Effect of Chitosan, betaig-h3 and Human Bone Morphogenic Protein-4 on Early Bony Consolidation in Distraction Osteogenesis of the Canine Mandible

ABSTRACT

Sixteen dogs were used to study the effect of bone morphogenic protein(BMP-4), betaig-h3 and chitosan during the early bony consolidation stage in the distracted zones of mandibles. The lateral surface of the mandibular body was exposed in the subperiosteal plane and vertical osteotomy was carried out on the mandibular body. An external distraction device was applied to the mandibular body about 1 cm apart from the osteotomy line. Mandibular distraction was started 5 days after the mandibular osteotomy at a rate of 2 mm per day for a total of 10 mm distraction for 5 days. The experimental group was divided into 4 groups: control group, BMP-4 group, betaig-h3 group and chitosan group depending on the injected material into the distracted area. Four dogs were allocated to each group. On the day of completion of distraction, 0.5 ml of BMP-4, 0.5 ml of betaig-h3, 0.5 ml of 5% chitosan solution was injected respectively into the distracted area of each group with the same amount of tripolyphosphate in dual syringe for solidification of the injected solution. In the control group, 1 ml of tripolyphosphate was injected into the distracted area. After injection of the study materials, the distraction device was left in place for 4 or 7 weeks to allow bony consolidation. Radiographs were taken weekly. Two dogs in each group, a total of eight dogs, were sacrified in 4 weeks, and another eight dogs in 7 weeks after completion of distraction. Bone specimens of the distracted mandibles were taken for histologic examination. The mineral density of the distracted bone was measured during the radiological procedures and analysed by the computer. In the radiographs of the distracted areas of the mandibles, the control group has shown a mostly radiolucent zone but the other groups have shown the radiodense zones with various width of central radiolucent zones. The central radiolucent zone became narrower in time and vertical thickness of the radiodense zone was about twice thicker in 7 weeks than that of 4 weeks after finishing bone distraction. BMP-4 group showed the thickest radiodense zone and the chitosan group shows the thinnest radiodense zone. The mineral density of bone was highest in the BMP-4 group and lowest in the control group. In the histological findings of the distracted areas of mandibles, the control group showed whole fibrous tissue but the other groups showed new woven bones with central narrow fibrous interzone. The degree of new bone formation was most remarkable in the BMP-4 group and was least remarkable in the chitosan group. In conclusion, there was an active formation of a new bone in the distracted area of the mandible by injection of BMP-4, betaig-h3 and chitosan. The new bone formation was most remarkable in the BMP-4 group followed by betaig-h3, chitosan and control group. These findings suggest that BMP-4 is clinically worth using for early bony consolidation in the distraction osteogenesis.