[Studies on biocompatibility of apatite-silicone composite material and investigation of its clinical application]

As reconstructive and prosthetic material of the bone or soft tissue, the author developed a hydroxyapatite composite with silicone (HA-Si composite and studied its biocompatibility to the bone and investigated its clinical application. Si and HA-Si composite containing 30wt%, 50wt%, 70wt% of HA particles were implanted into the rabbit femurs and 2, 4, 12 weeks after, the histological observation was performed. On the surface of the Si fibrous tissue was formed directly, but with the composite, of with the higher HA content, new trabecula were formed from the cortical bone 2 weeks after and the bone developed and contacted the surface directly 4 weeks after and then progressed along the surface. Twelve weeks after the remodeling of the bone progressed and the lamellar structure was recognized. In the bone marrow region new bone formation was observed along the composite and the lamellar structure was recognized. The 70wt% composite showed a good affinity like hydroxyapatite. This composite had elasticity and good handling and biocompatibility to the bone, and it was suggested to be potentially useful for implantation. The 70wt% composite was applied in the clinical cases: mandibular reconstruction (8 cases), additional implantation for deformity of the face (3 cases), alveolar ridge augmentation (3 cases) and supporting of the retention of facial prosthesis (2 cases). The results in the cases of mandibular reconstruction were not satisfactory, however those in the other cases were good so far now. Therefore it was considered that the 70wt% HA-Si composite could be useful in the statical condition.