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Distraction osteogenesis of the porcine mandible: histomorphometric evaluation of bone.

Distraction osteogenesis is a technique for skeletal lengthening that exploits the body's innate capacity for bone formation in response to tension forces on the repair callus. The authors developed a distraction osteogenesis model with a semiburied device in the Yucatan minipig mandible because of similarities between human and porcine mandibular anatomy, temporomandibular function, chewing patterns, and bone turnover rates. The purpose of this study was to measure histomorphometric bone fill after different latency periods, rates of distraction, and duration of neutral fixation in the minipig mandible. In addition, the relationship between histomorphometric bone fill and clinical stability was investigated. Mandibular osteotomies in 20 female Yucatan minipigs weighing 25 to 30 kg were distracted with modified semiburied distraction devices. Variables included 0-day or 4-day latency; 1-mm, 2-mm, or 4-mm daily distraction rates; gap size of 7 or 12 mm; and evaluation after neutral fixation for various lengths of time. Specimens were fixed in 2% paraformaldehyde, pH 7.4, before being embedded in methylmethacrylate. Sections were prepared from the region just below the inferior alveolar canal. The area of new bone formation within the gap was measured and expressed as a percentage of the total area of the distraction gap. Bone fill ranged from 0 to 100 percent. A pilot study with 7-mm advancements showed similar bone fill with 0-day or 4-day latency, but with poor reproducibility. Mandibles that were distracted to 12 mm at 1 mm per day exhibited nearly complete bone fill, either with 0-day latency (average, 93 percent) or 4-day latency (average, 100 percent). Mandibles that had been distracted for 3 days at 4 mm per day showed moderate osteogenesis and clinical stability with increasing time of neutral fixation. Bone fill was significantly correlated with clinical stability (Spearman r = 0.801, p = 0.001). Histological examination showed exuberant periosteal osteogenesis in distracted mandibles, even in those that showed poor bone fill and clinical stability. Thus, the periosteum appears to be a major source of new bone formation. These results show that osteogenesis was nearly complete with 1 mm per day and 0-day or 4-day latency. These results are consistent with the authors' previously reported clinical and radiographic observations that a latency period is not necessary for successful healing of the mandibular distraction osteogenesis wound.

Animals↗

Functional significance of bone density measurements in children with osteogenesis imperfecta.

BACKGROUND: The treatment of osteogenesis imperfecta has been directed at improvement of bone mineral density, yet the importance of bone mineral density in predicting functional and clinical outcome in this patient population has not been demonstrated. We used a validated functional outcome measure to identify the relationship between bone mineral density and physical function in children with osteogenesis imperfecta, and we also evaluated the relationship of bone mineral density to the rate of surgery and fracture in patients with osteogenesis imperfecta. METHODS: Twenty patients (age range, four to seventeen years) with osteogenesis imperfecta who had undergone bone mineral densitometry as measured by dual x-ray absorptiometry of the lumbar spine, wrist, and proximal aspect of the femur between November 1999 and April 2001 were retrospectively analyzed. Functional outcome was measured with use of the Pediatric Outcomes Data Collection Instrument. These questionnaires were completed by the parents of all twenty patients and, in addition, by fifteen patients in the study who were between the ages of eleven and eighteen years. Fracture and surgery rates were calculated on the basis of the number of documented fractures and surgical procedures that the patient had had from the time of the initial presentation until the time of the latest follow-up visit. RESULTS: There were significant relationships between the bone mineral density of the lumbar spine and the scores obtained on the parent-completed questionnaires with regard to upper-extremity functioning (r = 0.57, p < 0.01), transfers and basic mobility (r = 0.55, p = 0.01), sports and physical functioning (r = 0.55, p = 0.01), and global functioning (r = 0.60, p < 0.004). There were also significant relationships between the bone mineral density of the wrist and the scores obtained on the child-completed questionnaires with regard to upper-extremity functioning (r = 0.82, p < 0.01), sports and physical functioning (r = 0.76, p < 0.01), and global functioning (r = 0.83, p = 0.001). There were significant negative relationships between the bone mineral density of the lumbar spine and the rate of fractures (r = -0.69, p < 0.001) and the bone mineral density of the lumbar spine and the rate of surgery (r = -0.60, p < 0.01). CONCLUSIONS: There is a relationship between bone mineral density and the functional outcome, rate of fracture, and rate of surgery in patients with osteogenesis imperfecta. Bone mineral density appears to be an indicator of disease severity and may be predictive of long-term functional outcome. To establish specific guidelines for treatment, more data on normative bone-mineral density in children with osteogenesis imperfecta will be needed.

