Effects of Anti–Receptor Activator of Nuclear Factor Kappa B Ligand Antibody and Zoledronic Acid on Periapical Lesion Development in Mice

Antiresorptive drugs are widely used to treat osteoporosis and other systemic bone diseases, although their efficacy for local bone resorption after localized inflammation has not been fully elucidated. We examined the effects of an anti–receptor activator of nuclear factor kappa B ligand (RANKL) antibody and the bisphosphonate zoledronic acid (ZOL) on periapical lesion (PL) development in mice. Dental pulp of lower first molars in mice was removed, with the exposed dental pulp chambers left open to the oral environment to induce apical periodontitis. An anti-RANKL antibody or ZOL was intraperitoneally injected once per week until postoperative day 21, and then micro–computed tomographic imaging and histologic analyses were performed. PL enlargement was inhibited by both the anti-RANKL antibody and ZOL in a dose-dependent manner, and a reduction of inflammatory cell infiltration in apical tissues inhibited periapical bone resorption. The anti-RANKL antibody decreased the number of osteoclasts in periapical tissues, whereas ZOL suppressed periapical bone resorption with osteoclast numbers maintained. Although the administration of each of the antiresorptive drugs increased femoral bone mass, femoral bone mineral density in the PL group was lower compared with the sham-operated group. These results suggest that an antiresorptive drug administered systemically is distributed to areas of local inflammation in the jaw can prevent PL development.