DENTAL IMPLANTS

Alveolar Sandwich Osteotomy in Resorbed Alveolar Ridge for Dental Implants: A 4-Year Prospective Study Amir Laviv, DMD,* Ole T. Jensen, DDS, MSc,y Eyal Tarazi, DMD,z and Nardy Casap, DMD, MDx Purpose:

To answer whether severe vertical alveolar defects can be resolved using the sandwich osteotomy technique with xenograft material as filler and to evaluate the predictability of this procedure.

Materials and Methods:

Ten graft sites (5 mandibular and 5 maxillary) in 9 patients treated at the Department of Oral and Maxillofacial Surgery, Hadassah Medical Center, were included in the present study. The patients underwent vertical bone augmentation using the sandwich osteotomy technique filled with xenograft material. The degree of bone augmentation was analyzed clinically at surgery and 4 to 6 months later from the computed tomography images taken just before the sites had been rehabilitated using dental implant insertion. A trephine histologic analysis was performed during implantation at 1 maxillary site.

Results:

The mean vertical bone gain in the interval between the sandwich osteotomy and implementation was 6 mm (range 4 to 10), and it remained stable after 4 to 6 months. In 2 cases, additional horizontal bone augmentation was needed. All graft sites were rehabilitated using dental implants with satisfactory results. In 3 cases, gingival porcelain was required for the final prosthesis. Histologic examination revealed vital segmentized bone and remodeling of the filled gap.

Conclusions: The interpositional alveolar bone graft using xenograft filler appears to be a viable and predictable alternative to block grafting or guided bone regeneration, resulting in good final results, with substantial vertical bone gain, even for challenging cases. Ó 2014 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 72:292-303, 2014

The treatment of vertical alveolar defects is a most challenging condition in alveolar ridge augmentation. In previous decades, many bone augmentation techniques have been developed, and debate has been ongoing concerning which procedure would be preferable and implementable in such challenging situations.1 Onlay bone grafting, using an autogenous bone graft harvested from another intra- or extraoral site, has been the procedure considered the reference standard

by most surgeons. Reportedly, with this procedure, the average vertical bone gain will be 4 to 5 mm, with significant complications of graft exposure and a rate of up to 40% of onlay graft resorption. This procedure has not been commonly used because another donor site is required, and it has had high associated morbidity.2-4 Some surgeons have recommended using short implants when encountering the vertical alveolar defect.

*Attending Physician, Department of Oral and Maxillofacial

Address correspondence and reprint requests to Dr Laviv: Depart-

Surgery, Hebrew University–Hadassah Faculty of Dental Medicine,

ment of Oral and Maxillofacial Surgery, Hebrew University–Hadassah

Jerusalem, Israel.

Faculty of Dental Medicine, PO Box 12272, Jerusalem 91120 Israel;

yVisiting Professor, Hebrew University–Hadassah, Jerusalem,

e-mail: [email protected]

Israel.

Received April 29 2013

zAttending Physician, Department of Prosthodontics, Hebrew University–Hadassah Faculty of Dental Medicine, Jerusalem, Israel.

Ó 2014 American Association of Oral and Maxillofacial Surgeons

Accepted September 30 2013

xAssociate Professor, Department of Oral and Maxillofacial

0278-2391/13/01228-7$36.00/0

Surgery, Hebrew University–Hadassah Faculty of Dental Medicine,

http://dx.doi.org/10.1016/j.joms.2013.09.036

Jerusalem, Israel.

