Alveolar Bone Regeneration Using DentoGen®Wilcko et al After Bone Loss Surrounding a Dental ImplantDr. M. Chen1 • Dr. J. Chesnoiu-Matei2 • Dr. N. Tovar2 • Dr. S. Mamidwar3 AbstractBackground: Regeneration and preservation able bone loss surrounding the den-of alveolar bone surrounding a dental implant tal implant. The patient complained ofis essential for implant success. This process sensitivity to pressure and pain. After placementcan be affected by a number of local and sys- of MGCSH in the defect area, the surround-temic factors. In this clinical case, medical- ing soft-tissue was repositioned using sutures.grade calcium sulfate hemihydrate (MGCSH,DentoGen®, Orthogen, LLC, Springfield, Results: At the one-year follow-up visit, noNJ) was used to repair a bone defect result- gingival recession was observed. Comput-ing from peri-impantitis surrounding a failing erized tomography scan and radiographsdental implant. MGCSH is a bone graft that showed bone had completely healed. Thestimulates bone growth and acts as a mem- patient had no complaints of pain or discomfort.brane barrier to prevent soft-tissue infiltration. Conclusions: MGCSH helped to sta-Methods: Clinical examination revealed bilize the exposed implant by stim-mild peri-implantitis and consider- ulating bone growth around it.KEY WORDS: Bone Regeneration, Calcium Sulfate, Bone Graft, Dental Implant, Peri-implantitis. 1. California Center for Implant Dentistry, San Jose, CA, USA2. New York University College of Dentistry, New York, NY, USA 3. Orthogen, LLC, Springfield, NJ, USA The Journal of Implant & Advanced Clinical Dentistry • 49
Chen et al INTRODUCTION interface from soft tissue, epithelium and gingi- val corium.14,15 Medical Grade Calcium SulfatePeri-implantitis is associated with soft tissue Hemihydrate (MGCSH) (DentoGen®, Orthogeninflammation, bleeding, suppuration, and rapid LLC, Springfield, New Jersey, USA) is a bonebone loss surrounding implants. Left untreated, graft material that can also be used as a mem-it could lead to failure of the implant. Typical brane barrier. Thus separating the bone andtreatment modality includes access flap proce- implant structures from soft tissue. MGCSHdures,1 local or systemic antibiotic treatment2,3 can either be used alone as a bone graft, com-and decontamination of the exposed implant bined with allogenic or autogenous tissue as asurface.1,3 Guided bone regeneration (GBR) is binder, or as both a binder and membrane.16,17often then attempted to restore bone around theimplant for re-osseointegration.4 GBR is a surgi- MGCSH has been used as a bone graft forcal procedure primarily associated with implant over 110 years.18 It is completely biodegrad-cases that present with bone defects such as able, osteoconductive,17 and does not causedehiscence and fenestration.4 The goal of bone an inflammatory response.19 Two concurrentregeneration therapy is to restore the height and mechanisms are triggered by the degradationwidth of the lost bone around natural teeth and of MGCSH. The first mechanism involves thedental implants that are at risk of survival.5 Sev- release of calcium and sulfur ions in the defecteral GBR interventions have been investigated to area; this results in the formation of carbonateregenerate alveolar bone and promote re-osseo- apatite20 and stimulation of calcium ion cellularintegration using various bone graft materials activity.21 The precipitation of carbonate apatiteand/or by the placement of a barrier membrane.3 leads to a temporary, local drop in pH. This drop causes demineralization of the surface of exist- Rapid alveolar bone regeneration is essen- ing bone resulting in exposure of bioactive mol-tial for the re-osseointegration of a dental implant ecules and the release of growth factors andthat lacks bony support as a result of trauma bone morphogenetic proteins (BMPs). Theseor disease. Regeneration is orchestrated by proteins further stimulate the growth of bone inthe careful conservation of the wound heal- defects filled with CS21-24. This clinical case dis-ing process which can be affected by infec- cusses the use of MGCSH as both a graft andtion of the extracted tooth,6 difficulty during a barrier membrane as the method of interven-tooth extraction,7-9 the patient’s age,8,10 heavy tion for bone regeneration in a case of bone losstobacco use,11 and/or allergy.12 Once a den- surrounding a single maxillary dental implant.tal implant is placed, the implant-bone interfacemust be preserved to prevent implant failure. CASE REPORT Since soft tissue grows fifteen times faster A Caucasian female, age 33, presented complain-than woven bone, it can interfere with the regen- ing of localized discomfort and sensitivity to pres-eration of bone and prevent the bond between sure on a central maxillary incisor dental implantthe implant and bone.13 Therefore, in order to that replaced tooth #8. She could not bite or putfacilitate the regenerative process, a membrane pressure on the tooth. The overall medical his-barrier can be used to isolate the bone-implant50 • Vol. 4, No. 3 • May/June 2012
Chen et alFigure 1A: Dental implant threads exposed. Figure 1B: MGCSH bone graft material placed over the implant and surrounding defect area.tory of the patient was normal and no contrain-dication in medication intake was reported. The Figure 1C: Soft tissue repositioned and placed over thedental implant was placed two years prior to the graft.onset of this event by a periodontist. Intra-oralclinical examination revealed a grayish area on field, New Jersey, USA) was placed over thethe facial aspect of the implicated region. Threads exposed surface (Figure 1B) functioning as bothof the implant were exposed through the gingi- a bone graft and a barrier. A non-resorbable con-val tissue on the labial side. On palpation of the tinuous suture (Cytoplast, Osteogenics Biomedi-area, mild edema and bone loss were felt around cal, Lubbock, Texas, USA) was used to repositionthe implant. The tissue was irritated and exhib- surrounding soft tissue over the MGCSH siteited mild swelling. Probing around the implant (Figure 1C). The patient was advised to takerevealed no pocketing or communication with the oral clindamycin 150mg 4 times a day for 5 daysfenestration defect; however, there was sensiti- with the first dose given the day before surgery.zation upon mastication. Implant was not mobile. Pain medication was prescribed on the day of surgery. Instructions concerning basic oral After discussing different treatment alter-natives, the conclusive approach was to per-form a bone regeneration technique withan attempt to restore the dental implant. Local anesthesia with Lidocaine was given tothe patient. The implant was fully exposed usingapical surgery procedures (Figure 1A). The fen-estration area was rinsed with sterile saline solu-tion. MGCSH putty, formed by adding saline toMGCSH, (DentoGen® Orthogen, LLC, Spring- The Journal of Implant & Advanced Clinical Dentistry • 51