Adolescent↗

[Ectopic osteogenesis of tissue engineered bone with slow-released bioactive factors].

OBJECTIVE: To study the ectopic osteogenesis of tissue engineered bone with recombinant human bone morphogenetic protein/transforming growth factor-beta (rhBMP/TGF-beta) or WO-1 slow-released factors. METHODS: Partial demineralized freeze-dried bone (PDFDB) of pig was used as scaffold material. rhBMP/TGF-beta or WO-1 were pre-coated on the surface of material by means of vacuum negative pressure absorption, and then coated with polylactic acid (PLA) to make slow-released material. There were six group: PDFDB material (group A); PDFDB combined with osteoblasts (group B); PDFDB material with rhBMP/TGF-beta slow-released system (group C); PDFDB material combined with rhBMP/TGF-beta slow-released system osteoblasts (group D); PDFDB with WO-1 slow-released system (group E); PDFDB material combined with WO-1 slow-released system and osteoblasts (group F) were implanted in bilateral lower limbs of 36 Newzealand rabbits respectively (6 rabbits in each groups). Histological, histochemical and biochemical analysis were detected 2, 4, 6, 8 weeks after operation. RESULTS: Within the observation periods, no osteogenesis was observed in group A. The osteogenesis in group B, D, F were superior to that of group C and E (P < 0.05). The osteogenetic activity in group C and E was delayed. The quantity and quality of osteogenesis in group D and F were 2 weeks ahead of time compared with group B, and 4 weeks to that of group C and E. The newborn calcification content was superior to that of group A, C, and E (P < 0.05). CONCLUSIONS: The osteogenesis of PDFDB materials with BMP/TGF-beta or WO-1 is slower than that of which combined with osteoblasts. Simple material PDFDB has no ectopic osteogenesis.

Animals↗

[Maxillofacial surgery and distraction osteogenesis--history, present, perspective].

The distraction osteogenesis is processes of planning and controlled tension over a bone after osteotomy or corticotomy. The purpose is lengthening on the base of forming a new bone tissue with normal biological characteristics. It presents historical development. The distraction osteogenesis adapts to the needs of oral maxillo-facial surgery in last ten years. The first step was a lengthening of the lower jaw with extraoral apparatus (McCarthy 1992). The surgical techniques and the principals of G. Ilizarov are shown in the overview. It describes the biological aspects of the distraction osteogenesis--the phenomena tension--stress, as such as the effect not only over the bone but over the surrounding soft tissues, blood vessels and nerves. It presents the distraction osteogenesis used in maxillo-facial surgery--mandibular distraction, distraction of alveolar bone, of mid-third face, cranio-orbito-maxillar distraction osteogenesis. Because of easy surgical technique, clinically proved by stable functional and aesthetic results, the distraction osteogenesis has perspectives in future time.

Facial Bones↗

[Development of a novel in-vitro culture device simulating distraction osteogenesis and expression of osteoblast cytoskeleton].

OBJECTIVE: To establish a novel in-vitro culture device simulating distraction osteogenesis, and to understand the the changes of cytoskeleton of osteoblasts under different magnitudes of mechanical distraction. METHODS: A novel in-vitro culture device simulating distraction osteogenesis was developed with titanium and silicon membrane. The expressions of F-actin cytoskeleton subjected to different magnitudes of distraction were observed in situ under a confocal laser scanning microscope, and protein levels of actin and tubulin alpha were analyzed by electrophoresis of Western blot. RESULTS: The mode of culture device simulating distraction osteogenesis was similar to that of distraction osteogenesis used in clinic. After 24 h mechanical distraction with physiological magnitude, F-actin of osteoblasts was organized and paralleled to the direction of distraction forces. After 24 h mechanical distraction with hyperphysiological magnitude, however, F-actin of osteoblasts became reorganized and disrupted, and protein levels of actin and tubulin alpha decreased. CONCLUSIONS: The novel in vitro culture device simulating distraction osteogenesis is suitable for the study of distraction osteogenesis in vitro. Physiological mechanical distraction causes organization and rearrangement of actin cytoskeleton. However, hyperphysiological mechanical distraction results in reorganization and disruption of actin cytoskeleton.

