Osteonecrosis of the jaws (ONJ) is a complication of antiresorptive medications, such as
denosumab or
bisphosphonates, prescribed to patients with bone
malignancy or
osteoporosis. The most common instigating local factor in ONJ pathogenesis is
tooth extraction. However, in adults the great majority of teeth are extracted due to
dental disease. Here, we have investigated alveolar bone healing after extraction of healthy teeth or teeth with naturally occurring periradicular disease in mice treated with high dose
zoledronic acid (ZA), a potent
bisphosphonate, or OPG-Fc, a RANKL inhibitor. C57BL/6 mice were treated for eight weeks and in vivo micro-CT was performed to identify spontaneously occurring periradicular lesions around the roots of maxillary molars. Then, extractions of molars with and without
dental disease were performed in all groups. Four weeks later, animals were euthanized and maxillae were dissected and analyzed. Clinically, all vehicle animals with extraction of healthy or diseased teeth, and most OPG-Fc or ZA animals with extraction of healthy teeth showed normal mucosal healing. On the contrary, most animals with OPG-Fc or ZA treatment and extraction of diseased teeth demonstrated impaired healing with visible mucosal defects. Radiographically, bone socket healing was significantly compromised in OPG-Fc and ZA-treated mice with periradicular disease in comparison to other groups. Histologically, all vehicle animals showed normal mucosal healing and socket remodeling. OPG-Fc and ZA animals with extraction of healthy teeth showed normal mucosal healing, woven bone formation in the socket, and decreased remodeling of the original socket confines. OPG-Fc and ZA animals with extraction of diseased teeth showed mucosal defects, persistent prominent inflammatory infiltrate, bone exposure and areas of
osteonecrosis. These findings support that
dental disease is critical in the pathogenesis of ONJ, not only as the instigating cause for
tooth extraction, but also as a compounding factor in ONJ development and pathophysiology.