Bond Strength of Composite Resin to Enamel: Assessment of Two Ethanol Wet-Bonding Techniques

Objective: Ethanol wet-bonding (EWB) technique has been stated to decrease degra- dation of resin-dentin bond. This study evaluated the effect of two EWB techniques on composite resin-to-enamel bond strength. Materials and Methods: Silicon carbide papers were used to produce flat enamel surfaces on the buccal faces of forty-five molars. OptiBond FL (OFL) adhesive was applied on enamel surfaces in three groups of 15 namely: 1. Enamel surface and OFL (control); 2.Protocol 1 of the EWB technique: absolute ethanol was applied to water-saturated acid-etched enamel surfaces for 1 minute before the application of ethanol-solvated hydrophobic adhesive resin of OFL 3 times; 3.Protocol 2: progressive ethanol replacement; water was gradually removed from the enamel matrix using ascending ethanol concentrations before OFL application. Composite build-ups were made and the specimens were stored for 24 hours at 37°C and 100% relative humidity. Shear bond strength test was performed using a universal testing machine at 1 mm/min crosshead speed. Fracture patterns were evaluated mi- croscopically. Data were analyzed with one-way ANOVA and Fisher’s exact test (α=0.05). Results: There were no significant differences in bond strength between the groups (P=0.73). However, regarding failure patterns, the highest cohesive enamel fractures were recorded in groups 2 and 3. Conclusion: In this study, although both methods of EWB did not influence immediate bond strength of composite resin to enamel, the majority of failure patterns occurred cohesively in enamel.