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However, such procedures are limited to the posterior region and cannot be used in the anterior esthetic zone when a high smile line is present that exposes the alveolar bone height deficiency.5-7 Others have recommended guided bone regeneration (GBR). Allografts, xenografts, or a mixture of these materials with autogenous bone grafting have been used in GBR procedures, with a reported vertical bone gain of 2 to 7 mm. The most common complication of GBR has been early membrane exposure, in up to 18.4% of cases, which, consequently, can compromise the final outcome of the rehabilitation.2,8-11 In distraction osteogenesis, the reported vertical bone gain has ranged from 5 to 15 mm. The main problem has been control of the vector with palatal and/or lingual distracted segment inclination.2,12,13 A relatively modern technique for vertical bone augmentation is sandwich osteotomy, which has proved relatively safe, with successful long-term results, in both the mandible and the maxilla. The technique is executed by segmentalizing the alveolar bone through a minimal vestibular incision (similar to osteotomies such as alveolar distraction osteogenesis), transporting the segment attached to the periosteum to the desired 3-dimensional planned area, and fixing it with plate and screws. Most studies have used autogenous bone graft as the filler for the created gap.14-22 There are only 5 published studies (3 case reports and 2 retrospective case studies) in which another bone substitute, such as allografts, collagen matrix, or alloplast, were introduced into the gap.16,23-26 The objective of the present prospective study was to apply this technique for vertical bone augmentation of 4 to 10 mm, filling the created gap with xenograft material, and to assess the procedure in terms of bone gain, success rate, segment vitality, and complications.

Materials and Methods A total of 10 severely resorbed alveolar ridges in 9 patients (6 females, 3 males, 17 to 57 years), who had been treated at the Department of Oral and Maxillofacial Surgery, Hadassah Medical Center, from June 2008 to October 2012, were included in the present prospective study. The Hadassah Medical Center institutional review board approved the present study, and all participants signed an informed consent agreement. Patients with severely resorbed alveolar ridges in the vertical dimension requiring vertical bone gain of 4 to 10 mm and who desired fixed prosthesis rehabilitation using dental implants were included in the present study. The sandwich osteotomy procedure was performed as an alternative to onlay bone grafting, distraction osteogenesis, or guided bone regeneration. All procedures were done with the patient under either

sedation (using intravenous diazepam) or general anesthesia. The technique used a buccal vestibular incision made high in the vestibule. With a sagittal saw or a high-speed narrow bore, the alveolar bone was segmentalized through the vestibular incision using a horizontal cut about 5 to 10 mm below the crest of the ridge. Next, 2 lateral connecting vertical oblique cuts were created 2 mm distally to the last tooth. The osteotomy was completed by breaking the lingual cortical bone with a small chisel, creating a free trapezoid-shaped bone segment, and preserving its palatal/lingual periosteum and soft tissue attachment (Fig 1A). The length of the segments was matched to the deficient, resorbed alveolar ridge. The segment was displaced crestally to the desired 3-dimensional place and fixed with 1.5- to 2-mm titanium plates (KLS Martin Microplate System, T€ uttlingen, Germany; Fig 1B). The bone gain (ie, the created gap) was measured intraoperatively. Next, the gap was filled with xenograft material (BioOss, Geistlich Pharma AG, Wolhusen, Switzerland; Fig 1C) without a barrier membrane, and the vestibular mucosal incision was sutured with Vicryl sutures. All patients were prescribed 1 dose of oral amoxicillin 1000 mg preoperatively, followed by a 7-day postoperative course of amoxicillin 500 mg 3 times daily. For patients with a penicillin allergy, clindamycin 300 mg was prescribed preoperatively and continued (300 mg) 3 times daily for 7 days postoperatively. After 4 to 6 months of healing, a dental computed tomography (CT) scan was performed, the fixation plates and screws were removed, and dental implants were placed (Zimmer Dental, Carlsbad, CA; or MIS Implant Technologies, Shlomi, Israel) using either a standard implantation technique, with or without a guide stent, or real-time navigation surgery. The bone gain in the gap between the bone segment and the original bone was measured and analyzed for its shape from the CT scan taken just before implantation. This measurement was compared with the bone gain measured clinically immediately after surgery. A 2.2-mm trephine histopathologic specimen was taken during implantation from 1 maxillary implantation site. It was stained with hematoxylin and eosin and Masson trichrome stains for histologic evaluation of the bone segment vitality.

