Purpose: To evaluate the effect of three enamel conditioners and four restorative materials on enamel shear bond strengths.
Materials and methods: 120 bovine incisors were polished to 600-grit and randomly assigned to three enamel adhesive systems (n=40): Syntac Single Component with phosphoric acid etching (PA-SSC), Syntac Single Component without phosphoric acid etching (SSC), and Experimental Prompt L-Pop (LPI), a self-etching adhesive. The specimens were restored with one of four resin restorative materials (n=10): (1) Compoglass F, a high-viscosity compomer; (2) Compoglass Flow, a low-viscosity compomer; (3) Tetric Ceram, a high-viscosity resin-based composite (RBC); and (4) Tetric Flow, a low-viscosity RBC. After thermocycling, shear tests were carried out with an Instron Universal Testing Machine. Mean enamel bond strengths were analyzed with ANOVA and Duncan post hoc test at P < or = 0.05.
Results: PA-SSC resulted in higher mean bond strengths than LP1, but the difference was not statistically significant. Both PA-SSC and LP1 resulted in statistically higher mean bond strengths than SSC at P < or = 0.0001. The lowest mean bond strengths of all the groups were obtained when SSC was used with an RBC (Tetric Ceram or Tetric Flow). SSC and PA-SSC resulted in statistically higher mean bond strengths when used with a compomer than when used with an RBC, regardless of the viscosity. Although recommended to be used only with compomers, LP1 resulted in statistically similar enamel bond strengths when used with the composite of corresponding viscosity (Tetric Ceram vs. Compoglass F; Tetric Flow vs. Compoglass Flow). LP1, however, resulted in higher enamel bond strengths when combined with Tetric Ceram than when combined with Tetric Flow. When the results were pooled for "viscosity", high-viscosity restorative materials resulted in higher bond strengths than low-viscosity materials at P < or = 0.041. When the data were pooled for "restorative material", compomers resulted in higher bond strengths than composites at P < or = 0.0001.