. plaque could be expected to have 80% more disease than IL-1 genotype negative individuals with Porphyromonas MICROBIAL RISK FACTORS gingivalis. In this context, smoking and Porphyromonas gingivalis could be considered as primary risk factors and Whilst a number of periodontal pathogens have been IL-1 genotype as a secondary risk factor. On the other identified these same organisms can be found as part of hand, certain IL-10 genotypes (ATA/ACC or ACC/ACC) the microbiota of periodontally healthy individuals. A were associated with less disease progression and could longitudinal study of the natural history of periodontal be considered as protective genotypes. People with these pathogens demonstrated that they exhibit a high degree protective genotypes could expect to have 25% less disease of volatility in terms of acquisition and loss over time1 than those with other genotypes. Alternatively, those with suggesting that a dynamic relationship exists not only non-protective genotypes could expect to have the same between constituents of the biofilm but also with the host. amount of disease as an individual 15 years older with a Porphyromonas gingivalis showed less volatility and was protective genotype. However, more importantly, this study the only organism associated with progression of periodontal showed that smoking can over-ride any protective genotype disease in this longitudinal study. However, newer molecular effect. techniques such as high throughput sequencing are enabling More recent research has focused on the peripheral blood the identification of uncultivable phylotypes and the focus is and salivary transcriptomes rather than on alterations in the shifting towards viewing the oral biofilm from a microbial gene sequences themselves in order to identify susceptibility ecological perspective. The complexity of microbial to periodontal disease. In these studies both whole genomic interactions and communication within the biofilm and with and focused gene arrays are being used to identify patterns the host is now actively being researched. Indeed, combined of gene expression associated with periodontal disease and genomic and proteomic analyses of host-biofilm interactions following treatment. However, at this stage it remains to may ultimately be useful in disease prediction, prevention, be determined whether or not susceptible patients can be diagnosis and treatment and lead to individualised risk identified on the basis of differential gene expression. profiling. ENVIRONMENTAL RISK FACTORS GENETIC RISK FACTORS The influence of environmental factors on disease Specific polymorphisms in a large number of genes progression is well recognized. For example, stress can lead that may be associated with periodontal disease have been to more rapid progression of periodontal disease and in this studied over the past decade with inconsistent findings. * Presented at the Twentieth Convocation of the Royal Australasian College of Dental Surgeons, Perth, Western Australia. March 2010
MARY CULLINAN, GREGORY SEYMOUR 87 context the influence of the hypothalamic-pituitary-adrenal REFERENCES axis on regulation of the local immune response is being investigated. The effect of smoking has been investigated 1. Cullinan MP, Hamlet SM, Westerman B, Palmer JE, Faddy MJ, Seymour over many years and studies have consistently shown that GJ. Acquisition and loss of Porphyromonas gingivalis, Actinobacillus smokers have increased numbers of deep pockets and actinomycetemcomitans and Prevotella intermedia over a 5-year period: greater loss of attachment and alveolar bone, as well as a The effect of a triclosan/copolymer dentifrice. J Clin Periodontol 2003; poorer response to treatment than non-smokers. It is now 30:532-41. recognized that the healing capacity of smokers is impaired to such an extent that it is only 28% of that of non-smokers3 2. Cullinan MP, Westerman B, Hamlet SM, Palmer JE, Faddy MJ, Lang and this may be fundamental in explaining the increased NP, Seymour GJ. A longitudinal study of interleukin-1 gene polymorphisms disease expression observed in smokers.4 and periodontal disease in a general adult population. J Clin Periodontol 2001;28:1137-44. It is increasingly recognized that environmental factors as well as microbial factors may exert an epigenetic effect, 3. Cullinan MP, Westerman B, Hamlet SM, Palmer JE, Faddy MJ, that is, cause a change in phenotype or gene expression Seymour GJ, Middleton PG, Taylor JJ. Progression of periodontal disease without altering the underlying DNA sequence and it is this, and IL-10 gene polymorphism. Journal of Periodontal Research 2008;43: which may be responsible for determining the nature of the 328-33. host response. 4. Faddy MJ, Cullinan MP, Palmer J, Westerman B, Seymour GJ. Ante- CONCLUSION dependence modelling in a longitudinal study of periodontal disease: the Unravelling the complexities of gene-environmental effect of age, gender and smoking status. J Periodontol 2000;71:454-9. interactions may lead to enhanced individual risk profiling and more targeted treatment in the future. Address for correspondence: Department of Oral Sciences, School of Dentistry University of Otago PO Box 647 Dunedin 9054, New Zealand [email protected]
