Recombinant human bone morphogenetic protein 2 combined with an osteoconductive bulking agent for mandibular continuity defects in nonhuman primates.

PURPOSE: Recombinant human bone morphogenetic protein 2 (rhBMP-2) is an option for reconstructing mandibular continuity defects. A challenge of this technique is the need to maintain sufficient space to avoid compression of the defect. A compression-resistant matrix (CRM) provides a bulking agent that provides support during the bone formation phase. MATERIALS AND METHODS: Thirteen Rhesus Macaque monkeys were used to evaluate different forms of an osteoconductive bulking agent compared with an absorbable collagen alone placed into a critical-sized mandibular defect. A total of 5 groups (26 defects) were evaluated: group A, rhBMP-2/absorbable collagen sponge (ACS) (1.5 mg/mL); group B, rhBMP-2/ACS with ceramic granules (15% hydroxyapatite/85% ß-tricalcium phosphate) at 1.5 mg/mL; group C, rhBMP-2 (2.0 mg/mL) with a CRM; group D, rhBMP-2 (0.75 mg/mL) with a CRM; and group E, a CRM alone. RESULTS: Histology and micro computed tomography were used to evaluate and compare new bone formation in the defects. The reconstructed bone was evaluated with regard to the new bone formation, residual voids, and density. Animals treated with the CRM and rhBMP-2 at 2.0 mg/mL (group C) showed significantly higher amounts of new bone formation, bone density, and reduced voids when compared with rhBMP-2 and ACS (1.5 mg/mL) (P < .05). CONCLUSION: The carrier system CRM combined with rhBMP-2 and a reconstruction plate results in significantly higher bone density and better space maintenance than rhBMP-2 combined with ACS in a nonhuman primate mandibular bone repair model.

Use of a porcine collagen matrix as an alternative to autogenous tissue for grafting oral soft tissue defects.

PURPOSE: Soft tissue grafting is often required to correct intraoral mucosal deficiencies. Autogenous grafts have disadvantages including an additional harvest site with its associated pain and morbidity and, sometimes, poor quality and limited amount of the graft. Porcine collagen matrices have the potential to be helpful for grafting of soft tissue defects. PATIENTS AND METHODS: Thirty consecutive patients underwent intraoral grafting to re-create missing soft tissue. Defects ranged in size from 50 to 900 mm(2). Porcine collagen matrices were used to reconstruct missing tissue. Indications included preprosthetic (22), followed by tumor removal (5), trauma (2), and release of cheek ankylosis (1). RESULTS: The primary efficacy parameters evaluated were the degree of lateral and/or alveolar extension and the evaluation of re-epithelialization and shrinkage of the grafted area. Overall, the percentage of shrinkage of the graft was 14% (range, 5%-20%). The amount of soft tissue extension averaged 3.4 mm (range, 2-10 mm). The secondary efficacy parameters included hemostatic effect, pain evaluation, pain and discomfort, and clinical evaluation of the grafted site. All patients reported minimal pain and swelling associated with the grafted area. No infections were noted. CONCLUSION: This porcine collagen matrix provides a biocompatible surgical material as an alternative to an autogenous transplant, thus obviating the need to harvest soft tissue autogenous grafts from other areas of the oral cavity.

The effects of resorbable membrane on human maxillary sinus graft: a pilot study.

PURPOSE: To investigate the effects of resorbable membrane on new bone formation in human maxillary sinus graft using anorganic bovine bone material histomorphometrically in a split-mouth study design. MATERIALS AND METHODS: This prospective pilot study included six patients who required bilateral sinus augmentations prior to implant treatment. Each patient was grafted with anorganic bovine bone (Bio-Oss). The experimental side was covered with resorbable membrane (Bio-Gide) over the grafted sinus, and the control side was left uncovered. After 8 months of healing (range, 7 to 9 months), implants were placed. Biopsy samples were obtained from each side through the previously grafted sinus window and evaluated. Statistical analysis was performed using the Mann-Whitney U test at a significance level of alpha = .05. RESULTS: The control side appeared to have a significantly greater amount of soft tissue than the experimental side (P = .026), whereas no significant differences in the amount of new bone were observed (P = .937). CONCLUSION: Resorbable membranes significantly reduced the amount of soft tissue formed in the sinus grafted with anorganic bovine bone material but had no effect on new bone formation.

Pivotal, randomized, parallel evaluation of recombinant human bone morphogenetic protein-2/absorbable collagen sponge and autogenous bone graft for maxillary sinus floor augmentation.