Chen et alFigure 1D: Radiograph 1 year after surgery.hygiene were given to the patient, and the patient Figure 1E: CT scan demonstrates the growth of bonewas advised to not brush teeth for 24 hours. surrounding the implant after 1 year. At the follow-up visits, patient had no com- In this case report, MGCSH was success-plaints. The site was seen to be healing well fully used as both a graft and a membrane toon clinical examination. At the one-year follow- enhance the bone growth process by separatingup visit, radiographs showed bone had fully soft tissue from the dental implant-bone interface,grown around the implant (Figure 1D). The hence allowing the stimulation and formation ofpatient no longer complained of discomfort blood vessels and preventing tissue ingrowth. Atand the area was no longer sensitive, uncom- the one-year follow-up visit, no gingival recessionfortable or painful when masticating. A hard or inflammatory response was observed. Basedstructure resembling bone was felt on clinical on radiographic analysis, CT evaluation and clini-examination of the area, and CT scan evalua- cal examination, the bone had completely healedtion of the site confirmed the presence of bone. and the patient showed no signs of pain or dis- comfort. There was no sensitization upon touch or DISCUSSION mastication. Jovanovic25 followed a treatment regi- men consisting of the removal of tissue granula-The careful and rapid regeneration of bone in adefect area is essential in normalizing implantfunction. The combination of antimicrobial treat-ment and GBR techniques has routinely beenused for treating bone loss surrounding implantsas a result of peri-implantitis. MGCSH is a bonegraft material that can be used alone, as a binderwith other bone graft materials, or as a membranebarrier to separate a defect area from soft tissue.52 • Vol. 4, No. 3 • May/June 2012
Chen et altion, preparation of the implant surface, and the indications in implant dentistry with excellentplacement of expanded polytetrafluouroethylene efficacy and predictability.28 Previous research(ePTFE) barrier membranes, which resulted in has shown that calcium sulfate is biodegrad-the effective treatment of bone defects formed able, biocompatible and osteoconductive. Itaround implants in dogs. Carpio et al.26 con- stimulates formation of blood vessels in theducted a controlled clinical study compar- defect area29 and causes the release of growthing collagen barrier membranes versus ePTFE factor from the surrounding defects. The com-barrier membranes to treat peri-implant bone bination of these mechanisms makes calciumdefects. Xenograft or autograft was used to fill sulfate an effective bone graft. The results ofthe bone defects. The results of this study prove this case study and a review of the literaturethat both collagen and ePTFE barriers are suit- confirm that the following treatment modality isable for achieving GBR of osseous defects sur- effective in treating peri-implant bone defectsrounding dental implants. In another case report formed as a result of peri-implantitis: 1) Flappublished by Scarano et al.27 calcium sulfate Surgery; 2) Cleaning of the peri-implant area;was grafted to treat the peri-implant bone defect 3) Local or systemic antimicrobial treatment;in a 47-year old patient. After 4 months, at the 4) Placement of effective bone graft and bar-time of abutment placement, a small biopsy was rier membrane in the bone defect. MGCSHobtained from the interface of bone and implant. is an effective alternative for this purpose.Transmission electron microscopy of the biopsyconfirmed complete resorption of grafted cal- CONCLUSIONScium sulfate and the presence of mature vitalbone. Similar results were seen by Paolanto- In this surgical case report, medical gradenio et al.17 who used pure MGCSH as a graft calcium sulfate hemihydrate (MGCSH) wasand membrane barrier to regenerate bone in found to be an effective bone graft and mem-periodontal intrabony defects. They showed brane barrier with the ability to provide radio-that there is significant improvement in probing graphic evidence of bone regeneration in adepth, clinical attachment level, gingival reces- dental implant-bone interface. MGCSH is asion and residual bone level when compared cost-effective option with simple handling char-to open flap debridement.17 In a study con- acteristics that prevents soft tissue ingrowthducted by Aichelman-Reidy et al.7, as a binder and assists in the regeneration of bone. ●with demineralized freeze-dried bone allograftmaterial and membrane, MGCSH was shown Correspondence:to promote the bone formation in patients with Dr. Mike Chenchronic periodontitis. After 6 months there California Center for Implant Dentistry, Sanwas a reduction in probing depth and gains in Jose, CA, USAclinical attachment level and bone defect level. Phone: 408‐629‐6704 Email: [email protected] Calcium sulfate has been used quite exten-sively for bone regeneration for a variety of The Journal of Implant & Advanced Clinical Dentistry • 53