Ann Roy Australas Coll Dent Surg 2010;20:88 RADIOLOGIC INVESTIGATION OF THE TEMPOROMANDIBULAR JOINT Bernard Koong, BDSc(W.Aust), MSc(OMR)(Toronto)* Associate Professor Koong consults full time at a multidisciplinary private radiology group in Western Australia. He is a Clinical Associate Professor at the University of Western Australia, delivering undergraduate and postgraduate OMR programmes. The temporo-mandibular joint (TMJ) and related pain/ The potential consequence of ruling out TMJ arthropathy dysfunction is a common presenting complaint in dental and as a result of the inappropriate prescription of an imaging orofacial practice. modality is obvious. In addition, while degenerative disease and articular discal abnormalities are more common, The limited value of the panoramic radiograph in the other conditions ranging from erosive arthropathies to evaluation of the TMJ should be recognized. The bony benign and malignant tumours also affect the TMJ. The structures can be examined with multidetector computed radiologic interpretive skill set of those responsible for tomography (MCT) and cone beam (CB) 3D imaging the radiologic examination must be considered. The systems. The relative weaknesses of CB imaging, notably in consequence of mismanagement of TMJ pain/dysfunction relation to scatter, low signal-to-noise ratio, beam hardening related to undiagnosed or misdiagnosed pathology has been and potential motion artefacts must be recognized. Soft documented. tissues are not well visualized in CB imaging, in contrast to MCT. The effective doses delivered vary dramatically Address for correspondence: between CB machines and only some are ultra low dose. c/o Envision Medical Imaging MCT doses are more protocol dependent. The articular Suite 5, 178 Cambridge Street disc and other associated soft tissues of the TMJs are best Subiaco, Western Australia 6014 evaluated with magnetic resonance imaging (MRI), although [email protected] the bony structures are also visualized with this technique. The decision to employ MCT, CB or MRI in the examination of the TMJ is made on an individual case-by-case basis, requiring a thorough clinical examination and understanding of the strength and weaknesses of the available modalities. Other imaging techniques, such as nuclear medicine and ultrasound are occasionally employed. * Presented at the Twentieth Convocation of the Royal Australasian College of Dental Surgeons, Perth, Western Australia. March 2010
Ann Roy Australas Coll Dent Surg 2010;20:89 ABSTRACTS OF PAPERS WHERE ARE WE TODAY WITH PERIODONTAL REGENERATION? Lisa JA Heitz-Mayfield, BDS, MDSc, Odont Dr* Lisa Heitz-Mayfield is currently Adjunct Professor at La Trobe University, Victoria, Honorary Professor at the University of Hong Kong, Associate Professor at The University of Sydney, NSW and Professor at the Centre for Rural and Remote Oral Health, The University of Western Australia and also maintains a specialist practice in West Perth. The presentation outlined the clinical applications for the therapy and infrabony, furcation and recession defects were use of regenerative techniques in periodontology. Criteria for discussed. appropriate selection of patients, defect and surgical approach were addressed and an update on surgical techniques for Address for correspondence: the use of barrier membranes, biological agents and bone 41 Mann Street substitute materials were presented. The latest evidence for Cottesloe Western Australia 6011 the predictability and expected outcomes of regenerative heitz.mayfi[email protected] THE VERTICAL DIMENSION : THE MOST IMPORTANT FACTOR FOR ALL DENTISTS Michael Woods,DDSc(Melb), FRACDS, FRACDS Orth, DOrthRCS(Eng), CertOrth(Oklahoma)* Dr Woods is a Diplomate of the American Board of Orthodontics and a former Professor and Head of Orthodontics at the Melbourne Dental School. The functional properties and relationship is of the own research into clinical aspects of the mandibular muscles mandibular muscles are closely associated with growth and and the vertical dimension of the face. development of the dentofacial complex. Those muscles and the implications of differences in underlying vertical Address for correspondence: facial pattern affect day-to-day treatment decisions in all 549 Dandenong Rd disciplines of dentistry -- not just orthodontics and oral Malvern Victoria 3143 and maxillofacial surgery. This presentation highlighted [email protected] these implications. It was illustrated with 10 year follow-up clinical case material and references made to the author’s INFLUENCE OF ORTHODONTIC TOOTH MOVEMENT ON PERIODONTAL DEFECTS Kwan-Yat Zee, BDS, MDSc, Odont Dr, FCDSHK, FHKAM* Associate Professor Zee is a Staff Specialist and Head of Periodontology at Westmead Centre for Oral Health and a Clinical Associate Professor and Head of Periodontology in the Faculty of Dentistry at the University of Sydney. Periodontally susceptible patients who have experienced additional attachment loss was particularly evident when drifting, migration, extrusion, flaring and tooth loss may the tooth was moved into the infrabony pocket. The paper require adjunctive orthodontic