The Art of Block Grafting

Toscano et al Table 1: Comparison of Ramus vs Symphysis block grafting Mandibular Bone Volume Type of Bone Post-Op Complications Symphysis ~5-10cc Corticocancelious Altered incisor sensation = 29% (Intramembranous) Temporary paresthesia = 9.6% ~4-7mm thick ~2cm long Incision dehissence = 10.7% Ptosis ~1cm in height Lip incontinence Mandibular ~5cc Mostly cortical IAN damage Ramus (Intramembranous) Buccal nerve damage ~4mm thick ~3cm long Trismus ~1cm in height Manbibular fracture ing the technique which will achieve the desired superior to the symphysis donor site, patients ridge augmentation needed for dental implants. have reported no altered sensation in their molar teeth after ramus block graft harvest.23,24,30,31 The mandibular ramus donor site is associ- ated with fewer postoperative complications, Graft resorption during healing at the recipi- in comparison to the symphysis region (Table ent site is always a possibility with any bone block 1).23,24,30,31 Misch found that in fifty block graft grafting procedure.32 Resorption rates for both cases the ramus donor site was associated symphysis and ramus grafts using modern tech- with zero complications after 6 months of heal- niques, however, are reported as very miniscule ing. Incision dehiscence during healing at the with published articles finding 0-25% during heal- ramus donor site occurs with comparatively less ing.12,13,17,20,23-25 Using the techniques described frequency. Additionally, patients are less able to in this article the authors have observed near zero discern neurosensory disturbances in the poste- resorption during healing in the majority of cases. rior buccal soft tissues compared with the lower lip and chin.20,23,24 Although the incision along PREOPERATIVE ASSESSMENT the external oblique ridge could damage the buc- AND PREPARATION cal nerve, reports of postoperative sensory loss in the buccal mucosa are rare and will most likely go Proper preoperative assessment is paramount unnoticed by the patient20 In contrast to the teeth to successful execution of symphyseal and ramus buccal shelf graft harvests. As with any 48 Vol. 2, No. 2 March 2010

Toscano et al Resorption Indications Contraindications Advantages Disadvantages 0-25% Ridge augmentation Inadequate donor Access quality Greater post-op for dental implants site without 3-5mm of bone complications 0-25% (Block or particulate) Esthetic concerns “safety zone” to Potential for limited (chin ptsosis) Particulate bone mental nerves, particulate marrow source for peridontal lower border, and incisor apices harvest after regeneration or block removal sinus augmentation Inadequate donor Mostly cortical Access Ridge augmentation site without >1.5cm bone Mostly cortical for dental implants between donor site (Block or particulate) No esthetic bone and IAN concerns Particulate bone source for peridontal regeneration or sinus augmentation surgery, a thorough medical history must be an extraoral exam to rule out any pre-existing reviewed. Elective procedures for treatment esthetic, functional, or neurological defect. The of partial edentulism are generally reserved intraoral exam should begin with assessment of for patients in ASA 1 or ASA 2 physical sta- the recipient site to be augmented, to ensure tus, which includes patients who are systemi- the symphysis or ramus can provide sufficient cally healthy or with only a mild to moderate bone volume for the desired final implant posi- well controlled systemic disease. 33 Patients tion. Pulp testing of the mandibular anterior or with uncontrolled or severe systemic diseases posterior teeth nearby should be performed to should be medically optimized by their physi- ensure no pre-existing pulpal necrosis or peri- cians prior to becoming candidates for these apical pathology exists nearby to the area(s) procedures. Practitioners should proceed with of proposed bone harvest or augmentation. caution in patients who are tobacco users, as well as patients with metabolic diseases which For the symphysis graft an assessment of affect bone metabolism or wound healing when the height of attachment of the mentalis mus- using these procedures, such as diabetes mel- cle, the periodontal, caries, and endodontic litus, osteoporosis, or immunocompromise. health of the mandibular anterior teeth should be made. Also a measurement of the width Clinical examination for a potential sym- and thickness of attached gingiva at the lower physeal or ramus graft patient should include incisors and the depth of the mandibular ante- The Journal of Implant & Advanced Clinical Dentistry 49

Toscano et al rior vestibule should be made to assist in the Figure 1: The “rule of 5’s” of symphysis bone block selecting the appropriate incision design. harvesting respects the surrounding vital structures to prevent damage to the dentition, sensory innervation of For the ramus buccal shelf graft, clinical the mental nerve, and the inferior border of the mandible. assessment is important to identify the location of the inferior alveolar and mental nerve relative beyond the proposed osteotomy margins of the to the graft harvest and recipient sites. The peri- block and the surrounding structures, providing odontal, caries and endodontic health of the man- a margin of safety to prevent potential morbid- dibular posterior teeth should also be assessed. ity.34 Symphyseal thickness measured from the lateral cephalometric radiograph must be suffi- Radiographic examination is extremely cient for obtaining the desired block size with- important to assessing whether a patient’s out violating the lingual cortex of the mandible. specific symphyseal and/or ramus anatomy is sufficient for graft harvest. At a minimum, For the ramus graft it is important to assess preoperative radiographs should include 1) a the distance from the external oblique ridge panoramic radiograph to locate adjacent struc- to the superior aspect of the inferior alveolar tures, 2) periapical radiographs of the man- canal. A minimum distance of 10mm is needed dibular anterior or posterior teeth to rule-out to safely remove a ramus block graft without periapical pathology, 3) a lateral cephalomet- injury to the inferior alveolar nerve. When mea- ric radiograph to assess bone thickness and suring this distance on two-demensional radio- quality of the symphyseal region. Addition- graphs the clinician must be aware that the ally, assessment by conventional or cone-beam external oblique ridge where ramus graft har- computed tomography (CT) is recommended vest is often accomplished is not always the to best evaluate the thickness and quality of most superior point on the panoramic radio- the symphyseal and ramus region across the graph of this region. Additionally the absence entire length and width of the potential har- vest site, as well as the recipient graft site. Examination of the radiographs must ensure that a bone block harvest and fixation of the desired thickness and size will not encroach on surrounding vital structures including the mental foramena (including anterior loops), inferior alve- olar nerve (including mental foramen), the api- ces of the mandibular incisors and canines, the inferior border of the mandible, nor the lingual cortex of the mandibular symphyseal region. For the symphysis graft, the “Rule of 5’s” should be respected in assessing and perform- ing block harvest (Figure 1). This rule requires that at least 5mm of uninvolved bone is present 50 Vol. 2, No. 2 March 2010

Toscano et al Figure 2: Three types of incision design options are Bone block grafting surgery can be a very available for symphysis access. The sulcular approach, the stimulating procedure for many patients. While attached gingiva approach, and the vestibular approach. these procedures can be comfortably delivered under local anesthetic only, anesthetic man- of impacted third molars or retained roots which agement of the patient should be evaluated may complicate harvest should be confirmed. on a case by case basis. Anesthetic options including local anesthetic only, oral sedation, PREOPERATIVE PREPARATION IV conscious sedation, or general anesthesia are appropriate to offer to each patient during Prior to the day of surgery, patients are started the preoperative decision making consultation. on an oral regimen of steroids and antibiotics to prevent postoperative swelling and infection. Infection control during this type of proce- Steroid medications consist of either a meth- dure is of utmost importance. Flap refection and ylprednisone dose pack, or 12mg per day of advancement in advanced ridge augmentation dexamethasone tablets beginning the day prior procedures involves exposure and entry into sev- to the surgery.35 Studies have shown that when eral anatomic spaces including the submental, steroid medications are delivered prior to surgi- submandibular, sublingual, buccal, and canine cal incision, anti-inflammatory effects postop- spaces, which can put the patient at risk for airway eratively are much greater.35,36 Antibiotics are compromise or spread of infection to the brain if prescribed preoperatively because during the postoperative complications present. Prevention surgery oral bacteria are most certainly intro- of these complications is paramount. Infection duced into the bone. Having a blood level of control for bone block grafting should include use antibiotic in the system preoperatively means of sterile drapes, gowns, and preoperative 0.12% that the newly formed blood clot around the chlorhexidine intraoral rinse, as well as peri- graft site will have the benefit of containing anti- oral skin preparation with an approved surgical biotic during early wound healing to assist the scrub, such as 4% chlorhexidine/alcohol swabs. body in clearing the oral bacteria introduced dur- ing the surgery. Broad spectrum antibiotics such GRAFT RECIPIENT SITE as penicillin or doxycycline are recommended. The recipient site to be grafted should be accessed prior to beginning surgery at the donor harvest site. This sequence is important so that the recipient site may be measured and assessed to determine the size, volume and shape of bone block(s) required to achieve the desired result. Use of a surgical guide which indicates the desired final implant position is helpful to assess the amount and position of grafting required. Crestal incision and full thickness flap reflection is the preferred method at the recipient site. Inci- The Journal of Implant & Advanced Clinical Dentistry 51

Toscano et al Table 2: Incision design options for symphysis block graft harvest (Gapski 2001) Indications Sulcular Attached Gingiva Vestibular Shallow vestibule Requires 3mm of Periodontally compromised Tense mentalis keratinized gingiva lower incisors Healthy periodontium Crown margins on lower incisors Deep vestibule Advantages Reduced bleeding Prevents gingival Least potential for Reduced trauma recession periodontal compromise Easier ap retraction Reduced bleeding Reduced trauma Easier retraction Easier suturing Disadvantages Potential for Scarring More complicated recession and Need for vertical suturing (must suture crestal bone loss release at distal Exposure of crown extent of incisions muscle layer) margins if present Gingival recessions Increased dehissence possible if root Increased bleeding dehissences exist Increased edema sions and reflection should be wide enough for gingiva approaches have the benefits of reduc- complete access to the site, and for adequate tions in both post-op wound dehiscence and access for later tissue release for passive clo- intraoperative bleeding compared to the ves- sure. Once the desired block size has been mea- tibular approach, however these two techniques sured, the recipient site can be covered with moist are limited by the clinical situation. Use of the gauze while the donor block harvest proceeds. sulcular approach requires that there are no pre-existing periodontal diseases or crown SYMPHYSIS BLOCK margins which could become exposed by inci- GRAFT HARVEST sion in this area. Gapski, et al published an excellent review of incision design options for Access to the mandibular symphysis area can symphysis graft procedures outlining the indi- be achieved by one of three different incision cations, advantages and disadvantages of each designs, 1) sulcular, 2) attached gingiva, or 3) technique, summarized in Table 2.37 Selection vestibular (Figure 2). The sulcular and attached 52 Vol. 2, No. 2 March 2010

