Effects of topical administration of clodronate on alveolar bone resorption in rats with experimental periodontitis

Background: We examined whether topical administration of a bisphosphonate clodronate could prevent alveolar bone loss in rats with experimental periodontitis. Methods: On day 0, elastic rings were placed around the cervix of the right and left maxillary first molars (M-1) to induce inflammatory periodontitis. Fifty mul of clodronate solution at a concentration of either 0 (0.9% NaCl), 20, 40, or 60 mM was injected into the subperiosteal palatal area adjacent to the interdental area between M-1 and M-2 on either the left or right (experimental) side on days 0, 2, 4, and 6. The contralateral side served as a control and received 0.9% NaCl solution without clodronate. The animals were sacrificed on day 7. Results: Histological examination and determination of bone mineral density in the interdental alveolar bone area between M-1 and M-2 revealed that placement of an elastic ring caused severe vertical and horizontal bone resorption on the control side, while the topical administration of clodronate significantly prevented such alveolar bone loss. The number of osteoclasts on the experimental side was decreased compared with the control side. Furthermore, many of the osteoclasts on the experimental side were detached from the surface of the alveolar bone and had degenerated appearances, such as rounded shapes and a loss of polarity. Conclusions: These results suggest that topical administration of clodronate may be effective in preventing osteoclastic bone resorption in periodontitis.