treatment. Previous studies described some of the available data relating to clinical have shown that tooth movement can be performed in adults results of orthodontic tooth movement on periodontal with reduced but healthy periodontium without further defects, including using intrusive movement for over-erupted periodontal deterioration. Conversely, adults who did not but treated periodontally involved teeth. have healthy periodontal tissue may experience further breakdown and tooth loss during orthodontic treatment. Address for correspondence: Animal studies showed orthodontic movement may enhance Level 3, Periodontics the rate of destruction of the connective tissue attachment Westmead Centre For Oral Health of teeth with inflamed infrabony pockets, and the risk for Westmead NSW 2145 [email protected] * Presented at the Twentieth Convocation of the Royal Australasian College of Dental Surgeons, Perth, Western Australia. March 2010
Ann Roy Australas Coll Dent Surg 2010;20;90 CORRELATION OF SERUM AND GCF ADIPOKINES IN OBESE SUBJECTS Robert Fell, BDS(Hons), FRACDS* Kwan-Yat Zee, BDS, MDSc, Odont Dr, FCDSHK(Perio), FHKAM(Dental Surgery) Manish Arora, BDS, MPH, PhD Dr Fell is a Periodontics Registrar (Dental Officer), in a Specialist training post in the field of periodontics at the University of Sydney. Associate Professor Zee is Head of Periodontics, Westmead Centre for Oral Health and Clinical Associate Professor for the University of Sydney. Dr Manish Arora is a Senior Lecturer for the University of Sydney in Population Oral Health. PURPOSE found in all serum and 78% of healthy GCF samples. There was no correlation between the levels of cytokines found in Inflammatory cytokines (Il-6, TNF-α) released by serum with those found in the GCF of healthy sites. A trend adipose tissue in obese subjects may enhance the local for a correlation was present in some subjects but not others. immune response in the periodontal tissues. It is unclear Detection of cytokines from gingivitis sites was variable. whether the cytokines released by adipose tissue in serum Similar to healthy sites, gingivitis sites display a trend for are proportionately present in the gingival crevicular fluid correlation in some but not all subjects. However, limited (GCF). gingivitis sites were available for analysis. The aim of this study was to correlate, in obese patients, CONCLUSION the GCF levels of IL-6 and TNF-α with the levels found in Although statistical power is limited, preliminary results serum. suggest a lack of correlation between the levels of IL-6 and TNF-α in serum and GCF from healthy sites. This is MATERIALS AND METHODS consistent with previous reports on other inflammatory mediators. These results also suggest that future studies Thirty six obese patients were recruited from obesity examining the relationship between BMI and gingival clinics at Westmead Hospital. Obesity was defined using cytokine levels should also examine serum samples. Overall, a body mass index ≥ 30 kg/m2. Patients with conditions this suggests that the effect of obesity on periodontitis may known to affect periodontal tissues, such as uncontrolled not be dependent on the amount of cytokine released into diabetes (HbA1c >8%) and smoking, were excluded. circulation. Serum and GCF samples from 27 of the 36 subjects Address for correspondence: have been collected and analysed for IL-6 and TNF-α using Periodontics commercially available ELISA kits. Within each subject Westmead Centre for Oral Health GCF was collected from two healthy sites (n=27 subjects) Westmead Hospital and two sites with bleeding on probing (n=13 subjects). NSW 2145, Australia The GCF samples were collected using standardized filter [email protected] paper† which was placed into the gingival crevice to a depth of ≤ 1 mm for 30 seconds. Blood contaminated strips were excluded. The levels of IL-6 and TNF-α in the GCF were compared and correlated with the levels found in serum. RESULTS TNF-α was detectable in 88% of serum samples but in only 60% of healthy GCF samples. In contrast, IL-6 was * Young Lecturer presentation at the Twentieth Convocation of the Royal † Perio-Flow, Henry Schein / Halas, Sydney NSW Australasian College of Dental Surgeons, Perth, Western Australia. March 2010
Ann Roy Australas Coll Dent Surg 2010;20;91 ATHLETIC MOUTH GUARD DESIGN, FACIAL SKELETAL PROFILE AND THEIR EFFECTS ON UPPER AIRWAY RESPIRATORY FUNCTION / VENTILATION IN ATHLETES Dieter Gebauer, BDSc, MBBS (Hons), Grad Dip Dent, Grad Dip Hosp Dent* Raymond Williamson, BDS, MDSc, PhD, FRACDS, FFDRCS (Irel), FDSRCS (Eng), FRACDS (OMS) Karen Wallman , BEd, BSc (Hons), PhD Dr Gebauer is Senior Registrar in Oral and Maxillofacial Surgery at the Royal Perth Hospital, Wellington Street Campus. Professor Williamson is Head of Department and Director of Training in the Department of Oral and Maxillofacial Surgery, Royal Perth Hospital, School of Dentistry in the University of Western Australia. Dr Wallman is Senior Researcher in the School of Sport Science, Exercise and Health at the University of Western Australia. Many athletes refuse to wear mouth guards because of e. A repeated measure ANOVA was used to assess whether a belief that they