Influence of different Er,Cr:YSGG laser parameters on long-term dentin bond strength of self-etch adhesive.

The aim of the present study was to evaluate the effects of erbium, chromium: yattrium-scandium-gallium-garnet (Er,Cr:YSGG) laser frequency on microtensile bond strength (μTBS) of a self-etch adhesive to dentin after 15-month water storage. The Er,Cr:YSGG laser can safely be used on dental hard tissue. However, no study has compared the effects of Er,Cr:YSGG laser parameters and aging by water storage on the bonding effectiveness of self-etch adhesives to dentin. Thirty-five bovine teeth were randomly assigned to the following seven groups (n = 5): group I (diamond bur with high-speed handpiece (control)), group II (Er,Cr:YSGG laser 3 W/50 Hz), group III (Er,Cr:YSGG laser 3 W/35 Hz), group IV (Er,Cr:YSGG laser 3 W/20 Hz), group V (Er,Cr:YSGG laser 6 W/50 Hz), group VI (Er,Cr:YSGG laser 6 W/35 Hz), and group VII (Er,Cr:YSGG laser 6 W/20 Hz). Clearfil SE Bond was applied to the prepared dentin, and the composites were placed and cured. Resin-dentin sticks with an approximate cross-sectional area of 0.8 mm(2) were obtained, and bond strength tests were performed at 24 h and 15 months of water storage after bonding. Data were analyzed with Kruskal-Wallis and Mann-Whitney U tests (p < 0.05). Laser irradiation resulted in significantly lower bond strengths when compared to bur treating. Fifteen-month water storage reduced bond strength for all groups. There was no significant difference among the effects of different laser frequencies on bond strength. It can be concluded that Er,Cr:YSGG laser used at the tested parameters may alter the dentin bond durability of self-etch adhesive.