Photobiomodulation and TRP Expression in Dentin Hypersensitivity

Objectives: The aim of this study was to evaluate the effect of photobiomodulation on the TRPA1 and TRPM8 expression of mice with dentin hypersensitivity (DH).
Methods: 38 male Wistar rats (n=38) were randomly assigned to a split-mouth study: C - Control (right jaw); L – GaAlAs laser (780-830nm - E = 0.5J; t = 7s; D = 18J / cm2; P = 70mW) in the left jaw; DH – DH (right jaw); DHL - DH + Laser (left jaw). DH was assessed by acid drink, ad libitum, for 30 days. LLLT was performed on the 24th, 26th and 28th days. The buccal surface of the molars was periodically stimulated with water at 15 degrees for 5 seconds, followed by a pain test, on 15th, 22th, 24th, 26th, 28th and 30th days. In the Laser groups, the pain tests were performed pre- and post-irradiation. After euthanasia, the dental elements were stored in RNA stabilizer solution (RNAlater) until the moment of its manipulation, when the extraction of total RNA and cDNA synthesis were performed. The primers for GAPDH, TRPA1 and TRPM8 were designed and the quantification of the genes was performed by means of RT-PCR. Statistical analysis (p <0.05): Friedman test for degree of pain over time; Wilcoxon for intra-group comparisons, within each time and side comparison; Mann-Whitney for comparison between groups and for comparison of the gene expression in relation to the different groups.
Results: It was possible to correlate pain scores and the increase of TRPs A1 and M8. DH and DHL showed significant increase in both TRPs expression. LLLT was able to modulate the pain but not the expression of TRPs. DHL had the lowest pain scores.
Conclusions: It was concluded that the laser was effective in reducing pain, but this reduction could not be associated with modulation of the A1 and M8 TRPs expression.