Actins↗

Lack of either chondrocyte hypertrophy or osteogenesis in Meckel's cartilage of the embryonic chick exposed to epithelia and to thyroxine in vitro.

Osteogenesis was not initiated when Meckel's cartilages from embryonic chicks of Hamburger and Hamilton (H. H.) stages 38 and 39 were recombined with mandibular epithelia obtained from embryos of H. H. stage 22 (a stage when an epithelial-mesenchymal interaction elicits osteogenesis from mandibular mesenchyme) and grafted to the chorioallantoic membranes of host embryos for 7 to 21 days. Failure of osteogenesis was not because the cartilage inhibited or blocked the osteogenesis-initiating capabilities of mandibular epithelium for mandibular epithelia could still elicit osteogenesis when removed from Meckel's cartilages and recombined with mandibular mesenchyme. Chondrocyte hypertrophy is associated with osteogenesis in other cartilages, including Meckel's cartilage from rodent embryos. However, Meckel's cartilages from chick embryos of H. H. stages 34, 38, and 39 failed to hypertrophy when cultured in the presence of 7.5 nM thyroxine (3,3',5-triiodo-L-thyroxine), although H. H. stage 28 tibial chondrocytes cocultured with Meckel's cartilage did hypertrophy. Therefore, avian Meckelian chondrocytes fail to hypertrophy or to produce osteoprogenitor cells in response to stimuli known to evoke these events in other skeletal cells.

Animals↗

The dentition in the osteogenesis imperfecta syndromes.

The deciduous and permanent teeth in some patients with osteogenesis imperfecta syndromes are blue or brown and opalescent. As shown by radiologic examination, the pulp chambers and root canals are completely or partially obliterated by abnormal dentin. The junctions between the crowns and roots are more constricted than normal. Deciduous opalescent teeth lose their enamel readily and wear more easily than normal. Unusual wear does not occur as frequently in permanent opalescent teeth as in deciduous teeth. No relationship has been shown between the number of fractures or deformity and the degree to which the teeth are affected. In contrast, other patients with osteogenesis imperfecta have normal teeth. These clinical differences in the dentitions support the concept of genetic heterogeneity is osteogenesis imperfecta and provide information useful in genetic counseling. The differential diagnosis of opalescent teeth in osteogenesis imperfecta is not difficult provided that detailed clinical and radiologic examinations of the dentition are performed. Patients with osteogenesis imperfecta and opalescent teeth should be evaluated as soon as the deciduous teeth erupt, so that an attempt can be made to prevent loss of tooth structure. However, methods of dental care in osteogenesis imperfecta are not well delineated and deserve further study.

Amelogenesis Imperfecta↗

Age-related changes in bone formation, osteoblastic cell proliferation, and differentiation during postnatal osteogenesis in human calvaria.

We have determined the age-related changes in the growth characteristics and expression of the osteoblast phenotype in human calvaria osteoblastic cells in relation with histologic indices of bone formation during postnatal calvaria osteogenesis. Histomorphometric analysis of normal calvaria samples obtained from 36 children, aged 3 to 18 months, showed an age-related decrease in the extent of bone surface covered with osteoblasts and newly synthesized collagen, demonstrating a progressive decline in bone formation during postnatal calvaria osteogenesis. Immunohistochemical analysis showed expression of type I collagen, bone sialoprotein, and osteonectin in the matrix and osteoblasts, with no apparent age-related change during postnatal calvaria osteogenesis. Cells isolated from human calvaria displayed characteristics of the osteoblast phenotype including alkaline phosphatase (ALP) activity, osteocalcin (OC) production, expression of bone matrix proteins, and responsiveness to calciotropic hormones. The growth of human calvaria osteoblastic cells was high at 3 months of age and decreased with age, as assessed by (3H)-thymidine incorporation into DNA. Thus, the age-related decrease in bone formation is associated with a decline in osteoblastic cell proliferation during human calvaria osteogenesis. In contrast, ALP activity and OC production increased with age in basal conditions and in response to 1,25(OH)2 vitamin D3, suggesting a reciprocal relationship between cell growth and expression of phenotypic markers during human postnatal osteogenesis. Finally, we found that human calvaria osteoblastic cells isolated from young individuals with high bone formation activity in vivo and high growth potential in vitro had the ability to form calcified nodular bone-like structures in vitro in the presence of ascorbic acid and beta-glycerophosphate, providing a new model to study human osteogenesis in vitro.

Age Factors↗

[Stimulation and evaluation on maxillary distraction osteogenesis using CASSOS 2001].

