Purpose: Medication-related osteonecrosis of the jaw (MRONJ) is a complication of antiresorptive therapy, including bisphosphonates and denosumab. Although bone scintigraphy (BS) detects early metabolic changes, its diagnostic role in MRONJ and its role in assessing systemic skeletal involvement remain unclear. This study analyzed BS tracer uptake patterns and their association with MRONJ severity and clinical variables. Materials and Methods: This retrospective study analyzed 319 patients diagnosed with MRONJ from 2010 to 2019. Three-phase BS, cone-beam computed tomography (CBCT), and clinical data were reviewed. Tracer uptake intensity in the jaw was visually graded, and extra-jaw skeletal uptake was categorized by region and number of involved sites. Associations between the MRONJ stage, jaw uptake intensity, and skeletal uptake beyond the jaw were analyzed. Results: Higher tracer uptake intensity in the jaw was associated with advanced MRONJ stages (P<0.001), particularly Stage 3. However, the number of skeletal sites beyond the jaw did not correlate with the MRONJ stage (P=0.512).Distribution of local and systemic tracer uptake in body patterns across MRONJ Stages did not show statistical significance. Conclusion Elevated tracer uptake in the jaw correlates with advanced MRONJ stages and broader skeletal tracer uptake, suggesting a potential link between local disease severity and systemic skeletal involvement. However, skeletal uptake beyond the jaw does not independently predict the MRONJ stage, suggesting that systemic bone involvement alone may not reflect increased disease severity.

BACKGROUND: Subcutaneous emphysema refers to swelling caused by the presence of air or gas in the interstices of loose connective tissue. In the head and neck area, it may follow the fascial planes and is characterized by sudden swelling, crepitus on palpation, infrequent pain, and air emboli on radiography. It usually occurs as a complication in dental treatment. Some reports have described subcutaneous emphysema caused by dental procedures; however, severe emphysema related to peri-implantitis after treatment has not been documented. Accordingly, the current report describes a rare case of subcutaneous cervical emphysema resulting from the use of an air-powder abrasive device to treat peri-implantitis. CASE PRESENTATION: Based on a review of the existing literature and the present case, nine cases of subcutaneous emphysema due to air-powder abrasive device have been reported. In most cases, the emphysema resolved over time after treatment with prophylactic antibiotics; among these, two were related to peri-implantitis management. CONCLUSION: Considering the frequent use of air-powder abrasive devices to treat peri-implantitis, the potential risk of iatrogenic emphysema related to this procedure needs to be addressed more extensively.
Anti-Bacterial Agents ; Connective Tissue ; Emphysema ; Head ; Mediastinal Emphysema ; Neck ; Palpation ; Peri-Implantitis ; Radiography ; Subcutaneous Emphysema