Results The data from the 10 implantation sites in 9 patients (patient 5 underwent both maxillary and mandibular augmentation) are summarized in Table 1. Figure 2 depicts the comparative bone gain determined by the clinical measurement immediately after surgery and from the CT scan performed 4 to 6 months later, before the insertion of the dental implant (the CT scans for

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ALVEOLAR SANDWICH OSTEOTOMY FOR IMPLANTS

FIGURE 1. Sandwich osteotomy technique. A, Osteotomy segmentalization in the mandible, with 1 horizontal cut and 2 vertical oblique cuts, creating a trapezoid segment of mobile bone attached to its lingual and palatal periosteum and soft tissue. B, Mobilized segment moved to the desired 3-dimensional position and fixed with plates and screws. C, Gap filled with xenograft material. Laviv et al. Alveolar Sandwich Osteotomy for Implants. J Oral Maxillofac Surg 2014.

patients 1, 7, and 8 had been lost, and no measurements could be performed). In the 10 implantation sites, the vertical bone gain ranged from 4 to 10 mm (mean 6), and it remained stable before implant placement, except in patient 2, in whom a 1-mm difference was found between the clinical bone gain and the preimplantation bone gain (10 and 9 mm, respectively). The implant integration and bone levels remained clinically stable during the follow-up period. The area of bone gain (the gap filled with the xenograft material), analyzed from the CT scan, was trapezoidal in all cases and fit the gap space (Fig 3). Several resolved complications were observed during the follow-up period. In patients 1 and 2, additional horizontal augmentation (with xenograft material) was applied on the day of dental implant insertion. Patient 2 had undergone major pretreatment of a bone defect that had occurred owing to 2 previous failed implantations attempted by her dentists. Although she had a total of 9 mm of bone gain (according to the CT scan), the final prosthetic unit necessi-

tated 2 mm of pink gingival porcelain, which was esthetically accepted (Fig 4). In all cases, except for 1 (patient 1), the soft tissue had advanced with the bone segment. Thus, a keratinized soft tissue graft was not needed before the final rehabilitation. Patient 5 had a minor palatal fistula that had been created by the osteotomy with the chisel during surgery. It closed spontaneously during the first postoperative week. Patient 5 had had major bone defects after a gunshot wound, and the final prosthesis was created using gingival interdental papilla porcelain, which was esthetically accepted (Fig 5). Patients 7 and 8 had bone exposure noted 2 weeks after the surgical procedure. These mandibular cases were treated with daily local irrigation of saline. In both, the bone exposure had closed spontaneously within 1 month. During implantation, 6 months after the surgical sandwich osteotomy, a 2.2-mm trephine histopathologic specimen was taken from the maxilla of patient 5 to evaluate the vitality of the bone segment. The

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Table 1. CLINICAL AND SURGICAL DATA OF 10 SANDWICH OSTEOTOMIES

Pt. No./ Age Case No. (yr) Gender

Site (Teeth No.)

Vertical CT-Measured Bone Gain Bone Gain at Cause of Bone at Surgery Implantation (mm) (mm) Resorption

1/1

20

F

Mx (left central and Dentoalveolar lateral incisors) trauma

2/2

49

F

3/3

48

F

4/4

21

M

5/5

25

M

Mx (right central incisor to left first premolar edentulous ridge) Mx (right lateral incisor to left lateral incisor edentulous ridge) Mx (left central and lateral incisors) Mx (right canine to right central incisor edentulous ridge)

5/6

25

M

6/7

18

M

7/8

57

F

8/9

51

F

9/10

57

F

Mn (left central incisor to right lateral incisor edentulous ridge) Mn (right central and lateral incisors) Mn (left second premolar to second molar edentulous ridge) Mn (left second premolar and first molar) Mn (right second premolar to second molar edentulous ridge)

Complications/Other Surgical Procedures/Comments

6

NA

10

9

Periodontal resorption

4

4

Additional horizontal augmentation needed during implantation; keratinized gingiva surgery applied before final rehabilitation Additional horizontal augmentation needed during implantation; final prosthetics included 2 mm of pink gingival porcelain —

