Masato Manabe

Osseointegration of dental implants in rabbit bone with low mineral density

PURPOSE The purposes of this study were to establish an experimental animal model with bone of low mineral density, and to then investigate the reaction of the bone-implant interface in these experimental animals. MATERIALS AND METHODS To prepare the experimental model, rabbits were ovariectomized and fed a 0.15% low-calcium diet. The bone mineral density (BMD) of the tibia was periodically measured by dual-energy X-ray absorptiometry. Approximately 1 month after the introduction of the low-calcium diet, when BMD had decreased to about 12% less than that of control rabbits, a titanium implant (TI) was inserted into the tibia of each rabbit. At 2, 4, 8, and 12 weeks after the insertion of the TI, the rabbits were killed, and the reaction of the bone tissue surrounding the TI was examined both histologically and radiographically. RESULTS The combined ovariectomy and low-calcium diet produced rabbits having bone with low mineral density, and the histologic features of the tibia in these rabbits were consistent with those in human osteoporotic bone. In control rabbits, new bone formation surrounding the TI was evident 2 weeks after its insertion, and the TI surface was almost completely covered with new bone after 8 weeks. In contrast, new bone formation in the experimental rabbits was delayed, but considerable direct bone contact with the TI was observed after 12 weeks. CONCLUSION These results suggest that osteoporotic bone may affect the healing period of bone tissue after the insertion of dental implants, but that osseointegration of dental implants may be obtained even in osteoporotic bone.