Effect of Doubling Application Time of All-in-one Adhesive Resins on Shear Bond Strength of Composite Resin to Enamel

Abstract

Background and Objectives: Despite acceptable bond strength of self-etch adhesive resins to dentin, some concerns remain regarding their bonding effectiveness to enamel. The purpose of this study was to evaluate the effect of doubling application time of all-in-one adhesive resins on shear bond strength of composite resin to bovine enamel. Materials & Methods: Subsequent to removing the roots and mounting 176 intact bovine incisors in acrylic resin, the facial enamel surface was abraded with silicon carbide papers. The samples were randomly divided into 8 groups of 22. In groups 1-4, four types of all-in-one adhesive resins, including Clearfil S3 Bond, G Bond, Absolute 2 and Opti Bond All-In-One were respectively used according to the suggested time by the manufacturer. In groups 5-8, the same adhesive resins were used for twice as much time recommended by the manufacturer. Then the composite of each adhesive was placed in the plastic mold and cured. Subsequent to thermocycling, the shear bond strength test was carried out and the data were analyzed. Results: The highest bond strength value was related to Opti Bond All-In-One and the lowest value was related to Absolute 2. The adhesive resin type and time showed a statistically significant influence on bond strength (P<0.0005). Moreover, there were statistically significant differences among different adhesive resins (P<0.0005). Furthermore, the interaction between the adhesive resin type and time was statistically significant (P<0.0005). Doubling the application time resulted in a significant increase in bond strength only in two adhesive resins, Clearfil S3 Bond and G Bond (P<0.0005). Conclusion: The adhesive resin type was effective in bond strength to enamel and doubling the application time of Clearfil S3 Bond and G Bond adhesive resins resulted in a considerable increase in bond strength to enamel.