PURPOSE: The purpose of this prospective study was to evaluate the safety and effectiveness of recombinant human morphogenetic protein-2 (rhBMP-2) on an absorbable collagen sponge (ACS) compared with an autogenous bone graft when used for 2-stage maxillary sinus floor augmentation. The study assessed new bone formation, placement integration, and functional loading after 6 months and long term for 2 years. MATERIALS AND METHODS: A total of 160 subjects were randomized, enrolled, and followed from January 1999 to February 2004 at 21 centers in the United States. The subjects with less than 6 mm of native bone height were treated with 1.50 mg/mL rhBMP-2/ACS or with an autograft. The height and density measurements were quantified by computed tomography scans. Core biopsies were obtained at dental implant placement and used for histological analysis. Safety was evaluated by oral examinations, radiographs, serum chemistries, and hematology. RESULTS: A significant amount of new bone was formed by 6 months postoperatively in each group. The mean change in bone height in the rhBMP-2/ACS subjects was 7.83 +/- 3.52 mm versus 9.46 +/- 4.11 mm for the bone graft subjects. At 6 months after dental restoration, the induced bone in the rhBMP-2/ACS group was significantly denser than that in the bone graft group. No marked differences were found in the histologic parameters evaluated between the 2 groups. The new bone was comparable to the native bone in density and structure in both groups. The success rate for the rhBMP-2/ACS group was 79% (64 of 81 subjects), and 201 of 251 implants placed in the bone graft group and 199 of 241 implants placed in the rhBMP-2/ACS group were integrated, retained, and functional at 6 months after loading. No adverse events were deemed related to the rhBMP-2/ACS treatment. The autograft group was noted to have a 17% rate of long-term parasthesia, pain, or gait disturbance related to the bone graft harvest. CONCLUSIONS: The results of our multicenter, randomized, prospective, clinical trial have shown the effectiveness and safety of rhBMP-2/ACS compared with bone graft for sinus floor augmentation. The study's primary endpoint was exceeded, and the implants placed in rhBMP-2/ACS and bone graft groups performed similarly after functional loading.

Implant success in distracted bone versus autogenous bone-grafted sites.

Endosseous implants are the treatment of choice for restoring function and reconstructing most edentulous areas of the maxilla and mandible. In general, alveolar bone defects can be reconstructed by either distraction osteogenesis or autogenous bone grafting. After alveolar reconstruction, endosseous implants are used to support and retain the prosthesis for restoration of form and function. Eighty-two consecutive patients requiring alveolar augmentation prior to implant placement were evaluated. All patients were given treatment options for reconstructing their alveolar defects, which included autogenous bone grafting vs distraction osteogenesis. Sixty-five patients received autogenous grafts (anterior iliac crest: 44; retromolar: 17; tibia: 2; chin: 2), and 17 patients underwent distraction osteogenesis prior to implant placement. A total of 184 implants were placed in the autogenous bone-grafted sites and 56 implants in the distracted bone sites. Implants placed in sites restored with autogenous bone grafts had an implant success rate of 97% (178/184), whereas implants placed in distracted bone sites had a success rate of 98% (55/56). In the autogenous grafted group, 3 implants failed in the posterior mandible, one in the anterior maxilla, one in the anterior mandible, and one in the posterior maxilla. In the distraction group, one implant failed in the posterior mandible. Both techniques are associated with good success rates. There was no statistical difference between implant success in autogenous bone vs distracted bone sites in this group of patients.

Reconstruction of mandibular continuity defects with bone morphogenetic protein-2 (rhBMP-2).

