Purpose: The effect of three different bonding strategies on the shear bond strength of a resin composite to fluorotic enamel surfaces was investigated. Materials and Methods: Thirty-six noncarious extracted human molars with fluorosis and 36 without fluorosis were scraped clean from any remaining tissue, and then were divided into three subgroups according to the tested dentin bonding systems. The resin composite was bonded to the teeth using three different adhesive systems: Peak LC Bond with an etch-and-rinse technique (Ultradent Products), Peak LC Bond with a self-etching technique using Peak SE Primer (Ultradent Products), and Xeno V (Dentsply Caulk) using a one-bottle self-etching technique. Following the photopolymerization of the resin composites, thermocycling was performed 5000 times. Shear bond strengths were tested using the Shimadzu Universal Testing Machine until failure. The analysis of the fractured enamel surfaces was performed using an optical microscope (Nikon ECLIPSE ME 600) at 10X and 1000X magnification, and the images were analyzed with an image analyzer (LUCIA 4.21). The data obtained were analyzed with two-way ANOVA and the Bonferroni test at a significance level of p < 0.05. Results: Mean shear bond strengths in MPa of the groups were: Peak LC Bond, self-etching, on fluorotic enamel 13.23 ± 2.58 and on nonfluorotic enamel 17.81 ± 2.90; Peak LC Bond, etch-and-rinse, on fluorotic enamel 16.77 ± 2.32 and on nonfluorotic enamel 21.13 ± 2.74; one-bottle self-etching Xeno V on fluorotic enamel 10.79 ± 2.14 and on nonfluorotic enamel 14.58 ± 2.99. Conclusion: Fluorosis adversely affected the bonding performance of all the bonding systems to enamel. The use of the etch-and-rinse dentin bonding technique produced higher bond strengths of the resin composite tested to fluorotic and nonfluorotic enamel compared to both self-etching techniques.
Keywords: fluorosis, resin composites, shear bond strength, enamel bonding