Toscano et al of the access incision technique should be Figure 3: Symphysis block osteotomy completed using a made based on clinical findings and provider saggital saw with 0.7mm thick blade. Note that this block preference, since all methods offer equally has been harvested to the right of the midline, avoiding favorable access to the symphyseal region. violation of the midline bone strut of the symphysis. The sulcular and attached gingiva inci- recipient site should be re-measured and trans- sions involve full thickness muco-periosteal flap ferred to the symphysis to indicate the desired reflection, lifting the mentalis muscle off with block size by making notches in the bone at the periosteum as reflection proceeds to the the corners of the block outline. Pikos rec- inferior border of the anterior mandible. When ommended that the block outline be 2mm performing the vestibular incision, a more tech- larger than the target size to allow for contour- nically demanding approach is needed. This ing of the block after removal.2 When select- incision is made through the mucosa 1-2mm ing the area of the symphysis for block harvest, below the mucogingival junction followed by avoid violating the midline strut of bone in partial thickness dissection apically for 3mm the anterior most portion of the symphysis, to preserve 3mm of periosteum and mentalis known as the mental protuberance. If neces- muscle fibers on the bone, which will later be sary two blocks can be harvested from each used to reattach the mentalis muscle. Below side of the midline, leaving a 3mm midline this point a full thickness incision is made and strut to retain support for the chin profile.12 full thickness reflection proceeds beyond this point. When performing the access incision Osteotomy can be performed with a rotary careful attention must be paid to the position bur, saggital saw, or piezotome instrument. of the mental nerves to prevent trans-section The latter two instruments are preferred over a of these areas at the distal extent of the inci- rotary bur due to the narrow width of the result- sions bilaterally. The rule of 5’s should again be ing cut, reducing bone lost during osteotomy. respected here, and potential risk for severing of While most rotary burs are at least 1mm in the nerves is least using the sulcular approach. diameter, use of a saggital saw or piezotome instrument results in a precise cut of only 0.5- Reflection of the soft tissues away from the anterior mandible is performed by blunt dissection below the periosteum. Elevation should proceed until the mental foramina are located and the inferior border of the mandi- ble is reached. Block harvest can begin once these structures have been identified. Com- bined with radiographic measurements from the incisal edges or CEJ’s of the mandibular anterior teeth, the “rule of 5’s” can be applied to identify the target area for safe block har- vest. Prior to beginning the osteotomy, the The Journal of Implant & Advanced Clinical Dentistry 53

Toscano et al Figure 4: The block is loosened with mallet and chisels. Figure 5: Once the block as been freed by shearing forces, The periphery of the osteotomy is rede ned with the chisel it can be lifted by undermining with curved chisels and and the width of the chisel is used to begin shearing the gently lifted out. The need to use excessive force at this block o it’s cancellous base without lifting upwards. stage indicates the block is not su ciently free and risks fracture. 0.7mm in width which preserves bone and also recipient site for hemostasis (Figure 6). Alterna- results in comparatively less surgical trauma to tively, the harvest site may be grafted with Freeze the bone.38,39 Osteotomies should penetrate the Dried Bone Allograft (FDBA) if desired, especially cortical layer, giving close attention to the depth in cases where a large block has been removed. of each cut relative to the width of the symphysis found on pre-operative radiographic evaluation to Closure at the donor site depends on the inci- prevent violation of the lingual cortex (Figure 3). sion method utilized. When closing the vestibu- The terminal end of each cut around the block lar approach, a resorbable suture is first used to should cross over itself in an “x-like” pattern to secure the mentalis muscle to the 3mm perios- ensure complete release of the block. Once teal/muscle layer left on the bone during the initial cuts are complete, narrow chisels can be used to incision. This is achieved by interrupted sutures refine the outline of the block and begin to shear at regular intervals across the mentalis release. the cortico-cancellous block off of the underly- The overlying mucosa is then closed with a non- ing trabecular bed (Figures 4 and 5). Care and wicking continuous interlocking suture. (Figure patience must be taken when releasing the block 10) For sulcular and attached gingiva incisions to preserve the entire block volume. Overzeal- the mentalis muscle remains attached to the peri- ous lifting of the block before it is completely free osteum and does not need to be sutured. Clo- may result in its fracture. After block removal an sure of these latter two incision types involves absorbable collagen sponge is placed in the interrupted sutures at papilla areas (sulcular) or along the attached gingival incision line. Appli- 54 Vol. 2, No. 2 March 2010

Toscano et al Figure 6: After the block is removed, the donor site Figure 7: The block is carefully shaped to assist in stable is packed with an absorbable collagen sponge for and close adaptation to the recipient bed. Care should hemostasis. The site may also be grafted with particulate be taken to avoid over-reducing the bone block graft. If bone. excessive changes are needed to achieve stability, then the recipient site should be adjusted as well. Figure 8: The block is xed with at least two xation Figure 9: The periphery of the bone block is mortised screws to ensure stability and anti-rotation. Screw with freeze dried bone allograft (FDBA) and a collagen osteotomies through the block should be lagged so membrane is placed over the entire graft, extending 3mm that threads do not engage. Intramarrow penetration is beyond the block in all directions. performed under the block, at the recipient bone bed, prior to xation. The Journal of Implant & Advanced Clinical Dentistry 55

Toscano et al Figure 10: Closure at the donor site. Figure 11: The appearance of the block upon reentry after 4 months of healing indicates a favorable healing outcome. Minimal resorption was observed. Figure 13: Final abutment and restoration in place. Figure 12: Radiographic appearance of the implant placed incision design for access to the ramus can pro- in the graft at the time of uncovering. ceed by two different approaches: 1) Vestibu- lar or 2) Sulcular. The vestibular incision begins cation of an extraoral pressure dressing (elas- in the buccal vestibule, medial to the external tic chin-cup) to the symphysis area for 48-72 oblique ridge, and extends anteriorly and later- hours post-operatively is advisable to prevent ally to the retromolar pad (Figures 18, 19). This hemorrhage and promote initial healing which technique has the advantage of not disturbing supports reattachment of the mentalis muscle. the periodontium of the adjacent teeth. Alter- natively, the sulcular incision starts intrasucu- RAMUS BUCCAL SHELF larly around the mandibular molars and then BLOCK HARVEST extends from the distal facial line angle of the Harvest of a block bone from the mandibular ramus buccal shelf has features similar to a sag- ittal split ramus osteotomy (Figures 14-17). The 56 Vol. 2, No. 2 March 2010

Toscano et al Figure 14: Pre –op facial view of Siebert’s I defect post Figure 15: Incisal view of Siebert’s I Defect tooth # 10 prior extraction of tooth #10 prior to ramus block grafting. to ramus grafting. Figure 16: Flap re ected #10 revealing osseous defect Figure 17: Facial view of ap re ected #10 revealing the prior to grafting. extent of the osseous defect to be grafted. second molar along the external oblique ridge. reflection proceeds by blunt dissection, expos- The sulcular technique is beneficial when the ing the anterolateral aspect of the ramus. The receipient site is nearby, such as the mandibu- flap may elevated superiorly along the external lar first molar region. Regardless of the incision oblique ridge and anterior ramus with a notched design selected, the incision up the ascending ramus retractor or ramus stripper to the base ramus should no higher than the level of the of the coronoid process (Figures 20, 21). The occlusal plane. This minimizes the possibility of tissues can then be held out of the way with severing the buccal branch of the facial nerve, a coronoid clamp for maximum visualization. the buccal artery or exposing the buccal fat pad, where these structures are located. After The ramus osteotomy procedure is accom- the incision, sub-periosteal full thickness flap plished in similar fashion to the symphysis graft with regard to penetrating the cortical layer The Journal of Implant & Advanced Clinical Dentistry 57

Toscano et al Figure 18: A surgical marking pen is used to outline area Figure 19: Vestibular incision complete revealing area of the vestibular incision. of ramus buccal self (marking pen outlines area of ramus block to be removed). and controlling effective x-pattern cut-through at the block corners to ensure a free release. osteotomies proceeds as superior cut, then ante- As with the symphysis graft, the osteotomy can rior, then posterior, and finally the inferior cut, facil- be accomplished with a rotary bur, piezoelec- itated by the pneumonic “SAPI”. Radiographic tric saw, or saggital saw, the latter two having verification of the position of the mandibular canal the advantage of more conservative cutting.38, 39 relative to the external oblique ridge and anterior aspect of the ramus must be completed prior The ramus osteotomy is started anterior and to initiation of the osteotomy. The superior cut inferior to the coronoid process at a point where should reflect the desired length and thickness of adequate thickness develops. The order of the the bone block. This cut is usually made approxi- 58 Vol. 2, No. 2 March 2010

Toscano et al Figure 20: A ramus stripper produced by KLS Martin, Figure 21: The ramus stripper is used to strip the Tuttlingen, Germany. periosteum o the external oblique ridge to give maximum access to the ramus buccal shelf. Figure 22: Surgical cuts made with a sagital saw prior to Figure 23: Ramus block graft is outfractured with chisels outfracture of the ramus block. via gentle tapping, the periphery of the osteotomy is rede ned with the chisel and gentle outfratured. The Journal of Implant & Advanced Clinical Dentistry 59

Toscano et al Figure 25: Ramus block graft prior to xation to the receipt site. Figure 24: Ramus area after removal of the block prior to Figure 26: Incisal view of ramus block graft xated with closure. two KLS bone xation screws. mately 4 mm medial to the external oblique ridge will connect the posterior and anterior vertical but can approach up to 6 mm depending on the cuts, completing the outline of the block. This anatomy. It may be extended anteriorly as far as final cut should not generally extended through the distal aspect of the first molar area, depend- the cortex, but rather only functions to create a ing on local anatomy. The anterior and posterior score line to facilitate out-fracture for ultimate vertical cuts are made in parallel to the desired removal of the block. Full cortical penetration length and width of the block, and are limited is avoided in the inferior cut due to it’s proximity in their inferior extent by the anatomic position to the mandibular canal in many cases. More of the mandibular canal, which determines the experienced clinicans may prefer to make this block width (Figure 22). The inferior osteotomy cut completely through the cortex; however 60 Vol. 2, No. 2 March 2010



Toscano et al Figure 28: Block xated in place and further is mortised with FDBA and PRP. Prior, Intramarrow penetration is made through the block to the underlying receipt bone to provide blood supply to the block. Figure 27: Side view of the block xated (Note how much Figure 29: Block is cover with Ossix membrane and ap is augmentation can be achieved). released for passive closure and sutured closed. the authors suggest caution with this practice. alveolar nerve lies within the cancellous bone Once the osteotomies are completed, nar- below the ramus harvest area. Next a wider wedge chisel or Potts elevator may be inserted row chisels are used to progressively re-trace and carefully levered to loosen the block and each cut and ensure complete cortical pen- pry the segment free. A double chisel tech- etration. Once again, care must be used to nique may also be incorporated to facilitate limit chisel penetration to just beyond the out-fracture while protecting the lingual plate cortical layer and to prevent greenstick frac- and inferior alveolar nerve from injury (Fig- ture of the block if out-fracture is attempted ures 23-25). Following removal of the bone too quickly. Careful control of the chisel pen- block, any sharp edges around the ramus area etration and angle is critical, since the inferior 62 Vol. 2, No. 2 March 2010

Toscano et al are smoothed with a round bur or bone file. A Figure 30: Incisal view of ramus block post 4 months hemostatic dressing or platelet rich plasma healing (Note new ridge augmentated for proper implant may be placed into the donor area. Alterna- placement). tively a particulate bone allograft (such as FDBA) may be placed in the defect as well, bone of the underlying recipient site. Use of at especially in the case of large block harvest least two screws is recommended, since total (Figures 26-28). Closure of the donor area immobility of the block graft during healing is a is best completed with an interrupted or run- critical factor in successful bone integration.40 ning horizontal mattress resorbable suture to evert the wound edges for maintenance of The lagged block should be stabilized in primary closure during healing (Figure 29). place at the recipient site with a large hemo- stat and the first screw site should be drilled BONE BLOCK PREPARATION, with the appropriately sized twist drill through FIXATION, AND CLOSURE OF the first lagged block hole. A periodontal probe may then be placed in the first hole to retain THE RECIPIENT SITE position, and the second screw site prepared. The block is then removed and intramarrow pen- The fixation procedure is essentially the same etration of the recipient site is performed using whether the block is sourced from the ramus or a small diameter twist drill (1.0mm) to optimize the symphysis. A separate basin of sterile saline blood supply and new bone formation around is used to store the block and make adjustments the new graft.41 The smaller twist drill size will with rotary burs in a straight handpiece, holding allow the surgeon to differentiate between fixa- the block firmly using hemostats designed for tion screw sites and penetration sites. The this purpose (Figure 7). The free bone block block can then be repositioned and the first must first be shaped and adapted to the recipi- screw may then be inserted, but not fully tight- ent site. The block should be adjusted so that it ened. Once both screws are in place, they sits flat upon the receipient site without rocking may be tightened to ensure the block is stable and with intimate contact with the underlying against the receipient bed. Use caution not host bone. Care should be taken not to reduce the block extensively in order to achieve this fit, since this sacrifices critical volume of grafted bone. Alternatively if extensive adjustment is required, the recipient site can also be shaped. Once stability and intimate contact has been achieved, the fixation screw sites should be selected and the block should be pen- etrated in a “lagged” fashion with a twist drill which is larger than the final screw diameter so that the fixation screw threads will not engage the block, but rather engage only the cortical The Journal of Implant & Advanced Clinical Dentistry 63

