Evaluation of effects of photodynamic therapy on bisphosphonate-related osteonecrosis of the jaws in rats

Bisphosphonates are synthetic analogs of inorganic pyrophosphate and are drugs that suppress bone destruction caused by osteoclasts. Bisphosphonate-related osteonecrosis of the jaw (BRONJ) was first introduced in 2003 and its scope was expanded by the name medication-related osteonecrosis of the jaw (MRONJ), since 2014. The aim of this study was to evaluate the effects of photodynamic therapy on tissue samples by histopathological and histomorphometric examination and serum TRACP-5b (Tartrate-resistant acid phosphatase-5b) measurement in rats. MRONJ is defined as a non-healing exposed bone presence in the jaw that lasts longer than 8 weeks in patients without radiotherapy due to the use of antiresorptive or antiangiogenic drugs. Since the beginning of the 20th century, medical use of photodynamic therapy (PDT) has started and in recent years, it has become an important treatment option especially with its effect on microorganisms and tumors. Photodynamic therapy can be described briefly as inactivation of cells, microorganisms, or molecules through the light. In this study, 24 Sprague-Dawley male rats were divided into 3 groups consisting of 8 animals. Zoledronic acid was administered to group 1 and 2 and 0.9% sodium chloride was administered to group 3 intraperitoneally. After the injections were completed, dental extractions were performed. Photodynamic therapy was applied to group 2, three times a week for 2 weeks after the extraction. At the 16th week, sacrification was performed. As a result, photodynamic therapy has led to a decrease in epithelial opening and inflammation and an increase in the formation of new bone. Serum TRACP-5b values were shown to decrease significantly in osteonecrosis. In this study, PDT was shown to be useful for the prevention of MRONJ. Additional animal and human studies should confirm the findings.