生体内吸収性材料HA/PLLA複合体を応用した骨延長装置による垂直的歯槽骨増生法

二次的インプラント埋入に対する増生骨の骨反応についての実験的研究

抄録

The purpose of this study was to establish a vertical alveolar ridge augmentation using a distraction device composed of bioresorbable HA/PLLA composites, and to safely apply dental implants to a distraction area. The distraction device comprised titanium bone screws, HA/PLLA transport plates, and base plates. Six beagle dogs were used for the experiment. Both premolars of the mandible were extracted previously, and the distraction device was placed after 12 weeks. After a latency period of 7 days, the box-forming segment was raised vertically by 7mm at 1.0mm/day by rotating a screw. After distraction, two implants were placed into the left side of the mandible after a retention period of 6 weeks (group A) or into the right side after a retention period of 12 weeks (group B) to penetrate the transport segment and the distraction area. The beagles were killed after 3 months of implantation, and the distraction area, implant surround and HA/PLLA surround were estimated and studied clinically, radiologically and histologically. The bone-implant contact rate (BIC) was measured in both groups. During the experiment, infection and lack of the distraction device were not recognized. The transport segments rose with rotation of the bone screw and we observed that spaces were formed between the transport segment and basal bones. From long-term observation with X-ray, intraosseous spaces showed a gradual increase of impermeability, and bone regeneration was histologically recognized between the intraosseous spaces. The BIC of group B was higher than that of group A. Histologically, foreign-body reaction was not significant around HA/PLLA. These results showed that vertical alveolar distraction was possible by this distraction device. A suitable retention period was important for osseointegration of the implant in the distraction area. It is considered that tissue damage caused by HA/PLLA was extremely small.