DENTAL IMPLANTS
Use of Sintered Xenograft Over Allograft for Ridge Augmentation: Technique Note Michael S. Block, DMD,* and Arshad Kaleem, DMD, MDy Patients often present with tooth or implant complications with loss of significant bone width and the need for bone volume for implant placement and maintenance of ridge contour for esthetics. The technique described is a low-morbidity, highly predictable method to restore these sites. A case series of 12 patients followed for 2 years is presented. Ó 2014 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 72:496-502, 2014 Patients who have bone loss adjacent to failing teeth or implants require grafting for implant placement. The final result in the esthetic zone must include bone volume for implant stability and a convex ridge form to simulate the esthetic ridge form of a root prominence. This report describes a method to achieve the necessary form and function of the reconstructed site. Alveolar bone is maintained by the presence of teeth in the jaw. Soon after a tooth is extracted, the alveolar ridge undergoes dimensional changes. Alveolar bone undergoes 3 to 4 mm of horizontal bone loss and 1 to 1.5 mm of vertical height decrease in a period of 6 months,1 with width loss up to 5 mm after tooth extraction.2,3 Bone loss after extraction is greater on the facial surface of the alveolar ridge.4,5 The facial bone loss is believed to result from resorption of bundle bone, which functions to anchor teeth to the alveolar bone. Bundle bone resorbs soon after tooth extraction. Lingual bone consists of bundle and lamellar bone and resorbs less after tooth extraction.6 Alveolar resorption presents a clinical challenge when restoring dentition with implants. Preserving and maintaining the alveolar ridge volume after extraction is critical for future implant treatment. The aims of ridge preservation techniques are to provide sufficient alveolar bone that will optimize implant placement, prevent implant failure owing to dehiscence and fenestration, and improve esthetics. The success rate for implants placed in regenerated bone is the same as bone in a healed socket site.7 In a randomized study of 40 patients, Barone et al8 concluded that in extraction sites without grafting,
there was horizontal bone loss approximating 4.3 mm. In socket grafted with sintered xenograft covered by a collagen membrane, bone loss was 2.5 mm (P < .05). Dental implants have been placed in fresh extraction sockets in an attempt to preserve alveolar ridge anatomy.9,10 After 4 months at re-entry surgery, 56% of horizontal buccal bone and 30% of lingual bone resorbed. Although the implants integrated, bone volume decreased. In a similar study, immediate implant placement with and without immediate loading failed to prevent bone loss that occurs naturally after tooth loss.11
Bone Width Studies With Allograft in Sockets Alone Mineralized freeze-dried bone allograft is considered osteoconductive, forming a scaffold for new bone formation.12,13 Feuille et al14 grafted alveolar sites in a small sample of patients using mineralized freeze-dried bone allograft covered by a nonresorbable reinforced membrane. After 6 months, alveolar width changed from a mean of 4.3 2.0 mm to a mean of 7.4 2.4 mm. Histologic evaluation of the biopsy sample confirmed new bone formation. They did not report long-term changes in the bone augmentation using allograft. Zubillaga et al15 performed a similar study and found complete loss of the augmentation within a short period. The use of allograft as a long-term stable ridge augmentation material when the labial bone is thin or absent is not clear.
*Private Practice, Metairie, LA.
Received June 27 2013
yResident, Department of Oral and Maxillofacial Surgery, Louisiana State University School of Dentistry, New Orleans, LA.