make breathing difficult. Mouth guards there was any statistical difference between the three groups provide protection from concussion, dento-alveolar injury, of data at minimal, moderate and maximal levels of exercise. and fracture of the facial skeleton. This study aims to assess f. Logistic regression analysis will be used to determine the respiratory function of a large number of athletes whilst whether there are any trends in the data that would suggest they are wearing different types of custom mouth guards that craniofacial morphology have an effect on subjects who during various sporting scenarios. wear mouth guards. The authors‘ hypothesis is that a custom mouth guard The results show that there is no statistical difference in will have no effect on respiration in athletes either at rest or respiratory parameters between the three groups at minimal, whilst exercising. moderate and maximum intensity levels of exercise. Thirty one male subjects were recruited in the study Address for correspondence: 15 Rhonda Ave Willetton a. Patient’s skeletal measurements were then obtained by Perth measurements of standard lateral cephalometric radiography. Western Australia 6155 [email protected] b. Two mouth guards of different design were fabricated for each subject. c. The subject was tested three times – wearing no mouth guard / mouth guard A and mouth guard B. d. The respiratory data collected include ventilation (Ve), oxygen consumption (VO2) at mild, moderate and maximum intensity of exercise. * Young Lecturer presentation at the Twentieth Convocation of the Royal Australasian College of Dental Surgeons, Perth, Western Australia. March 2010
Ann Roy Australas Coll Dent Surg 2010;20;92 CLINICAL AND RADIOGRAPHIC EVALUATION OF NOBELACTIVETM DENTAL IMPLANTS: A PROSPECTIVE SPLIT-MOUTH COMPARATIVE STUDY Danny Sai-Wah Ho, BDS(Hons) (Syd), FRACDS* Dr Ho is in the Doctor of Clinical Dentistry (Periodontics) programme at the University of Sydney. PURPOSE RESULTS Poor bone quality at a surgical site is a common problem Preliminary results have shown comparable healing in implant therapy due to the difficulty in achieving primary responses between the test and control implants. Marginal stability during implant insertion. The innovative design of bone level changes surrounding the implants during the the NobelActiveTM implant† is specifically designed to be initial healing period were also comparable when examined used in “soft” bone situations. The purpose of this study is using subtraction digital radiography. Survival rates were to conduct a pilot randomized controlled trial to evaluate lower with the test implants, though failures could be linked the clinical and radiographic efficacy of the NobelActive™ to other factors. system. ACKNOWLEDGMENTS MATERIALS AND METHODS The author would like to acknowledge the guidance and Using a split-mouth design, the NobelActiveTM implant assistance provided by his supervisor, Associate Professor was compared with a contralaterally matched Brånemark Stephen Yeung, and the clinical assistance of the surgeons. implant.† Both implants were placed in a single surgical Implant fixtures and components were kindly donated by procedure using a one-stage protocol and reviewed at monthly Nobel Biocare Australia. intervals. NobelActiveTM implants† were functionally loaded with provisional restorations at one month and all implants Address for correspondence: were restored with final crowns three months post-fixture Discipline of Periodontics placement. The implant was assessed using final rotation Faculty of Dentistry torque values, resonance frequency analysis, clinical University of Sydney parameters, digital subtraction radiography, and cone beam 2 Chalmers Street computed tomography. Surry Hills NSW 2010 [email protected] * Young Lecturer presentation at the Twentieth Convocation of the Royal † Nobel Biocare, Australia Australasian College of Dental Surgeons, Perth, Western Australia. March 2010
Ann Roy Australas Coll Dent Surg 2010;20;93-94 CORONECTOMY AS THE TREATMENT OF CHOICE IN WISDOM TEETH SHOWING RADIOGRAPHIC SIGNS OF CLOSE PROXIMITY TO INFERIOR DENTAL NERVE Yiu Yan Leung, BDS(HK), MDS (OMFS)(HK), MOS RCS (Edin)* Lim Kwong Cheung, BDS, FDSRCPS, FFDRCS, FRACDS, FRACDS(OMS), FHKAM(DS), FCDSHK, PhD Dr Leung is a PhD(OMFS) candidate and Professor Leung is the Chair Professor of the discipline of Oral and Maxillofacial Surgery in the Faculty of Dentistry, The University of Hong Kong, Hong Kong. ABSTRACT The aim of the study is to compare the prevalence of post-operative inferior dental nerve (IDN) deficit after coronectomy with total removal of wisdom teeth showing specific radiographic signs of close proximity to IDN. A randomized clinical trial comparing total removal and coronectomy of wisdom tooth was conducted. Analyses of the correlations of IDN deficit and various radiographic signs of wisdom tooth roots showing close proximity to IDN were performed. Two radiographic signs were found to be positive predictors of intra-operative IDN exposure. Specific radiographic signs or the presence of two or more radiographic signs are positive predictors of post-operative IDN deficit. The study concluded that darkening of the wisdom tooth root and presence of two or more specific signs in radiographs significantly increased the risk of IDN deficit in lower wisdom tooth surgery. Coronectomy can significantly reduce the prevalence of an IDN deficit in patients with lower wisdom teeth showing radiographic signs of close proximity to IDN. It also carries less surgical morbidities when compared with total removal of lower wisdom tooth. INTRODUCTION subsequently required re-operation to remove the retained root.