RESUMO
BACKGROUND: This study investigated the effect of antimicrobial photodynamic therapy (PDT), using methylene blue (MBO) and photobiomodulation therapy (PT), on the alveolar bone of rats submitted to bisphosphonate-induced osteonecrosis of the maxillaries (OMB) model using zoledronic acid (ZA). METHODS: Sixty rats divided into six groups were used: SALINE, PDT, ZA, ZA+PDT, ZA+PT, and ZA+MBO. Three weekly administrations (Days 0, 7, and 14) of ZA 0.20 mg/kg or saline solution were performed. After one month (Day 42), the exodontia of the left lower first molars were performed. An additional dose of ZA was administered at Day 49. PDT was performed on days 42, 45, 49, and 54. One month after exodontia (Day 70), the animals were euthanized to obtain samples for imaging and microscopic analysis. ANOVA/Bonferroni tests were used for statistical analysis. RESULTS: The ZA+PDT group showed a significantly lower percentage of apoptotic osteocytes than the ZA group (p < 0.001). The ZA+MBO, ZA+PT, and PDT groups significantly reduced the number of mononuclear cells compared to the ZA group (p < 0.001). The ZA+PT and ZA+PDT groups showed a significant reduction in the number of CD 68+ (p < 0.001) and CD3+ (p = 0.002) cells compared to the ZA group. The number of cells expressing INF-y had a significant reduction in the groups co-treated with PT and PDT compared to the ZA group (p < 0.001). CONCLUSIONS: We conclude that PDT and PT attenuated the severity of OMB and the inflammatory process due to a reduction of macrophages, T lymphocytes, and cytokines that stimulate the activity of these cells.