Accepted November 7 2013 Ó 2014 American Association of Oral and Maxillofacial Surgeons
Address correspondence and reprint requests to Dr Block: Center
0278-2391/13/01407-9$36.00/0
for Dental Reconstruction, 110 Veterans Memorial Blvd, Metairie, LA
http://dx.doi.org/10.1016/j.joms.2013.11.002
70005-4948; e-mail: [email protected]
496
497
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Sintered Xenograft Bovine- or equine-derived bone is a xenograft. It has a crystalline structure and a calcium-to-phosphate ratio similar to human bone.16 Sintered xenograft may be slowly replaced by newly formed bone; however, because the sintering process increases the crystallinity of the bone particles, it may not clinically resorb and often will be present years after placement.17-20 By using this process, the xenograft is very slow to resorb. Sintered xenograft has been successfully used for ridge and sinus augmentation.21 This material acts as a scaffold for new bone formation at the interface between bone and xenograft, with fibrous tissue present in parts of the graft,22 maintaining the form of the augmentation because of its presence.23 Allograft resorbs and is replaced by bone.24,25 Wang et al24 described a layering technique using different graft materials to augment dehisced or deficient alveolar bone around dental implants. In their case series of 5 patients, implant defects averaging 10.5 mm were treated with a layering technique. Autogenous bone, collected during osteotomy preparation for implantation, was used as an inner layer in close contact with the implant. When autogenous bone harvest volume was not adequate, demineralized bone allograft was used. An outer layer of bovine sintered xenograft was placed on the allograft to preserve and maintain the augmented bone. A third layer of absorbable collagen was placed to prevent soft tissue and nonosteogenic cell invasion into the grafted site. Six months later, on re-entry, grafted sites were found to be covered with bone. Poulias et al26 reported a modified layered approach in 24 patients. Socket grafting was performed with allograft alone in 12 patients, and the remaining patients received an intrasocket allograft and an overlay of xenograft on intact, thin buccal bone. The 2 groups had a resorbable membrane placed over the graft. Measurements were recorded before bone grafting and 4 months later. A mean horizontal width loss of 1.6 0.8 mm (P > .05) was seen in the group with only the socket graft, and that in the xenograft onlay group was 0.3 0.9 mm (P > .05). Overall, they found a significant difference between the 2 groups. Sintered xenograft has been used to augment a thin edentulous ridge with a long-lasting collagen membrane of a PDLLA, D-lactide and L-lactide foil used to retain the graft. In a retrospective follow-up evaluation, there was 1 mm of augmentation width loss after 2 years.27 This showed that sintered xenograft could be used to augment ridge width, with maintenance of the ridge form within the follow-up period reported. This is different than the use of allograft alone and is consistent with the finding that the choice of graft material does influence ridge form.28-30
Based on this evidence-based clinical information, the reported technique uses an intrasocket graft of mineralized bone allograft with an onlay of sintered xenograft to reconstruct horizontal defects in sites that are planned for implant placement. The sites reported in this series showed loss of the labial bone with significant horizontal ridge deficiency, often in the esthetic zone, associated with the need for tooth extraction. The hypothesis of this case series was that this technique would be a method of minimal morbidity that would result in sufficient ridge width for an implant restoration. The goal of this report is to present a technique that may result in less crestal resorption than that seen with allograft or autogenous particulate grafts. This case series is a retrospective chart review and was granted an exemption by the Louisiana State University Health Sciences Center (institutional review board #8440).
Technique Patients who required removal of an infected tooth or implant, with the need for bone formation in the site of implant placement in the alveolus and the need to maintain ridge contour and width over time, were included in this case series. Goals for the augmentation included avoidance of unesthetic scars from the reconstruction, the formation of viable bone in the implant site, restoration of ridge contour for esthetics, a low level of patient morbidity, and predictability of the ridge form augmentation. These patients prepared for surgery by using an antibacterial rinse for 3 days before surgery. They started antibiotics the evening before surgery. At the time of surgery, the surgical site was lightly prepared with a solution of povidone and iodine. Local anesthesia was infiltrated in the vestibule and palate. For this method, incisions were made in the sulcus of the teeth and at the crest if there was an edentulous site. A full-thickness envelope flap was elevated, often to the level of the piriform rim. Teeth with root tips, implants, root canal materials, and granulation tissue were removed. The site was irrigated with sterile saline. No bone perforations were made. No other site preparation was performed. The periosteum was incised and released to allow for a tension-free closure. The periosteal release was performed early in the procedure to allow for time for hemostasis control. Mineralized allografts of cortical or cancellous particles (250 mm to 1 mm) were hydrated. Clinicians may note that the small particles may occasionally flow with blood and the 1-mm particles can occasionally work themselves out of the wound. The allograft was placed onto the exposed cleaned socket or bone defect to the meet the horizontal projection of the
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adjacent bone. Gauze was used to compact the graft. Then, the sintered xenograft was placed on the allograft to an approximate xenograft thickness ranging from 1.5 to 3 mm, based on the estimation of the thickness by the surgeon and by evaluation of the conebeam scan. After the onlay graft was stabilized by light pressure using sterile gauze, the flap was closed with resorbable sutures. No membranes were used unless the superior bone contour was flat and there was a tendency for graft migration. When this method was used for defects of at least 3 tooth sizes, a long-lasting collagen membrane was used to cover the xenograft under the flap for greater graft position maintenance. After the incisions were closed, the provisional prosthesis was adjusted, if necessary, to eliminate pressure on the crest. Flanges were removed from removable prostheses. If possible, tooth-borne vacuum-form provisional prostheses were preferred. Postoperative treatment included a liquid to very soft diet and antibiotics for 7 days. Patients were advised to use non– alcohol-based rinses, with no antibacterial rinses. Diluted salt water was preferred as the rinse. An immediate low-radiation cone-beam scan was taken to check graft position and density. Approximately 4 to 6 months after augmentation, a cone-beam scan was taken to determine the amount of bone and graft available for implant placement. The cone-beam scan was loaded into computed tomographic planning software to allow for virtual implant placement. From the virtual implant placement, an accurate surgical guide was fabricated. At the time for implant placement, elevation of the labial tissue was avoided to prevent inadvertent graft elevation. Palatal flaps were used to expose the site for implant placement or flapless procedures were used. Elevation of flaps was avoided because the authors did not want to raise the
graft with the elevated flap, which can occur after particulate ridge augmentation. Elevation of a flap in this situation was not indicated. Histology was not performed; thus, the specific material within the site is not known.
