Effect of Different Acid-Etchings on the Shear Bond Strength to the Enamel Using the Fifth-Generation Dentin Bonding Agent

Changes in the enamel structure using a suitable acid for adequate time are the basic method of retention and strength of the composite restorations. This in vitro study aimed to compare the effect of different acid etching on the shear bond strength to the enamel surface using the fifth-generation dentin bonding. In total, 80 human pre-molar teeth were collected and divided into four groups of 20 teeth per group based on the acid etching of Morva-Etch, Kimia, Ultra-Etch, and Etch-Rite. After enamel etching and using Single Bond (3M ESPE-USA), 2 mm cross-sectional mold filled with Z250 composite (3M ESPE-USA)was placed on the treated tooth surface and cured. The samples were then placed in a thermocycler (500 cycles) (30 sec at 55˚C, 20 sec at 25˚C, and 30 sec at 5˚C). Furthermore, the shear bond strength was measured and recorded using the Instron testing machine with a crosshead speed of 0.5 mm/min and a force of 120 N through a knife blade with a final thickness of 0.5 mm. The obtained data were statistically analyzed in SPSS software (version 24) using one-way ANOVA and Tukey’s test. A p-value less than 0.05 was considered statistically significant. The results of one-way ANOVA showed a significant difference among the studied groups regarding shear bond strength (p < 0.05). The Tukey’s test also revealed that the shear bond strength of Morva-Etch acid etching was significantly higher than that of the other groups; however, no significant difference was found among the other acid etchings in this regard. According to the results of this study, the shear bond strength of Iranian Morva-Etch to the enamel was the highest, compared to the other groups. Moreover, Kimia, Ultra-Etch, and Etch-Rite provided sufficient shear bond strength to the enamel.