The effect of bisphosphonate on alveolar bone resorption following mucoperiosteal flap surgery in the mandible of rats.

Following elevation of a full thickness flap a transient burst of regional remodeling occurs. This phenomenon is termed in orthopedic surgery as regional accelerated phenomenon (RAP), beginning with accelerated resorption activity followed by a slow process of bone regeneration. Recently we have demonstrated that a mucoperiosteal surgical flap of rat mandible is producing a typical RAP process. Bisphosphonates are synthetic compounds that are taken up preferentially by the skeleton and suppress osteoclast-mediated bone resorption by a mechanism that is not yet fully understood. Amino bisphosphonate has been shown to inhibit active bone resorption without interfering with bone formation. In this study we evaluated the effect of amino bisphosphonate on bone resorption associated with a mucoperiosteal flap used as a resorptive model. We compared the effect of amino bisphosphonate in rats using IV administration with topical application at 3 dose levels. The results show that topical application of all 3 doses (0.15, 0.75, and 1.5 mg/ml) had no inhibiting effect on bone resorption after surgery, while IV administration at 0.5 mg/kg body weight significantly reduced the bone resorption. Interestingly, in the non-operated side, amino bisphosphonate increased mineral density.