Vertical distraction osteogenesis in the human mandible: a prospective morphometric study

Vertical distraction osteogenesis has received considerable interest as a way to augment bone prior to implant placement. However, very little is known regarding the appropriate distraction protocols in the human mandible. In this study, we evaluate the effect of the distraction rate and the duration of neutrofixation on bone formation and closure of the gap in the human mandible. Vertical distraction was performed in the atrophic mandible of 16 edentulous patients, aged 62+/-6 years. The bone was distracted for approximately 10 mm at a rate of either 0.5 or 1 mm/day. Bone biopsies were taken after 7-20 weeks of neutrofixation. Histological analysis demonstrated newly formed bone in the distraction gap in all biopsies. The bone was predominantly of the woven type. After 10 weeks of neutrofixation, the gap was bridged by new bone in two out of three intact samples in the 0.5 mm/day group, but not in two intact samples of the 1 mm/day group. Histomorphometry revealed longer bone trabeculae (P=0.02) and a somewhat increased bone volume in the area where new bone formation started (P=0.07) in the group of patients having the 0.5 mm/day of distraction rate than in the 1 mm/day group. We conclude that in elderly patients, a distraction rate of 0.5 mm/day results in faster osteogenesis in the distraction gap than a rate of 1 mm/day. A minimum of 10 weeks of neutrofixation seems to be needed to close a 10 mm gap after cessation of distraction.     

Alveolar distraction osteogenesis of bone graft reconstructed mandible

This case report describes a patient who had severe mandibular bony deficiency as a result of excision of aggressive central giant cell granuloma. The defect was reconstructed with iliac bone graft. Four years later vertical distraction osteogenesis was performed on the grafted mandible in order to obtain a satisfactory bony height of mandibular ridge. Distraction osteogenesis can be a good alternative for the reconstruction of mandibular deficiencies.     

Alveolar distraction osteogenesis: a systematic review

This literature review was performed to analyse the outcomes of clinical studies of alveolar distraction osteogenesis (DO) listed by PUBMED between January 1996 and December 2006. A PUBMED search identified 128 articles on alveolar DO. Twenty articles covering 209 cases were analysed, considering location, device and procedural parameters, rate of augmentation, aspect of final implant placement and follow up. The mean latency period was 7.26+/-2.31 days, distraction rate 0.71+/-0.27 mm/day, rate of augmentation 6.88+/-2.52 mm and consolidation period 12.22+/-5.58 weeks. A total of 469 implants were placed and followed post loading for an average of 14.19+/-11.03 months, with a survival rate of 97%. Of the different procedural parameters, only the difference between mean consolidation period for failed (8.10+/-2.51 weeks) and successful (12.43+/-5.62 weeks) implants was statistically significant (P=0.01). Use of DO may be advantageous in terms of the success rate of implants placed in augmented sites, but there is still a lack of sufficient data based on long-term follow up. Future experimental studies should evaluate the application of different methods with a view to shortening the overall treatment period and improving the performance of implants placed in distracted alveolar ridges.     

Alveolar distraction osteogenesis for bone augmentation of severely atrophic ridges in 10 consecutive cases: a histologic and histomorphometric study

BACKGROUND: This study analyzed bone healing in surgically osteodistracted maxillary and mandibular ridges histologically and histomorphometrically at two different times to determine the best time to insert dental implants. METHODS: Ten consecutive patients with severe maxillary (two patients) or mandibular (eight patients) atrophy underwent surgical osteodistraction with an extraosseous distractor. Seven days after the surgery, the distractor was activated at a rate of 1 mm/day until achieving the planned bone lengthening. The distractor was removed after a consolidation period of 70 days. Bone biopsies were obtained at implant insertion: 70 days after the end of distraction on the day of distractor removal in six patients (group A) or 180 days afterwards in four patients (group B). The biopsies were evaluated histologically and histomorphometrically to measure the osteocyte lacunar area (OLA). RESULTS: The histologic and histomorphometrical analysis of the distracted bone 70 days after the end of distraction showed well-organized lamellar bone. At 180 days, the bone was more compact and mature; the mineralization of the matrix was greater; and an increased, but small, amount of marrow space was evident (35% versus 45%). The mean OLA was 80.11 +/- 27.59 microm2 in group A and 70.4 +/- 33.58 microm2 in group B. The difference between the two biopsy groups was not significant (P = 0.315). CONCLUSION: The results of this study showed that there was definitely similar bone formation in the distracted area for both healing periods, and placing implants clinically worked in both of these time periods in the limited number of cases observed.     

Alveolar distraction osteogenesis and implant placement in a severely resorbed maxilla: a clinical report

Atrophy of maxillary alveolar bone can result in severe defects of the alveolar ridge. Such defects can make it difficult to achieve esthetic and functional restorations. This clinical report describes the use of alveolar distraction osteogenesis to promote the formation of new bone and soft tissue in a large, severely resorbed segment of maxillary alveolus.     