Chen et alDisclosure 16. O rsini M, Orsini G, Benlloch D, Aranda JJ, Sanz M. Long-term clinical resultsThe authors report no conflicts of interest with anything mentioned in this paper. on the use of bone-replacement grafts in the treatment of intrabony periodontal defects. Comparison of the use of autogenous bone graft plus calciumReferences sulfate to autogenous bone graft covered with a bioabsorbable membrane. J1. B arboza EP, Caula AL, Carvalho WR. Crestal bone loss around submerged Periodontol 2008;79(9):1630-7. and exposed unloaded dental implants: a radiographic and microbiological 17. P aolantonio M, Perinetti G, Dolci M, Perfetti G, Tete S, Sammartino G, descriptive study. Implant Dent 2002;11(2):162-9. Femminella B, Graziani F. Surgical treatment of periodontal intrabony defects with calcium sulfate implant and barrier versus collagen barrier or open flap2. M ombelli A, Lang NP. Antimicrobial treatment of peri-implant infections. Clin Oral debridement alone: a 12-month randomized controlled clinical trial. J Periodontol Implants Res 1992;3(4):162-8. 2008;79(10):1886-93.3. P ersson LG, Berglundh T, Lindhe J, Sennerby L. Re-osseointegration after 18. P eltier LF. The use of plaster of Paris to fill defects in bone. Clin Orthop treatment of peri-implantitis at different implant surfaces. An experimental study in 1961;21:1-31. the dog. Clin Oral Implants Res 2001;12(6):595-603. 19. al Ruhaimi KA. Effect of adding resorbable calcium sulfate to grafting materials4. O h TJ, Meraw SJ, Lee EJ, Giannobile WV, Wang HL. Comparative analysis of on early bone regeneration in osseous defects in rabbits. Int J Oral Maxillofac collagen membranes for the treatment of implant dehiscence defects. Clin Oral Implants 2000;15(6):859-64. Implants Res 2003;14(1):80-90. 20. Chan H MD, Ricci JL. In Vitro Dissolution of Calcium Sulfate: Evidence of5. G uarnieri R, Pecora G, Fini M, Aldini NN, Giardino R, Orsini G, Piattelli A. Bioactivity. Transactions of 7th World Biomaterials Congress 2004:627. Medical grade calcium sulfate hemihydrate in healing of human extraction sockets: clinical and histological observations at 3 months. J Periodontol 21. R icci J, Alexander H, Nadkarni P, Hawkins M, Turner J, Rosenblum S, Brezenoff 2004;75(6):902-8. L, Deleonardis D, Pecora G. Biological mechanisms of calcium sulfate replacement by bone. Bone Engineering, edited by J. Davies, Toronto, Ont.,6. a l-Khateeb TL, el-Marsafi AI, Butler NP. The relationship between the indications Canada: em squared Inc.; 2000. for the surgical removal of impacted third molars and the incidence of alveolar osteitis. J Oral Maxillofac Surg 1991;49(2):141-5; discussion 145-6. 22. Carinci F, Piattelli A, Stabellini G, Palmieri A, Scapoli L, Laino G, Caputi S, Pezzetti F. Calcium sulfate: analysis of MG63 osteoblast-like cell response7. A ichelmann-Reidy ME, Heath CD, Reynolds MA. Clinical evaluation of calcium by means of a microarray technology. J Biomed Mater Res B Appl Biomater sulfate in combination with demineralized freeze-dried bone allograft for the 2004;71(2):260-7. treatment of human intraosseous defects. J Periodontol 2004;75(3):340-7. 23. Q uarles LD. Cation sensing receptors in bone: a novel paradigm for regulating8. F ield EA, Speechley JA, Rotter E, Scott J. Dry socket incidence compared after a bone remodeling? J Bone Miner Res 1997;12(12):1971-4. 12 year interval. Br J Oral Maxillofac Surg 1985;23(6):419-27. 24. Walsh WR, Morberg P, Yu Y, Yang JL, Haggard W, Sheath PC, Svehla M,9. Turner PS. A clinical study of “dry socket”. Int J Oral Surg 1982;11(4):226-31. Bruce WJ. Response of a calcium sulfate bone graft substitute in a confined cancellous defect. Clin Orthop Relat Res 2003(406):228-36.10. MacGregor AJ. Aetiology of dry socket: a clinical investigation. Br J Oral Surg 1968;6(1):49-58. 25. Jovanovic SA, Kenney EB, Carranza FA, Jr., Donath K. The regenerative potential of plaque-induced peri-implant bone defects treated by a submerged11. M eechan JG, Macgregor ID, Rogers SN, Hobson RS, Bate JP, Dennison M. membrane technique: an experimental study. Int J Oral Maxillofac Implants The effect of smoking on immediate post-extraction socket filling with blood and 1993;8(1):13-8. on the incidence of painful socket. Br J Oral Maxillofac Surg 1988;26(5):402-9. 26. Carpio L, Loza J, Lynch S, Genco R. Guided bone regeneration around12. Sicilia A, Cuesta S, Coma G, Arregui I, Guisasola C, Ruiz E, Maestro A. endosseous implants with anorganic bovine bone mineral. A randomized Titanium allergy in dental implant patients: a clinical study on 1500 consecutive controlled trial comparing bioabsorbable versus non-resorbable barriers. patients. Clin Oral Implants Res 2008;19(8):823-35. JPeriodontol 2000;71(11):1743-9.13. Wang HL, Boyapati L. “PASS” principles for predictable bone regeneration. 27. S carano A, Orsini G, Pecora G, Iezzi G, Perrotti V, Piattelli A. Peri-implant bone Implant Dent 2006;15(1):8-17. regeneration with calcium sulfate: a light and transmission electron microscopy case report. Implant Dent 2007;16(2):195-203.14. E l Helow K, El Askary Ael S. Regenerative barriers in immediate implant placement: a literature review. Implant Dent 2008;17(3):360-71. 28. K utkut A, Andreana S. Medical-grade calcium sulfate hemihydrate in clinical implant dentistry: a review. J Long Term Eff Med Implants 2010;20(4):295-301.15. W ang HL, Greenwell H, Fiorellini J, Giannobile W, Offenbacher S, Salkin L, Townsend C, Sheridan P, Genco RJ. Periodontal regeneration. J Periodontol 29. Strocchi R, Orsini G, Iezzi G, Scarano A, Rubini C, Pecora G, Piattelli A. Bone 2005;76(9):1601-22. regeneration with calcium sulfate: evidence for increased angiogenesis in rabbits. J Oral Implantol 2002;28(6):273-8.54 • Vol. 4, No. 3 • May/June 2012
