Shear Bond Strength of Self-etching Adhesives to Cavities Prepared by Diamond Bur or Er, Cr:YSGG Laser and Effect of Prior Acid Etching

Purpose: To compare and evaluate shear bond strength of self-etching adhesives bonded to cavities prepared by diamond bur or Er, Cr:YSGG laser and the effect of prior acid etching on shear bond strength. Materials and Methods: Ninety-six caries-free human premolars were selected and divided into 2 groups depending on mode of cavity preparation (48 teeth each). Cavities were prepared with Er, Cr: YSGG laser in group 1 and diamond burs in an air-turbine handpiece in group 2. Groups 1 and 2 were further subdivided into three subgroups of 8 teeth each, which were bonded with sixth-or seventh-generation adhesives with or without prior acid etching, followed by restoration of all samples with APX Flow. These samples were subjected to shear bond strength testing. In addition, the surface morphology of 24 samples each from groups 1 and 2 was evaluated using SEM. Data were analyzed using the Shapiro-Wilk test, one- and two-way ANOVA, the t-test, and the least significant difference test, which showed that the data were normally distributed (p > 0.05). Results: The shear bond strength of adhesives in cavities prepared by Er, Cr: YSGG laser was significantly higher than in diamond bur-prepared cavities (p < 0.05). SEM analysis showed a smear-layer-free anfractuous surface on laser-ablated teeth, in contrast to conventional bur-prepared teeth. Conclusions: The Er, Cr: YSGG laser-ablated surface proved to be more receptive for adhesion than those prepared by diamond bur irrespective of the bonding agent used. Seventh-generation adhesives yielded higher shear bond strength than did sixth-generation adhesives. Prior acid etching decreased the shear bond strength of self-etching adhesives.