Effect of different surface treatments on the shear bond strength of one-step and two-step universal adhesives to enamel and dentin

Abstract

This study evaluated the effect of surface treatments on the shear bond strength of one- and two-step universal adhesives applied to enamel and dentin. Eighty extracted human molars were allocated to five experimental conditions: etch-and-rinse phosphoric acid application, Er:YAG pretreatment, aluminum oxide air abrasion, sodium bicarbonate air abrasion, and self-etch application without additional pretreatment. Each condition was divided into two adhesive subgroups, G2 Bond Universal and Prime&Bond Universal, with eight specimens in each adhesive system × experimental condition × dental substrate subgroup ( n = 8). After adhesive application and composite build-up, specimens were stored in distilled water at 37 °C for 24 h and aged by 5,000 thermocycles between 5 °C and 55 °C before SBS testing. Failure modes were evaluated using stereomicroscopy, and representative specimens were examined qualitatively by scanning electron microscopy. Data were analyzed using three-way ANOVA and Tukey’s post hoc test (α = 0.05). “The three-way ANOVA showed that adhesive system, surface treatment method, and dental substrate significantly affected SBS values ( p < 0.001), with significant two-way and three-way interactions among these factors ( p ≤ 0.003). G2BU showed significantly higher shear bond strength in enamel with ER, Er:YAG laser, and aluminum oxide air abrasion than SE. In dentin, no significant differences were found among treatments. PBU showed significantly higher bond strength with ER than with the other treatments in enamel, whereas in dentin ER showed significantly higher values than SE. Adhesive failure predominated in PBU groups, whereas mixed failures were more frequent in enamel specimens bonded with G2BU. Surface treatment method and adhesive strategy significantly influenced the shear bond strength of universal adhesives. Surface treatment selection when using universal adhesives should be tailored according to both the adhesive system and the dental substrate to achieve more predictable bonding outcomes.