Diagnostic Criteria for Osteonecrosis of the Jaw (ONJ)
Definition and Terminology
- The American Society of Clinical Oncology recommends the term "medication-related osteonecrosis of the jaw" (MRONJ) when referring to bone necrosis associated with pharmacologic therapies in patients with a history of bone-modifying agent (BMA) or angiogenic inhibitor treatment 1, 2
- MRONJ can involve either the mandible or the maxilla in patients receiving BMAs 3
- The condition is characterized by exposed bone or bone that can be probed through a fistula in the maxillofacial region that does not heal within 8 weeks in patients with no history of radiation therapy to the jaws or metastatic disease to the jaws 1, 2
Risk Factors and Associated Medications
- The American Society of Clinical Oncology identifies BMAs, including bisphosphonates (e.g., zoledronic acid, pamidronate) and denosumab, as medications linked with MRONJ in patients with advanced cancer 1, 3
- MRONJ occurs in approximately 1% to 9% of patients with advanced cancer receiving BMAs 1
- Modifiable risk factors that increase MRONJ risk include poor oral health, invasive dental procedures, ill-fitting dentures, uncontrolled diabetes mellitus, and tobacco use in patients treated with BMAs 2
Diagnostic Approach
- Clinical intraoral examination, including direct visual inspection for exposed bone and probing for fistulas that lead to bone, is recommended for patients with suspected MRONJ 1, 2
- Radiographic examination, including panoramic radiographs and cone-beam or fan-beam computed tomography, is recommended for patients with suspected MRONJ 5
- The following staging system is recommended for MRONJ:
- At risk: No apparent necrotic bone in patients treated with BMAs 4
- Increased risk: No clinical evidence of necrotic bone but nonspecific clinical findings, radiographic changes, and symptoms 4
- Stage 1: Exposed/necrotic bone or fistulas probing to bone in asymptomatic patients without evidence of infection 6
- Stage 2: Exposed/necrotic bone or fistulas probing to bone with infection (pain, erythema, with/without purulent drainage) 6
- Stage 3: Exposed/necrotic bone or fistulas probing to bone with pain, infection, and one or more of: exposed bone extending beyond alveolar bone, pathologic fracture, extraoral fistula, oral-antral/oral-nasal communication, or osteolysis extending to inferior border of mandible or sinus floor 4, 6
Diagnostic Pitfalls and Caveats
- The American Society of Clinical Oncology recommends not relying solely on radiographic signs for diagnosis of MRONJ, as this may lead to overestimation of disease frequency 7
- Distinguishing MRONJ from other conditions, such as osteoradionecrosis and metastatic disease to the jaws, is crucial for accurate diagnosis 1, 8
- The 8-week timeframe for non-healing exposed bone is critical for diagnosis - shorter durations may represent normal healing processes 1, 2
- Biopsy of suspicious lesions is generally not recommended as it may exacerbate the condition 9