Dentoalveolar trauma Gunshot wound

4

4



4

4

Gunshot wound

7

7

Dentoalveolar trauma

6

NA

Palatal fistula that closed spontaneously after 1 wk without intervention; final prosthetics included pink gingival porcelain of interdental papilla Final prosthetics included 2 mm of gingival porcelain; final prosthesis made with small gap to allow interimplant cleaning —

Periodontal resorption

5

NA

Bone exposure treated with local irrigation and follow-up, healing uneventful

Failed implants

7

7

Bone exposure treated with local irrigation, healing uneventful

Periodontal

6

6

Part of total jaw fixed rehabilitation; 2 implants placed in that area

Failed implants

Abbreviations: Mn, mandible; Mx, maxilla; NA, not available; Pt. No., patient number. Laviv et al. Alveolar Sandwich Osteotomy for Implants. J Oral Maxillofac Surg 2014.

specimen was stained with hematoxylin and eosin and Masson trichrome stains (Fig 6). Histologic examination demonstrated that the segmentalized bone, which was detached from the original bone but had remained attached to its palatal and lingual soft tissue and periosteum, contained osteocytes and bone marrow fat spaces. We could identify xenograft particles, surrounded intimately with the newly formed bone, and that had started the remodeling process at the former gap. This indicated that the segmentalized bone was vital.

Discussion The sandwich osteotomy technique, associated with interpositional bone grafting, was first described by Schettler and Holtermann27 in 1977 for denture retention in edentulous mandible augmentation and has been applied in subsequent years with variations in the surgical technique.19,28-30 This method of mandibular or maxillary augmentation has been documented in various studies. In most of these studies, the gap created between the segmented bone and basal bone

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ALVEOLAR SANDWICH OSTEOTOMY FOR IMPLANTS

FIGURE 2. Ten implantation sites with 4- to 10-mm vertical alveolar augmentations. Blue indicates the measured bone gain during surgery; red, the measured bone gain from the computed tomography scan taken before implantation (computed tomography data not available for patients 1, 7, and 8). Laviv et al. Alveolar Sandwich Osteotomy for Implants. J Oral Maxillofac Surg 2014.

FIGURE 3. Example of computed tomography scan measurements. Computed tomography scan of patient 3 revealed a measured bone gain of 4 mm. In all cases, the area of bone gain was trapezoidal and fit the filled gap space. Laviv et al. Alveolar Sandwich Osteotomy for Implants. J Oral Maxillofac Surg 2014.

was filled with an interpositional autogenous bone graft.14-22 Only in 5 retrospective case studies or case series were other bone substitutes, such as allograft, collagen matrix, or alloplast, introduced into the created gap.16,23-26 The present prospective study was performed for augmentation of severely resorbed maxillary or mandibular alveolar ridges (with 4 to 10 mm of vertical deficiency) using the sandwich osteotomy technique and with the interbone gap filled with BioOss xenografts without a barrier membrane. The observed mean vertical bone gain was 6 mm (range 4 to 10). Eventually, all sites were treated with dental implants for rehabilitation with fixed dentures on the implants. A possible improvement for the suggested surgical procedure might include using a piezoelectric drill for the bone cuts, rather than a sagittal saw or a highspeed narrow bore. Using a piezoelectric drill would allow the bone cuts to be performed in a thinner, accurate manner, avoiding possible injury to the attached lingual and palatal soft tissue. In 2 mandibular cases (patients 8 and 9), complications of bone segment exposure occurred and were treated with local daily irrigation. They eventually healed uneventfully and were rehabilitated using dental implants. We believe that because the mandible is denser bone with a limited blood supply, and the segmentalization procedure is more technique sensitive, this procedure in the mandible would be more prone to bone exposure. Nonetheless, the final results were good.

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FIGURE 4. Patient 2. A, At admission, demonstrating the large bony defect. B, Sandwich osteotomy procedure, with clinically evident 10-mm bone gain. C, Bone gain of 9 mm seen on the preimplantation computed tomography scan. (Fig 4 continued on next page.) Laviv et al. Alveolar Sandwich Osteotomy for Implants. J Oral Maxillofac Surg 2014.

