Bond strength of resin composite to caries-affected dentin after remineralization by different remineralizing agents: An in vitro study.

Background: Following selective caries removal, the efficacy of bonding to the dentin substrate is questionable due to alterations in mineral content and the quality of remaining dentin, especially in deep proximal cavities.

Objectives: The aim of the study was to evaluate the microtensile bond strength of resin composite to artificially demineralized dentin and sound dentin compared to demineralized dentin that underwent different remineralization protocols. Additionally, the study sought to evaluate the effect of the 2 bonding modes (total-etch/self-etch) on the applied remineralizing agent, and to analyze the failure mode.

Material and methods: The study utilized 30 sound proximal molar surfaces. They were randomly divided into 5 groups based on the remineralization protocols, as follows: sound dentin as positive control (G1); artificially demineralized dentin but without surface treatment as negative control (G2); and artificially demineralized dentin surface groups with surface treatments (sodium fluoride (NaF) solution (G3), nano-hydroxyapatite (nHAp) (G4), and a combination of remineralizing agents (G5)). Different modes of application of the bonding agent (total-etch (B1) and self-etch (B2)) were implemented. Then, a nanohybrid composite was applied and light cured. The microtensile bond strength test was performed, and the failure mode was evaluated.

Results: The application of the total-etch mode resulted in a statistically significant difference between microtensile bond strength values of remineralization protocols. The NaF and nHAp groups (G3 and G4) exhibited the highest values. A statistically significant difference was observed between the microtensile bond strength values of remineralization protocols in the self-etch mode. The positive control, NaF, nHAp, and combined groups (G1, G3, G4, and G5) showed the highest values. The negative control group (G2) in both bonding modes demonstrated the lowest microtensile bond strength.

Conclusions: All remineralization protocols applied to demineralized dentin demonstrated an improvement in bond strength that was equivalent to sound dentin. All remineralized dentin surfaces exhibited a favorable failure mode in comparison to the negative control group.