The effect of remineralization pretreatments on the enamel bond strength of demineralized and sound enamel: An in vitro study

Background: During tooth preparation, the clinician may face a hard remineralized enamel surrounding the cavity with unknown effects on the enamel bond strength. This study aims to assess the effect of remineralizing pretreatments with casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) or CPP-amorphous calcium fluoride phosphate (CPP-ACFP) on the bond strength of composite resin and sound or demineralized enamel. Materials and Methods: This study employed an in vitro experimental factorial design. A total of 144 enamel surfaces were prepared and randomly divided into 12 groups (G1-G12). The surfaces of G7-12 were demineralized to create a lesion (L), while G1-6 were assigned to the sound (S) enamel group. The three pretreatment protocols were CPP-ACFP, CPP-ACP, or no pretreatment for a 10-day pH-cycling period. A composite rod was bonded to the surfaces using a self-etch or total-etch bonding system. Shear force was applied, and the bond strengths of the specimens were measured. The data were analyzed using the Kruskal–Wallis test, followed by pairwise comparisons using Dunn’s test. The significance level for all tests was set at 0.05. Results: The sound (S) groups (33.81 ± 8.48) showed a significantly higher bond strength than the lesion (L) groups (25.77 ± 6.69). Among the pretreatments, CPP-ACFP-pretreated groups had the highest bond strength (33.86 ± 8.87). Pairwise comparisons showed significant differences between CPP-ACFP-treated demineralized enamel and control demineralized enamel in both bonding systems ( P = 0.019 and P = 0.025 for Clearfil SE and Optibond FL, respectively). Conclusion: Pretreatment of demineralized enamel with CPP-ACFP before using total-etch and self-etch systems results in a bond strength comparable to that of sound enamel, making it clinically acceptable.