One of the advantages of the procedure is that when bone exposure results, it occurs in the location of the vestibular sutures and not in the crestal

alveolar ridge. Therefore, the segmentalized bone remains attached to its lingual soft tissue, stays rigidly fixated in position, and does not resorb during the

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FIGURE 4 (cont’d). D,E, View of final restoration. Laviv et al. Alveolar Sandwich Osteotomy for Implants. J Oral Maxillofac Surg 2014.

healing period, resulting in sufficient vertical bone augmentation. In 2 patients, the sandwich osteotomy technique succeeded in realizing a vertical gain; however, additional horizontal augmentation was needed before

dental implant insertion. This was accomplished successfully, with a satisfactory final outcome. In 3 cases, the final prosthesis was executed using ‘‘gingival porcelain.’’ This was used to satisfy the prosthetic needs. In patient 5, the mesiodistal edentulous

FIGURE 5. Patient 5 after a gunshot wound. A, View before treatment (both maxillary and mandibular deficiency). B, Stent demonstrating the mandibular deficiency. C, View during sandwich osteotomy. D, View during follow-up before dental implant insertion. (Fig 5 continued on next page.) Laviv et al. Alveolar Sandwich Osteotomy for Implants. J Oral Maxillofac Surg 2014.

LAVIV ET AL

FIGURE 5 (cont’d). E, Computed tomography dental scan before implantation (with 7-mm vertical bone gain between the white lines), revealing adequate bone gain correlated with the opaque stent. (Fig 5 continued on next page.) Laviv et al. Alveolar Sandwich Osteotomy for Implants. J Oral Maxillofac Surg 2014.

span was short. The only alternative was to use 2 adjacent dental implants for rehabilitation of 3 missing teeth; therefore, the dental papilla could not be developed properly. In patients 2 and 6 (vertical bone gain of 9 and 7 mm, respectively), a large bone gain occurred that required overcoming a long crown height rehabilitation after dental implant insertion. We realized that the final alveolar ridge height was parallel to the cemento–enamel junction of the adjacent teeth; however, all these patients were finally rehabil-

299 itated, with esthetically acceptable restorations, as judged by the patients. Most suggested techniques for vertical bone augmentation have not followed biologic principles. Guided bone regeneration and onlay bone graft apply augmentation with bone from a different donor site or bone substitutes and require the use of flap covering; thus, they can unfavorably affect the attached gingiva. One of the main advantages of the sandwich osteotomy technique (in contrast to the other proposed techniques) is its use of the biologic principle of a buccal vestibular detached bone segment that remains attached to its palatal and lingual aspect, thus preserving its blood supply. The future augmented area will be situated in position without interruption of the soft tissue. Just as we have observed in the present study, only 1 patient (patient 1) required additional keratinized soft tissue surgery before final rehabilitation for esthetic reasons. The procedure can cause stretching of the undetached soft tissue and some fibrosis of the crestal gingiva and, therefore, does not require additional soft tissue manipulation. Histologically, the segmented bone, attached to its palatal base, remained vital after 6 months. Ours are the first published human histologic data proving this. Therefore, we have concluded that the procedure of moving the bone segment to its required place and fixating it will keep the bone segment vital. Consequently, the dental implant procedure can be performed in a vital bone environment that will provide and sustain the osseointegration environment. Future histologic specimens should be examined to strengthen and prove our assumption. We would like to emphasize that for the technique to succeed, the segment should be elevated only to the level of the cemento–enamel junction of adjacent teeth. It can be expected that anything above that will resorb. Also, the volume of the osteotomized segment is very important, and we have used segments not narrower than 5 mm. Additional studies are necessary to determine the minimal volume necessary for success. In conclusion, the sandwich osteotomy technique using xenograft material to fill the created gap is safe in both the mandible and the maxilla. In the mandible, more bone exposure can be expected; however, most of the time, this will not jeopardize the final outcome of the rehabilitation. The main advantages of the procedure include not needing a second harvest site (whether intraoral or extraoral), a relatively large amount of vertical bone gain (#9 mm in the present study), and the possibility of placing the detached segment in the desired 3-dimensional exact position for future rehabilitation.

