Two cases of tooth resorption in patients receiving denosumab therapy

BACKGROUND: Multiple external cervical root resorption (MECRR) is a rare, aggressive form of root resorption affecting multiple permanent teeth at the cementoenamel junction. A possible association between denosumab (DMAb), a receptor activator of nuclear factor-κB ligand (RANKL)-inhibiting antiresorptive medication, and MECRR has been proposed, although evidence remains limited. CASE DESCRIPTION: Two retrospective cases of MECRR were identified, including a 72-year-old woman receiving DMAb for osteoporosis and a 65-year-old man receiving high-dose DMAb for metastatic prostate cancer. In both cases, MECRR was first detected approximately 5 years after beginning DMAb therapy, without known predisposing factors. Lesions progressed despite professional intervention and rapidly worsened after DMAb cessation. Histology revealed multinucleated clastic cells with external resorption of cementum and dentin. One hypothesis is that localized, RANKL-independent osteoclastogenesis may potentially contribute to MECRR during DMAb treatment, subsequently exacerbated by rebound osteoclast activity on drug withdrawal. PRACTICAL IMPLICATIONS: These cases illustrate a temporal association between DMAb therapy and MECRR but do not establish causality. Early recognition in patients receiving DMAb is important given the irreversible nature of MECRR. Interdisciplinary communication is important, and prospective and mechanistic studies are needed to clarify risk factors and develop preventive strategies.