Consolidation period in alveolar distraction: a pilot histomorphometric study in the mandible of the beagle dog

PURPOSE: Osteogenic alveolar distraction remains in an experimental stage. The present study aimed to compare histologic and histomorphometric results with 2 different consolidation periods (4 and 8 weeks) to determine which period obtained better bone quality after distraction with a prototype alveolar distractor. MATERIALS AND METHODS: Five beagle dogs were used. Four underwent alveolar distraction in an edentulous segment of the right mandible. After a 7-day latency period, distraction was carried out at a rate of 1 mm/d for 5 days; the consolidation period was 4 weeks in 2 dogs (group 1), and 8 weeks in the other 2 (group 2). The fifth dog was used as control (group 3); it underwent removal of its right premolars but not distraction. Histologic and histomorphometric studies were conducted. RESULTS: One animal from each distraction group was withdrawn from the study because of wound dehiscence that allowed invasion of mucosa into the distraction chamber, which was incompatible with bone regeneration. In the group 1 animal, a predominance of immature woven bone was observed in the distraction chamber, whereas the group 2 animal showed a predominance of immature parallel-fibered bone. The group 1 and 2 animals that remained in the study differed in bone area density in the distraction chamber (36.61% +/- 9.79% versus 58.72% +/- 8.30%), bone perimeter in the distraction chamber (262.89 +/- 10.46 mm versus 201.44 +/- 22.64 mm), total height attained (21.31 +/- 0.32 mm versus 18.37 +/- 0.50 mm), lingual trabecular width (134.00 +/- 15.56 versus 229.50 +/- 29.24), buccal trabecular width (90.00 +/- 4.24 mm versus 154.50 +/- 21.64 mm), lingual osteoid area density (4.08% +/- 0.46% versus 1.61% +/- 0.33%), and buccal osteoid area density (3.75% +/- 1.28% versus 2.09% +/- 0.79%). CONCLUSION: Quantitative and qualitative differences in newly formed bone were observed after 4 and 8 weeks of consolidation. These preliminary results serve as a basis for further experimental research with larger samples and for clinical studies.     

Alveolar ridge augmentation by distraction osteogenesis

Distraction osteogenesis is an alternative method for reconstructing atrophic alveolar bone. Fourteen patients underwent vertical alveolar distraction by the LEAD SYSTEM-Endosseous Alveolar Distraction System (Stryker Leibinger, Kalamazoo, MI). An alveolar segmental osteotomy was carried out and the vertical distraction device was mounted. In patients with an extensive alveolar defect, two distraction devices were placed in order to better control the vector of elongation in both bone edges. The distraction was started on the fourth postoperative day at a rate of 0.8 mm/day for 10-16 days, followed by a consolidation period of 60 days. Vertical distraction osteogenesis (VDO) was completed successfully in all patients with segment lengths in the range of 8 to 13 mm and with an average of 10.3 mm. Subsequently, the devices were removed and 23 threaded titanium dental implants were placed for osteointegration. Earlier mineralization in the vertically distracted area was seen radiographically during the consolidation period. In a follow up of 6-20 months after the distraction, 22 implants were successfully osteointegrated while one implant failed due to improper distracted segment stability. As a result of alveolar distraction, a segment of mature bone was transported vertically in order to lengthen the crest for better implant anchorage, either for aesthetic purposes or for functional prosthetic requirements. The main advantages of VDO are: (1) augmentation of alveolar bone height with new bone formation and simultaneous expansion of the soft tissues; (2) no bone harvesting is necessary; (3) the technique has a lower morbidity rate compared with conventional techniques; (4) it makes the insertion of longer dental implants feasible.     

Nicotine impairs distraction osteogenesis in the rat mandible

Distraction osteogenesis (DO) has gained clinical acceptance as a surgical technique for treatment of congenital craniomaxillofacial deficiencies requiring skeletal expansion. The use of this technique elsewhere requires more information on overcoming difficult clinical settings, for which new animal models will be needed. The aim of this study was to develop and validate a model of impaired DO of the rat mandible with nicotine. Twenty rats underwent a right vertical mandibular body osteotomy, after which distraction began with custom-made percutaneous devices and a 3-day latency period, 6-day distraction (0.25 mm twice daily) and 30 days of neutral fixation. Rats received either nicotine or placebo slow-release pellets. Specimens were analysed after removal of the devices for quantitative radiographic bone fill, amount of bone advancement and histological features. The mean radiographic bone-fill score with nicotine treatment was 75% of that with placebo (P=0.0036). The nicotine-treated rats had less (49%) elongation than the placebo-treated controls (P=0.0008). Histological analysis demonstrated less bone, vascularity and cellular activity in nicotine-treated rats. This study shows that nicotine reproducibly inhibits osteogenesis, vascularity and bone lengthening in mandibular DO.     