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An Evaluation of the Accuracy of Multiple ImplanWtilcko et al Impression Techniques: An in Vitro StudyDr. Manesh Lahori1 • Dr. Lanka Mahesh2 • Dr. Rahul Nagrath3 • Shweta Singh4AbstractBackground: Movement of impression copings ADA type III stone. A single calibrated examinerinside the impression material using an open-tray blinded to the nature of the impression techniqueimpression technique during clinical and labora- used examined all definitive casts to evaluate thetory phases may cause inaccuracy in transferring positional accuracy (mm) of the implant analogsthe 3-dimensional spatial orientation of implants using a profile projector (at original magnifica-intraorally to the definitive cast. Consequently tion ×10). These measurements were comparedthe restoration may require corrective proce- to the measurements calculated on the refer-dures. This in vitro study evaluated the accuracy ence resin model which served as control. Dataof 3 different impression techniques using poly- were analyzed with a 1-way analysis of variance.vinylsiloxane impression material to obtain aprecise definitive cast for a multi-unit implant res- Results: No significant difference was foundtoration with multiple internal connection implants. among the 3 groups. Group NM and group SB variation from the acrylic resin model was greaterMaterials and Methods: A reference acrylic than that of group S. The distance was 70 µm (SDresin model with 4 internal connection implants ± 15.8) greater on group NM casts, 44µm (SDwas fabricated. Fifteen impressions of this model ±39.1) greater on group S casts, and 48µm (SDwere made with square impression copings using ± 32.7) greater on group SB casts. group NM andan open-tray technique. Three groups of 15 speci- group SB variation from the acrylic resin modelmens were made with different impression tech- was greater than that of group S. The distance wasniques: in the first group, nonmodified square 124 µm (SD ± 55.5) greater on group NM casts,impression copings were used (NM group); in the 92µm (SD ± 58.9) greater on group S casts,second group, square impression copings were and 124µm (SD ± 55.5) greater on group SB.used and joined together with autopolymerizingacrylic resin before the impression procedure (S Conclusions: Within the limitations of thissplinted group); and in the third group, sandblasted study, using a 4-implant model, the accuracysquare impression copings and coated with adhe- of casts obtained by impressions of internalsive were used (SB group). Implant analogs were connection implants, was similar for splintedscrewed into the square impression copings in and sandblasted square impression copings.the impressions. Impressions were poured withKEY WORDS: Dental implants, prosthodontics, impression techniques, impression materials1. Professor and Head, Department of Prosthodontics, KD Dental College, Mathura, India 2 Private practice, New Delhi, India 3. Senior Lecturer, Department of Prosthodontics, KD Dental College, Mathura, India 4. Post Graduate Deptartment of Prosthodontics, K.D Dental College Mathura, India The Journal of Implant & Advanced Clinical Dentistry • 57
Lahori et alFigure 1: Reference acrylic resin model with implants Figure 2: Primary cast.numbered 1 to 4 (right to left). nique and the direct(open tray) technique.2 INTRODUCTION The indirect technique may be less difficult clinically; however it has been shown to haveDental implants have become a quite success- greater instability in transferring the implantful method for restoration of fully and partially position.3 The open tray technique allows foredentulous patients. An important factor for the impression coping to remain in the impres-success with implant-supported restoration is sion. This reduces the effect of implant angula-the passive fit between the superstructure and tion, the deformation of the impression materialthe abutments. Reproducing the intraoral rela- upon recovery from mouth, and removes thetionship of implants through impression proce- concern for replacing the coping back intodures is the first step in achieving an accurate, its respective space in the impression.1passively fitting prosthesis. The critical aspectis to record the 3-dimensional orientation of Movement of impression copings insidethe implant as it occurs intraorally, rather than impression material during clinical and labo-reproducing fine surface detail. The accu- ratory phases may cause inaccuracy in trans-racy of impression procedure lies in reproduc- ferring 3-dimensional spatial orientation ofing the intraoral relationship of the fixtures so implants intraorally to definitive cast. To ensurethat same could be transferred to the cast so maximum accuracy, the importance of splintingthat a passive framework could be fabricated.1 transfer copings and coping modification before recording of the definitive impression has been Several impression techniques have been emphasized.2 The materials used to splint cop-advocated to achieve a definitive cast that ings are composite resin, plaster, or acrylicwill ensure the passive fit of a prosthesis on resin.4 Several authors advocate connecting theosseointegrated implants. There are two pri-mary techniques: the indirect(closed tray) tech-58 • Vol. 4, No. 3 • May/June 2012
Lahori et alFigure 3: Base plate relief wax over the implant area. Figure 4: Thermoplastic sheet was adapted over cast.Figure 5: Two-part mold of silicone impression material in Figure 6: Custom tray over reference model.a dental flask. that splinted technique had inaccurate resultsimpression copings together prior to impres- because splinted techniques use a large amountsion making with acrylic resin to provide the of acrylic resin that can cause distortion due tobest result. Different techniques for splinting resin shrinkage during polymerization. There-implant transfer copings with acrylic resin have fore pattern resin has been given preference inbeen tested such as scaffold of dental floss, some studies because of its low polymerisationprefabricated acrylic resin bars, and stainless shrinkage.4 There is an alternative procedure insteel burs.5 However, some authors suggested The Journal of Implant & Advanced Clinical Dentistry • 59