FIGURE 1. Preoperative view showing translucent left central incisor secondary to internal resorption. This patient had trauma to the tooth 6 years previously when playing baseball. The tooth was treated with subluxation and root canal therapy.
FIGURE 3. A sulcular incision was made extending to the 2 adjacent teeth. A full-thickness flap was developed and a periosteal release was made. The shell of the tooth was removed, leaving a soft tissue remnant and a translucent film of bone over the root canal material.
Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
FIGURE 2. Cross-sectional image shows loss of tooth structure with the root canal material remaining. There is an obvious loss of labial bone. Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
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FIGURE 6. Sintered xenograft was placed over the allograft. No membrane was used. The incisions were closed without tension. FIGURE 4. The root canal material was removed in 1 piece and the bone was cleaned.
Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
Methods for Evaluation Twelve patients with 14 single-tooth sites were followed for 2 years after augmentation. Their preoperative cone-beams scans were compared with scans taken immediately after grafting and with the longestterm scans. After the augmentation had healed and the implants had been placed, no further cone-beam scans were taken, to minimize the patients’ overall radiation dose. Digital periapical radiographs were used to assess implant health from implant placement. Because of the variability of timing, objective statistical evaluation was difficult to analyze. Descriptive statistics were used. The cone-beam software was used to measure ridge width on scans preoperatively, immediately after grafting, 3 to 6 months after grafting, and after implant placement. Patients were concerned about excessive radiation. Because the implants were stable and the peri-
apical radiographs appeared excellent, there was no clinical need to expose the patients to unnecessary radiation. Thus, no long-term post-restoration cone-beam scans were taken. One person measured the width of the ridge 2 mm from the crest. Each cone-beam scan had the axial spline centered on the ridge through the pulp chambers of the adjacent teeth. The cross section was measured and recorded to the nearest 0.1 mm. Means and standard deviations were determined. The data
FIGURE 5. An allograft was placed using mineralized cortical bone.
FIGURE 7. Cross-sectional image immediately after grafting shows restoration of the thickness of the ridge with a 12-mm ridge height.
Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
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FIGURE 10. An incision was made on the crest in a curvilinear manner with release incisions to the palate. A palatal flap was reflected. The implant was placed. This photograph shows the driving mount of the Ankylos B11 C/X implant (Dentsply Implants, Waltham, MA), which was chosen owing to the width of the ridge and 12 mm of height to the nasal floor. Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
FIGURE 8. The patient returned 1.8 years later for the implant. This cross-sectional image of the graft site shows maintenance of the form and a dense layer of the xenograft mimicking cortical bone.
period to evaluate the graft’s dimension before implantation. Depending on the patient’s age and systemic conditions, the time for cone-beam scanning to plan the implants varied. An earlier period was chosen when computed tomographic guidance was used for implant placement, allowing for more time for planning and stent fabrication.
Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
Results
shown are used descriptively and were not analyzed for statistical significance. The decision to group the 3- to 6-month periods was based on a relatively small sample and the use of this
For the 14 sites reviewed, all incisions healed uneventfully. Implants were placed in all but 3 patients. These 3 patients have not yet had their implants placed because they are involved with financial or personal issues. The average ridge width before grafting was 5.4 1.4 mm. The average ridge width immediately after grafting was 9.0 0.5 mm. The average ridge width
FIGURE 9. The patients’ ridge form was good, with a mature later of soft tissue over the edentulous ridge.
FIGURE 11. The healing abutment was placed to allow for optimal soft tissue healing.
Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
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4. The resorption rate of the material over time should be taken into consideration to plan the sequencing of therapies, such as implant placement, additional contour grafting, and pontic and site development. Ridge form maintenance by a nonresorbable material is critical for esthetic concerns. 5. The material should be relatively inexpensive, readily available, and should not transfer pathologic conditions.