†,3,4 Some of these studies were lacking a large sample Lower wisdom tooth impaction is a common phenomenon size or a well-designed methodology, so that further evidence in the population. Many of the impacted lower wisdom teeth to justify its use is required. are indicated for removal due to recurrent pericoronitis and dental caries. Inferior dental nerve (IDN) injury is a rare The aims of this study are to identify the specific yet significant complication in lower wisdom tooth surgery. radiographic signs from panoramic radiographs that are It is because the anatomical course of the IDN within the positive predictors of post-operative IDN deficit in lower inferior dental canal often runs in close proximity to the wisdom tooth surgery, and to compare the prevalence of root of the lower wisdom tooth. Although the prevalence of post-operative IDN deficit and safety of coronectomy with IDN injury in lower wisdom tooth surgery has been low in total removal of wisdom teeth showing specific radiographic recent studies,1 the risk of IDN injury remains high if there signs of close proximity to IDN. are specific radiographic signs showing close proximity of the wisdom tooth root to the IDN.2 A recent evidence-based METHODS review conducted by the authors’ centre has concluded that multiple factors including deep impaction, increased age, Patients presenting to the Discipline of Oral and intra-operative IDN exposure and specific radiographic signs Maxillofacial Surgery, Faculty of Dentistry, The University are associated with an increased risk of post-operative IDN of Hong Kong, for the removal of impacted lower wisdom deficit in lower wisdom tooth surgery.† Yet, if a problematic teeth between June 2006 and June 2008 were recruited lower wisdom tooth with a high risk of IDN injury needs into this randomized controlled trial if their lower wisdom to be removed, it becomes a difficult decision for both the teeth showed one or more of the radiographic signs on the surgeon as well as the patient. panoramic radiograph: A. darkening of the root; B. abrupt narrowing of the root; C. interruption or loss of the ID Coronectomy literally means cutting off the crown from canal white line; D. displacement of the ID canal by the a tooth. It is a newer method of wisdom tooth surgery where root; E. abrupt narrowing of one or both of the canal white the surgeon removes only the crown of the impacted lower lines. Patients with systemic disease or local factors that wisdom tooth and leaves the root in place. The hypothesis is may predispose to infection, or their wisdom teeth had that the crown is the cause of pericoronitis and dental caries, pulpal caries or any related pathology were excluded. The so by its removal the problem can be solved, and by leaving patients were randomized to receive either total removal the root behind IDN injury can be avoided. Previous studies (control group) or coronectomy of the lower wisdom tooth on coronectomy have shown variable results, with significant (coronectomy group). For the coronectomy group, the root was morbidity like persistent root exposure and infection, which further trimmed down 3-4 mm below the crestal bone. All * Young Lecturer presentation at the Twentieth Convocation of the Royal † Leung YY, Cheung LK. Risk Factors of Neurosensory Deficits in Lower Australasian College of Dental Surgeons, Perth, Western Australia. March Third Molar Surgery: An Evidence-based Review of Prospective Studies. 2010 International Journal of Oral and Maxillofacial Surgery (submitted)
94 CORONECTOMY AS THE TREATMENT OF CHOICE IN WISDOM TEETH wounds were closed primarily and no antibiotics were given rate decreased gradually, reaching 2.97 mm (SD, 1.47 mm) post-operatively. In the Control Group, intra-operatively in the 12th postoperative month. At 24 months, the mean the operators inspected the extraction socket with copious total movement of the root was found to be 3.06 mm (SD, irrigation and careful suction after surgical removal of 1.67 mm). the lower wisdom tooth to check on the presence of IDN exposure and this was recorded in the operation records. CONCLUSION Exposure of IDN was defined as a tubular whitish soft tissue structure running in an antero-posterior direction at the level The study concluded darkening of the wisdom tooth the wisdom tooth socket consistent with the radiograph as root and presence of two or more specific radiographic suggested by Tay and Go.6 signs significantly increases the risk of IDN deficit in lower wisdom tooth surgery. Coronectomy can significantly reduce The patients were reviewed post-operatively at 1 week, 1 the prevalence of IDN deficit in patients with lower wisdom month, 3 months, 