Toscano et al Figure 31: Facial view of Ramus block post 4 months Figure 32: Implant placed in site #10 in well healed ramus healing after xation screws removed. block graft. to overtighten and fracture the block (Figure let derived growth factor (rh-PDGF), or bone 8). Additionally, the block itself may be pen- morphogenic protein-2 (BMP-2).43-45 The etrated to facilitate vascular ingrowth, however mortised graft is then covered with a bar- this is less necessary with symphyseal grafts rier membrane to prevent epithelial and con- due the the cancellous base already present. nective tissue ingrowth into the integrating new bone. (Figure 9) The membrane should At this time flap release should be performed extend at least 3mm beyond the graft mar- to ensure passive closure of the graft, and allow gins. Comparative studies have shown less time for hemostasis to occur after periosteal bone resorption occurs when membranes are releasing incisions, prior to placement of addi- used in conjunction with bone block grafts.32,46 tional particulate graft material and a barrier membrane. Typically conventional periosteal Closure of the recipient site is critical to releasing incisions are adequate for closure, success in block grafting. Wound dehissence however in larger grafts additional use of mylo- at the recipient site has been associated with hyoid muscle release, and/or a superficial split more block resorption or complete loss of the thickness flap technique may be necessary.42 grafted bone. Suture used should be of a non- wicking monofilament type, such as ePTFE. The surrounding area of the block is then Passive closure of the crestal incision directly mortised with a particulate bone graft, prefer- over the block is achieved by horizontal mat- ably a mineralized graft such as FDBA or anor- tress sutures which evert the wound margins, ganic bovine bone, which can be mixed with allowing connective tissue upon connective tis- additional growth factor matrices to improve sue contact. The everted wound margin and wound healing and bone regeneration such the ridge crest is then secured with interrupted as platelet rich plasma (PRP), enamel matrix sutures along its length at regular intervals. derivative (EMD), recombinant human plate- 64 Vol. 2, No. 2 March 2010

Toscano et al POSTOPERATIVE cision of the overlying tissue, following the MANAGEMENT same incision lines used in the first surgery. The block stability should be assessed clini- Postoperative medications are aimed at control cally and fixation screws removed (Figures 11, of pain, swelling, and infection. Prescriptions of 30-31). Implants can then be placed using the an NSAID and a narcotic pain medication such appropriate drilling protocol specified by the as hydrocodone and acetaminophen are ade- implant manufacturer, and restored after suf- quate for pain control in most patients. Contin- ficient integration time (Figures 12, 13, 32.) ued use of systemic steroid medication (which began preoperatively, as discussed earlier) is CONCLUSIONS recommended for up to 5 days post-operatively. Completion of the tapered methylprednisone Alveolar ridge augmentation is a necessity in dose pack, or 2-3 further days of 12mg per day many cases which present in clinical practice dosing of dexamethasone are acceptable.35 to facilitate adequate bone volume for implant Also continued use of a post-operative antibi- placement. The bone block grafting techniques otic, while controvertial, is warranted for the described here, which integrate the principles of reasons discussed earlier. Sutures should be guided bone regeneration, provide a predictable retained in place as long as they appear to be and efficient technique for achieving desired providing wound stability, which in many cases outcomes with a minimum of block resorp- is as long as 14 days.47 If during post-opera- tion and nominal post-operative morbidity. tive followup wound dehiscence is observed with either exposure of the membrane and bone Correspondence: graft or the donor site may occur. Management Dr. Nicholas Toscano should include close followup, continued antibi- 116 Central Park South, Suite 3 otic coverage, and topical application of 0.12% New York New York 10019 Chlorhexidine gluconate with a cotton tipped [email protected] applicator several times per day.48 These mea- sures will result in either eventual closure of Disclaimer: The views expressed in this article the dehiscence, or progressive dehiscence are those of the authors and do not reflect the and loss of the graft and the course of such opinion of the Department of Defense or Navy complications is dependent on close followup. Medicine. IMPLANT PLACEMENT After successful initial healing, symphysis and ramus block grafts should be allowed to mature for 4-5 months prior to uncovering and implant placement.12,20 During the healing phase the block integrity can be evaluated radiographi- cally. Reentry to the block site requires rein- The Journal of Implant & Advanced Clinical Dentistry 65

Toscano et al Disclosure 16. Buser DA, Bragger U, Lang N, Nyman S. 34. Hunt DR, Jovanovic SA. Autogenous bone The authors report no conflicts of interest with Regeneration and enlargement of jaw bone harvesting: A chin graft technique for particulate anything mentioned in this article. using guided tissue regeneration. Clin Oral and monocortical bone blocks. Int J Periodontics Implants Res. 1990 Dec;1(1):22-32. Restorative Dent. 1999; 9(2):165-73. References 1. Schropp L, et al. Bone healing and soft tissue 17. Pikos MA. Block autografts for localized ridge 35. Alexander RE, Throndson RR. A review of augmentation: Part II. The posterior mandible. perioperative corticosteroid use in dentoalveolar contour changes following single-tooth extraction: Implant Dent. 2000;9(1):67-75. surgery. Oral Surg Oral Med Oral Pathol Oral a clinical and radiographic 12-month prospective Radiol Endod. 2000 Oct;90(4):406-15. study. Int J Periodontics Restorative Dent. 2003 18. Schwartz-Arad D, Levin L, Sigal L. Surgical Aug;23(4):313-23. success of intraoral autogenous block onlay 36. Bahn SL. Glucocorticosteroids in dentistry. J Am 2. Lekholm U, Gunne J, Henry P, et al. Survival of bone grafting for alveolar ridge augmentation. Dent Assoc. 1982;105:476-481. the Branemark implant in the partially edentulous Implant Dent. 2005;14:131-138. jaws: A 10-year prospective multicenter study. Int 37. Gapski R, Wang HL, Misch CE. Management of J Oral Maxillofac Implants 1999;14:639-645. 19. Neiva RF, Gapski R, Wang HL. Morphometric incision design in symphysis graft procedures: 3. Buser DA. Localized Ridge Augmentation Using analysis of implant-related anatomy in Caucasian A review of the literature. J Oral Implantol. GBR, I. Surgical Procedures in the Maxilla. Int J skulls. J Periodontol. 2004 Aug;75(8):1061-7. 2001;27(3):134-142. Periodontics Restorative Dent 1993; 29-45. 4. Tolman D. Reconstructive Procedures With 20. Misch CM. Comparison of intraoral donor sites 38. Vercellotti T. Piezoelectric surgery in Endosseous Implants in Grafted Bone: a Review for onlay grafting prior to implant placement. Int implantology: a case report--a new piezo- of Literature. Int J Oral Maxillofac Implants 1995; J Oral Maxillofac Implants. 1997; 12:767-776. electric ridge expansion technique. http:// 10: 275-294. www.ncbi.nlm.nih.gov/pubmed/1120357 5. Feuille F, Knapp CI, Brunsvold MA, Mellonig 21. Hammack BL, Enneking WF. Comparative 5?itool=EntrezSystem2.PEntrez.Pubmed. JT. Clinical and Histologic Evaluation of Bone- vascularization of autogenous and homogenous Pubmed_ResultsPanel.Pubmed_ Replacement Grafts in the Treatment of Localized bone transplants. J Bone Joint Surg. RVDocSum&ordinalpos=2> Int J Periodontics Alveolar Ridge Defects. Part 1: Mineralized 1960;42:811 Restorative Dent 2000; 20(4):358-465. Freeze-Dried Bone Allograft. Int J Periodontics Restorative Dent. 2003;23:29-35. 22. Kusiak JF, Zins JE, Whitaker LA. The early 39. Vercellotti T, Nevins ML, Kim DM, Nevins M, 6. Scipioni A, Bruschi G, Calensi G. The Edetulous revascularization of membranous bone. Plast et al. Osseous response following resective Ridge Expansion Technique: A Five Year Study. Reconstr Surg. 1985;76(4):510-516. therapy with piezosurgery. Int J Periodontics Int J Periodontics Restorative Dent 1994;14:451- Restorative Dent. 2005 Dec;25(6):543-9. 459. 23. Pikos MA. Facilitating implant placement with 7. Enislidis G, Wittwer G, Ewers R. Preliminary chin grafts as donor sites for maxillary bone 40. Sohn DS, Ahn MR, Lee WH, Yeo DS, Lim SY. Report on a Staged Ridge Splitting Technique for augmentation--Part I. Dent Implantol Update. Piezoelectric osteotomy for intraoral harvesting Implant Placement in the Mandible: A Technical 1995 Dec;6(12):89-92 of bone blocks. Int J Periodontics Restorative Note. Int J Oral Maxillofac Implants 2006;21:445- Dent. 2007 Apr;27(2):127-31. 449. 24. Pikos MA. Facilitating implant placement with 8. Emtiaz S, et al. Alveolar Distraction Osteogenesis: chin grafts as donor sites for maxillary bone 41. Hjorting-Hansen E, Worsaae N, Lemons JE. Historical and Biologic Review and Case augmentation-Part II. Dent Implantol 1996; Histologic response after implantation of porous Presentation. Int J Periodontal Res Dent 2006; 7:1-4 hydroxylapatite ceramic in humans. Int J Oral 26:529-541. Maxillofac Implants. 1990 Fall;5(3):255-63. 9. Salama H, Salama M, Kelly J. The orthodontic- 25. Pikos MA. Block autografts for localized ridge periodontal connection in implant site augmentation; Part I. The posterior maxilla. 42. Majzoub Z, et al. Role of intramarrow penetration development. Pract Periodontics Aesthet Dent. Implant Dent 1999; 8:279-284. in osseous repair: A pilot study in the rabbit 1996; 8(9): 923-32. calvaria. J Periodontol. Dec;70(12):1501-10. 10. Triplett R, Schow S. Autologous Bone Grafts 26. Linklow LI. Bone transplants using the 1999. symphysis, the iliac crest, and synthetic bone and Endosseous Implants: Complementary materials. J Oral Implantol. 1983;11:211-247. 43. Greenwell H, Vance G, Munninger B, Johnston, Techniques. J Oral Maxillofac Surg, 1996; 54: H. Superficial layer split thickness flap for 486-494 27. Jensen J, Sindet-Pedersen S. Autogenous maximal flap release and coronal positioning: A 11. Tolman D. Reconstructive Procedures With mandibular bone grafts and osseointegrated surgical technique. Int J Periodontics Restorative Endosseous Implants in Grafted Bone: a Review implants for reconstruction of the severely Dent. 2004; 24:521-527. of Literature. Int J Oral Maxillofac Implants 1995; atrophied maxilla: A preliminary report. J Oral 10: 275-294 Maxillofac Surg. 1991;49:1277-1287. 44. Marx, RE. Platelet-rich plasma: evidence 12. Pikos MA. Mandibular block autografts for to support its use. J Oral Maxillofac Surg alveolar ridge augmentation. Atlas Oral 28. Raghoebar GM, Meijndert L, Kalk WW, Vissink 2004;62(4): 489-96. Maxillofacial Surg Clin N Am. 2005; (13):91- A. Morbidity of mandibular bone harvesting: a 107. comparative study. Int J Oral Maxillofac Implants. 45. Jung RE, Thoma DS, Hammerle CH. 13. Misch CM, Misch CE. The repair of localized 2007 May-Jun;22(3):359-65. Assessment of the potential of growth factors severe ridge defects for implant placement using for localized alveolar ridge augmentation: a mandibular bone grafts. Implant Dent. 1995 29. Weibull L, Widmark G, Ivanoff CJ, Borg E, systematic review. J Clin Periodontol. 2008 Winter;4(4):261-7. Rasmusson L. Morbidity after Chin Bone Sep;35(8 Suppl):255-81. 14. Keith JD, Petrungaro P, Leonetti JA, et al. Clinical Harvesting - A Retrospective Long-Term Follow- and Histological Evaluation of a Mineralized Up Study. Clin Implant Dent Relat Res. 2008 Jul 46. Boyan BD, Weesner TC, Lohmann CH, Block Allograft: Results from the Development 23. [Epub ahead of print] Andreacchio D, Carnes DL, Dean DD, Cochran Period (2001-2004). Int J Periodontics DL, Schwartz Z. Porcine fetal enamel matrix Restorative Dent 2006;26:321-327. 30. Pikos M.A. Lateral ridge augmentation using derivative enhances bone formation induced by 15. Lyford RH, Mills MP, Knapp CI, Scheyer ET, monocortical autografts-a five-year retrospective demineralized freeze dried bone allograft in vivo. Mellonig JT. Clinical Evaluation of Freeze- study of 98 patients. In submission 2000: Oral J Periodontol. 2000 Aug;71(8):1278-86. Dried Block Allografts for Alveolar Ridge Surgery, Oral Medicine, Oral Pathology, Oral Augmentation: A Case Series. Int J Periodontics Radiology and Endodontics 47. Antoun H, Sitbon JM, Martinez H, Missika P. A Restorative Dent. 2003;23:417-25. prospective randomized study comparing two 31. Bahat O, Fontanesi RV. Complications techniques of bone augmentation: onlay graft of Grafting in the Atrophic Edentulous or alone or associated with a membrane. Clin Oral Partially Edentulous Jaw. Int J Perio Rest Dent Implants Res. 2001 Dec;12(6):632-9. 2001;21:487-495. 48. Hiatt W, Stallard RE, Butler ED, Badgett, B. 32. Widmark, G., B. Andersson, and C.J. Ivanoff, Repair following mucoperiosteal surgery with Mandibular bone graft in the anterior maxilla for full gingival retention. J Periodontol 1968; 39: single-tooth implants. Presentation of surgical 11-16. method. Int J Oral Maxillofac Surg, 1997. 26(2): p. 106-9. 49. Murphy KG. Postoperative healing complications associated with Gore-Tex Periodontal Material. 33. Internet reference: American Society of Part II. Effect of complications on regeneration. Anesthesiologists. ASA Physical Status Int J Periodontics Restorative Dent. 1995 Classification System. http://www.asahq.org/ Dec;15(6):548-61. clinical/physicalstatus.htm 66 Vol. 2, No. 2 March 2010