FIGURE 12. This cross-sectional radiograph shows the implant in position with the intact labial graft. The implant was restored after 4 months for implant integration. Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
3 to 6 months after grafting was 8.6 1.0 mm. The average longest-term evaluated ridge width was 8.5 0.8 mm. Radiographic evaluation showed a homogenous bone density within the socket before implant placement (Figs 1 to 12). The overlying sintered xenograft appeared similar to a thin cortical bone layer and did not resorb during the period evaluated in this case series.
Discussion The clinician should consider the following points when choosing materials to reconstruct an implant site that involves an extraction socket and horizontal bone deficiency. 1. Space should be maintained. Bone can repopulate a graft and re-create a bone volume similar to the pre-extraction size. 2. The bone formed where the implant is to be placed should be sufficiently dense to allow primary stability of the implant. The material placed should have osteoconductive features to enhance bone formation. 3. The material that retains the implant should resorb within a selected period with replacement by autogenous bone that is normal to the site.
These patients present with a dental history that has resulted in significant bone loss and often thinning of the tissues. They desire to be restored back to their original condition. They also have limitations on chair time and they desire the reconstruction to be as minimally invasive and as pain free as possible. There are other options available for these patients, which often require the use of autogenous bone harvested from a separate site or the use of expensive materials, which are contained within carriers such as mesh. These methods can result in excellent ridge reconstruction. The amount of width gained based on the results given is only 3 mm at 3 to 6 months and may be attributable to the xenograft only. This may be true in some cases and not true in others. The result of the method is that the augmentation was stable over time. The technique described in this case series is another alternative for the clinician to choose for the patient.
References 1. Hammerle CH, Araujo MG, Simion M: Osteology Consensus Group 2011: Evidence-based knowledge on the biology and treatment of extraction sockets. Clin Oral Implants Res 23(suppl 5):80, 2012 2. Lekovic V, Camargo PM, Klokkevold PR: Preservation of alveolar bone in extraction sockets using bioabsorbable membranes. J Periodontol 69:1044, 1998 3. Lekovic V, Kenney EB, Weinlaender M, et al: A bone regenerative approach to alveolar ridge maintenance following tooth extraction. Report of 10 cases. J Periodontol 68:563, 1997 4. Araujo MG, Lindhe J: Dimensional ridge alterations following tooth extraction. An experimental study in the dog. J Clin Periodontol 32:212, 2005 5. Araujo MG, Sukekava F, Wennstrom JL, et al: Ridge alterations following implant placement in fresh extraction sockets: An experimental study in the dog. J Clin Periodontol 32:645, 2005 6. Tan WL, Wong TL, Wong MC, et al: A systematic review of postextractional alveolar hard and soft tissue dimensional changes in humans. Clin Oral Implants Res 23(suppl 5):1, 2012 7. Buchmann R, Khoury F, Faust C, et al: Peri-implant conditions in periodontally compromised patients following maxillary sinus augmentation. A long-term post-therapy trial. Clin Oral Implants Res 10:103, 1999 8. Barone A, Aldini NN, Fini M, et al: Xenograft versus extraction alone for ridge preservation after tooth removal: A clinical and histomorphometric study. J Periodontol 79:1370, 2008 9. Botticelli D, Berglundh T, Lindhe J: Hard-tissue alterations following immediate implant placement in extraction sites. J Clin Periodontol 31:820, 2004
502 10. Paolantonio M, Dolci M, Scarano A, et al: Immediate implantation in fresh extraction sockets. A controlled clinical and histological study in man. J Periodontol 72:1560, 2001 11. Blanco J, Linares A, Perez J, et al: Ridge alterations following flapless immediate implant placement with or without immediate loading. Part II: A histometric study in the beagle dog. J Clin Periodontol 38:762, 2011 12. Wang RE, Lang NP: Ridge preservation after tooth extraction. Clin Oral Implants Res 23(suppl 6):147, 2012 13. Becker W, Becker BE, Caffesse R: A comparison of demineralized freeze-dried bone and autologous bone to induce bone formation in human extraction sockets. J Periodontol 65:1128, 1994 14. Feuille F, Knapp CI, Brunsvold MA, et al: Clinical and histologic evaluation of bone-replacement grafts in the treatment of localized alveolar ridge defects. Part 1: Mineralized freeze-dried bone allograft. Int J Periodontics Restorative Dent 23:29, 2003 15. Zubillaga G, Von Hagen S, Simon BI, et al: Changes in alveolar bone height and width following post-extraction ridge augmentation using a fixed bioabsorbable membrane and demineralized freeze-dried bone osteoinductive graft. J Periodontol 74:965, 2003 16. Block MS: Treatment of the single tooth extraction site. Oral Maxillofac Surg Clin North Am 16:41, 2004 17. Berglundh T, Lindhe J: Healing around implants placed in bone defects treated with Bio-Oss: An experimental study in the dog. Clin Oral Implants Res 8:117, 1997 18. Artzi Z, Tal H, Dayan D: Porous bovine bone mineral in healing of human extraction sockets. Part 1. Histomorphometric evaluations at 9 months. J Periodontol 71:1015, 2000 19. Wetzel AC, Stich H, Caffesse RG: Bone apposition onto oral implants in the sinus area filled with different grafting materials: A histologic study in beagle dogs. Clin Oral Implants Res 6: 155, 1995 20. Van Steenberghe D, Callens A, Geers L, Jacobs R: The clinical use of deproteinized bovine bone mineral on bone regeneration in conjunction with immediate implant installation. Clin Oral Implants Res 11:210, 2000