6 months, 12 months and 24 months. teeth showing radiographic signs of close proximity to IDN. It also carries less surgical morbidity when compared with RESULTS total removal of lower wisdom teeth. Root migration after coronectomy tends to halt or slow down drastically after one Three hundred and thirty three lower wisdom teeth (155 year post-operatively.Aphase IV clinical trial of coronectomy successful coronectomies, 178 controls) in 215 patients of lower wisdom tooth is indicated to investigate the long underwent surgery. Nine patients in the control group term safety and the fate of the retained root. presented with IDN deficit, compared with one in the coronectomy group (p=0.023). IDN exposure was noted in REFERENCES 13.5% (24/178) of the subjects in the control group, among those 20.8% presented with IDN deficit. Among the five 1. Cheung LK, Leung YY, Chow LK, Wong MC, Chan EK, Fok YH. radiographic signs, darkening of root and displacement Incidence of neurosensory deficits and recovery after lower third molar of IDN by the root were radiographic signs which were surgery: a prospective clinical study of 4338 cases. Int J Oral Maxillofac significantly related to IDN exposure (p = 0.001 and p = Surg 2010 Jan 8. [Epub ahead of print] 0.019, respectively). Darkening of root was shown to be the 2. Blaeser BF, August MA, Donoff RB, Kaban LB, Dodson TB. Panoramic only radiographic sign significantly related to post-operative radiographic risk factors for inferior alveolar nerve injury after third molar IDN deficit in the control group (p=0.016). When two or more extraction. J Oral Maxillofac Surg 2003;61: 417-21. radiographic signs were present the risk of IDN deficit was 3. Knutsson K, Lysell l, Rohlin M.Postoperative status after partial removal significantly increased (p = 0.001). Coronectomy has shown of the mandibular third molar. Swed Dent J 1989;13:15-22. to be significantly safer in terms of IDN deficit risk in the 4. Freedman GL.Intentional partial odontectomy: review of cases. J Oral wisdom teeth where there is radiographic darkening of the Maxillofac Surg 1997;55:524-6. root (p = 0.02) and those showing two or more radiographic 5. O’Riordan BC. Coronectomy (intentional partial odontectomy of signs (p = 0.005). Fewer subjects reported pain in the first lower third molars). Oral Surg Oral Med Oral Pathol Oral Radiol Endod post-operative week in the coronectomy group (p = 0.005). 2004;98:274-80. No dry sockets were noted in the coronectomy group, which 6. Tay AB, Go WS. Effect of exposed inferior alveolar neurovascular was an advantage when compared with the control group bundle during surgical removal of impacted lower third molars. J Oral with a 2.8% rate of dry socket. Infection rate was similar Maxillofac Surg 2004;62:592-600. between the two groups at all time of review (p > 0.05). Coronal migration of the retained root after coronectomy Address for correspondence: was noted by serial radiographs. The rate of root migration was fastest in the first three postoperative months, with a Oral and Maxillofacial Surgery mean movement of 1.90 mm (SD, 1.23 mm), and then the Prince Philip Dental Hospital 34 Hospital Road, Hong Kong [email protected]
Ann Roy Australas Coll Dent Surg 2010;20;95-96 EARLY WOUND HEALING FOLLOWING A MECHANICAL CLEANSING POST-SURGICAL PROTOCOL - A RANDOMIZED CONTROLLED TRIAL Jessica Elizabeth O’Neill, BDS (Hons), MFDS RCS (Ed)* Lisa JA Heitz-Mayfield, BDS, MDSc, Odont Dr Bradley Curtis, BDS, MPH, GCert, FICD Dr O’Neill is a Registrar in Periodontics at the University of Sydney, NSW. Lisa Heitz-Mayfield is currently Adjunct Professor at La Trobe University, Victoria, Honorary Professor at the University of Hong Kong, Associate Professor at The University of Sydney, NSW and Professor at the Centre for Rural and Remote Oral Health, The University of Western Australia and also maintains a specialist practice in West Perth. Dr Curtis is an Associate Lecturer in Epidemiology and Biostatistics at the University of Sydney. INTRODUCTION Patients following the control protocol rinsed twice daily for 1 min with 10 mL of 0.2% chlorhexidine for 28 Post operative plaque control is a critical factor in the days. Patients following the test protocol followed the successful outcome of periodontal surgery and implant control protocol for the first three days. From day 3 to placement.1-3 Periodontal literature has consistently identified 28 a soft toothbrush† was used to locally apply 10 mL of chlorhexidine as a chemical agent capable of adequately 0.2% chlorhexidine to the wound, twice daily. Patients preventing biofilm formation when used appropriately.4,5 were instructed to dip the toothbrush into the 10 mL of However, the optimum technique, frequency and duration of chlorhexidine and wipe the dento-gingival area with light chlorhexidine use post-surgery is not known. vertical strokes. This was to be repeated until 10 mL had been applied to the surgical area. Full mouth rinsing with chlorhexidine has been associated with adverse effects, such as staining of the teeth and tongue, Baseline measurements included probing depth, distortion of taste and mucosal irritation,6,7 and these adverse recession, presence of