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Evaluating the E cacy of Bone Marrow Aspiration Lin et al Added to Grafts in Oral defects: 2 Clinical Reports Sherman Lin, DDS1 23 Abstract Background: Autogenous bone has long been Results: After approximately 5 months of heal- considered the “gold standard” in bone grafting ing, a bone core biopsy sample was taken from materials. A novel technique has been developed the sinus augmentation site with a trephine to harvest patients own bone marrow aspirate drill. Histomorphometric analysis of the sam- from the iliac crest as the source for obtaining ple revealed 36% new vital bone formation. adult stem cells, progenitor cells for osteo- Dental implants were delivered and ultimately blasts, growth factors and cytokines. The aim of restored without complication. In the patient this study is to introduce and evaluate the bone treated with block allografts, the grafts inte- marrow aspirating technique as it is described grated with the host bone demonstrating good and applied to oral bone grafting surgery. vitality, vascularity, and adequate thickness to place 3 dental implants. Neither patient experi- Materials and methods: A maximum of 4 cc enced any complications from the intraoral surgi- bone marrow was aspirated from a single site cal sites or at the bone marrow aspiration sites. for two patients. In the first patient, two block allograft sources for scaffolding were used for Conclusion: Histomorphometric analysis sup- the anterior ridge augmentation procedure. The ports the clinical findings that bone marrow blocks were shaped, injected with heparinized aspirate combined with allograft or alloplast marrow aspirate, and secured in the surgical grafts are effective alternatives to autogenous site with bone screws. In the second patient, bone grafts in the oral region. While it does pure phase -tricalcium phosphate particulates require a secondary harvest site for acquisi- were mixed with bone marrow aspirate for aug- tion of marrow aspirate, patient morbidity is mentation of the right and left maxillary sinuses. minimal and offers an alternative to the conven- tional method of harvesting autogenous bone. KEY WORDS: Autogenous bone, Iliac crest, bone marrow aspirate, adult stem cells, bone graft 1. Private practice, San Diego, California, USA 2. Private practice, Encino, California, USA 3. Private practice, Riverside, California, USA The Journal of Implant & Advanced Clinical Dentistry 71

Lin et al INTRODUCTION clinical case reports, the technique proposed. Unlike the procedures for harvesting autog- There are a plethora of grafting options to support bone grafting as an adjunct to den- enous bone, the aspiration of bone marrow tal implant therapy. While a large variety of does not require an open surgical site. This grafting techniques have been developed, the technique was developed in 20053 and is a bone grafts used to accomplish these tech- relatively simple procedure with minimal mor- niques are not created equally. Autogenous bidity or complication that can be performed in bone is still considered to be the “gold stan- an outpatient setting. The bone marrow aspi- dard” in the realm of grafting materials as it rant is combined with a matrix used to augment is the only material that provides all three fun- osseous defects. The large flat bones of the damental mechanisms of osteoconduction, body are rich in red active marrow and are an osteoinduction, and osteogenesis. However, excellent source of adult stem cells and osteo- autogenous bone may increase morbidity and progenitor cells. Three possible locations are complications for the patient as it requires a available for harvesting bone marrow from an second surgical site for harvesting donor bone. adult patient: 1) the anterior iliac crest; 2) the posterior ileum; 3) the sternum. The anterior To avoid secondary surgical donor sites, Iliac crest is selected as the primary location bone allografts, xenografts, and alloplasts may due to its relative ease of access and safety. be used. While the supply of these products is virtually unlimited, they do not contain the viable Bone marrow aspirant is not used alone to cells that are present in autogenous grafts. To augment bony defects. An osteoconductive solve this problem, a novel and simple surgical scaffold is necessary to serve as a matrix and technique that retains the standard of autog- vehicle for the aspirated cells to attach and enous bone grafting without its inherent draw- mature. The authors recommend the use of a backs and limitations has been developed.1 This porous, slowly resorbable, biodegradable, and technique utilizes the patient’s own iliac crest biocompatible scaffold material. Beta-trical- as the source for obtaining adult stem cells cium phosphate -TCP) is an excellent material that can differentiate to osteogenic progeny for of choice as it will facilitate cell ingrowth and osteoblast formation and hematopoietic stem vascularization of the graft from the surround- cells for endothelial cell formation.2 The vital ing tissues.4-6 If other materials such as block cells and growth factors are aspirated through allografts are used, the graft material must the iliac crest with a minimally invasive needle be stabilized at the recipient site with screws, aspirating technique. While this is technically a guided bone regenerative membranes, and/ secondary surgical site, patient morbidity asso- or titanium mesh depending on the procedure. ciated with the needle aspiration is minimal. The aspirate is then combined with allograft, xeno- Smiler and Soltan7,8 published their clini- graft , or alloplast graft materials that serve as a cal findings and histomorphomeric analy- scaffold or a matrix for the grafting site. The aim sis for bone marrow aspiration procedures of this study is to introduce and evaluate, by two mixed with various grafts for oral bone graft- ing sites in 2007. After 4-7 months of heal- 72 Vol. 2, No. 2 March 2010

Lin et al ing, percentages of vital bone ranged between Figure 1: Pre-surgical appearance of the severely 31-54% depending on the healing time and atrophied anterior ridge from Case 1. type of graft used. Published histomorpho- metric results from studies using conven- CASE REPORTS tional methods of autogenous bone grafts mixed with various scaffolds typically dem- Case 1: onstrate percentages of vital bone between A 33 year old healthy male patient presented 27-38%.9-16 Comparing the percentages of with a severely atrophic maxillary anterior ridge vital bone from bone marrow aspirant and spanning from right lateral incisor to left central autogenous bone grafts, the bone marrow incisor (figure 1). Patient history revealed that aspirant offers higher osteogenic induction. he had gone through two prior unsuccessful bone grafting surgeries. The first failed surgery MATERIALS AND METHODS utilized particulate allograft with a non-resorb- able membrane while the second failed surgery Two patients were treated with grafting pro- utilized autogenous bone blocks harvested from cedures mixed with bone marrow aspirant. In patient’s symphysis. As a consequence of the both cases, bone marrow aspirant was obtained multiple surgeries, the patient developed dense from the anterior iliac crest. When obtain- scar tissue at the surgical site. Despite previ- ing bone marrow aspirant, the aspiration site ous unsuccessful attempts, the patient still is identified and marked under sterile condi- desired a fixed prosthesis to replace his miss- tions. The skin at the surgical site is cleansed ing anterior teeth. After obtaining an informed with iodine and anesthetized with local anes- consent from the patient, the bone marrow thesia through infiltration of the subcutaneous aspiration technique was performed for the tissue. A larger needle is used to anesthetize patient. The patient was locally anesthetized the periosteum and probe to confirm the pre- and an alveolar crestal incision was made in the cise location of the bone to be aspirated. A bone marrow aspiration needle is then inserted through the cortical bone into the cancellous compartment. Penetration through the cortical bone is achieved with steady pressure, rotat- ing the aspiration needle back and forth until a change in resistance is felt. Once the aspira- tion needle is in the cancellous compartment, 2 to 4cc of marrow aspirate is obtained. With higher aspiration volumes, dilution of the mar- row-derived cells by peripheral (venous) blood will occur. Therefore, the needle should be redirected or a new aspiration site selected if more than 4 cc of marrow aspirate is needed. The Journal of Implant & Advanced Clinical Dentistry 73

Lin et al Figure 2: Initial entry of ridge defect from Case 1. Figure 3: Tomography showing block allograft xated with bone screw. Figure 4: Re-entry of Case 1 graft site after 6 months of Figure 5: Immediate post-surgical radiograph of 3 implant healing. xtures delivered in Case 1. edentulous ridge with adjacent vertical releas- ing incisions (figure 2). A wide base full thick- ness mucoperiosteal flap was raised to ensure adequate blood flow to the flap and the peri- osteum. The recipient site was then prepared by decorticating the labial bone using a small round #6 carbide bur with copious irrigation. Two block allografts were contoured to fit within the prepared recipient sites at the lateral and central incisor regions. When contouring the block allografts, care was taken to avoid remov- 74 Vol. 2, No. 2 March 2010

