Longevidade do efeito antinociceptivo de diferentes protocolos de biomodulação em animais induzidos à hipersesibilidade dentinária

Resumo (EN)

Objectives: This research aimed to evaluate the longevity of the antinociception from different photobiomodulation protocols in animals that are induced to dental hypersensibility (DH) and the relation with the β-endorphine levels. Methods and Materials: 160 male wistar rats, were divided in 8 groups (n=20): Control (water), DH (isotonic), L1 (660nm), L2 (880nm), L1L2 (both), DHL1, DHL2 and DHL1L2. The DH was induced by the isotonic drink during the period of 35 days. The photobiomodulation protocol was: 660 and 880 - 1J, 3,5J/cm², 100mW, 10s, 0,028cm², continuosly. The nociceptive behavior was evaluated on baseline and imediate in each time, 0, 2, 7 and 14 days, through scores (0-3), after a jet of water at 4°C, on the lower right molar. 5 of the animals/group/time were euthanized and their bloods were collected so the amount of β-endorfine could be evaluated. Their mandibules were also extracted, so the dental surface could be analized by scanning electron microscopy (MEV). To measure the pain levels, McNemar, Kruskal-Wallis e Friedman tests were done. To quantify the β-endorphine levels, normality and homoscedasticity tests were made, folowed by ANOVA, and for correlation, a Spearman Test. Results: The results pointed a statiscally relevant pain reduction over time in all of the irradiation protocols, with no statistic difference between them, with a bigger reduction during 7 to14 days (similar between them) when compared to 0 to 2 days (similar between them). The MEV showed a tubular exposure on the DH groups. There was an increase on the β-endorphine concentration levels on the irradiated groups, during all its times and moderate negative relation between its pain and concentration levels. Conclusions: The results suggest that the PBM application with red laser (660nm), infra-red (880nm) or its association promoted antinociceptive effects on the DH animal model, possibly mediated by the β-endorphine plasmatic concentration increase.