Lahori et alimpression making for implant-supported pros- tic sheet of 2 mm was adapted over this casttheses that employ square impression copings (fig. 4) to ensure uniform thickness of customthat have been sandblasted to roughen their trays. A two-part mold was fabricated with theexternal surfaces at a supragingival level and thermoplastic sheet and putty addition siliconethen coated with adhesive. This is done to avoid impression material in a dental flask (fig. 5) tothe possibility of the coping rotating inside the make identical 2mm thick replicate trays. Theimpression at the moment of analog screwing. custom trays were made with autopolymeris- ing tray resin. The trays were perforated in the The purpose of the study was to evalu- region where implants were placed to pro-ate the accuracy of multiple implant impres- vide access for the pick-up copings (fig. 6).sion techniques using square impressioncopings, splinted impression copings and Impression Procedures: The impressionsandblasted impression copings coated with trays were coated with manufacturer recom-adhesive so as to obtain a precise defini- mended impression adhesive 5 min beforetive cast for a multi-unit implant restoration. each impression was made. Tray adhesive was applied thinly and evenly over the inner surface MATERIALS AND METHODS of each tray and extended approximately 3 mm onto the outer surface of the tray along periph-Fabrication of the Reference Cast: An ery. The adhesive was allowed to dry for 15acrylic resin edentulous model of maxil- min before impression. The impression copingslary arch was fabricated for the study (fig. were secured on the implants using a torque1). Four internal connection 3.75× 11mm wrench calibrated at 10 N-cm. Fifteen polyvi-implants were placed in acrylic resin model. nylsiloxane impressions were made accordingThe 4 implants in the acrylic resin model to the manufacturer’s directions using one-stepwere sequentially numbered 1 through 4 from technique. The heavy consistency polyvinylsi-left to right. Three location marks (2 ante- loxane impression material was loaded insiderior marks and 1 posterior mark) were made the impression tray and light consistency poly-on base of acrylic resin model to standard- vinylsiloxane impression material was meticu-ize tray positioning during impression making. lously syringed around the impression copings to ensure complete coverage of the copings.Fabrication of Custom Trays: A primary The impression of the reference resin modelcast analog (fig. 2) to the reference model was was made until the tray was fully seated onpoured in type III stone and utilized for the pro- the 3 location marks and maintained in posi-duction of the custom trays. The implant area tion throughout the polymerization time. Impres-on cast was covered by 2 layers of base plate sion material was allowed to set for 12 minwax (fig. 3) to allow consistent thickness of from the start of mixing to compensate for theimpression material and palatal region acts as delayed polymerization time at room tempera-stop. An irreversible hydrocolloid impression of ture. After the impression material had set, thecast was made to obtain another cast on whichall custom trays were molded. A thermoplas-60 • Vol. 4, No. 3 • May/June 2012
Lahori et alscrews were loosened and the trays removed dardized gap space was left between the singlewith the transfer copings retained in them. pieces. The square impression copings wereFive impressions with square impression cop- then readapted to the implants in resin modelings were made for each of 3 different impres- and resplinted with same acrylic resin. Thesion techniques represented by the 3 groups. impression procedure was then accomplished. In the first group, impression copings as In the third group, (SB) impression cop-supplied by the manufacturer were used (non- ings were abraded with 50 µm aluminium oxidemodified square impression copings: NM particles at 2.5 atm pressure to roughen theirgroup). Each impression tray was seated, external surface and coated with adhesive andand the material was allowed to polymer- the impression procedure was accomplished.ize. The guide pins were released so that Implant analogs were fastened to the impres-the transfer copings remained in the impres- sion copings in the impressions. A 100 gm Typesion when the impression was removed. III dental stone was mixed with 22 ml of distilled water in amounts recommended by the manu- In the second group (S group), square facturer and poured into each. The casts wereimpression copings were splinted with dental retrieved from the impressions after 2 hour.floss and autopolymerising acrylic resin. Thetransfer copings were tied up with four com- DIFFERENT IMPRESSIONplete loops of dental floss and splinted with TECHNIQUE GROUPSautopolymerising acrylic resin (Pattern resin)and allowed to set for 3 minutes. Seventeen All casts were stored at room temperature forminutes after setting, the acrylic resin sub- a minimum of 24 hours before measurementsstructure and splinted transfer copings were were made. All clinical and laboratory proce-removed from the framework and the splints dures were performed by the same operator.were sectioned into 4 separate pieces with a Cover screws were fastened on implant analogshandpiece diamond disk and a 0.2-mm stan- and all definitive casts were evaluated for theFigures 7a-c: GROUP S - Nonmodified square impression copings rigidly splinted with pattern resin prior to impressionprocedure. The Journal of Implant & Advanced Clinical Dentistry • 61
Lahori et alFigure 8: GROUP NM - Nonmodified square impression Figure 9: GROUP SB - Sandblasted square impressioncopings. copings.Figure 10: Open tray impression with pick-up. Figure 11: I mpression with analogs in place.positional accuracy of the implant analogs using magnified image of the object onto the screena profile projector (Dynascan Profile Projec- in the form of a shadow (original magnificationtor). The profile projector consists of a screen × 10). The profile projector allows measure-with horizontal and vertical reference lines and ment of linear distances with an accuracy ofwas equipped with a light source to project a 2 µm. Two measurements were made per speci-62 • Vol. 4, No. 3 • May/June 2012