Lin et al Figure 6: Pre-surgical panoramic radiograph from Case 2. Figure 7: Obtaining marrow aspirate from anterior iliac crest. ing the cancellous component. Preparation in this manner enables the bone marrow aspirate Figure 8: Marrow aspirate/alloplast mixture is injected to fully saturate the cancellous compartment into prepared maxillary sinuses. of the block graft. Four millilitres of hepranized bone marrow aspirate was obtained from the sis to replace her existing denture. Panoramic patient’s anterior iliac crest and impregnated radiographic evaluation revealed bilateral pneu- into the bone blocks. The two blocks were then matization of the maxillary sinuses with minimal stabilized with bone screws (figure 3). Excess residual bone height (figure 6). Evaluation of graft was grounded with a bone mill, mixed anterior maxilla revealed adequate bone height with the bone marrow aspirate, and mortised and width for implant placement. The patient’s around and over the fixated bone blocks. A history revealed a compromised medical condi- periosteal releasing incision was used with the tion of osteoporosis and the patient had been mucoperiosteal flap to allow for primary closure. on oral bisphosphonate therapy for the past year and a half. After consultation with her After 6 months, a second surgery was per- attending physician and obtaining clearance, formed to remove the fixation screws and place three implants 3.4 x 10mm in size (figures 4, 5). Five additional months after implant place- ment, all implants had osseointergrated success- fully and a 3 unit anterior bridge was delivered. Case 2: A 59 year old woman presented with a com- pletely endentulous maxillary arch and expressed the desire to have a complete fixed prosthe- The Journal of Implant & Advanced Clinical Dentistry 75

Lin et al Figure 9: 4 month post-surgical panoramic radiograph Figure 10: Panoramic radiograph following dental implant delivery. Figure 11: Histologic core sample from Case 2 Figure 12: High power histomorphometric image showing demonstrating the trabecular pattern of newly formed new bone formation (stained red), osteoid (stained bone. Vital bone is stained in red. brown), osteoblasts (stained blue), and residual β-TCP particles the bisphosphonate therapy was terminated cially designed sinus lifting elevator, the sinus two months prior to seeking implant therapy. membrane was carefully lifted without any perforations. Four millilitres of bone marrow To facilitate implant delivery, bilateral max- aspirate was obtained from patient’s anterior illary sinus lifts with bone marrow aspirate iliac crest in the manner previously described were performed. A #6 round carbide bur and (figure 7) and mixed with 10cc of pure phase a piezoelectric surgical unit were used for the osteotomy of the sinus window. Using a spe- -TCP particulate of 500-1000µm in size. The 76 Vol. 2, No. 2 March 2010

Lin et al mixture was syringed into the prepared sinus ous failed attempts at bone augmentation. The cavities (figure 8); care was taken not to over combination of bone allografts, alloplasts, and compact the graft material to ensure space for adult stem cells aspirated from bone marrow angiogenesis and cellular apposition. The lat- of the anterior iliac crest eliminated the need eral windows were covered with resorbable for harvest of secondary autogenous bone. membranes and the flaps were primarily closed. CONCLUSION Approximately five months later, a total of eight implants were delivered (figures 9,10). The efficacy of the bone marrow aspirating pro- During implant placement, a 3mm diameter tre- cedure to reconstitute defective sites in the oral phine core sample was taken from the left molar region is evident clinically and through histo- region. Histomorphometric analysis (figures 11, morphometric analysis of bone core samples. 12) of the bone core showed 36% new bone Aspiration of bone marrow cells from the iliac with 91% vitality. The remainder of the core crest in conjunction with a non-viable matrix included 9% residual graft and 55% interstitial is an effective procedure and results in less material. Five months after implant delivery, the patient morbidity than grafting with conven- implants were restored with a fixed appliance. tional autogenous bone harvesting techniques. The promising results of this case report and DISCUSSION other studies evaluating bone marrow aspi- rate for treatment of dental defects may war- Muschler et al17 determined that in a healthy rant additional studies and clinical trials. adult, 2cc of marrow aspirate provides an average of 36 million marrow nucleated Correspondence: cells, of which 360 stem cells would be avail- Sherman Lin able for bone regeneration. An average ratio 12925 El Camino Real J-28 of 1 stem cell per 100,000 marrow cells is San Diego, CA 92130 found in healthy individuals, with the high- Tel: 858 259 2225 est majority of the marrow cells belonging to the various hematopoietic lineages. In vitro Dennis Smiler & Muna Soltan studies have shown that a mean of 2,400 16661 Ventura Blvd. Suite 826 alkaline phosphate positive colony form- Encino CA 91436 ing units for osteoblasts can be plated from Tel: 818 995 7971 2cc of marrow. This number diminishes with age and in the presence of systemic disease. The histologic analysis of the trephine core from Case 2 (36% new bone) compares favor- ably to previous research of bone marrow aspi- rates and autogenous bone grafts. The two cases described in this report were successfully treated with dental implants in spite of previ- The Journal of Implant & Advanced Clinical Dentistry 77

Lin et al AADDVVERETIRSETWISITHE Disclosure: The authors report no conflicts of interest with anything mentioned within this TODAY! article. Reach more customers References with the dental 1.Smiler D, Soltan M. Bone Marrow Aspiration: Technique, grafts, and reports. profession’s first truly interactive Implant Dent 2006; 15:229-232. paperless journal! 2 Soltan M, Smiler D. Bone Marrow: Orchestrated cells, cytokines, and Growth factors for bone regeneration. Implant Dent 2009; 18(2):132-141. Using recolutionary online technology, JIACD provides its readers with an 3 Soltan M, Smiler D, Gailani F. A new standard for bone grafting: Autogenous stem cells. Implant Dent 2005; 14:322-324. experience that is simply not available with traditional hard copy paper journals. 4 Fleming J, Cornell C, Muschler GF. Bone cells and matrices in orthopedic tissue engineering. Orthop Clin North Am 2000; 31:357-374. 5 Muschler G, Nakamoto C, Grifith L. Engineering principles of clinical cell based tissue engineering. J Bone Joint Surg 2004; 86-A:1541-1558. 6 Bauer TW, Muschler GF. Bone graft materials. Clin Orthop Relat Res 2000; 371: 10- 27. 7 Smiler DG, Soltan M, Lee JW. A histomorphogenic Analysis of Bone grafts augmented with adult stem cells. Implant Dent 2007; 16: 1-5. 8 Soltan M, Smiler DG, et al .Bone Block allograft impregnated with bone marrow aspirate. Implant Dent 2007; 16: 329-333. 9 Pejron G, Lorenzetti M, Mozzzati M, et al.Sinus floor augmentation with autogenous iliac bone block grafts:A histological and histomorphometrical report on the two-step surgical technique. Int J Oral Maxillofac Surg 2002;31:383-388. 10 Peleg M,Garg A, Misch C,et al. Mxillary sinus and ridge augmentation using a surface-derived autogenous bone graft. J Oral Maxillofac Surg 2004; 62:1535-1544. 11 Hans-Dieter J, Wenz B. Histomorphometric analysis of natural bone mineral for maxillary sinus augmentation. Int J Oral Maxillofac Implants 2004;19:199-207. 12 Tarnow D, Wallace S, Cho S, et al. Histomorphometric comparison of a biphasic bone ceramic to anorganic bovine bone for sinus augmentation: 6-8 month postsurgical assessment of vital bone formation. A pilot study. Int J Periodontics Restorative Dent 2008; 28: 273-81. 13 Schopper C, Moser D, Wanschitz F, et al. Histomorphologic findings on human bone samples six months after bone augmentation of the maxillary sinus with Algipore. J Long Term Eff Med Implants 1999; 9:203-213. 14 Zozano L, Tojo M J, et al. Maxillary sinus lift with intraoral autogenous bone and B-Tricalcium phosphate: Histological and histomorphometric clinical study. Med Oral Patol Oral Cir Bucal 2007;12(7): E532-6. 15 Szabo G, Huys L,Coulthnard P. A prospective multicenter randomized clinical trial of autogenous bone versus B-tricalcium phosphate graft alone for bilateral sinus elevation: Histologic and histomorphometric evaluation. Int J Oral Maxillofac Implants 2005; 20:371-381. 16 Froum S, Tarnow D, Wallace S. The use of a mineralized allograft for sinus augmentation: An interim histological case report from a prospective clinical study. Compendium 2005; 26:259-268. 17 Muschler GF, Boehm C Easley K. Aspiration to obtain osteoblast progenitor cells from human bone marrow: The influence of aspiration volume. J Bone Joint Surg 1997;19:1699-1707. WWW.JIACD.COM 78 Vol. 1, No. 9 December/January 2010

COURSE DATE Advanced Guided Surgery March 26, 2010 DESCRIPTION OF COURSE COURSE CONTENT August 2, 2010 This advanced course is for the clinician who Advanced Guided Surgery Time - 8:00am—5:00pm is already certified and experienced with the Registration: 7:30am NobelGuideTM protocol and the knowledge to for positioning the implants in bone perform virtual surgery for Teeth In An HourTM and developing the surgical guide FEATURING treatment. Course participants are asked to and prothesis for complex bring their laptops with the installed Procera NobelGuideTM treatment THOMAS J. BALSHI, DDS, FACP software as a portion of the program will Board Certified Prosthodontist require its use. More challenging tasks with surgical guide in challenging patients the Procera software such as placing implants GLBENoaNrdJ.CWeOrtLifFieINdGPEroRs, tDhModDo, nFAtiCstP that are tilted off axis, for example, the placement of the adjustable or posterior implants of the All-On-4TM technique, standard abutments and prosthesis pterygomaxillary implants, and zygoma implants are reviewed. An advanced guided EDUCATIONAL OBJECTIVES surgery case is reviewed.Then, live patient CT data will be distributed to the course 1). To demonstrate the treatment planning participants for conversion and 3D planning and pre-surgical aspects of complex of the case. Live surgery of the same patient treatment. will follow.The live treated case will deviate from the standard NobelGuideTM protocol and 2).To provide clinical instruction and the course will emphasize the necessary steps hands-on dental implant virtual surgical to avoid potential inaccuracies with those training. deviations. 3).To provide clinical patient EDUCATIONAL GOAL management before, during and after dental implant virtual surgery Participants will have the knowledge to plan rehabilitation. advanced surgeries on the Procera software as well as perform the advanced surgery for EDUCATIONAL METHODS complex treatment. This course utilizes: Surgery STEBPioHmENedFic. aBlAELnSgHinI,eMe.rB.E. “Surgeon’s Eye View” of the live surgical procedure Please refer to the web site iffe.net for complete instructor bio information. Sponsored by IFFE is an ADA CERP Recognized Provider. ADA CERP is a service of the The Institute For Facial Esthetics American Dental Association to assist dental professionals in identifying quality providers of continuing dental education. ADA CERP does not and Nobel Biocare approve or endorse individual courses or instructors, nor does it imply acceptance of credit hours by boards of dentistry. Concerns or complaints TUITION: $ 1,250.00 about a CE provider may be directed to the provider or to ADA CERP at www.ada.org/goto/cerp. IFFE designates this activity for 8 hours continuing education credit. Visit our web site: http://www.iffe.net For More Information and Registration, contact Linda at 215-643-5881 or at [email protected] IFFE reserves the right to cancel the course at any time with no responsibility other than full refund of money paid to IFFE. No refunds for cancellations made within 48 hours of the course. Continuing education credit issued for participation in this CE activity may not apply towards license renewal in all States.





