Histology of the Dental Extraction Sites of Bisphosphonate Treated Rats

Abstract

Bisphosphonate is a drug given to both men and women who are experiencing decreasing bone density and strength. When patients taking bisphosphonate undergo some sort of jaw trauma (i.e. tooth extraction, accident), they can experience necrosis or cell death of the jawbone. Our hypothesis is that bisphosphonate molecules bound to the bone matrix contribute to bone necrosis. For my thesis, a histological analysis of the mandibles from bisphosphonate treated rats after dental extraction with and without removal of bisphosphonates from the extraction site of the bone was done. Histological sections of the jaw from bisphosphonate treated rats after bilateral extraction of the first and second molar teeth were taken. On one side, the extraction site was treated with EDTA to chelate bisphosphonates from the bony wall of the tooth socket. The other side of the rat’s jaw was treated with Saline. I then evaluated the vitality of alveolar bone by counting the number of dead versus live osteocytes around the extraction site and comparing the ratios between the chelated and un-chelated sides from each rat. The study determined whether removal of localized bisphosphonates is beneficial to preserve bone vitality after dental extraction. As expected, the percentage of live osteocytes decreased in the alveolar bone of animals treated with Zoledronate (ZA), a strong dose of bisphosphonate. Furthermore, there was a trend of increased percentage of live cells when EDTA was used, although the differences were not statistically significant. These results support other studies in our laboratory that have shown that localized bisphosphonates play a role in the osteonecrosis associated with ZA treatment. It, therefore, provides evidence that localized bisphosphonates contribute to the etiology of bone necrosis in patients undergoing bisphosphonate treatment.