Estudo do efeito de três métodos de envelhecimento na resistência de união do esmalte e dentina

Abstract

To evaluate the effects of three artificial aging methods (water storage, thermocycling and NaOCl storage) on the degradation of a universal adhesive, in enamel and dentin. Ninety–six non-carious human third molars were sectioned mesio-distally at the middle third, polished with 600-grit SiC and divided according to the aging method: water storage, thermocycling and NaOCl storage. A universal adhesive (Scotchbond Universal) was applied in enamel and dentin, on self-etch and etch-and-rinse mode. Starch tubing was used as matrix to perform 1mm² of area of cylindrical composite resin restorations. The specimens were submitted to μSBS test. The μSBS values in MPa were subject to three-way ANOVA and post hot Tukey test (p<0.05). Weibull Analysis was also performed to estimate the probability of failure. Three-way ANOVA revealed that substrate (p=0.00) and aging protocol (p<0.00) had significant effect on bond strength, but the factor adhesive was not significantly different (p=0.27). Weibull distribution presented the highest modulus m in the group of SH5h on etch-and-rinse on dentin while on enamel, the highest m was presented in the control group W24h, also on etch-and-rinse mode. No significant reductions in SBSs of universal adhesives were observed after methods of artificial aging. The bond strength of enamel group, with self-etch protocol, was reduced by thermocycling. In contrast, the groups were insensitive to long-term water storage and increased the values with storage in NaOCl solution.