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Factors Driving Peri-implant Ketabi et al Crestal Bone Loss - Literature Review and Discussion: Part 4 2 Mohammad Ketabi, DDS, MDS1 3 Abstract Many factors contribute to the cumula- guage refereed journals for the decade pre- tive crestal bone loss seen around ceding May 2008 and attempted to identify endosseous dental implants. This the major factors associated with peri-implant can create confusion for the practicing clini- bone loss. This fourth and final installment of cian and lead to undesirable outcomes. In this this article series examines biomechanical fac- four part review series, we have searched the tors such as delayed versus early loading, literature for papers published in English lan- disuse atrophy, and dental implant overload. KEY WORDS: Crestal bone loss, dental implants, causative factors 1. Dean, Professor and Chairman, Department of Periodontology, Faculty of Dentistry, Islamic Azad University (Khorasgan Branch), Arghavanieh, Isfahan, Iran 2. Professor Emeritus, Faculty of Dentistry & Center for Biomaterials, University of Toronto 3. Professor, Discipline of Periodontology and Oral Reconstructive Center, Faculty of Dentistry, University of Toronto The Journal of Implant & Advanced Clinical Dentistry 83

Ketabi et al INTRODUCTION focusing on a specific pre-defined question to be answered by a systematic review was not feasible Many factors, both biological and biomechanical, and therefore no meta-analysis was attempted. will have a cumulative impact on the final amount of bone loss seen with dental implants. It is DISCUSSION important for clinicians to understand all of these factors in addition to their relative contributions A number of biomechanical related factors may and interactions. This is the last installment of a contribute to peri-implant crestal bone loss. four part series reviewing factors that drive peri- The most common of such factors include: implant crestal bone loss. Part one of this review examined surgical and anatomical factors associ- Early versus Delayed Loading ated with peri-implant crestal bone loss. Part two A submerged healing interval was part of the reviewed patient and biologic width factors. Part original protocol proposed for the success- three examined implant geometry, surface rough- ful osseointegration of 2-piece minimally rough ness, length, and diameter. This fourth and final threaded dental implants.1 More recent research, installment of this article series examines biome- however, has shown that in some situations early chanical factors such as delayed versus early load- controlled loading may be of advantage in minimiz- ing, disuse atrophy, and dental implant overload. ing crestal bone loss. Vandamme et al2 compared experimentally controlled immediate loading versus MATERIALS AND METHODS no loading of tapered threaded implants in a rab- bit long bone model and concluded that controlled A literature search of papers published in ref- early loading led to accelerated formation of miner- ereed journals in the English language for the alized bone onto the implant surface. De Smet et decade preceding May 2008 was performed al3 reported that early controlled force application by computer using the National Library of Medi- to particle-blasted threaded implants increased cine and SCOPUS Cochrane Oral Health Group bone mass compared to non-loaded controls in databases. Search strategy included a specific similar experiments in guinea pig tibiae. Meyer et series of terms and key words. The reference al4 used mini-pigs to study the effects of imme- lists of identified publications, relevant textbooks diate loading of conical threaded implants with and professional workshops also were scanned. laser grooves in the collar region. They reported that compared to non-loaded implants, immedi- Relevant references were selected on the ately loaded ones did not show detrimental altera- basis of their titles and abstracts. As the final tions in early bone healing when examined using selection method, full texts of publications iden- backscatter scanning electron microscopy. Piat- tified as possibly relevant were reviewed for telli et al5,6 studied the effects of immediate load- more detailed evaluation. Publications reviewed ing compared to non-loading of rough surfaced included experimental animal studies, prospec- (TPS) threaded implants in monkeys. The immedi- tive and retrospective human clinical studies, a ately loaded implants had greater bone-to-implant few case reports and relevant review papers. contact and what appeared to be greater crestal Because of the limited numbers of available stud- ies for some factors and their heterogeneity, 84 Vol. 2, No. 2 March 2010

Ketabi et al bone density in retrieved histologic specimens. µ represents microstrain) can lead to disuse- Esposito et al7 conducted a systematic review mode remodeling and bone resorption (e.g. in alveolar bone after tooth loss). Vaillancourt et of randomized controlled human clinical trials con- al17 used finite element analysis models to con- cerning the effects of immediate, early and con- firm that some of the crestal bone loss seen with ventional loading of dental implants. None of their partially porous-surfaced implants having a 2mm meta-analyses including those addressing effects long polished collar segment was due to disuse of immediate loading on crestal bone loss revealed atrophy. Stresses equal to 1.6 MPa were deter- any statistically significant effects. The only two mined to be needed to avoid bone loss due to studies that they included on the effects of imme- disuse atrophy with canine mandibular implants. diate loading on crestal bone loss were those of Cannizzaro and Leone8 and Hall et al.9 Marginal Implant Overload bone loss by 2 years was zero to 1mm for 95.7% Bone strains within a physiologic range will of implants with immediate versus 93.3% with stimulate modeling to strengthen the affected delayed loading. Bone loss greater than 1mm bone. However, repeated strains beyond a was seen in 4.3% versus 6.7% for immediate maximal threshold (4,000 micro-strain) for versus delayed loading. Crater-type peri-implant modeling can cause microscopic fatigue resorption frequently developed with delayed damage including micro-fractures that the loading but, not with immediate loading of these affected bone is unable to repair18 resulting implants. Additional studies by Engquist10,11 in bone resorption.19 Thus, bone stress expe- and Schincaglia12 found similar findings as well. rienced by a dental implant due to excessive occlusal loads can lead to marginal bone loss. After his review of literature, Ostman13 con- cluded that “only the outcome of immediate- Misch et al20 and Isidor21 have published loaded implants in the totally edentulous mandible review articles on the possible relationship can be regarded as well documented.” He sug- between occlusal overload and peri-implant bone gested the following requirements for success of loss, noting that clinical evidence in humans is pri- immediately loaded implants including: 1) excel- marily anecdotal as, there have to date been no lent primary stability; 2) moderately rough implant prospective controlled clinical studies investigat- surface; 3) prolonged stabilization by splinting; ing a direct link. Most data concerning this topic 4) controlled occlusion. In another review of lit- have been collected from animal experiments.22-24 erature, Nkenke and Fenner14 recommended Duyck et al25 used a rabbit long bone model to that “more high-level evidence-based studies evaluate histologic levels of crestal bone loss are needed to demonstrate the relative merits of around machine turned threaded dental implants immediate compared to conventional loading.” in response to no loading (controls), static load- ing, and dynamic loading. The statically-loaded Disuse Atrophy implants received a continuous horizontal force Some strain is essential for bone homeostasis.15,16 of 3 kg (29.4 N); while, the dynamically-loaded Strains below a critical lower threshold range implants received a cyclic (once per day over the (10 to 200 x 10-6 strain, i.e. 10 to 200µ where The Journal of Implant & Advanced Clinical Dentistry 85

Ketabi et al 14-day study period; 90 cycles per day in week 1 loss after loading. Rangert et al30 suggested that and 270 cycles per day in week 2) computer-mon- excessive occlusal loads on an implant with for itored load of 1.5kg (14.7 N). With the control example bruxism, use of distal cantilevers or sin- and statically-loaded implants no signs of crestal gle-implant molar restorations with other than bone loss were seen and, there was a tendency centric occlusal contacts, may create bending for the latter implants to show greater bone-to- moments in an implant that will increase stresses implant contact on their compressive surfaces. in marginal bone with its resorption and, may However, the dynamically-loaded implants demon- even cause implant body fracture. Finite element strated crater-shaped marginal bone defects and model studies suggest that use of wider diam- significantly (P < .007) less marginal bone den- eter implants and/or splinted restorations31 may sity than the other two load groups. The effect of decrease the risk of occlusal overload-related relative movement at the bone-to-implant interface crestal bone loss. In the case of patients who during early peri-implant tissue healing has been brux, using more implants and providing occlusal studied by others. While quantitative data on the night guards also may help to reduce overload.32 limits of movement (micromovement) to inhibit osteogenesis (through cell differentiation to the Quality of prosthesis or confounding fac- osteoblast lineage) is limited, studies by Pilliar et tors such as implant surface roughness or level al26 suggested that for porous-surfaced implants, of experience also may be an issue. While some bone formation would occur provided rela- investigators33,34 reported increased marginal tive shear displacements at the bone-to-implant bone loss when distal cantilevers were used with interface were below 50 microns. Simmons et machine turned threaded implants, Wennstrom al27 extended this study to suggest threshold et al reported no difference in crestal bone loss strains of 8% for appositional bone formation with moderately rough threaded implants sup- and 3% for localized de novo bone formation. porting fixed partial dentures with or without dis- tal cantilevers after 5 years in function. Type of There is some case report and retrospective osseointegration will impact any effects of splint- case series data on occlusal overload and peri- ing. For example, sintered surface implants implant crestal bone loss in humans. Quirynen et which develop integration by bone ingrowth and al28 evaluated 93 patients with various restorations mechanical interlocking show significantly less supported by machine turned threaded implants. crestal bone loss for non-splinted than for splinted Excessive ( >1mm after year one) crestal bone restorations, i.e. the reverse of the usual outcomes loss was linked to overload associated with lack with threaded implants. Likewise, while excessive of anterior occlusal contact, presence of para- crown-to-root ratios may lead to greater crestal functional activity and implant-supported res- bone loss with threaded implant designs,35 but torations in both jaws in the same patient. In a is not the case with sintered surface implants. retrospective assessment of 589 machine turned threaded implants, Naert et al29 suggested that Amongst interesting case reports, Tawil36 overload from parafunctional habits may be the reported that placement of an unstable remov- most probable cause of excessive marginal bone able prosthesis on 3 previously well-integrated maxillary machine turned implants that had been 86 Vol. 2, No. 2 March 2010

Ketabi et al stable for 9 years caused noticeable radiographi- at insertion may benefit from controlled early or cally detectable bone loss about 2 of the implants even immediate (within 24 hrs) loading since within 6 months. However, elimination of the some investigators have shown less crestal traumatic occlusion by adjusting the prosthesis resorption with immediate versus delayed loading. and splinting of the 3 implants with a rigid bar The keys seem to be good initial implant stabil- reversed the radiographic changes in peri-implant ity (torque > 30 N cm and resonance frequency bone density over the following 18 months. Simi- value > 60)4 especially in bone of low density,38, larly, Leung et al37 reported angular crestal bone and controlling early forces with splinted transi- loss to the 7th thread around one of two narrow tional fixed restorations. Implants with moderately diameter (3.3mm) machine turned implants sup- rough surfaces may suffer less crestal bone loss porting a fixed prosthesis in hyper-occlusion. than machine turned implants with early/immedi- The prosthesis was removed and the implants ate loading but, this requires further investigation re-connected to healing abutments and, over the and may be site specific.39,40 Also worth not- next few months, radiographs suggested remin- ing is that non-submerged implants (as needed eralization of the crestal defect almost to initial for early/immediate loading) are likely to be more levels without any surgical or pharmacological superficially positioned because there is no intervention. The prosthesis was then re-inserted need to avoid the load of a provisional prosthe- with proper occlusal adjustment and, bone lev- sis. As a result, establishment of biologic width els stabilized at the second thread of the implant may require little or no crestal bone remodeling. and remained stable over the next 36 months. Implant collar design will affect strain on Some suggested guidelines for loading crestal bone. While polished collars are still threaded dental implants within physiologic limits of use until further evidence is provided about include: 1) ensuring optimal passive fit of the pros- extending moderately rough surfaces all the thesis; 2) developing ideal preload in the abutment way to the top of an implant, long ( >1.5mm screw; 3) reducing prosthesis cantilevers; 4) nar- but shorter if platform-switching is an avail- rowing bucco-lingual width of crowns; 5) flatten- able feature of the implant) polished collars ing cuspal inclines; 6) centering occlusal contacts can lead to some crestal bone loss due to over the implant body; 7)selecting adequate width, too low strains and disuse atrophy. Micro- length, and number of implants.35 However, most threads added to the collar segment also pro- of these factors have not been investigated using vide a means for delivering acceptable and prospective, well-designed clinical investigations. desirable levels of strain to crestal bone. CONCLUSIONS At the other extreme, excessive load created by prosthodontic design features or patient With traditional delayed loading of dental implants, factors like parafunction, have been linked to once integration is achieved, some strain on greater crestal bone loss. However, prospective peri-implant crestal bone is necessary to mini- clinical studies clearly demonstrating a direct mize crestal resorption. Interestingly, however, relationship between overload and bone loss threaded dental implants that are well stabilized have not been reported. Micro-strains in excess The Journal of Implant & Advanced Clinical Dentistry 87

