Osteoconductive Capacity of Hydroxyapatite Implanted Into the Skull of Diabetics

Diabetes mellitus can cause various diseases, including loss of bone mineral density as a characteristic manifestation of osteoporosis. In this condition, bone is more vulnerable to pathologic fractures that can be treated by implantation of biomaterial grafts. The aim of this study was to evaluate the osteogenic capacity of hydroxyapatite implanted into bone defects in the skull of nonobese diabetic mice. Fifteen nonobese diabetic mice were divided into 3 groups: control (nondiabetic), spontaneously diabetic, and spontaneously diabetic receiving insulin replacement applied subcutaneously into the dorsum. Defects were created experimentally in the skull with a surgical bur and filled with hydroxyapatite granules. The animals were killed 4 weeks after surgery, and samples were obtained for analysis. Quantitative methods were used for measurement of the new bone formation. Data were analyzed by analysis of variance followed by the Tukey test (P < 0.05). Radiographic results showed good radiopacity of the hydroxyapatite; however, radiolucent spots were seen between the hydroxyapatite granules in the diabetic groups, indicating infiltration of connective tissue. Microscopic results showed projections of newly formed bone from the margin of bone defect toward the implant. The quantity of newly formed bone was significantly higher (P < 0.05) than that observed in the diabetic groups. The recipient area of diabetic groups contained a larger amount of connective tissue as demonstrated by radiographic analyses. In conclusion, the osteogenesis guided by the properties of hydroxyapatite may even occur in bone suffering from the effects of diabetes, but the quantity of newly formed bone is lower, and the process is slower.