SINTERED XENOGRAFT VERSUS ALLOGRAFT 21. Barone A, Crespi R, Aldini NN, et al: Maxillary sinus augmentation: Histologic and histomorphometric analysis. Int J Oral Maxillofac Implant 20:519, 2005 22. Orsini G, Scarano A, Piattelli M, et al: Histologic and ultrastructural analysis of regenerated bone in maxillary sinus augmentation using a porcine bone-derived biomaterial. J Periodontol 77:1984, 2006 23. Artzi Z, Tal H, Dayan D: Porous bovine bone mineral in healing of human extraction sockets: 2. Histochemical observations at 9 months. J Periodontol 72:152, 2001 24. Wang HL, Misch C, Neiva RF: ‘ Sandwich’’ bone augmentation technique: Rationale and report of pilot cases. Int J Periodontics Restorative Dent 24:232, 2004 25. Scarano A, Pecora G, Piattelli M, et al: Osseointegration in a sinus augmented with bovine porous bone mineral: Histological results in an implant retrieved 4 years after insertion. A case report. J Periodontol 75:1161, 2004 26. Poulias E, Greenwell H, Hill M, et al: Ridge preservation comparing a socket allograft alone to a socket allograft plus a facial overlay xenograft: A clinical and histologic study in humans. J Periodontol 84:1567, 2013 27. Block MS, Ducote CW, Mercante DE: Horizontal augmentation of thin maxillary ridge with bovine particulate xenograft is stable during 500 days of follow-up: Preliminary results of 12 consecutive patients. J Oral Maxillofac Surg 70:1321, 2012 28. Iasella JM, Greenwell H, Miller RL, et al: Ridge preservation with freeze-dried bone allograft and a collagen membrane compared to extraction alone for implant site development: A clinical and histologic study in humans. J Periodontol 74: 990, 2003 29. Horowitz RA, Mazor Z, Miller RJ, et al: Clinical evaluation alveolar ridge preservation with a beta-tricalcium phosphate socket graft. Compend Contin Educ Dent 30:588, 2009 30. Simon BI, Von Hagen S, Deasy MJ, et al: Changes in alveolar bone height and width following ridge augmentation using bone graft and membranes. J Periodontol 71:1774, 2000
Use of Sintered Xenograft Over Allograft for Ridge Augmentation: Technique Note Michael S. Block, DMD,* and Arshad Kaleem, DMD, MDy Patients often present with tooth or implant complications with loss of significant bone width and the need for bone volume for implant placement and maintenance of ridge contour for esthetics. The technique described is a low-morbidity, highly predictable method to restore these sites. A case series of 12 patients followed for 2 years is presented. Ó 2014 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 72:496-502, 2014 Patients who have bone loss adjacent to failing teeth or implants require grafting for implant placement. The final result in the esthetic zone must include bone volume for implant stability and a convex ridge form to simulate the esthetic ridge form of a root prominence. This report describes a method to achieve the necessary form and function of the reconstructed site. Alveolar bone is maintained by the presence of teeth in the jaw. Soon after a tooth is extracted, the alveolar ridge undergoes dimensional changes. Alveolar bone undergoes 3 to 4 mm of horizontal bone loss and 1 to 1.5 mm of vertical height decrease in a period of 6 months,1 with width loss up to 5 mm after tooth extraction.2,3 Bone loss after extraction is greater on the facial surface of the alveolar ridge.4,5 The facial bone loss is believed to result from resorption of bundle bone, which functions to anchor teeth to the alveolar bone. Bundle bone resorbs soon after tooth extraction. Lingual bone consists of bundle and lamellar bone and resorbs less after tooth extraction.6 Alveolar resorption presents a clinical challenge when restoring dentition with implants. Preserving and maintaining the alveolar ridge volume after extraction is critical for future implant treatment. The aims of ridge preservation techniques are to provide sufficient alveolar bone that will optimize implant placement, prevent implant failure owing to dehiscence and fenestration, and improve esthetics. The success rate for implants placed in regenerated bone is the same as bone in a healed socket site.7 In a randomized study of 40 patients, Barone et al8 concluded that in extraction sites without grafting,
there was horizontal bone loss approximating 4.3 mm. In socket grafted with sintered xenograft covered by a collagen membrane, bone loss was 2.5 mm (P < .05). Dental implants have been placed in fresh extraction sockets in an attempt to preserve alveolar ridge anatomy.9,10 After 4 months at re-entry surgery, 56% of horizontal buccal bone and 30% of lingual bone resorbed. Although the implants integrated, bone volume decreased. In a similar study, immediate implant placement with and without immediate loading failed to prevent bone loss that occurs naturally after tooth loss.11