Lahori et alFigure 12: Cast with analogs. Figure 13: Measurement of distances between the analogs with profile projector.men and measurements were performed bysame operator to minimize source of error. 3. A one-way statistical analysis of vari- ance (ANOVA) was performed to ana- The following measurements were evalu- lyze the difference among 3 groups.ated on the reference control acrylic resinmodel and the definitive cast replicas (fig. 13): With the use of the profile projector, numerical1. The distance between the external sharp difference in distance between implants was evaluated. Distances between the 2 posterior edges of the projected silhouetted form of implants were all different than those recorded the cover screw of left and right posterior on the resin model; group NM and group SB implants (1 and 4). variation from the acrylic resin model was2. The distance between external sharp edges greater than that of group S. The distance was of the projected silhouetted form of the 70 µm (SD ± 15.8) greater on group NM casts, cover screw of left and right anterior 44µm (SD ±39.1) greater on group S casts, and implants (2 and 3). 48µm (SD ± 32.7) greater on group SB casts.RESULTS Distances between the 2 anterior implants were different than those recorded on the1. Horizontal distances measured between pos- resin model; group NM and group SB varia- terior implants (no. 1 and 4) were obtained tion from the acrylic resin model was greater and then the mean was calculated for all than that of group S. The distance was 124 3 groups of impression techniques. µm (SD ± 55.5) greater on group NM casts, 92µm (SD ± 58.9) greater on group S casts,2. Horizontal distances measured between and 124µm (SD ± 55.5) greater on group SB. anterior implants (no. 2 and 3) were obtained and then the mean was calculated for all Results are further described 3 groups of impression techniques. in Tables 1a-b and Graphs 1a-b. DISCUSSION The objective of making an impression in implant dentistry is to accurately relate an analog of the The Journal of Implant & Advanced Clinical Dentistry • 63
Lahori et alTable 1a Table 1bimplant or implant abutment to the other structures techniques showed more accuracy with pick-in the dental arch. This is affected by use of an up technique,6-9 than with transfer technique.10,11impression coping which is attached to the implantor implant abutment. The impression coping takes Different modifications are recommended bytwo general forms- transfer and pick up. Charac- various authors to increase impression accuracyteristics of transfer type impression coping are that while recording an implant impression to avoidthey remain in the mouth on removal of set impres- the movement of the impression coping andsion, the analog is attached to the impression cop- transfer the three dimensional spatial orienta-ing after removal from mouth and this assembly is tions of the implants positions thereby ensur-replaced in the indentation left on set impression. ing accuracy of master casts. Some authorsNo custom tray is required for this type of impres- advocate connecting the impression copingssion. Characteristics of the pickup type impres- together intra orally prior to impression makingsion coping are that they are removed from mouth with acrylic resin5,7,10,12 and others advocatedtogether with impression. They require access to treatment of impression copings with air-bornethe retaining screw to allow release of the screw particle abrasion and impression adhesive.13-18prior to removal of the impression coping — impres-sion assembly; the analogs are attached to the Custom autopolymerising acrylic resin traysimpression copings while they are embedded in were utilized in present study because elas-the impression tray. A custom tray with access tomeric materials are more accurate if usedto the impression coping screws is required. in 2 to 3 mm of uniform thickness in elasto- meric impression techniques. The shrinkage Many articles have been written and of impression material from the impressionmany in vivo studies have been carried out specimen during setting would be magni-to improve the fidelity of impressions over fied with greater bulks of impression material,the use of pick up type impression cop- because of the impression material preferen-ings alone. Various studies comparing accu- tially adhering to the tray rather than the speci-racy of pick-up and transfer impression men.19 All the custom trays in the study were perforated because the bonding strength64 • Vol. 4, No. 3 • May/June 2012
Lahori et alFigures 14 a-c: Equipment used for data measurement and recording.of adhesives used with can be improved was more accurate than two-step.20 There arenearly 50% by adding perforations to the tray. no significant differences with regard to preci- sion between the one- and the two-step tech- In the study, addition silicone was applied by niques using a-silicones (Hung et al.1992;20means of the one-step technique. Both heavy Idris et al. 199521) and one step technique isbody and light body material were mixed simul- easier to perform, time saving clinically. Accord-taneously while impression making to avoid ing to Wenz, the 2-step VPS impression wasearly partial polymerization of any of the mate- significantly less accurate than 1-step puttyrial. Acc to Hung et al., accuracy of the one- and light-body VPS combination impression.22step impression technique was not differentfrom the two-step impression technique except Elastomeric impression materials have beenat one of the six dimensions where one-step found to be highly accurate without splinting The Journal of Implant & Advanced Clinical Dentistry • 65
Lahori et alimpression copings. Acc to Hung et al. the pre- shrinkage, it is somewhat surprising to learncision of addition reaction silicones was more that it does not affect transfer impression tech-dependent on the material than on the tech- niques adversely under the conditions of thesenique.20 Various impression materials were experiments. These observations find supporttested, but polyether and VPS were used most in other studies where it was found that splint-frequently. Vinyl polysiloxane impression materi- ing had no consequence in the transfer tech-als have been widely accepted because of their niques that were investigated. Many authorsexcellent dimensional stability, superior recovery have reported that splinting the copings didn’tfrom deformation, and precise reproduction of significantly improved the impression accuracy.details. There were 11 studies comparing the Phillips and colleagues used a patient modelaccuracy of polyether and VPS and 10 stud- with 5 nonparallel implants and concludedies reported that the accuracy did not differ. that the amount of displacement between non- splinted