Internal Resorption of Multiple Posterior Teeth in a Patient Diagnosed with Hyperparathyroidism: A Case Report

This case reports a 46-year-old man with end-stage renal disease and internal resorption (IR) affecting multiple posterior teeth. IR involves odontoclast's removal of dentin within pulp chambers and root canal space. Typically, asymptomatic until detected on radiographs, IR is relatively rare, so the etiology and pathogenesis are poorly understood. Patients' radiographs with cone-beam computed tomography revealed extensive IR in multiple premolars and all remaining molar teeth. Blood tests and hormonal assay measured elevated phosphorus and parathyroid hormone levels consistent with secondary hyperparathyroidism. Histopathology showed highly vascularized and inflamed pulp tissues with numerous odontoclast-like multinucleated giant cells along dentinal walls and in resorption lacunae. Immunohistochemistry showed that multinucleated giant cells and adjacent mononuclear precursors stained strongly for tartrate-resistant acid phosphatase like osteoclasts. Extraction of crown-root fractures and endodontic treatment with crown restorations for all IR teeth effectively arrested disease progression at 9 months' follow-up. Elevated parathyroid hormone from secondary hyperparathyroidism that promotes bone osteoclast activity may also stimulate odontoclasts causing IR.