OBJECTIVE: To simulate maxillary distraction osteogenesis and evaluate the change of soft and hard tissue before and after treatment, using Computer-Assisted Simulation System for Orthognathic Surgery( CASSOS 2001). METHODS: A fourteen-year-old boy with severe maxillary hypoplasia, due to unilateral cleft lip and palate, was analysed by cephalometric analysis. The simulations of maxillary distraction osteogenesis (Le Fort I osteotomy and Le Fort II osteotomy) were re-analysed. After the treatment, cephalometric analysis was preformed again. The data were compared. RESULTS: The maxillary hypoplasia was well treated using maxillary distraction osteogenesis; Compared with Le fort I osteotomy, more satisfactory results can be obtained by Le fort I distraction osteogenesis. CONCLUSION: Maxillary distraction osteogenesis is a better way to treat severe maxillary hypoplasia with operated CLP than maxillary osteotomy. CASSOS 2001 can help surgeons and patients on simulation and evaluation of maxillary distraction osteogenesis, and on decision of treatment plan.

English Abstract↗

Effect of neoadjuvant chemotherapy on distraction osteogenesis in the goat model.

Neoadjuvant chemotherapy potentially can have an adverse effect on bone healing in distraction osteogenesis whether given before or concomitant with distraction osteogenesis. It was the purpose of the current study to determine if administration of chemotherapy before distraction adversely affects bone generation in distraction osteogenesis. Twenty-four adult dairy goats were divided randomly into two groups: a control group having distraction osteogenesis only and a chemotherapy group, receiving one course of Adriamycin before distraction osteogenesis. The animals were sacrificed at 6 weeks, 12 weeks, or 24 weeks and the lengthened tibias were evaluated by radiologic studies, biomechanical testing, and histologic analysis. All goats receiving chemotherapy showed systemic adverse effects. In a multifactorial analysis of the lengthened bones, there was no statistically significant difference between the control goats versus goats that received chemotherapy; indicating that there was no sustained inhibitory effect on bone formation by the chemotherapy. These findings suggest that a prior course of chemotherapy with Adriamycin may not be a contraindication to limb lengthening for limb salvage after resection of an osteosarcoma.

Animals↗

[mRNA expression of activin a and follistatin in rabbit mandibular distraction osteogenesis].

OBJECTIVE: To examine the mRNA expression of activin A(ACT A) and follistatin(FS) during mandibular lengthening and to elucidate the regulating pattern of during mandibular distraction osteogenesis. METHODS: Skeletally mature white New Zealand rabbits were established right mandibular distraction osteogenesis models and the mandibles were lengthened 7 days after osteomy. At the end of latency period and the end of distraction period, 10, 20, 30, 40 and 60 days after fixation, the regenerating tissue of animals' lengthened mandibles and that of the other side normal mandibles were harvested to extract RNA and to analyse ACT A, FS mRNA by RT-PCR. RESULTS: The expression of ACT A mRNA was not detectable in normal bone tissue and ACT A mRNA began to express at the end of latency period. The expression of ACT A mRNA increased gradually along with the beginning of distraction and reached the peak on the 10th and 20th days of distraction which was 5.04 and 4.98 times as much as that of the end of latency period, respectively. The trend of expression of FS mRNA during mandibular distraction osteogenesis was the same as expression of ACT A mRNA. CONCLUSION: ACT A/FS play an important role during rabbit mandibular distraction osteogenesis. To examine the mRNA expression of activin A(ACT A) and follistatin(FS) during mandibular lengthening and to elucidate the regulating pattern of during mandibular distraction osteogenesis.

Activins↗

Segmental mandibular regeneration by distraction osteogenesis. An experimental study.

We report the use of distraction osteogenesis for segmental mandibular regeneration. This technique has been used in thousands of patients in the Soviet Union to regenerate as much as 30 cm of tubular bone in the extremities. However, we are unaware of previous experimental or clinical reports of segmental mandibular regeneration by distraction osteogenesis. In a canine model, 2.5-cm segmental mandibular defects were filled with regenerate bone in 25 days at a rate of 1.0 mm/d using bifocal distraction osteogenesis. The diameters of the regenerate segments were comparable with preexisting mandible, and all animals resumed normal oromandibular function following regeneration. The regenerate bone was evaluated radiographically, angiographically, and histologically. In the control group without distraction osteogenesis, the segmental defects failed to fill with regenerate bone. The theoretical basis for distraction osteogenesis, a detailed description of the technique, and a review of previous studies on experimental mandibular lengthening are presented.