Quality and quantity of bone following alveolar distraction osteogenesis in the human mandible

PURPOSE: The purpose of this prospective study on humans were to evaluate (a) the clinical outcome of alveolar distraction osteogenesis for the correction of vertically deficient edentulous mandibular ridges, (b) the clinical outcome of dental implants placed in the distracted areas, and (c) the quality and quantity of the bone that had formed in the distraction gap. MATERIAL AND METHODS: Seven patients presenting vertically deficient edentulous ridges were treated by means of distraction osteogenesis with an intraoral alveolar distractor. Approximately 3 months after consolidation of the distracted segments, 20 ITI solid screw SLA implants were placed in the distracted areas. Three to 4 months later, abutments were connected and prosthetic loading of the implants started. During implant site preparation, bone biopsies were taken at the implant sites with trephine burrs for histologic and histometric analyses. RESULTS: The mean follow-up after the initial prosthetic loading was 18 months (range 12-24 months). The mean bone gain obtained at the end of distraction was 7 mm (range 5-9 mm). The cumulative success rate of implants 2 years after the onset of prosthetic loading was 95%, whereas the survival rate of implants was 100%. The newly formed bone consisted of woven bone reinforced by parallel-fibered bone with bone marrow spaces between the bone trabeculae. The bone area fraction in the distraction region ranged from 21.6% to 57.8% (38.5+/-11.7%). DISCUSSION AND CONCLUSIONS: Results from this study showed that (a) distraction osteogenesis is a reliable technique for the correction of vertically deficient edentulous ridges, (b) the regenerated bone withstood the functional demands of implant loading, (c) survival and success rates of implants placed in the distracted areas were consistent with those of implants placed in native bone, and (d) there is sufficient bone volume and maturity in the distracted region for primary stability of the implant.     

Alveolar distraction osteogenesis for implant site development

Alveolar distraction osteogenesis can be a valuable tool for implant site development. Simultaneous regeneration of hard and soft tissue and an overall decrease in treatment time compared with other methods of site preparation can be an advantage. The authors advocate the concept of "prosthetically driven alveolar distraction." Surgical planning should begin with visualization of the final restoration to determine the volume and position of the soft and hard tissue deficiency. Surgical guides will help the surgeon determine the vector of distraction. Adherence to surgical principles to avoid damage to adjacent vital structures and maintain vascular supply to the transport segment is necessary for success. Bone grafting may be necessary before or after distraction to increase the surgical success of the procedure. Close follow-up is needed to verify the appropriate distraction vector and volume. Patient management and acceptance should be considered in distractor design and placement.     

Dentigerous cyst after distraction osteogenesis of the mandible

Damage to the dentition or tooth follicle is often cited as a potential complication of Distraction Osteogenesis (DO). The authors describe a case of a dentigerous cyst that developed following DO of the mandible. The possible histogenic mechanisms and the management are outlined. Understanding the causes of dentigerous cysts as well as the anatomy of the neonatal mandible may help avoid such a complication in the future.     

Complications in alveolar distraction osteogenesis of the atrophic mandible

To improve the starting point for placement of dental implants, 45 patients suffering from atrophied edentulous mandibles, with a vertical height varying between 7.3 and 15.8mm, were treated by alveolar vertical distraction osteogenesis (VDO). The mean follow-up period was 3 years, ranging from 1 to 7 years. Associated complications, as occurred during instalment of the distractor device, VDO period and consolidation phase, and also after dental implant placement, were evaluated. Observed complications were: early fractures (2%), late fractures (17%), bleeding or haematoma (4%), infections (6%), skin perforation (2%), mucosal dehiscence (8%), sensory disturbances (28%), sagging chin (13%) and failure of dental implants (13%). In 10 patients 2 complications and in 1 patient 3 complications were monitored. All complications occurred in the first year. It is concluded that VDO to restore vertical bone height in patients with mandibular atrophy is a surgically delicate technique with a high risk of various complications. The likelihood of the most striking complication, namely fracture occurrence, increases with decreasing residual bone height.     

Imaging the neonatal mandible for accurate distraction osteogenesis

The position of mandibular teeth is difficult to document in the neonatal patient. Panorex images are difficult to obtain in an uncooperative pediatric patient. The new technique presented by the authors uses computed tomographic data to create a curved, reformatted image of the mandible, and generates an image similar to a panorex image. This curved, reformatted mandibular image provides accurate visualization of the mandible and mandibular teeth. This technique allows for precise pin placement and osteotomy in distraction osteogenesis.     

Vertical alveolar distraction osteogenesis with complications in a reconstructed mandible

We report here a case of vertical alveolar distraction osteogenesis with many complications that required further surgical interventions. A 54-year-old man underwent mandibular resection followed by iliac bone grafting as the result of large mandibular odontogenic keratocyst. Eleven months later, alveolar vertical distraction osteogenesis was applied to the patient for prosthetic rehabilitation. Fracture of the basal bone occurred in the consolidation period, and the fracture was fixed by the titanium miniplate system. Radiographic examination after completion of distraction osteogenesis confirmed a radiolucent area in half of the distracted area between the basal bone and the transport segment, and when the distractor was removed the radiolucent area was filled with fibrous granulation tissue. The granulation tissue was removed and endosteal implants were inserted together with a bone graft. Ultimately, all implants were osseointegrated, and adequate esthetics and function of the implant-supported prosthesis were achieved.