超薄層HAコーティングインプラントの実験的研究

―第1報　病理組織学的検討―

抄録

Although hydorxyapatite (HA) is biocompatible material, it cannot support the biological load when used as a simple substance. In view of this, a titanium implant whose surface was coated with HA was developed. A thick HA coating, however, leads to peeling, shedding, and erosion, which causes harmful effects on the living body, resulting in implant removal.
These problems can be solved by developing an implant thinly coated with HA. Although there are several methods to coat implants with HA, the heat decomposition method is the only technique to coat them with ultrathin HA.
In the present animal experiment, we prepared implants ultrathinly coated with HA (4 μm) by the heat decomposition method, and inserted them into the femurs of rabbits. The changes of the tissues around the implants were histopathologically evaluated over time.
The implant used was Platon Implant of 3.0×6 mm whose pure titanium surface was coated with HA by the heat decomposition method (HA type). We prepared pure titanium implants as controls matched for shape (Ti type).
The implanted sites were observed 2, 4, 8, and 12 weeks after implantation.
According to regular technique, resected femur samples were embedded in Rigolac and horizontally cut into non-decalcification polish sections of approximately 60 μrn in thickness.
All the non-decalcification polish samples collected during observation periods were stained with toluidine blue,to study the changes with time of the tissues around the implants, from the aspect of histopathology.
Although osteogenesis was recognized in the tissues around implants at 2 and 4 weeks after implantation, osteogenesis observed around HA type was more remarkable than that observed around Ti type. Low power magnification, at and after the eighth week, disclosed an increase in bone density in the tissues around both types of implants, and the histoiogical differences between the areas around HA type were gradually obliterated. The high power magnification, however, showed closer contact of HA implant surface with bone.
These experimental results suggested that implants coated with HA by the heat decomposition method could be used in clinical treatment because of their practical usefulness.