Bone Width Studies With Allograft in Sockets Alone Mineralized freeze-dried bone allograft is considered osteoconductive, forming a scaffold for new bone formation.12,13 Feuille et al14 grafted alveolar sites in a small sample of patients using mineralized freeze-dried bone allograft covered by a nonresorbable reinforced membrane. After 6 months, alveolar width changed from a mean of 4.3 2.0 mm to a mean of 7.4 2.4 mm. Histologic evaluation of the biopsy sample confirmed new bone formation. They did not report long-term changes in the bone augmentation using allograft. Zubillaga et al15 performed a similar study and found complete loss of the augmentation within a short period. The use of allograft as a long-term stable ridge augmentation material when the labial bone is thin or absent is not clear.
*Private Practice, Metairie, LA.
Received June 27 2013
yResident, Department of Oral and Maxillofacial Surgery, Louisiana State University School of Dentistry, New Orleans, LA.
Accepted November 7 2013 Ó 2014 American Association of Oral and Maxillofacial Surgeons
Address correspondence and reprint requests to Dr Block: Center
0278-2391/13/01407-9$36.00/0
for Dental Reconstruction, 110 Veterans Memorial Blvd, Metairie, LA
http://dx.doi.org/10.1016/j.joms.2013.11.002
70005-4948; e-mail: [email protected]
496
497
BLOCK AND KALEEM
Sintered Xenograft Bovine- or equine-derived bone is a xenograft. It has a crystalline structure and a calcium-to-phosphate ratio similar to human bone.16 Sintered xenograft may be slowly replaced by newly formed bone; however, because the sintering process increases the crystallinity of the bone particles, it may not clinically resorb and often will be present years after placement.17-20 By using this process, the xenograft is very slow to resorb. Sintered xenograft has been successfully used for ridge and sinus augmentation.21 This material acts as a scaffold for new bone formation at the interface between bone and xenograft, with fibrous tissue present in parts of the graft,22 maintaining the form of the augmentation because of its presence.23 Allograft resorbs and is replaced by bone.24,25 Wang et al24 described a layering technique using different graft materials to augment dehisced or deficient alveolar bone around dental implants. In their case series of 5 patients, implant defects averaging 10.5 mm were treated with a layering technique. Autogenous bone, collected during osteotomy preparation for implantation, was used as an inner layer in close contact with the implant. When autogenous bone harvest volume was not adequate, demineralized bone allograft was used. An outer layer of bovine sintered xenograft was placed on the allograft to preserve and maintain the augmented bone. A third layer of absorbable collagen was placed to prevent soft tissue and nonosteogenic cell invasion into the grafted site. Six months later, on re-entry, grafted sites were found to be covered with bone. Poulias et al26 reported a modified layered approach in 24 patients. Socket grafting was performed with allograft alone in 12 patients, and the remaining patients received an intrasocket allograft and an overlay of xenograft on intact, thin buccal bone. The 2 groups had a resorbable membrane placed over the graft. Measurements were recorded before bone grafting and 4 months later. A mean horizontal width loss of 1.6 0.8 mm (P > .05) was seen in the group with only the socket graft, and that in the xenograft onlay group was 0.3 0.9 mm (P > .05). Overall, they found a significant difference between the 2 groups. Sintered xenograft has been used to augment a thin edentulous ridge with a long-lasting collagen membrane of a PDLLA, D-lactide and L-lactide foil used to retain the graft. In a retrospective follow-up evaluation, there was 1 mm of augmentation width loss after 2 years.27 This showed that sintered xenograft could be used to augment ridge width, with maintenance of the ridge form within the follow-up period reported. This is different than the use of allograft alone and is consistent with the finding that the choice of graft material does influence ridge form.28-30
Based on this evidence-based clinical information, the reported technique uses an intrasocket graft of mineralized bone allograft with an onlay of sintered xenograft to reconstruct horizontal defects in sites that are planned for implant placement. The sites reported in this series showed loss of the labial bone with significant horizontal ridge deficiency, often in the esthetic zone, associated with the need for tooth extraction. The hypothesis of this case series was that this technique would be a method of minimal morbidity that would result in sufficient ridge width for an implant restoration. The goal of this report is to present a technique that may result in less crestal resorption than that seen with allograft or autogenous particulate grafts. This case series is a retrospective chart review and was granted an exemption by the Louisiana State University Health Sciences Center (institutional review board #8440).