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ALVEOLAR SANDWICH OSTEOTOMY FOR IMPLANTS

FIGURE 5 (cont’d). F, Insertion of the dental implants. G, View 33 months after sandwich osteotomy procedure. H, Final restoration during follow-up, with gingival porcelain seen on the final restoration that was esthetically acceptable. I, Radiograph of the final restoration. Laviv et al. Alveolar Sandwich Osteotomy for Implants. J Oral Maxillofac Surg 2014.

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FIGURE 6. Histologic trephine specimen retrieved from patient 5 during drilling of the implant site. A, Hematoxylin and eosin stain showing segmentalized bone at the bottom, with vital bone (wide arrow) and bone marrow fat inside the bone (1). Xenograft particles (black stars) can be seen in the upper apical part of the specimen. (Fig 6 continued on next page.) Laviv et al. Alveolar Sandwich Osteotomy for Implants. J Oral Maxillofac Surg 2014.

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ALVEOLAR SANDWICH OSTEOTOMY FOR IMPLANTS

FIGURE 6 (cont’d). B, Masson trichrome stain showing segmentalized bone at the bottom, with vital bone (wide arrow) and bone marrow fat inside the bone. Xenograft particles (yellow stars) can be seen in the upper apical part, surrounded by newly forming bone (short white arrows pointing at the pale blue stain of the forming bone). Laviv et al. Alveolar Sandwich Osteotomy for Implants. J Oral Maxillofac Surg 2014.

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3. Cordaro L, Amade DS, Cordaro M: Clinical results of alveolar ridge augmentation with mandibular block bone grafts in partially edentulous patients prior to implant placement. Clin Oral Implants Res 13:103, 2002 4. Bernstein S, Cooke J, Fotek P, Wang HL: Vertical bone augmentation: Where are we now? Implant Dent 15:219, 2006 5. Tawil G, Aboujaoude N, Younan R: Influence of prosthetic parameters on the survival and complication rates of short implants. Int J Oral Maxillofac Implants 21:275, 2006

LAVIV ET AL 6. Perdijk FB, Meijer GJ, Bronkhorst EM, Koole R: Implants in the severely resorbed mandibles: Whether or not to augment? What is the clinician’s preference? Oral Maxillofac Surg 15: 225, 2011 7. Felice P, Pellegrino G, Checchi L, et al: Vertical augmentation with interpositional blocks of an organic bovine bone vs. 7-mm-long implants in posterior mandibles: 1-Year results of a randomized clinical trial. Clin Oral Implants Res 21:1394, 2010 8. Esposito M, Grusovin MG, Worthington HV, Coulthard P: Interventions for replacing missing teeth: Bone augmentation techniques for dental implant treatment. Cochrane Database Syst Rev 1:CD003607, 2006 9. Chiapasco M, Romeo E, Casentini P, Rimondini L: Alveolar distraction osteogenesis vs. vertical guided bone regeneration for the correction of vertically deficient edentulous ridges: A 1–3-year prospective study on humans. Clin Oral Implants Res 15:82, 2004 10. Simion M, Trisi P, Piattelli A: Vertical ridge augmentation using a membrane technique associated with osseointegrated implants. Int J Periodontics Restorative Dent 14:496, 1994 11. Canullo L, Trisi P, Simion M: Vertical ridge augmentation around implants using e-PTFE titanium-reinforced membrane and deproteinized bovine bone mineral (Bio-Oss): A case report. Int J Periodontics Restorative Dent 26:355, 2006 12. Raghoebar GM, Heydenrijk K, Vissink A: Vertical distraction of the severely resorbed mandible: The Groninger distraction device. Int J Oral Maxillofac Surg 29:416, 2000 13. Raghoebar GM, Liem RSB, Vissink A: Vertical distraction of the severely resorbed edentulous mandible: A clinical, histological and electron microscopic study of 10 treated cases. Clin Oral Implants Res 13:558, 2002 14. Marchetti C, Trasarti S, Corinaldesi G, Felice P: Interpositional bone grafts in the posterior mandibular region: A report on six patients. Int J Periodontics Restorative Dent 27:547, 2007 15. Jensen OT, Kuhlke L, Bedard JF, White D: Alveolar segmental sandwich osteotomy for anterior maxillary vertical augmentation prior to implant placement. J Oral Maxillofac Surg 64:290, 2006 16. Lopez-Cedrun JL: Implant rehabilitation of the edentulous posterior atrophic mandible: The sandwich osteotomy revisited. Int J Oral Maxillofac Implants 26:195, 2011 17. Bormann KH, Suarez-Cunqueiro MM, von See C, et al: Forty sandwich osteotomies in atrophic mandibles: A retrospective study. J Oral Maxillofac Surg 69:1562, 2011

