Efeitos da ozonioterapia em masseter de rato em modelo experimental de dor inflamatória

Abstract

Introduction: The antinociceptive effect of ozone (O3) has been described in the literature and may be related to the increase in the endogenous antioxidant defense system, with impacts on cellular metabolism and tissue oxygenation. However, the effect of this minimally invasive therapy in the treatment of myofascial pain remains controversial, especially in those pains related to temporomandibular disorders. Objective: To evaluate the effects of ozone therapy on nociception, the inflammatory process and tissue repair in the masseter muscle of rats in a model of inflammation induced by carrageenan. Material e Methods:The inflammatory process was induced through the administration of lambda carrageenan in a 2% solution of 100 µL, in the right masseter of the rats, and the nociceptive threshold was evaluated using the digital analgesimeter for the von Frey test at 5 hours, 1, 3 hours and 7 days after its administration. The control group received saline under the same conditions. To evaluate the effect of ozone therapy (O3) on the nociception caused by carrageenan, the rats were treated with O3 at a dose of 0.0016 mg/kg in a volume of 0.01 ml immediately after administration of carrageenan or saline (O3+Car and O3+Sal). Ibuprofen at a dose of 14mg/kg was used as a positive control (Ibup+Car and Ibup+Sal). One and 8 days after the administration of carrageenan or saline, the animals were euthanized and the masseters processed for semiquantitative histological analysis. Results: The antinociceptive study showed statistically significant differences between the Sal and Car groups at 5h, 1d, 3d and 7d, between the Ca and Ibup+Car groups at 1d, 3d and 7, and between the Sal and O3-Sal groups at 5h and 7d. There was no difference in the nociceptive threshold variation between the Car and O3+Car groups. One day after carrageenan, histological evaluation of the Car group showed hemorrhage, edema and an acute inflammatory infiltrate occupying areas of intense tissue destruction, which were slightly more severe in the O3+Car group. In the period of 8 days, the Car and O3+Car groups shared the same histological findings, that is, chronic inflammatory infiltrate with some lymphocytes, many macrophages and rare mast cells associated with severe tissue damage. Unlike the Sal and Ibup+Sal groups, the O3+Sal group showed a mild chronic inflammatory infiltrate that filled small areas of tissue destruction. Some neutrophils were observed in the vicinity of regenerating muscle fibers in the groups submitted to ozone therapy. Conclusion: Intramuscular ozone therapy was not able to reduce nociception, muscle necrosis and degeneration, inflammation and edema induced by carrageenan in the masseter muscle, but it was potentially capable of stimulating repair in tissue injuries of inflammatory origin through a neutrophil-related pathway.