bleeding on probing and full mouth effects may detrimentally impact on the compliance of the plaque scores. Follow up examinations at days 7 and 14 patient with suggested cleansing protocols. included presence of tooth staining, wound closure, full mouth plaque scores, adverse events and patient centred Recent evidence suggests a modified mechanical outcomes. cleansing protocol is as effective as chemical protocols using chlorhexidine.8 There is no literature to date assessing Tooth staining was measured visually. The most mesial the effectiveness of a modified mechanical application of tooth in the surgical field, and the four maxillary anterior chlorhexidine on the early wound, without concomitant teeth were assessed. Patient centred outcomes included full mouth chlorhexidine rinsing. Thus it is currently not the patient’s acceptance of the cleansing protocol, taste known whether such a method would provide the benefits disturbance and postoperative pain. A 100 mm visual of traditional post-surgical cleansing protocols without the analogue scale (VAS) was used to evaluate patient centred adverse effects associated with full mouth chlorhexidine outcomes. Tooth staining was evaluated using the staining rinsing. index adapted from Cortellini et al.9 Baseline and follow up evaluations were repeated at day 28. The aim of the present study was to evaluate the effectiveness on plaque control and clinical healing, of a RESULTS specific mechanical cleansing protocol with application of chlorhexidine using a very soft toothbrush as an applicator, Forty-five patients completed the clinical trial. Statistical without full mouth rinsing after day 3. analysis indicated there were no significant differences between groups for baseline data (full mouth plaque score, MATERIALS AND METHODS sex, smoking, type of surgery). Both post-surgical protocols resulted in successful wound healing, measured by wound Following periodontal surgery or one-stage implant closure and absence of infection. Statistical analysis indicated surgery, 52 patients were randomly assigned to one of two there were no statistical differences between groups for post-surgical protocols. Subjects smoking more than10 patient centred outcomes, adverse events, or chlorhexidine cigarettes per day were excluded. Patients were recruited staining at surgically treated teeth. Chlorhexidine staining from the Periodontics Division of the Oral Restorative increased in both groups over the 28 day trial. After 7 days of Sciences Department at Westmead Centre for Oral Health chlorhexidine use, 18% of distal surfaces and 13% of incisal NSW, from a pool of patients requiring periodontal surgery tooth surfaces exhibited chlorhexidine staining, which had or implant placement. The study was approved by the Ethics increased to 80% (distal) and 27% (incisal) following 28 Committee from the Sydney West Area Health Service. days of use. * Young Lecturer presentation at the Twentieth Convocation of the Royal † TePe Special Care, Trolldent, Australia. Australasian College of Dental Surgeons, Perth, Western Australia. March 2010
96 EARLY WOUND HEALING FOLLOWING A MECHANICAL CLEANSING CONCLUSION 7. Gurgan CA, Zaim E, Bakirsoy I, Soykan E, Gurgan CA, Zaim E, et al. Short-term side effects of 0.2% alcohol-free chlorhexidine mouthrinse used A specific mechanical post-surgical protocol involving a as an adjunct to non-surgical periodontal treatment: a double-blind clinical localised application of chlorhexidine, may be recommended study. J Periodontol 2006;77:370-84. in the early wound healing period as an alternate to full 8. Heitz F, Heitz-Mayfield LJ, Lang NP. Effects of post-surgical cleansing mouth chlorhexidine rinsing. protocols on early plaque control in periodontal and/or periimplant wound healing. J Clin Periodontol 2004;31:1012-8. REFERENCES 9. Cortellini P, Labriola A, Zambelli, Pini Prato G, Nieri M, Tonetti M. Chlorhexidine with an anti discoloration system after periodontal 1. Nyman S, Rosling B, Lindhe J. Effect of professional tooth cleaning on flap surgery: a cross-over, randomized, triple-blind clinical trial. J Clin healing after periodontal surgery. J Clin Periodontol 1975;2:80-6. Periodontol 2008;35:614-20. 2. Nyman S, Lindhe J, Rosling B. Periodontal surgery in plaque-infected Address for correspondence: dentitions. J Clin Periodontol 1977;4:240-9. Westmead Centre for Oral Health Darcy Road 3. Rosling B, Nyman S, Lindhe J, Jern B. The healing potential of the Westmead NSW 2145 periodontal tissues following different techniques of periodontal surgery [email protected] in plaque-free dentitions. A 2-year clinical study. J Clin Periodontol 1976;3:233-50. 4. Löe H, Schiott CR. The effect of mouthrinses and topical application of chlorhexidine on the development of dental plaque and gingivitis in man. J Periodontol Res 1970;5:79-83. 5. Sekino S, Ramberg P, Uzel NG, Socransky S, Lindhe J. The effect of a chlorhexidine regimen on de novo plaque formation. J Clin Periodontol 2004;8:609-14. 6. Horwitz J, Machtei EE, Peled M, Laufer D. Amine fluoride/stannous fluoride and chlorhexidine mouthwashes as adjuncts to surgical periodontal therapy: a comparative study. J Periodontol 2000;71:1601-6.
