Bone associated with implants in diabetic and insulin-treated rats

Objectives: Diabetes is an increasingly prevalent disease with oral health manifestations. While diabetes clearly has an affect on bone, its impact on the healing of bone associated with dental implants is not completely understood. The purpose of this study was to measure bone response to implants in uncontrolled and insulin-controlled diabetic rats. Materials and methods: One hundred and fifty-two rats were divided into control, diabetic, and insulin groups. Rats received streptozotocin (65 mg/kg) to induce diabetes; animals in the insulin group also received a subcutaneous slow-release insulin implant. Titanium alloy implants (1.5 x 8 mm) were placed in the proximal tibiae of animals. Implants were harvested at 2, 7, 14, and 24 days and examined histologically. Bone or bone-like tissue adjacent to implants was quantified as a percent. Data were compared using a two-way analysis is variance (ANOVA) with time and treatment as primary independent factors. Results: Time and treatment were significant factors in predicting bone response to implants (P < 0.0001). Mean bone volume peaked at day 7 and decreased over time to day 24. Mean bone volume percent at 2, 7, 14, and 24 days (+/- SD) was 8.2 (+/- 8), 22.9 (+/- 8), 18.8 (+/- 10), and 14.9 (+/- 9), respectively. Mean total bone volume percent (adjusted for day) for control, diabetic, and insulin groups (+/- SD) was 12.4 (+/- 9), 22.6 (+/- 10), and 17 (+/- 7), respectively. Bone volume adjacent to implants in diabetic rats was significantly greater than controls (P < 0.05). Diabetic animals treated with insulin were not statistically different from controls. Conclusion: Induction of diabetes with STZ is associated with increased bone response compared with controls. This response was mediated by treatment with insulin.