PURPOSE: Several autogenous bone grafting techniques are available for the restoration of large continuity defects of the mandible. However, these procedures are associated with limitations involving postoperative morbidity, difficulty in ambulation, and pain. The development of a technique of surgical reconstruction not involving autogenous bone would offer new opportunities for facial bone reconstruction, particularly of the mandible. This study was instituted to observe the effect of rhBMP-2 in a collagen carrier without concomitant bone grafting material in the restoration of continuity critical-sized defects of the mandible. MATERIALS AND METHODS: A case review was made of 14 patients who were selected from a larger group having received BMP-2 in different categories of mandibular defects. The rhBMP-2 in all the cases reported here was used alone with the collagen carrier without concomitant bone materials. The cases involved lesions of the body and angle of the mandible in 2 categories: 1) defects resulting from neoplastic diseases, and 2) defects secondary to osteomyelitis (related to bisphosphonates or irradiation). A total dose of 4 to 8 mg of rhBMP-2 was delivered to the surgical site in concentrations of 1.5 mg per cc (depending on the size of lesion). Cases were followed over a period from 6 to 18 months. Occlusal function was restored with implant-borne or conventional prosthesis. RESULTS: All of the cases reported here had successful osseous restoration of the edentulous area followed by prosthetic treatment. Bone formation in the surgical area could be palpated at the end of 3 to 4 months and identified radiographically at the end of 5 to 6 months. The maintenance of a periosteal envelope was effected by the use of a superiorly placed minibar in the upper portion of the defect, or with the use of titanium mesh superiorly. This metallic tenting up to the mucosa is thought to be necessary to maintain the space for osseous regeneration. CONCLUSION: This study indicated that the use of rhBMP-2 without concomitant bone grafting materials in large critical sized mandibular defects produced excellent regeneration of the area establishing the basis for the return of prosthodontic function. This study tends to support the use of cytokines, particularly rhBMP-2, in osseous regeneration or repair of facial bones. The technique describes a new alternative to various types of autogenous bone grafting procedures for the treatment of critical sized bony lesions of the mandible.

Clinical applications of rhBMP-2 in maxillofacial surgery.

MATERIALS AND METHODS: Examples of defects including mandibular continuity defects, preprosthetic atrophic alveolar ridge deficiencies, traumatic defects, and maxillary clefts were included. RESULTS: All patients demonstrated osseous regeneration stimulated by rhBMP-2. CONCLUSION: rhBMP-2 is successful in regenerating bone in a variety of maxillofacial defects. In the future, rhBMP-2 will play a significant role in the treatment of bone deficiencies.

Draft genome sequence of Pseudomonas moraviensis strain Devor implicates metabolic versatility and bioremediation potential.

Pseudomonas moraviensis is a predominant member of soil environments. We here report on the genomic analysis of Pseudomonas moraviensis strain Devor that was isolated from a gate at Oklahoma State University, Stillwater, OK, USA. The partial genome of Pseudomonas moraviensis strain Devor consists of 6016489 bp of DNA with 5290 protein-coding genes and 66 RNA genes. This is the first detailed analysis of a P. moraviensis genome. Genomic analysis revealed metabolic versatility with genes involved in the metabolism and transport of fructose, xylose, mannose and all amino acids with the exception of tryptophan and valine, implying that the organism is a versatile heterotroph. The genome of P. moraviensis strain Devor was rich in transporters and, based on COG analysis, did not cluster closely with P. moraviensis R28-S genome, the only previous report of a P. moraviensis genome with a native mercury resistance plasmid.

Clinical, histologic, and histomorphometric evaluation of mineralized solvent-dehydrated bone allograf (Puros) in human maxillary sinus grafts.

Demineralized freeze-dried bone allografts (DFDBA) have been successfully used alone or in composite grafts for many decades. Little research has been done on the effect of retaining the mineral content of bone allografts. This study histologically and histomorphometrically evaluated a new mineralized bone allograft material placed in human atrophic maxillary sinuses. Seven partially edentulous patients requiring sinus grafts before implant placement were selected for this study Their age range was 56 to 81 years (mean 67.7 years). Test grafts consisted of a mineralized solvent-dehydrated cancellous bone allograft, and control grafts were a composite of DFDBA and deproteinized bovine bone xenograft (1:1). Bilateral cases (n = 3) received both test and control grafts on opposite sides, and unilateral cases received either a test (n = 3) or control (n = 1) graft only. At 10 months, core biopsies were taken from each graft site, and dental implants were placed into the augmented bone. All bone grafts resulted in new bone formation and all implants osseointegrated. Test grafts resorbed and were replaced by newly formed bone significantly faster and in greater quantities than were control grafts. No complications with grafts or implants were noted. Both test and control grafts achieved excellent results. The faster bone formation observed with the test graft may be due, in part, to its smaller particle size compared with the bovine portion of the control graft. Test grafts were either replaced by new bone or displayed new bone-to-particle surface contact in higher percentages than did control grafts. No differences in osseointegration or graft stability were noted 2 years after the study.

The multifocal nature of odontogenic keratocysts.

