Medication‐related osteonecrosis of the jaw: Osteoclast profile in comparison with osteoradionecrosis of the jaw and osteomyelitis of the jaw

Abstract Background Medication‐related osteonecrosis of the jaw (MRONJ) is a pathology condition of jaw bone caused by a side effect of medications prescribed for skeletal disease. The mechanism of MRONJ is still unknown now. Osteoclasts are cells directly influenced by the medication and the modification in cells metabolisms by the drugs lead to MRONJ. Thus, this study aimed to investigate the osteoclasts morphology, quantity, and comparing with other necrotic diseases. Methods Thirty‐eight (38) subjects, including cases with MRONJ ( n = 11), osteoradionecrosis of the jaw ( n = 9), osteomyelitis of the jaw ( n = 9), and normal jaw bone ( n = 9), were studied. Hematoxylin‐and‐eosin‐stained slides of these diagnosed cases were used to evaluate osteoclasts’ characteristics. Immunohistochemistry of TRAP was performed to observed the function of osteoclasts. These characteristics of osteoclasts were also evaluated in the relationship with the histological features using regression analysis. Results The results showed that osteoclasts in MRONJ enhance activity by increasing the size and the quantity ( p < 0.05). The presence of osteoblasts, inflammatory cells, and bacterial colonies showed a strong correlation with the change in morphology and the number of osteoclasts ( p < 0.05). However, the TRAP‐positive mean number and the TRAP intensity of osteoclasts in MRONJ did not show a significant difference with those in other groups ( p > 0.05). Conclusion In conclusion, osteoclasts in MRONJ increase the number and become bigger with multi‐nuclei which might relate to the presence of osteoblasts, inflammation, and microorganisms. This finding supports the idea osteoclasts might be the main key to investigate MRONJ.