Ann Roy Australas Coll Dent Surg 2010;20;97 INCIDENCE AND MAGNITUDE OF VIRIDANS STREPTOCOCCAL BACTERAEMIA CAUSED BY FLOSSING OR SCALING AND ROOT PLANING IN PATIENTS WITH CHRONIC PERIODONTITIS W.T. Zhang, BDSc* C. G. Daly, BDS, MSc, PhD, FRACDS, FICD D. Mitchell, MBBS, MMed Sci (Epi), FRACP, FRCPA B. Curtis, BDS, MPH, G.Cert, FICD Dr Zhang is a third year postgraduate student undertaking a DClinDent (Periodontics) at the University of Sydney. As- sociate Professor Daly is in the Discipline of Periodontics, Faculty of Dentistry of the University of Sydney. Dr Mitchell is Senior Staff Specialist at the Institute of Clinical Pathology and Medical Research, Westmead Hospital. Dr Curtis is an Associate Lecturer in Epidemiology and Biostatistics at the University of Sydney. BACKGROUND AND AIMS centrifugation and expressed as CFU/mL. Bacteria were identified to species level. Changes to antibiotic prophylaxis guidelines for the prevention of infective endocarditis (IE) have occurred RESULTS in part due to similar incidences of bacteraemia caused by No VSB was detected in any baseline samples. The oral hygiene procedures as compared with dental treatments incidence of VSB was 25% for flossing and 35% for SRP. for which antibiotic prophylaxis has traditionally been In the flossing group, all VSB was detected 30 seconds after provided. Viridans streptococci are important pathogens in flossing (N=5/20). In the SRP group, VSB was detected at IE. However, there is little evidence available comparing the 5 minutes during SRP (N=5/20) and 30 seconds after SRP magnitude of bacteraemia caused by oral hygiene activities (N=2/20). The mean magnitudes of VSB were 1.61 CFU/mL with that caused by periodontal treatment. The aims of this for flossing and 0.28 CFU/mL for SRP. study were to investigate the incidence and magnitude of viridans streptococcal bacteraemia (VSB) due to flossing as CONCLUSIONS compared with scaling and root planing (SRP) in the same It may be inconsistent to recommend prophylaxis for IE individual. for periodontal procedures but not for flossing in patients with periodontitis. MATERIAL AND METHODS Address for correspondence: Full-mouth flossing and single quadrant SRP were Disipline of Periodontics performed for 20 patients with moderate/severe chronic Faculty of Dentistry periodontitis at separate visits. Twenty millilitres of blood University of Sydney were collected as a baseline prior to the procedure and [email protected] further samples obtained 30 seconds and 10 minutes after completion of flossing, at 5 minutes during SRP and 30 seconds and 10 minutes after completion of SRP. The magnitude of the bacteraemia was investigated with lysis * Young Lecturer presentation at the Twentieth Convocation of the Royal Australasian College of Dental Surgeons, Perth, Western Australia. March 2010
Ann Roy Australas Coll Dent Surg 2010;20:98 ANNALS OF THE ROYAL AUSTRALASIAN COLLEGE OF DENTAL SURGEONS VOLUME 20 MARCH 2010 SCIENTIFIC PROGRAMME - PAPERS AND ABSTRACTS CONTRIBUTORS’ INDEX Arora M............................................................90 Koong B ..........................................................88 Bosshardt D......................................................36 Leung YY.........................................................93 Burrow MF.......................................................75 Leziy SS ...........................................................28 Cheung LK.......................................................93 Miller BA .........................................................28 Claes P..............................................................56 Mitchell D ........................................................97 Clement J .........................................................56 Ngo H...............................................................80 Cullinan MP .....................................................86 O’Neill JE ........................................................95 Curtis B ......................................................95, 97 Portnof J ...........................................................71 Daly CG ...........................................................97 Seymour GJ......................................................86 Darby I .............................................................52 Shand JM .........................................................71 Dimmitt SB ......................................................64 Smith A.............................................................50 Fell R................................................................90 Wallman K .......................................................91 Gebauer D ........................................................91 Walters M.........................................................56 Heggie AA........................................................71 Williams PAH ..................................................66 Heitz-Mayfield LJA ...................................89, 95 Williamson R .............................................46, 91 Ho DSW...........................................................92 Wong PD ..........................................................45 Ivanovski S.......................................................82 Woods MG .......................................................89 Kahler B ...........................................................59 Zee K-Y......................................................89, 90 Kilpatrick N .....................................................42 Zhang WT ........................................................97 All rights reserved. No part of this publication may be reproduced in any material form or by any means (graphic, electronic, or mechanical including photocopying, recording, taping, or information and retrieval systems) without the written permission of the Royal Australasian College of Dental Surgeons. Applications for the copyright holder’s written permission to reproduce any part of this publication should be addressed to the College. Photographs taken at the opening ceremony are copyright to Stephen D Barnby, Steve’s Photography, Perth The publication of statements, opinions or other material in this work carries no representation by or on behalf of the Royal Australasian College of Dental Surgeons express or implied of any belief in their truth or otherwise, in whole or in part, unless an express statement to that effect accompanies the item in question. Printed and published by the Proprietors, the Royal Australasian College of Dental Surgeons ROYAL AUSTRALASIAN COLLEGE OF DENTAL SURGEONS Incorporated Level 13/37 York Street, Sydney, New South Wales 2000 Australia Telephone: (02) 9262 6044 Facsimile: (02) 9262 1974 Email: [email protected] Website: http://www.racds.org
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