Ketabi et al of 4,000 are likely to produce micro-fractures Correspondence: and resorption in crestal bone, although losses Douglas Deporter, DDS, PhD in bone density if discovered early enough may [email protected] be responsive to remedial treatment aimed at eradicating the cause(s) of the overload. Disclosure 12. Schincaglia G, Marzola R, Giovanni G, Chiara 27. Simmons C, Meguid S, Pilliar RM. Mechanical The authors report no conflicts of interest with C, Scotti R. Replacement of mandibular molars regulation of localized and appositional bone anything mentioned in this article. with single-unit restorations supported by formation around bone interfacing implants. J wide-body implants: Immediate versus delayed Biomed Mater Res 2001; 55: 63-71. References loading. A randomized controlled study. Int J 1. Albrektsson T, Branemark PI, Hansson HA, Oral Maxillofac Impl 2008; 23: 474-480. 28. Quirynen M, Naert I, Van Steenberghe D. Fixture design and overload influence marginal bone Lindstrom J. Osseointegrated titanium implants. 13. Ostman P. Immediate/early loading of loss and fixture success in the Branemark Requirements for ensuring a long lasting, direct dental implants. Clinical documentation and System®. Clin Oral Impl Res 1992; 3: 104-111. bone to implant anchorage in man. Acta Orthop presentation of a treatment concept. Periodontol Scand 1981: 52: 155–170. 2000. 2008; 47: 90-112. 29. Naert I, Quirynen M, Van Steenberghe D, 2. Vandamme K, Naert I, Geris L, Vander Sloten Darius P. A study of 589 consecutive implants J, Puers R, Duyck J. Influence of controlled 14. Nkenke E, Fenner M. Indications for immediate supporting complete fixed prostheses. Part II: immediate loading and implant design on peri- loading of implants and implant success. Clin prosthetic aspects. J Prosth Dent. 1992; 68: implant bone formation. J Clin Periodont 2007; Oral Impl Res 2006; 17 (suppl 2): 19-34. 949-956. 34 :172-181. 3. De Smet E, Jaecques S, Jansen J, Walboomers 15. Lanyon L. Functional strain as a determinant for 30.. Rangert B, Krogh P, Langer B, van Roekel F, Vander Sloten J, Naert I. Effect of strain at bone remodeling. Calcif Tissue Int 1984; 36 N. Bending overload and implant fracture: low-frequency loading on peri-implant bone (re) (suppl 1): 56-61. A retrospective clinical analysis. Int J Oral modeling: A guinea pig experimental study. Clin Maxillofac Impl 1995;10: 326-334 Oral Impl Res 2008; 19: 733-739. 16. Martin R, Burr D, Sharkey N. Skeletal Tissue 4. Meyer U, Wiesmann H-P, Fillies T, Joos U. Early Mechanics. New York, NY: Springer-Verlag; 31. Bergkvist G, Simonsson K, Rydberg K, tissue reaction of the interface of immediately 1998. Johansson F, Derand T. A finite element analysis loaded dental implants. Int J Oral Maxillofac Impl of stress distribution in bone tissue surrounding 2003; 18: 489-499. 17. Vaillancourt H, Pilliar R, McCammond D. Finite uncoupled or splinted dental implants. Clin Impl 5. Piattelli A, Corigliano M, Scarano A, Costigliola element analysis of crestal bone loss around Dent Rel Res 2008; 10: 40-46. G, Paolantonio M. Immediate loading of titanium porous-coated dental implants. J Appl Biomater plasma sprayed implants: A histologic analysis in 1995; 6: 267-282. 32. Lobbezoo F, Brouwers J, Cune M, Naeije M. monkeys. J Periodontol 1998; 69: 321–327. Review article. Dental implants in patients with 6. Piattelli A, Corigliano M, Scarano A, Quaranta M. 18. Frost H. Bone’s Mechanostat: A 2003 Update. bruxing habits. J Oral Rehab 2006; 33: 152- Bone reactions to early occlusal loading of two- Anat Rec 2003; 275A: 1081-1101. 159. stage titanium plasma-sprayed implants: a pilot study in monkeys. Int J Perio Rest Dent 1997: 17: 19. Frost H. Some vital biomechanics of bone 33. Lindquist L, Rockler B, Carlsson G. Bone 162–169. grafting and load-bearing implants in dental and resorption around fixtures in edentulous patients 7. Esposito M, Grusovin M, Willings M, Coulthard maxillofacial surgery: A brief tutorial. In: Jensen treated with mandibular fixed tissue integrated P, Worthington H.The effectiveness of immediate, OT, ed. The Sinus Bone Graft. Ill: Quintessence prostheses. J Prosth Dent 1988; 59: 59-63. early, and conventional loading of dental implants: Publishing Co, Inc; 1998; pp17–29. A Cochrane systematic review of randomized 34. Wyatt C, Zarb G. Bone level changes proximal controlled clinical trials. Int J Oral Maxillofac Impl 20. Misch C, Suzuki J, Misch-Dietsh F, Bidez M. A to oral implants supporting fixed partial 2007; 22: 893-904. positive correlation between occlusal trauma prostheses. Clin Oral Impl Res 2002; 13: 162- 8. Cannizzaro G, Leone M. Restoration of partially and peri-implant bone loss: Literature support. 168. edentulous patients using dental implants with a Impl Dent 2005;14:108-116. micro-textured surface: A prospective comparison 35. Misch CE, Goodacre C, Finley J, Misch CM, of delayed and immediate full occlusal loading. Int 21. Isidor F. Influence of forces on peri-implant bone. Marinbach M, Dabrowsky T, English C, Kois J Oral Maxillofac Impl 2003; 18: 512-522. Clin Oral Impl Res 2006; 17 (suppl 2): 8-18. J, Cronin R. Consensus Conference Panel 9. Hall J, Payne A, Purton D, Torr B. A randomized Report: Crown-height space guidelines for controlled clinical trial of conventional and 22. MiyataT, Kobayashi Y, Araki H, Ohto T, Shin K. implant dentistry – Part 2. Impl Dent 2006; 15: immediately loaded tapered implants with screw- The influence of controlled occlusal overload 113-121. retained crowns. Int J Prosthodont 2006; 19: on peri-implant tissue. Part 3: A histologic study 17-19. in monkeys. Int J Oral Maxillfac Impl 2000;15: 36. Tawil G. Peri-implant bone loss caused by 10. Engquist B, Astrand P, Anzén B, Dahlgren S, 425-431. occlusal overload: Repair of the peri-implant defect following correction of the traumatic Engquist E, Feldmann H, Karlsson U, Nord P, 23. Isidor F. Histological evaluation of peri-implant occlusion. A case report. Int J Oral Maxillofac Sahlholm S, Svärdström P. Simplified methods bone at implants subjected to occlusal overload Impl 2008; 23:153-157. of implant treatment in the edentulous lower jaw. or plaque accumulation. Clin Oral Impl Res Part II: Early loading. Clin Impl Dent Relat Res 1997; 8: 1-9. 37. Leung K, Chew T, Wat P, Comfort M. Peri- 2004; 6: 90-100. implant bone loss: Management of a patient. Int J 11. Engquist B, Astrand P, Anzén B, Dahlgren S, 24. Kozlovsky A, Tal H, Laufer B-Z, Leshem R, Oral Maxillofac Impl 2001;16: 273-277. Engquist E, Feldmann H, Karlsson U, Nord P, Rohrer M, Weinreb M, Artzi Z. Impact of implant Sahlholm S, Svärdström P. Simplified methods overloading on the peri-implant bone in inflamed 38. Bergkvist G. Immediate loading of implants in of implant treatment in the edentulous lower and non-inflamed peri-implant mucosa. Clin Oral the edentulous maxilla. Swed Dent J 2008; 196 jaw: a 3-year follow-up report of a controlled Impl Res 2007; 18: 601-610. (Suppl): 10-75. prospective study of one-stage versus two- stage surgery and early loading. Clin Impl Dent 25. Duyck J, Ronold H, van Oosterwyck H, Naert 39. Conrad H, Schulte J, Vallee M. Fractures related Relat Res 2005; 7: 95-104. I, Vander Sloten J, Ellingsen J. The influence of to occlusal overload with single posterior static and dynamic loading on marginal bone implants: A clinical report. J Prosth Dent 2008; reactions around osseointegrated implants: An 99: 251-256. animal experimental study. Clin Oral Impl Res 2001;12: 207-218. 40. Froberg K-K, Lindh C, Ericsson I. Immediate loading of Branemark System® implants: A 26. Pilliar RM. Cementless implant fixation – toward comparison between TiUnite™ and turned improved reliability. Orthop Clin N Amer 2005; implants placed in the anterior mandible. Clin 36(1):113-119. Impl Dent Rel Res 2006; 8: 187-197. 88 Vol. 2, No. 2 March 2010

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Dental 3D Imaging Centers - Usage and FindingsW: inter et al Part IV – Anterior Extension of Inferior Alveolar Nerve From the Mental Foramen Alan A. Winter, DDS1 2 3 5 6 4 Abstract Background: This is part 4 of a 5 part study eval- anterior to the most mesial aspect of the men- uating data obtained from dental referral usage of tal foramen. The average length of the anterior radiological labs for three dimensional (3D) ana- extension from the mesial rim of the mental fora- tomical scans. Part IV of this series studied the men was 12.0mm on the right and 11.8mm on anterior extension of the inferior alveolar nerve; a the left. The average distance to the right eden- discussion of its clinical ramifications is included. tulous crest was 10.5mm and 11.0mm on the left side. 2.7% of edentulous patients (8/296) Methods: Data from 500 consecutive patients had the mental foramina exit on top of the alveo- sent to i-dontics dental radiological centers from lar crest. The distance from the anterior exten- 9 centers locations in 3 states were evaluated. Of sion of the canal to the apex of a tooth when the these patients, 296 mandibular scans were eval- dentition was present was 17.0mm bilaterally. A uated for: the length of the anterior extension of continuous loop, defined as an extension of the the IAN from the most mesial aspect of the mental canal that emanates from both the right and left foramen as identified in a 1mm slice; the distance mental foramina and is seen to connect in the mid- of the anterior extension from the edentulous line was viewed on 26.01% of patients (77/296). alveolar crest; the distance of the anterior exten- sion from the apices of teeth; how many ante- Conclusions: In this study of CBCT evalua- rior extensions of the IAN were connected from tion of 296 mandibular scans, the prevalence right to left at the midline; and how many men- and average length of the anterior loop of the tal foramina were located on the alveolar crest. IAN were higher than those found in other stud- ies. It is unclear if these higher findings are a Results: 296 mandibular scans were included in function of interpretation or a result of the accu- the study. Of these scans, 97% (287/296) had racy of dental cone beam scanners relative to the at least one measurable extension of the IAN methods of identification used in other studies. KEY WORDS: Cone beam computed tomography, inferior alveolar nerve, mental foramen, mandible, dental implants 1. Assistant Clinical Professor, Department of Periodontics and Implant Dentistry, New York University College of Dentistry 2.-5. Private practice, New York, USA 6. Director Maxillofacial Dental Radiology and Associate Professor of Clinical Dentistry, Columbia School of Dental Medicine The Journal of Implant & Advanced Clinical Dentistry 93