The odontogenic keratocyst, OKC, is a very aggressive intraosseos lesion with a recurrence rate of approximately 25 percent to 60 percent.' The tendency for this lesion to "return" after surgical treatment has prompted studies to obtain more information concerning the inherent nature of the lesion. The OKC lesions are usually treated with enucleation of the soft tissue lining, curettage and ostectomy of the bony margins, or with more aggressive block resection. The purpose of this study was to characterize the multifocal aspect of the OKC and to demonstrate the presence of cystic lesions remote from the margins of the primarily diagnosed cyst itself. A retrospective chart review was conducted of seven patients who had sustained a long history of recurrent OKCs. Three types of documentation were reviewed for each patient: Orthopantomograms, cephalograms, and CT scans, which had been taken over the long-term course of the disease, Detailed operation reports of surgical procedures to treat the OKC lesions, and; Large histologic specimens from the six patients who received total resection of the involved mandibular bodies. These hemimandibulectomy slides offered a unique opportunity to observe OKC activity throughout a wide osseous area. All patients hod been operated multiple times over a period of 10 to 21 years, coming eventually to mandibular resection. The operating surgeon in all of the cases was one of the authors, Philip J. Boyne, DMD, MS, DSc. All patients exhibited the multifocal nature of OKCs with demonstrable cyst formation at distant sites in the mandible. Two patients had local recurrences at the margins of the primary lesion in addition to cyst formation at distant sites. The authors concluded that clinicians should respect the multifocal nature of OKCs. The "recurrences" observed in OKCs may not necessarily be due to the degree of skill of the surgeon or the technique used to eradicate the primary cyst, but instead are probably a reflection of the multifocal nature of the pathologic lesion itself. The OKC is a very aggressive intraosseos lesion of the jaws, which not infrequently clinicians detect in the process of routine oral examination.

Ankylosis of the jaw in a patient with fibrodysplasia ossificans progressiva.

A case of fibrodysplasia ossificans progressiva (FOP) is presented. This uncommon connective tissue disease tends to produce progressing ectopic osteogenesis. Because there are no reported curative procedures for TMJ ankylosis occurring in this condition, a palliative surgical approach is described. Etiology, diagnosis, and prognosis of the disease is reviewed. Recent research in BMP cytokine-induced bone repair may allow new approaches to treating this debilitating disease in the future.

Effect of teeth with periradicular lesions on adjacent dental implants.

OBJECTIVES: It is generally accepted that dental implants should not be placed in infected sites. However, the effect of periradicular infections of natural teeth on adjacent osseointegrated implants is less understood. The purpose of this study was to evaluate effects of periradicular lesions on osseointegration of existing implants. Study design Forty titanium solid root-form implants were placed close to premolars in dogs. After healing following implant placement, the adjacent premolars were treated in 1 of 4 ways: group A, no treatment of the adjacent premolar; group B, induction of a periradicular lesion followed by nonsurgical root canal therapy of the premolar; group C, induction of a periradicular lesion followed by nonsurgical root canal therapy of the premolar and surgical detoxification of the implant surface; and group D, induction of periradicular lesion and no treatment of the tooth. After 7(1/2) months, block sections were prepared and the percentage of osseointegration was analyzed histomorphometrically. RESULTS: The average integration for implants in groups A-B was 54%, 74%, 56%, and 68%, respectively. One-way analysis of variance demonstrated no difference between the 4 groups ( P =.518). CONCLUSIONS: The results of this study indicate that teeth with periradicular lesions do not adversely affect adjacent titanium solid root-form implants.

Augmentation of the posterior maxilla by way of sinus grafting procedures: recent research and clinical observations.

This article presents some of the clinical problems with bony augmentation of the posterior maxilla using sinus lift procedures to effect alveolar bone reconstruction. The antral membrane and the bone of the antral floor have regenerative potential commensurate with other bone of the maxilla and mandible. The stem cells involved in the periosteum of the sinus floor and the mucoperiosteum of the oral cavity covering the osteotomy opening combine to form a very receptive site for grafting and surgical procedures. Distraction osteogenesis, with and without bone inductor cytokines, will play a prominent part in sinus floor augmentation and in posterior maxillary alveolar bone grafting in the future.

A method of treating the patient with postpubescent juvenile rheumatoid arthritis.

