Accelerates bone maturation with the synthetic 3-benzothiepin derivative in distraction osteogenesis in rats.

2004 Fiscal Year Final Research Report Summary

• Project/Area Number: 13672085
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Surgical dentistry
• Research Institution: Niigata University
• Principal Investigator: KOBAYASHI Tadaharu Niigata University, Medical and Dental Hospital, Lecturer, 医歯学総合病院, 講師 (80195792)
• Co-Investigator(Kenkyū-buntansha): SHINGAKI Susumu Niigata University, Graduate School of Medical and Dental Sciences, Associate Professor, 大学院・医歯学総合研究科, 助教授 (30134943) ; IZUMI Naoya Niigata University, Medical and Dental Hospital, Assistant, 医歯学総合病院, 助手 (10361908)
• Project Period (FY): 2001 – 2004
• Keywords: mandibular distraction osteogenesis / rat model of distraction osteogenesis / micro-computed tomography / accelerates bone maturation

Research Abstract

Distraction osteogenesis is a method of increasing bone length. The application of distraction osteogenesis to craniofacial surgery has altered the approach and treatment of congenital and acquired craniofacial defects. This study investigated the histologic and ultrastructural changes associated with mandibular distraction osteogenesis in animal model.
Male Wister rats, 12 weeks old and weighing about 400g, were purchased from Charls River Japan. The operation was performed under general anesthesia. The skin overlaying the right hemimandible was shaved and incised, and the mandible exposed. Four 1.2 x 12-mm titanium micro screws were placed anterior and posterior to the planned osteotomy site. The mandible was osteotomized between the 2nd and 3rd molars using a diamond disk, a custom-made distraction device consisting of a Jack-screw embedded in methyl methacrylate mold was applied, and the skin and soft tissue were closed in layers. After a 5-day latency period, the mandibles were dis tracted at a rate of 0.2 mm twice a day for 10 days and rats were sacrificed at four different time points (5,15,36,and 50 days) for histologic examination and three-dimensional micro-computed tomographic reconstructions.
After completion of distraction, obvious anterior cross-bite was recognized with a few radiopaque lines noted within the distraction gap. Three weeks after distraction, increasing radiopacity was noted within the distraction gap. Five weeks after distraction, fully ossified bony regenerate was demonstrated radiographically within the distraction gap. Histologic examination of the mandibles demonstrated typical endochondral bone formation and intramembraneous bone formation after completion of distraction. Three weeks after distraction, incresed newly formed bone was noted and resulted in a near complete closure of the distraction gap. Five weeks after distraction, the distraction gap was completely ossified and increasing evidence of regenerate bone remodeling to more mature lamellar bone was noted. In conclusion, the utility of this rat model of distraction osteogenesis was demonstrated