Medication-Related Osteonecrosis of the Jaw (MRONJ) Mistaken for Acute Apical Abscess.

The objective of this case study is to report on the diagnosis and treatment of medication-related osteonecrosis of the jaw (MRONJ), which was originally misdiagnosed and mistreated as endodontic disease. A patient was referred for worsening odontalgia despite root canal therapy on tooth No. 19 and a course of oral antibiotics. Examination demonstrated slight buccal swelling and tenderness in the left masseter and a 7-mm diameter area of exposed bone on the mandibular left lingual torus. Further history-taking revealed prior bisphosphonate therapy for metastatic breast cancer. MRONJ was identified as the likely diagnosis, and the patient was appropriately referred to oral and maxillofacial surgery where the diagnosis was confirmed and surgical debridement performed. The case study demonstrates how the symptomatology and presentation of MRONJ can resemble endodontic disease and that timely and appropriate treatment requires eliciting an in-depth medical history, reaching a complete pulpal and periapical diagnosis, and remaining attentive to the presence of exposed bone on examination.