Animals↗

Reconstruction of segmental mandibular defects by distraction osteogenesis for mandibular reconstruction.

BACKGROUND: Distraction osteogenesis is an established technique for the lengthening of long bones and correction of selected craniofacial deformities. Regenerate osteoid bone matrix formed during the distraction phase is malleable and can recreate the three-dimensional form of native bones. Animal experiments and early clinical experience have confirmed that distraction osteogenesis can be used for the reconstruction of segmental bony defects. Herein we discuss the principles of distraction osteogenesis in reference to reconstruction of segmental bony defects and report its clinical application of the mandible continuity defects. PATIENTS AND METHODS: Four patients (age, 7-83 years) with critical segmental mandibular defects (range, 3.5 cm-6.5 cm), resulting from ablative oncologic head and neck surgery underwent primary mandibular reconstruction by transport distraction osteogenesis. Two defects were at the angle and body region, one at the body, and the other at the parasymphysis and body region. Synthes Titanium Multi-vector and Leibinger Multi-guide distractors in bifocal (n = 2) and trifocal (n = 2) architecture were used after the stabilization of the segmental continuity defect using a defect-bridging mandibular reconstruction plate. Osteodistraction was carried out at a rate of 1 mm per day, with once or twice a day rhythm, after a 1-week latency period. The consolidation period was equal to the period of distraction. RESULTS: All patients tolerated the distraction procedure. Satisfactory bone formation was observed in two patients, and partial bone formation was seen in one patient. Treatment failure was encountered in one patient who had a second oral cavity primary tumor observed during the consolidation period, requiring interruption of the treatment sequence. CONCLUSIONS: Mandibular reconstruction with distraction osteogenesis is a potentially useful technique in selected patients with segmental mandibular continuity defects after ablative head and neck cancer surgery.

Aged↗

Differential effects of PD98059 and U0126 on osteogenesis and adipogenesis.

PD98059 and U0126 are considered as specific inhibitors of the p42/44 mitogen-activated protein kinases (MAPK) pathway, which affects osteogenesis and adipogenesis. Here, we show unexpected differential effects of PD98059 and U0126 on osteogenesis and adipogenesis as well as on estrogen (E2)-induced actions in osteoprogenitor KS483 cells. PD98059 dose-dependently inhibited osteogenesis indicated by cellular alkaline phosphatase (ALP) activity and nodule formation, but stimulated adipogenesis shown by the number of adipocytes. In contrast, U0126 slightly decreased osteogenesis but had no effects on adipogenesis, although it inhibited p42/44 MAPK more potently than PD98059. Furthermore, PD98059, but not U0126, counteracted E2-induced osteogenesis and adipogenesis. Transfection experiments showed that PD98059, but not U0126, had estrogenic transcriptional activity. Interestingly, both PD98059 and U0126 potentiated E2-induced estrogenic transcriptional activity in KS483 cells, which is opposite to the response in MCF7 breast cancer cells. Our data indicate that the cross-talk between growth factors and estrogen receptor (ER)-mediated pathways in KS483 cells is different from that in MCF7 cells. In summary, the differential effects of PD98059 and U0126 indicate their actions are not exclusively due to an inhibition of MAPK pathway. Caution should be taken in the interpretation of the results obtained using these inhibitors.

Adipocytes↗

Sustained proliferation accompanies distraction osteogenesis in the rat.

These studies were conducted to compare the local cellular proliferation patterns in the rat tibia during distraction osteogenesis with those during nondistracted fracture healing. Bone specimens from distraction osteogenesis and nondistracted fracture groups were analyzed 2, 10, and 20 days after surgery. Proliferation was determined by metabolic labeling with [3H]thymidine and by immunocytochemistry with an antibody to proliferating cell nuclear antigen. Videomicroscopy was used to count the cells staining positively within specified regions. The number of cells incorporating [3H]thymidine was positively correlated (r2 = 0.78) with the number of proliferating cell nuclear antigen positive cells on alternating serial slides. At day 2, the latter cells were largely confined to the bone marrow and periosteum in both groups, and the cell numbers per mm2 were also equivalent. At days 10 and 20, the proliferating cell nuclear antigen positive cells predominated in both the proximal and distal primary matrix front zones in the distraction osteogenesis group. In contrast, the proliferating cell nuclear antigen positive cells in the nondistracted fracture group were scattered throughout the healing area. Significantly more of these cells were in the primary matrix front zones than in any location within the nondistracted fracture-healing area. The number of these cells in the bone marrow adjacent to the surgical area declined from day 2 to day 10 in both groups. The results suggest that (a) proliferating cell nuclear antigen immunostaining is a reliable indicator of cycling cells; (b) by day 10, distraction osteogenesis is characterized by a zone-specific pattern of proliferating cells; and (c) distraction osteogenesis prolongs the stimulation of proliferation within the gap after fracture.

