Tomoo Oda

Alveolar ridge augmentation by distraction osteogenesis using titanium implants: an experimental study

The left mandibular premolars were extracted from five adult dogs. After twelve weeks, a box-shaped osteotomy of the alveolar bone was carried out and two 10 mm implants were placed 5 mm into the transport alveolar segment, leaving 5 mm exposed. The alveolar bone was vertically augmented 5 mm by screwing the implants. After distraction, the implants were left to integrate into the bone. Histological and radiographical evaluations showed the lifting of the transport segment and the development of new bone in the distraction area. Although integration of implants within both the transport segment and the regenerated bone was observed, two of the ten implants failed and partial bone resorption of the transport segment was noted.

Segmental mandibular reconstruction by distraction osteogenesis under skin flaps

In five adult dogs, molars were extracted and skin flaps from the neck prepared for delayed transplantation. Two weeks later, a 25-mm segment of the mandible was excised with surrounding periosteum and gingiva. The mandible was stabilized with a reconstruction plate and the intraoral defect repaired with a pedicled skin flap. A proximal transport segment was created and an external distraction device was applied. After one week, distraction of the transport segment was begun at a rate of 1 mm/day. After distraction was completed, the lengthening appliance was left in place for 12 weeks until the dogs were killed. Radiologic and histologic examination revealed new bone at the distraction site. The intraoral skin flap was pushed out of the defect as distraction progressed. Bony union of the transport segment to the distal stump was not achieved due to intervening soft tissue. These results suggest that it is feasible to bridge a mandibular defect that is covered with a skin flap, with distraction osteogenesis.

Effects of cortical bone perforation on periosteal distraction: an experimental study in the rabbit mandible.

PURPOSE To investigate tissue reactions using periosteal distraction with decorticating holes in a rabbit model. MATERIALS AND METHODS Twenty-five Japanese white rabbits weighing 3.2 to 3.7 kg were used. The periosteum was carefully detached, and the buccal cortical bone was porously perforated by drilling in the decortication group. Titanium mesh was placed between the periosteum and the cortical bone, with or without holes. A distraction screw was placed rigidly under the center of the mesh. After a 7-day latency period, the periosteum was distracted 0.5 mm per day for 8 consecutive days. Rabbits were sacrificed after consolidation periods of 4 and 8 weeks. Cross-sectional radiographs were evaluated with densitometry. Specimens were fixed, decalcified, and stained with hematoxylin and eosin. RESULTS At 8 weeks after periosteal distraction, the area of new bone formation averaged 25.7 +/- 5.1 mm2 and 12.9 +/- 3.2 mm2 (mean +/- SD) with and without decortication, respectively. In this study, periosteal distraction showed better bone regeneration on the lateral aspect of mandibles with rather than without decorticating holes. CONCLUSION Periosteal distraction with decorticating holes can be effective in augmenting atrophic bone.

Stability of a Locking Plate and Self-Drilling Screws as Orthodontic Skeletal Anchorage in the Maxilla: A Retrospective Study

PURPOSE The aim of this retrospective study was to determine the success rate of an orthodontic skeletal anchorage system consisting of a locking plate and 2 self-drilling screws to intrude the upper molars and detect factors that contribute to its stability. PATIENTS AND METHODS The subjects were 32 orthodontic and generally healthy patients who had skeletal anchorage plates placed supraperiosteally and unilaterally or bilaterally. The anchorage plate was considered successful if the plate remained stable throughout the period of intrusion of the upper molar without any movement, persistent pain, or infection and was then retrieved without difficulty. The success rates of the anchorage plate were statistically analyzed on the basis of clinically categorized variables. RESULTS The 32 patients comprised 6 male and 26 female individuals with ages ranging from 11.4 to 35.1 years. The overall success rate of the total 61 plates was 93.4%. No significant differences were observed among the respective success rates analyzed in accordance with gender, age, side of placement, and length of the screws. The thickness of the bony walls that supported the screws was significantly greater in the success group (mean 1.6 +/- SD, 0.2 vs 1.0 +/- 0.1 mm, P < .001). CONCLUSION Bone thickness is a critical factor in supporting the self-drilling screws and locking plate. Skeletal anchorage combining the plate and 2 screws promises a higher success rate with a thicker bone than with the threshold value of thickness that exists within the 1.1 to 1.4 mm range in the maxillary walls.

Two Cases of Distraction Osteogenesis in Lengthening Hypoplastic Mandible of Hemifacial Microsomia. Evaluation 3 Years after Distraction.

Mandibular lengthening by distraction osteogenesis was performed on two females (6 and 9 years old) with hemifacial microsomia to correct facial asymmetry. The follow up was done by cephalometric analysis for 3 years.The results were as follows:1) Three years after distraction, the morphological symmetry corrected by distraction had almost been maintained.2) However, a slight amount of deviation on affected side was noticed at the Menton.3) In lateral chepharogram, ∠SN-Pog did not changed for 3 years after distraction.4) Downward growth of the maxilla on the affected side was not observed. Open bite at lengthened side seemed to be closed by eruption of the permanent molars.