groups and the autopolymerising resin Many authors recommended splinting of splinted groups while making impressions wassquare impression copings while recording not stastically significant. Inturregui et al. andan implant impression for accurate spatial ori- Burawi et al. even reported that the splintedentation of implant positions. Different tech- technique exhibited more deviation from theniques for splinting impression copings with master model than the unsplinted techniqueacrylic resin have been tested, such as a scaf- did, and this was primarily associated with rota-fold of dental floss, prefabricated acrylic resin tional discrepancies around the long axes ofbars, orthodontic wire and stainless steel burs. the implants for the splinted technique. ThereDistortion associated with splinted transfer was a lack of significant differences betweentechniques can be related to residual polym- the techniques with respect to distortions dur-erization contraction of the acrylic resin used ing transfer procedures. However, connectingfor splinting. In the present study splinting the impression copings with acrylic resin is awith scaffold of dental floss along with pat- time consuming procedure. The results of thistern resin was used because of the low polym- study suggest that displacement of the internal-erization shrinkage of 0.37 % of pattern resin. connection impression copings during impres-In the study, pattern resin splint was sectioned sion removal and replica connection in theand resplinted in order to further minimize any direct nonsplinted technique can be controlleddiscrepancies due to polymerization shrink- by the elastic impression material and an expe-age. Mojon et al, have stated that the dimen- rienced practitioner to an extent similar to thatsional behaviour of resin, when separation and observed with the direct splinted technique.reuniting are done 17 minutes after the settingreaction, allows considerable reduction (80%) Vigolo et al. evaluated in vitro accuracy ofin the effects of polymerization shrinkage. definitive casts obtained from transfer impres- sions using square copings for replacement of It appears from the data of present study one tooth. The author concluded that impres-that splinting, per se, has little or no bearing sion transfer accuracy increases when copingson the results obtained. With polymerization66 • Vol. 4, No. 3 • May/June 2012
Lahori et alare air-borne particle abraded and adhesive For the nonsplinted group displacementcoated. In the current study the results of group is more as compared to splinting because theSB (Sandblasted and coated with adhesive) assembly was maintained only by the impres-were different than expected as there is no sig- sion material in the nonsplinted group. Fornificant difference between reference model the nonsplinted group, the distortion mainlyand sandblasted technique. The present study resulted from polymerisation-related shrinkagefindings are in contrast to the results of Vigolo of the impression material. The amount of theet al. from 200014 and 200315 but are in accor- displacement of each implant replica while fab-dance with 2004 findings of Vigolo et al.15 It ricating a definitive cast could be due to linearcould be hypothesized that the square design of setting expansion of dental stone. The expan-the impression copings was sufficient to stabi- sion of dental stone during setting can displacelize the material with no need for the additional impression coping-analog assemblies. Thereprocedure of sandblasting and adhesive coat- is very little chance of displacement of impres-ing square impression coping. These obtained sion coping-analog assemblies because of theresults could be due to the adhesive-coated setting expansion of dental stone with splinting.layer, which may make the copings’ surfaceless rough and could allow greater movement In the present study, the use of the 2of the copings, so that the mechanical union selected measurements between the externalbetween the impression material and rough edges of the most mesial and distal implantssurface is higher than with the adhesive layer. were dictated by the fact that this evaluation didThe results showed no difference between not require positional changes of the cast dur-square impression copings and sandblasted ing the measurements. Further assessmentssquare impression coping, therefore extra time such as the distance between the mesial andinvolved should be considered unnecessary. distal implants on one side or the other involvedThus from the results it could be suggested that various adjustments of the cast position werewhen using nonmodified or sandblasted square not done, which would have introduced an addi-impression coping, an accurate working cast is tional source of error to the measurements.more likely to be made. Nevertheless the clini-cian should choose less time consuming tech- It is of interest that throughout this investiga-nique (nonmodified) since it is much easier to tion, an exact reproduction of implant positionperform. This technique can be chosen when an was never accomplished. Interimplant distancesimmediate loading multiple implant impression in casts of both the groups (S and SB) alwayshas to be done, because in these cases, intra- varied. Clinically, this implies that precise fitorally splinting the square impression copings of a superstructure may be unattainable onwith floss and acrylic resin is not the preferred definitive casts from any impression techniqueoption, and there is the risk of interfering with and laboratory procedure currently in use andthe healing process of the recently operated that the terms precision and fit are relativetissue with the contact of the resin monomer. to the clinical assessment by the operator. Possible limitations of the present study design were that the measured distortions The Journal of Implant & Advanced Clinical Dentistry • 67
