Effect of Selective Etch on the Bond Strength of Composite to Enamel Using a Silorane Adhesive

An improvement in bond strength to enamel has been demonstrated with the use of phosphoric acid prior to bonding with self-etch methacrylate-based adhesive agents. No research has evaluated the effect of phosphoric-acid etching of enamel with a newer self-etch silorane adhesive. The purpose of this study was to evaluate the shear-bond strength of composite to enamel using the self-etch silorane adhesive compared to other self-etching methacrylate-based adhesives, with or without a separate application of phosphoric acid. Bovine incisors were sectioned using a diamond saw and mounted in plastic pipe. The bonding agents were applied to flattened enamel surfaces with or without the application of 35% phosphoric acid. The bonded tooth specimens were inserted beneath a mold, and composite was placed incrementally and light cured. The specimens were stored for 24 hours and six months in water and tested in shear. Data were analyzed with a three-way analysis of variance (ANOVA) to evaluate the effects of surface treatment, adhesive agent, or time on the bond strength of composite to bovine enamel (α=0.05). Significant differences were found between the groups based on surface treatment (p<0.01) or adhesive agent (p<0.01), but not on time (p=0.19), with no significant interactions (p>0.14). Phosphoric-acid etching of bovine enamel significantly increased the bond strength of the self-etch methacrylate and the silorane adhesives. The methacrylate-based adhesives had significantly greater bond strength to enamel than the silorane adhesive.