303 18. Jensen OT: Alveolar segmental ‘ sandwich’’ osteotomies for posterior edentulous mandibular sites for dental implants. J Oral Maxillofac Surg 64:471, 2006 19. Politi M, Robiony M: Localized alveolar sandwich osteotomy for vertical augmentation of the anterior maxilla. J Oral Maxillofac Surg 57:1380, 1999 20. Hashemi HM, Javidi B: Comparison between interpositional bone grafting and osteogenic alveolar distraction in alveolar bone reconstruction. J Oral Maxillofac Surg 68:1853, 2010 21. Bormann KH, Suarez-Cunqueiro MM, von See C, et al: Sandwich osteotomy for vertical and transversal augmentation of the posterior mandible. Int J Oral Maxillofac Surg 39:554, 2010 22. Yeung R: Surgical management of the partially edentulous atrophic mandibular ridge using a modified sandwich osteotomy: A case report. Int J Oral Maxillofac Implants 20:799, 2005 23. Choi BH, Lee SH, Huh JY, Han SG: Use of the sandwich osteotomy plus an interpositional allograft for vertical augmentation of the alveolar ridge. J Craniomaxillofac Surg 32:51, 2004 24. Sohn DS, Shin HI, Ahn MR, Lee JS: Piezoelectric vertical bone augmentation using the sandwich technique in an atrophic mandible and histomorphometric analysis of mineral allografts: A case report series. Int J Periodontics Restorative Dent 30:383, 2010 25. Moon JW, Choi BJ, Lee WH, et al: Reconstruction of atrophic anterior mandible using piezoelectric sandwich osteotomy: A case report. Implant Dent 18:195, 2009 26. Ewers R, Fock N, Millesi-Schobel G, Enislidis G: Pedicled sandwich plasty: A variation on alveolar distraction for vertical augmentation of the atrophic mandible. Br J Oral Maxillofac Surg 42:445, 2004 27. Schettler D, Holtermann W: Clinical and experimental results of a sandwich-technique for mandibular alveolar ridge augmentation. J Maxillofac Surg 5:199, 1977 28. Egbert M, Stoelinga PJW, Blijdorp PA, De Koomen HA: The ‘ three-piece’’ osteotomy and interpositional bone graft for augmentation of the atrophic mandible. J Oral Maxillofac Surg 44:680, 1986 29. Haers PEJ, Van Straaten W, Stoelinga PJW, et al: Reconstruction of the severely resorbed mandible prior to vestibuloplasty or placement of endosseous implants: A 2- to 5-year follow-up. Int J Oral Maxillofac Surg 20:149, 1991 30. Moloney F, Stoelinga PJW, Tideman H, De Koomen HA: Recent developments in interpositional bone-grafting of the atrophic mandible. J Maxillofac Surg 13:14, 1985

Alveolar sandwich osteotomy in resorbed alveolar ridge for dental implants: a 4-year prospective study.

To answer whether severe vertical alveolar defects can be resolved using the sandwich osteotomy technique with xenograft material as filler and to eva...
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