PURPOSE: Juvenile rheumatoid arthritis (JRA) is a perplexing and devastating disease for which establishment of a treatment protocol is difficult. The relatively low incidence and unknown cause of this disorder have made it difficult to establish when and how to intervene. Treatment protocols for the prepubescent patient (<12 years for girls and 14 years for boys), as well as for the adult, have been established. A protocol for postpubescence (ages 12 through 18 years) has yet to be established. This pilot study attempts to establish another treatment protocol for this particular subgroup of patients. PATIENTS AND METHODS: Five girls between the ages of 14 and 18 years with common facial deformities who were given a diagnosis of juvenile rheumatoid arthritis were reconstructed by orthognathic surgery and costochondral rib grafts. All underwent surgery performed by the first author and were followed for 4 to 14 years. Patients were in disease remission at the time of surgery, and all presented with the same skeletal/dental deformity and condylar destruction. RESULTS: Serial cephalograms were taken immediately presurgically (T1), immediately postsurgically (T2), and at latest recall (T3). Tracings were done by the same orthodontist with the use of Quick Ceph Image Pro software (Quick Ceph Systems, San Diego, CA). Mandibular position as it related to the success of costochondral and orthognathic surgery was assessed by gnathion position relative to nasion-basion at the cranial center, as described by Rickett's facial analysis. Patient long-term follow-up lasted from 4 to 14 years and had a mean duration of 9.6 years. The average increase in anterior/posterior direction (T1 to T2) was 22.7 mm with an average relapse (T2 to T3) of 1.5 mm. Four of 5 patients had a stable Class I occlusion on follow-up, and 1 developed a 3-mm open bite postoperatively. CONCLUSION: This pilot study offers a treatment protocol for the postpubescent juvenile patient with rheumatoid arthritis (aged 12 to 18 years) that is based on a single surgery with relative postoperative stability.

Bone morphogenetic protein-induced repair of the premaxillary cleft.

PURPOSE: The purpose of this study is to evaluate the bony regeneration of premaxillary clefts in humans using recombinant human bone morphogenetic protein type 2 in a collagen sponge carrier. PATIENTS AND METHODS: Twelve patients with unilateral clefted premaxillas were evaluated preoperatively and 4 months postoperatively. Ten patients were repaired with recombinant human bone morphogenetic protein type 2 while 2 others were grafted with anterior iliac crest particulate marrow cancellous bone. Computed tomographic studies were used to evaluate preoperative alveolar cleft volumes, postoperative bone bridge volumes, and preoperative and postoperative volume ratios. RESULTS: A preoperative and postoperative volume ratio for patients repaired with recombinant human bone morphogenetic protein type 2 ranged from 24.1% to 90.6% with a mean of 71.7%. Patients who were grafted with particulate marrow cancellous bone had similar preoperative and postoperative volume ratios ranging from 71.3% to 84.9% with a mean of 78.1%. CONCLUSIONS: Clefts of the anterior maxilla can have complete osseous regeneration induced by recombinant human bone morphogenetic protein type 2 as an effective alternative to conventional anterior iliac particulate marrow cancellous bone grafts.

Bone regeneration using rhBMP-2 induction in hemimandibulectomy type defects of elderly sub-human primates.

Our previous work has shown that total osseous reconstruction of large discontinuity hemimandibulectomy, critical-sized defects can be achieved easily in 8-year-old Macaca fascicularis monkeys (Boyne 1996). However the literature has indicated that animal aging decreases the BMP induction of stem cells in rats and in other rodent species. It was necessarily important that the rhBMP-2 be demonstrated in non-human primates to determine if this reduction in effectiveness also existed in the higher animals phylogenetically. The purpose of this study was to operate aged non-human primates duplicating the model used in middle-aged animals to demonstrate regeneration of hemimandibulectomy defects. This age group could be extrapolated to the 80-year-old clinic patient. Six non-human primates aged 20 years were rendered edentulous posteriorly and the mandibles allowed to heal. Three months postoperatively bilateral hemimandibulectomies were performed. The defects received BMP in a collagen sponge (Helistat) using a dose level of 0.75 mg of rhBMP-2. After the manner previously reported by Boyne (1996, 1999), at the end of four months the surgical sites were exposed by mucoperiosteal flap demonstrating complete regeneration of the critical-sized defects. The animals received two dental implants in restored areas. The implants were brought into function approximately four months later, and were allowed to function for eight months in all cases. The results indicate that the regeneration of mandibular critical-sized defects by the use of rhBMP-2 in aged animals is comparable to that of the middle-aged group. This study indicates that aged non-human primates, chronologically comparable to 80-year-old humans, respond as favorably to rhBMP-2 as do the middle-aged animals. Extrapolating the results to the clinical level, one would expect that rhBMP-2 would produce a comparable result in the regeneration of large hemimandibulectomy-type defects in clinical human patients.