Winter et al INTRODUCTION METHODS While there is an extensive literature analyz- Data from five hundred (500) consecu- ing the many aspects of the anterior loop that tive patients sent to i-dontics center from 9 extends from the mental foramen, including centers located in 3 states were evaluated. those that compare the frequency and accu- Scans were taken on either i-CAT (8 cen- racy of this landmark from radiographs, cadaver ters) or NewTom 3G scanners and uploaded dissection, and CT imaging,1-5 no study has to a central data center. All studies were measured the anterior extension of the inferior converted to SimPlant™ (Materialise, Glen alveolar nerve (IAN) relative to distance from the Burnie, MD). When not specified, the data edentulous crest, apices of teeth, and more. In was converted to SimPlant™ version 10. Greenstein and Tarnow’s exhaustive literature review of the anatomy and clinical ramifica- Two hundred and Ninety-six (296) man- tions of the mental foramen, they conclude that dibles were studied using the measuring tool since there is little correlation between view- on the SimPlant Master™ Program. The fol- ing the anterior loop on radiographic and its lowing were measured: the length of the ante- actual clinical location, they recommend “leav- rior extension of the IAN from the most mesial ing a 2mm zone of safety between an implant aspect of the mental foramen as identified in a and the coronal aspect of the nerve.”6 In their 1mm slice; the distance of the anterior exten- literature review, it is suggested to use CT sion from the edentulous alveolar crest; the scans to help identify the anterior loop. They distance of the anterior extension from the recommend that particular attention to varia- apices of teeth; how many anterior exten- tions in the anatomy in the area of the men- sions of the IAN were connected from right tal foramen must be considered in addition to to left at the midline; and how many mental both functional and esthetic demands in order foramina were located on the alveolar crest. to avoid complications to the neurovasculature. RESULTS This study evaluated various normal and abnormal landmarks noted in 500 consecu- Almost 97% of the 296 mandibles analyzed in tive patients referred to dental CT labs for a this study had at least one measurable extension variety of reasons, but most of which were for of the IAN anterior to the most mesial aspect the insertion of dental implants. Part I20 of this of the mental foramen (Figure 1). Fourteen study analyzed the demographics and reasons patients (4.73%) did not have an extension on for the patients being referred for CT scans; the right side; eleven patients (3.72%) did not Part II21 studied anatomic considerations of the have an extension on the left side. The average insertion of the lingual artery into the mandible; length of the anterior extension extending from Part III22 analyzed the frequency and location of the mesial rim of the mental foramen is 12.0 mm bifid canals. In this study, Part IV, the anterior on the right and 11.8 mm on the left (Figure 2). extension of the inferior alveolar nerve is stud- ied and its clinical ramifications are discussed. The distance was measured from the supe- rior portion of the anterior extension of the IAN to the edentulous crest. In most instances, the 94 Vol. 2, No. 2 March 2010

Winter et al Figure 1: 96.96% (287/296) of mandibles had an anterior Figure 2: The average length of the anterior extension extension; 3.03% (9/286) of patients did not have a from the mental foramen bilaterally is nearly 12.0 mm. measureable anterior extension of the IAN. Figure 3: Average measurement from the edentulous bone loss was level and the radiographic exten- alveolar crest the anterior loop was 10.5mm on right sion was parallel to the crest enabling a single anterior mandible. (Stereolithographic model courtesy of measurement either on the right or left side, BioMedical Modeling, Boston, MA). or both. The average depth of the extension under an edentulous right crest was 10.5mm Figure 4: Coronal CBCT slice demonstrating continuous and 11.0mm under the left side (Figure 3). canal. The distance from the anterior exten- sion of the canal to the apex of a tooth when the dentition was present was measured from the most anterior extent of the canal verti- cally to the apex of the adjacent tooth. The preponderance of teeth measured in this situ- ation was to the apices of the lateral inci- sors. In all instances, the measurement was vertical from the tooth apex to the top of the extended canal. Both right and left measure- ments were identical: 17.0mm from the ante- rior extent of the canal to the nearest root apex. A continuous loop, defined as an extension of the canal that emanates from both the right and left mental foramina and is seen to con- The Journal of Implant & Advanced Clinical Dentistry 95

Winter et al Figure 5: Continuous anterior extension of the canal with Figure 5a: Some of the many branches extending from the multiple branches extending from the main trunk. main canal and the anterior extension are highlighted. nect in the midline was viewed on 77 patients alveolar canals or mental foramina not eas- (26.01%). In Figure 4, the anterior extensions ily viewed on traditional 2D dental images of the canal can be seen in different coro- (periapical films or panoramic images). This nal (panoramic) slices of the same individual. study confirmed, along with other studies, that the alveolar ridge resorbs approximately 6.0- Figures 5 and 5A demonstrate a continu- 6.5mm when teeth are extracted, which is the ous anterior extension that joins in the mid- average distance noted between the ridge to line. Various branches emanate from the the anterior extension when compared to root canal displaying that may be viewed in CT apices to the anterior extension of the canal. images but not 2D X-rays. Eight (8) eden- tulous patients (2.70%) had the mental Using CT scans, Rothman found that the foramina exit on top of the alveolar crest. length of the anterior loop could be as long as 10.0mm19 compared to this study, where it was DISCUSSION found the average length for the anterior con- tinuation of the nerve 11.8mm on the left side The anterior loop of the mental nerve is com- and 12.0 mm on the right. What is apparent monly described as that part of the neuro- in this study is that the average length of the vascular bundle that transverses anterior anterior extension of the canal is greater than in and inferior to the mental foramen only to other reported studies. It is unclear if this find- loop back to exit the mental foramen.8-11 ing is a function of interpretation or is a result of the accuracy of dental cone beam scanners. When mandibles were dissected, the ante- What is clear is that these radiographic canals rior loop was detected in 60% of 37 cadaver exist, but their clinical importance is a matter of mandibles.12 The length of the loop in this speculation and requires further investigation. study12 ranged from 0.5 to 5mm. In another study, Neiva et al13 probed the anterior loop For example, are these radiographic canals in 22 cadavers, noting that it was present in filled with nerve and vascular tissues or are 88% of the patients and that its mean length they empty? Do they innervate gingival tis- was 4.13mm ranging from 1.0 - 11.0mm. sues? The answers to these questions are clinically relevant for a host of reasons. When Studies have found CT scans more accu- these anterior extensions of the canal are iden- rate than traditional 2D dental imaging14-18 and they should be considered for locating inferior 96 Vol. 2, No. 2 March 2010

Winter et al tified, should they be avoided during implant Disclosure placement? Should increased bleeding be Support for this study was generously given by Nobel Biocare AB Gothenberg, anticipated? Should the patient be informed Sweden (Grant 2006-492) and Imaging Sciences Inc., Hatfield, PA. that there is a chance there will be an altered sensation to the gingiva and adjacent tis- References sues if these canals are penetrated during 1. Gershenson A, Nathan H, Luchansky E. Mental foramen and mental nerve: implant surgery? Further investigation will help determine the answers to these questions. changes with age. Acta Anat (Basel) 1986; 126:21-28. CONCLUSIONS 2. Ulm CW, Solar P, Biahout R, Marejka M, Watzek G, Gruber H. Location of the mandibular canal within the atrophic mandible. Br J Oral Maxillofac Surg In this study 296 mandibles were studied 1993; 31:370-375. on dental cone beam scanners. The ante- rior extension of the IAN was measured rela- 3. Dharmar S. Locating the mandibular canal in panoramic radiographs. Int J tive to length and distance from edentulous Oral Maxillofac Implants 1997; 12:113-117. ridges or apices of teeth. The clinical ramifica- tions of this anatomic entity were discussed. 4. Kieser J, Kuzmanovic D, Payne A, Dennison J, Herbison P. Patterns of emergence of the human mental nerve. Arch Oral Biol 2002; 47:743-747. Correspondence: Dr. Alan Winter 5. Oguz O, Bozkir MG. Evaluation of location of mandibular and mental foramina [email protected] in dry, young, adult human male, dentulous mandibles. West Indian Med J 2002; 1:14-16. 6. Greenstein G, Tarnow D. The Mental Foramen and Nerve: Clinical and Anatomical Factors Related to Dental Implant Placement: A Literature Review. J Periodontol 2006. 77(12):1933-1943. 7. Mraiwa N, Jacobs R, Steenberghe D, Quirynen M. Clinical Assessment and Surgical Implications of Anatomic Challenges in the Anterior Mandible Clin Implant Dent Rel Res 2006; 5(4):219-225. 8. Kumanovic DV, Payne AG, Kieser JA, Dias GJ. Anterior loop of the mental nerve: A morphological and radiographic study. Clin Oral Implants Res 2003; 14:464-471. 9. Misch CE. Root form surgery in the edentulous mandible: Stage I implant insertion. Implant Dentistry, 2nd ed 1999. The CV Mosby Company; Saint Louis: 347-370. 10. Bavitz JB, Harn SD, Hansen CA, Lang M. An anatomical study of mental neurovascular bundle-implant relationships. Int J Oral Maxillofac Implants 1993; 8:563-567. 11. Jalbout Z, Tabourian G. Glossary of Implant Dentistry 2004. International Congress of Oral Implantologists; Upper Montclair, NJ: 16. 12. Solar P, Ulm C, Frey G, Matejka M. A classification of the intraosseous paths of the mental nerve. Int J Oral Maxillofac Implants 1994; 9:339-344. 13. Neiva RF, Gapski R. Wang HL. Morphometric analysis of implant-related anatomy in Caucasian skulls. J Periodontol 2004; 75:1061-1067. 14. Polland KE, Munro S, Reford G, Lockhart A, Logan G, et al. The mandibular canal of the edentulous jaw. Clin Anat 2001; 14(6): 445-452. 15. Sonick M, Abrahams J, Faiella RA. A comparison of the accuracy of periapical panoramic, and computerized tomographic radiographs in locating the mandibular canal. Int J Oral Maxillofac Implants 1994; 9:455-460. 16. Lindh C, Petersson A. Radiologic examination for location of the mandibular canal: A comparison between panoramic radiography and conventional tomography. Int J Oral Maxillofac Implants 1989; 4:249-253. 17. Bou Serhal C, Jacobs R, Flygare L, Quirynen M, van Steenberghe D. Perioperative validation of localization of the mental foramen. Dentomaxillofac radiol 2002; 31:39-43. 18. Klinge B, Petersson A, Maly P. Location of the mandibular canal: Comparison of macroscopic findings, conventional radiography, and computed tomography. Int J Oral Maxillofac Implants 1989; 4:327-332. 19. Rothman S. Dental Applications of Computerized Tomography 1998. Quintessence; Chicago: 42-24. 20. Winter AA, Yousefzadeh K, Pollack AS, Stein MI, Murphy FJ, Angelopoulos C: Dental 3D Imaging Centers - Usage and Findings: Part I – Demographics. J Implant Adv Clin Dent 2009;1(4):41-47. 21. Winter AA, Yousefzadeh K, Pollack AS, Stein MI, Murphy FJ, Angelopoulos C: Dental 3D Imaging Centers - Usage and Findings: Part II – Anatomic Findings of the Lingual Artery. J Implant Adv Clin Dent 2009;1(7):71-75. 22. Winter AA, Yousefzadeh K, Pollack AS, Stein MI, Murphy FJ, Angelopoulos C: Dental 3D Imaging Centers - Usage and Findings: Part III – Bifid Canal and Other Deviations of the Inferior Alveolar Nerve. J Implant Adv Clin Dent 2009;1(8):77-83. The Journal of Implant & Advanced Clinical Dentistry 97