Technique Patients who required removal of an infected tooth or implant, with the need for bone formation in the site of implant placement in the alveolus and the need to maintain ridge contour and width over time, were included in this case series. Goals for the augmentation included avoidance of unesthetic scars from the reconstruction, the formation of viable bone in the implant site, restoration of ridge contour for esthetics, a low level of patient morbidity, and predictability of the ridge form augmentation. These patients prepared for surgery by using an antibacterial rinse for 3 days before surgery. They started antibiotics the evening before surgery. At the time of surgery, the surgical site was lightly prepared with a solution of povidone and iodine. Local anesthesia was infiltrated in the vestibule and palate. For this method, incisions were made in the sulcus of the teeth and at the crest if there was an edentulous site. A full-thickness envelope flap was elevated, often to the level of the piriform rim. Teeth with root tips, implants, root canal materials, and granulation tissue were removed. The site was irrigated with sterile saline. No bone perforations were made. No other site preparation was performed. The periosteum was incised and released to allow for a tension-free closure. The periosteal release was performed early in the procedure to allow for time for hemostasis control. Mineralized allografts of cortical or cancellous particles (250 mm to 1 mm) were hydrated. Clinicians may note that the small particles may occasionally flow with blood and the 1-mm particles can occasionally work themselves out of the wound. The allograft was placed onto the exposed cleaned socket or bone defect to the meet the horizontal projection of the
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adjacent bone. Gauze was used to compact the graft. Then, the sintered xenograft was placed on the allograft to an approximate xenograft thickness ranging from 1.5 to 3 mm, based on the estimation of the thickness by the surgeon and by evaluation of the conebeam scan. After the onlay graft was stabilized by light pressure using sterile gauze, the flap was closed with resorbable sutures. No membranes were used unless the superior bone contour was flat and there was a tendency for graft migration. When this method was used for defects of at least 3 tooth sizes, a long-lasting collagen membrane was used to cover the xenograft under the flap for greater graft position maintenance. After the incisions were closed, the provisional prosthesis was adjusted, if necessary, to eliminate pressure on the crest. Flanges were removed from removable prostheses. If possible, tooth-borne vacuum-form provisional prostheses were preferred. Postoperative treatment included a liquid to very soft diet and antibiotics for 7 days. Patients were advised to use non– alcohol-based rinses, with no antibacterial rinses. Diluted salt water was preferred as the rinse. An immediate low-radiation cone-beam scan was taken to check graft position and density. Approximately 4 to 6 months after augmentation, a cone-beam scan was taken to determine the amount of bone and graft available for implant placement. The cone-beam scan was loaded into computed tomographic planning software to allow for virtual implant placement. From the virtual implant placement, an accurate surgical guide was fabricated. At the time for implant placement, elevation of the labial tissue was avoided to prevent inadvertent graft elevation. Palatal flaps were used to expose the site for implant placement or flapless procedures were used. Elevation of flaps was avoided because the authors did not want to raise the
graft with the elevated flap, which can occur after particulate ridge augmentation. Elevation of a flap in this situation was not indicated. Histology was not performed; thus, the specific material within the site is not known.
FIGURE 1. Preoperative view showing translucent left central incisor secondary to internal resorption. This patient had trauma to the tooth 6 years previously when playing baseball. The tooth was treated with subluxation and root canal therapy.
FIGURE 3. A sulcular incision was made extending to the 2 adjacent teeth. A full-thickness flap was developed and a periosteal release was made. The shell of the tooth was removed, leaving a soft tissue remnant and a translucent film of bone over the root canal material.
Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
FIGURE 2. Cross-sectional image shows loss of tooth structure with the root canal material remaining. There is an obvious loss of labial bone. Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
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FIGURE 6. Sintered xenograft was placed over the allograft. No membrane was used. The incisions were closed without tension. FIGURE 4. The root canal material was removed in 1 piece and the bone was cleaned.
Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
Methods for Evaluation Twelve patients with 14 single-tooth sites were followed for 2 years after augmentation. Their preoperative cone-beams scans were compared with scans taken immediately after grafting and with the longestterm scans. After the augmentation had healed and the implants had been placed, no further cone-beam scans were taken, to minimize the patients’ overall radiation dose. Digital periapical radiographs were used to assess implant health from implant placement. Because of the variability of timing, objective statistical evaluation was difficult to analyze. Descriptive statistics were used. The cone-beam software was used to measure ridge width on scans preoperatively, immediately after grafting, 3 to 6 months after grafting, and after implant placement. Patients were concerned about excessive radiation. Because the implants were stable and the peri-
apical radiographs appeared excellent, there was no clinical need to expose the patients to unnecessary radiation. Thus, no long-term post-restoration cone-beam scans were taken. One person measured the width of the ridge 2 mm from the crest. Each cone-beam scan had the axial spline centered on the ridge through the pulp chambers of the adjacent teeth. The cross section was measured and recorded to the nearest 0.1 mm. Means and standard deviations were determined. The data
FIGURE 5. An allograft was placed using mineralized cortical bone.
FIGURE 7. Cross-sectional image immediately after grafting shows restoration of the thickness of the ridge with a 12-mm ridge height.
Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
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FIGURE 10. An incision was made on the crest in a curvilinear manner with release incisions to the palate. A palatal flap was reflected. The implant was placed. This photograph shows the driving mount of the Ankylos B11 C/X implant (Dentsply Implants, Waltham, MA), which was chosen owing to the width of the ridge and 12 mm of height to the nasal floor. Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
FIGURE 8. The patient returned 1.8 years later for the implant. This cross-sectional image of the graft site shows maintenance of the form and a dense layer of the xenograft mimicking cortical bone.
period to evaluate the graft’s dimension before implantation. Depending on the patient’s age and systemic conditions, the time for cone-beam scanning to plan the implants varied. An earlier period was chosen when computed tomographic guidance was used for implant placement, allowing for more time for planning and stent fabrication.
Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
Results
shown are used descriptively and were not analyzed for statistical significance. The decision to group the 3- to 6-month periods was based on a relatively small sample and the use of this
For the 14 sites reviewed, all incisions healed uneventfully. Implants were placed in all but 3 patients. These 3 patients have not yet had their implants placed because they are involved with financial or personal issues. The average ridge width before grafting was 5.4 1.4 mm. The average ridge width immediately after grafting was 9.0 0.5 mm. The average ridge width
FIGURE 9. The patients’ ridge form was good, with a mature later of soft tissue over the edentulous ridge.
FIGURE 11. The healing abutment was placed to allow for optimal soft tissue healing.
Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
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4. The resorption rate of the material over time should be taken into consideration to plan the sequencing of therapies, such as implant placement, additional contour grafting, and pontic and site development. Ridge form maintenance by a nonresorbable material is critical for esthetic concerns. 5. The material should be relatively inexpensive, readily available, and should not transfer pathologic conditions.
FIGURE 12. This cross-sectional radiograph shows the implant in position with the intact labial graft. The implant was restored after 4 months for implant integration. Block and Kaleem. Sintered Xenograft Versus Allograft. J Oral Maxillofac Surg 2014.
3 to 6 months after grafting was 8.6 1.0 mm. The average longest-term evaluated ridge width was 8.5 0.8 mm. Radiographic evaluation showed a homogenous bone density within the socket before implant placement (Figs 1 to 12). The overlying sintered xenograft appeared similar to a thin cortical bone layer and did not resorb during the period evaluated in this case series.
Discussion The clinician should consider the following points when choosing materials to reconstruct an implant site that involves an extraction socket and horizontal bone deficiency. 1. Space should be maintained. Bone can repopulate a graft and re-create a bone volume similar to the pre-extraction size. 2. The bone formed where the implant is to be placed should be sufficiently dense to allow primary stability of the implant. The material placed should have osteoconductive features to enhance bone formation. 3. The material that retains the implant should resorb within a selected period with replacement by autogenous bone that is normal to the site.
These patients present with a dental history that has resulted in significant bone loss and often thinning of the tissues. They desire to be restored back to their original condition. They also have limitations on chair time and they desire the reconstruction to be as minimally invasive and as pain free as possible. There are other options available for these patients, which often require the use of autogenous bone harvested from a separate site or the use of expensive materials, which are contained within carriers such as mesh. These methods can result in excellent ridge reconstruction. The amount of width gained based on the results given is only 3 mm at 3 to 6 months and may be attributable to the xenograft only. This may be true in some cases and not true in others. The result of the method is that the augmentation was stable over time. The technique described in this case series is another alternative for the clinician to choose for the patient.
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