Impact of antimicrobial photodynamic therapy on micro-shear bond strength to dentin

To evaluate in vitro the bond strength through the micro-shear test of two adhesive systems (self-etching and total-etch), on bovine dentin surfaces after aPDT. For the aPDT, 0.01% methylene blue and two different light sources (red laser and LED) were used.Sixty samples were randomly divided into 6 groups (n = 10) for the micro-shear test: G1: self-etching adhesive (USB) without aPDT, G2: aPDT (laser) + USB, G3: aPDT (LED) + USB; G4: total-etch adhesive (ASB) without aPDT; G5: aPDT (laser) + ASB, G6: aPDT (LED) + ASB), followed by analysis of the fracture patterns of the samples. For statistical analysis, a two-way ANOVA (adhesive and treatment) and Tukey's test were performed, adopting a significance level of 5%.Regarding bond strength, there was no significant difference between the 6 groups analyzed. An adhesive fracture pattern predominated.Based on the results and the irradiation parameters used in this study, no changes in the bond strength of the resin to healthy dentin were observed after treatment with aPDT.