Animals↗

Muscle regeneration and fiber-type transformation during distraction osteogenesis.

The successful outcome of distraction osteogenesis depends in part on the adequate adaptation of the surrounding soft tissue. We characterized the adaptation of the tibialis anterior during distraction osteogenesis at different rates (0.7 and 1.4 mm/day) and amounts (15 and 30%) of lengthening. We documented the increased expression of neonatal and slow myosin heavy chain in the tibialis anterior of skeletally immature rabbits. There was neither expression of neonatal myosin heavy chain in the experimental soleus or in the slow muscle fibers of the tibialis anterior nor increased expression of slow myosin heavy chain in the soleus or gastrocnemius. The increased amount of neonatal myosin heavy chain was concentrated in the distal half of the muscle, whereas the increase in the number of fibers that were labeled with antibodies to slow myosin occurred to the same extent throughout the tibialis anterior. Electrophysiological methods showed that the tibialis anterior was functionally intact during and after distraction osteogenesis. We concluded that in the tibialis anterior of young, skeletally immature animals, distraction osteogenesis seems to induce a recapitulation of the developmental process without leading to functional changes. In addition, during distraction osteogenesis, a fiber-type transformation occurs similar to that observed in models of muscle overloading.

Animals↗

Locally applied nerve growth factor enhances bone consolidation in a rabbit model of mandibular distraction osteogenesis.

Distraction osteogenesis is widely used in treating deformities, defects, and fractures of both long bones and craniofacial bones. Demands for acceleration of bone consolidation are increased in distraction osteogenesis. Nerve growth factor (NGF) can enhance innervation and bone regeneration in a fracture model and stimulate differentiation of osteoblastic cells. In this study, we tested the ability of locally applied NGF to enhance bone regeneration in a rabbit model of mandibular distraction osteogenesis. Twenty rabbits underwent bilateral distraction osteogenesis with a rate of 0.5 mm per 12 h. Two times 0.04 mg human NGFbeta (hNGFbeta) in buffer was injected into the callus after distraction. The contralateral side received placebo injections. Rabbits were euthanized at consolidation times of 14 and 28 days. Specimens were subjected to radiography, callus dimensions measurement, mechanical testing, and bone histological and histomorphometric analysis. The maximum load, bone volume/total volume, mineral apposition rate of the 1st to 11th day, and mineralized bone percentage were significantly higher in the hNGFbeta side at 14 and 28 days (p<0.05). The data indicate that locally applied hNGFbeta can accelerate callus maturation and may be an option to shorten the consolidation period in distraction osteogenesis.

Administration, Topical↗

[Initial outcome of vertical distraction osteogenesis of the atrophic alveolar ridge].

Besides several conventional therapeutic regimens to treat severe forms of alveolar ridge atrophy the distraction osteogenesis is an alternative method. We introduced a new technique for the treatment of alveolar ridge atrophy encouraged by the advantages of distraction osteogenesis in the last decade. A new technique called "vertical distraction osteogenesis (VDO)" has been developed by our study group to move dentolous and edentolous segments of the alveolar process vertically with a device in microplate-design. Vertical distraction osteogenesis was completed successfully in nine patients with segments length ranging from 6.5 mm to 43 mm with an average of 23.7 mm. The vertical distraction rate was 9.9 mm on average in seven mandibular and two maxillar segments. In all cases we found good stability and the predicted movement of the segments. In contrast to bone transplantation an earlier mineralization in the vertically distracted area could be seen by radiological examination and biopsy. Five patients were treated with dental implants 12 weeks after distraction procedure. Main advantages of vertical distraction osteogenesis are: 1. No bone harvesting, 2. decreased resorption tendency, 3. lower morbidity compared with conventional techniques, 4. lower infection rate and 5. feasibility to insert dental implants 12 weeks after distraction procedure, 6. gain of soft tissue.

Adolescent↗