Lahori et aldid not completely evaluate the actual three- stastically similar to each other. There wasdimensional distortion of the impressions and no statistically significant difference amongthe axial rotations of the components were the casts produced by different test groups.not detected. In present study, the discrep- 3. S election of impression technique canancies were evaluated in a horizontal plane be based on the clinical situation andbetween paired implants. Under clinical con- the individual clinician’s preference.ditions and in multiple implant restorations, Further clinical investigations will be nec-these differences may vary if the discrepancies essary to confirm the results of the pres-are present in other spatial planes and if they ent in vitro study. Further studies are requiredoccur in opposite dimensions. Moreover, the to evaluate different impression materi-results of the present investigation were lim- als and implant impression techniquesited to a number of four implants and may not related to different clinical situations. ●be relevant for impressions made in the pres-ence of higher or lower numbers of implants. Correspondence: Dr. Manesh Lahori Professor and Head, Department of Prosthodontics CONCLUSIONS KD Dental College Mathura, UP, India Within the limitations of this study, Phone: 09810770434,the following conclusions were drawn: Email: [email protected]. When impressions made with nonsplinted, splinted and sandblasted impression cop- ings were compared, the casts obtained from splinted impression technique were closest to reference model, followed by sandblasted and nonmodified impression copings.2. T he differences between test groups wereATTENTION PROSPECTIVE AUTHORS JIACD wants to publish your article! For complete details regarding publication in JIACD, please refer to our author guidelines at the following link: http://www.jiacd.com/authorinfo/author-guidelines.pdf or email us at: [email protected] • Vol. 4, No. 3 • May/June 2012
Lahori et alDisclosure AADDVVERETIRSETWISITHEThe authors report no conflicts of interest with anything mentioned in this article. TODAY!References1. C onrad H.J., Pesun I.J., DeLong R., Hodges J.S. Accuracy of two impression Reach more customers with the dental techniques with angulated implants. J Prosthet Dent 2007;97: 349-356. profession’s first2. D el Acqua M.M., Chavez A.M., Amarat A.L., Compagnoni M.M., Mollo F.A. truly interactive Comparison of impression techniques and materials for an implant-supported paperless journal! prosthesis. Int J Oral Maxillofac Implants 2010; 25:771-776.3. A ssuncao W.G., Britto R.C., Barao V.A., Delben J.A., Santos P.H. Evaluation Using recolutionary online technology, of impression accuracy for implant at various angulations. Implant Dent 2010; JIACD provides its readers with an 19:167-174.4. C abral L.M., Guedes CG. Comparative Analysis of 4 Impression Techniques for experience that is simply not available Implants. Implant Dent 2007;16:187-194 with traditional hard copy paper journals.5. N aconecy M.M., Teixeira E.R., Shinkai R.S., Frasca L.C., Cervieri A. Evaluation of the Accuracy of 3 Transfer Techniques for Implant-Supported Prostheses with WWW.JIACD.COM Multiple Abutments. Int J Oral Maxillofac Implants 2004;19:192–198.6. C arr A.B. A Comparison of Impression Techniques for a Five-lmplant Mandibular Model. Int J Oral Maxillofac Implants l991; 6:448-455.7. B arrett M.G., Rijk W.G., Burgess J.O.. The Accuracy of Six Impression Implants. J Prosthodont 1993;2:75-82.8. P hillips K.M., Nicholls J.I., Rubenstein J. The accuracy of three implant impression techniques: A three-dimensional analysis. Int J Oral Maxillofac Implants 1994;9:533-40.9. D el’Acqua M.M., Arioli-Filho J.N., Compagnoni M.M., Mollo F.A. Accuracy of Impression and Pouring Techniques for an Implant-Supported Prosthesis. Int J Oral Maxillofac Implants 2008;23:226–236.10. Humphries R.M., Yaman P., Bloem T.J.. The accuracy of implant master casts constructed from transfer impressions. Int J Oral Maxillofac Implants 1990; 5:331-6.11. D eLaCruz J.E., Funkenbusch P.D., Ercoli C.,Moss M.E., Graser G.N., Tallents R.. Verification jig for implant-supported prostheses:A comparison of standard impressions with verification jigs made of different materials.J Prosthet Dent 2002;88:329-36.12. S pector M.R., Donovan T.E., Nicholls J.I.. An evaluation of impression techniques for osseointegrated implants. J Prosthet Dent 1990;63:444-7.13. H erbst D., Nel J.C., Driessen C.H., Becker P.J.. Evaluation of impression accuracy for osseointegrated implant supported superstructures. J Prosthet Dent 2000; 83:537-5214. V igolo P., Majzoub Z., Cordioli G. In vitro comparison of master cast accuracy for single-tooth implant replacement. J Prosthet Dent 2000;83:562-6.15. Vigolo P., Majzoub Z., Cordioli G.. Evaluation of the accuracy of three techniques used for multiple implant abutment impressions. J Prosthet Dent 2003;89: 186-92.16. Vigolo P., Fonzi F., Majzoub Z., Cordioli G.. An evaluation of impression techniques for multiple internal connection implant prostheses. J Prosthet Dent 2004;92:470-6.17. Vigolo P., Fonzi F., Majzoub Z., Cordioli G. Master cast accuracy in single-tooth implant replacement cases:an in vitro comparison -a technical note. Int J Oral Maxillofac Implants 2005;20:455–460.18. Assunaco G.W., Cardosso A., Gomes E.A., Tabata F.L., Santos P.H.,. Accuracy of impression techniques for implants. Part 1- Influence of transfer copings surface abrasion. J Prosthodont 2008;17:641-647.19. J ohnson G.H., Craig C.G. Accuracy of addition silicones as a function of technique J Prosthet Dent. 1986;55:2 197-203.20. Hung S.H., Daniel E.T., Eick J.D. Accuracy of one-step versus two-step putty wash addition silicone impression technique. J Prosthet Dent 1993;67:583-9.21. Idris B., Houston F., Claffey C. Comparison of the dimensional accuracy of one- and two-step techniques with the use of putty/wash addition silicone impression materials J Prosthet Dent 1995;74:535-41.22. W enz H.J., Hertrampf K. Accuracy of impressions and casts using different implant impression techniques in a multi-implant system with an internal hex connection. Int J Oral Maxillofac Implants 2008;23:39–47.23. L ee H., Hochstedler J.L., Ercoli C. The accuracy of implant impressions: A systematic review. . J Prosthet Dent 2008;100:285-291. The Journal of Implant & Advanced Clinical Dentistry • 69
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