A comparison of synovial fluid pressure after immediate versus gradual mandibular advancement in the miniature pig.

PURPOSE: Mandibular advancement is a commonly performed surgical procedure for the treatment of mandibular hypoplasia. With the increased use of rigid fixation, there has been a decrease in the amount of relapse but an increase in the amount of force transmitted to the condyles. Gradual advancement of the mandible by distraction osteogenesis slowly overcomes the soft-tissue envelope and may decrease the amount of force exerted on the condyles. The purpose of this study was to develop an animal model to measure the magnitude of pressure associated with immediate versus gradual mandibular advancement. MATERIALS AND METHODS: A 2.0-mm pressure transducer was placed in the superior joint space in 2 miniature pigs. In the first animal, immediate advancement of the mandible with rigid fixation was performed. The synovial fluid hydrostatic pressures were measured prior to surgery and postoperatively. A second animal underwent gradual advancement with distraction osteogenesis. The synovial fluid hydrostatic pressures were measured prior to and after each activation of the distraction device. The condyles were examined radiographically and microscopically. RESULTS: The superior joint space fluid pressures increased and remained elevated over a 5-week period after immediate advancement. In the gradually advanced mandible, the pressures were elevated but returned to near baseline prior to the activation the following day. CONCLUSION: This animal model is useful to directly measure the pressure that is exerted on the condyle. This will allow further studies to compare methods for mandibular advancement. It is likely that gradual advancement of the mandible by distraction osteogenesis produces less force and causes less condylar resorption than large mandibular advancement stabilized with rigid fixation.

De novo bone induction by recombinant human bone morphogenetic protein-2 (rhBMP-2) in maxillary sinus floor augmentation.

PURPOSE: This phase II study was designed to evaluate 2 concentrations of recombinant human bone morphogenetic protein-2 (rhBMP-2) for safety and efficacy in inducing adequate bone for endosseous dental implant in patients requiring staged maxillary sinus floor augmentation. MATERIALS AND METHODS: Patients were treated with rhBMP-2 (via an absorbable collagen sponge [ACS]), at concentrations of 0.75 mg/mL (n = 18), 1.50 mg/mL (n = 17), or with bone graft (n = 13). Bone induction was assessed by alveolar ridge height, width, and density measurements from computed tomography scans obtained before and 4 months after treatment and 6 months post-functional loading of dental implants (density only). RESULTS: Mean increases in alveolar ridge height at 4 months after treatment were similar among the groups; 11.3 mm, 9.5 mm, and 10.2 mm, respectively, in the bone graft, 0.75 mg/mL, and 1.50 mg/mL rhBMP-2/ACS treatment groups. Mean increases in alveolar ridge width (buccal to lingual) at the crest of the ridge were statistically different among the treatment groups; 4.7 mm, 2.0 mm, and 2.0 mm, respectively, in the bone graft, 0.75 mg/mL, and 1.50 mg/mL treatment groups (P

Distraction osteogenesis of the nasal and antral osseous floor to enhance alveolar height.

PURPOSE: The purpose of the study was to obtain information on the possibility of using distraction osteogenesis (DO) to increase the height of posterior atrophic maxillary alveolar ridges by distracting very small alveolar crest bone segments and, secondly, to determine if it is possible to distract the bony antral floor itself, producing new bone between the sinus membrane and the alveolar crest. MATERIALS AND METHODS: Three adult Papio anubis baboons were rendered edentulous in the posterior maxilla. Bilateral osteotomies were performed to produce a thin margin of crestal alveolar bone and in one area, a complete exposure of the antral floor. Distractors were placed against the antral and nasal floors and the thin 1- x 1.5-mm thick alveolar bone crest was distracted 10 mm over a period of 10 days. Animals were labeled with tetracycline at 3 and 4 months and were sacrificed at 5 months. RESULTS: A complete osseous regeneration of the nasal floor and alveolar ridge greater than 10 mm in height was produced in all cases. Histomorphometric analysis of the DO-induced osseous areas revealed cancellous bone with increasing thickness during the third and fourth month and formation of new bone cortices increasing in thickness during the same time. Significant new bone also formed in the antral floor areas that had been purposely interdicted by the osteotomies. CONCLUSION: The results of this study indicate that very small segments of bone of the posterior maxilla can be distracted to produce significant increases in the alveolar bone height and that a new osseous nasal-antral floor enhancement can be produced by this technique.