Comparative Evaluation of the Shear Bond Strength of Composite to Remineralized Dentin: An In Vitro Study

Background Caries-affected dentin is a partially demineralized substrate that retains its collagen matrix and has the potential to be remineralized. Recent biomimetic materials have shown potential in enhancing remineralization and improving composite bonding. The study aimed to compare the shear bond strength of composite resin to demineralized dentin after remineralization with three agents: silver diamine fluoride (SDF), nanohydroxyapatite (nHAp), and self-assembling peptide P11-4 (SAP P11-4). Materials and methods An in vitro, non-randomized, experimental study was conducted using sixty premolars with a single root, collected post-extraction, and equally divided into four groups: control, SDF, nHAp, and SAP. Remineralizing agents were applied to exposed dentin surfaces, followed by the placement of composite resin. After surface treatment with remineralizing agents, the resin-based composite was applied, and a universal testing machine was utilized to determine the shear bond strength. The modes of failure were examined using a stereomicroscope. One-way ANOVA and Tukey's post hoc test were used (p < 0.001). Results The SAP P11-4 group showed the highest mean bond strength (28.13 N), followed by the SDF groups and nHAP groups, while the control group demonstrated the lowest values. All remineralized groups exhibited significantly higher bond strength compared to the control (p < 0.001). Intergroup comparisons revealed statistically significant differences among all test groups, with SAP P11-4 significantly outperforming SDF and nHAP. Failure mode analysis revealed that SAP P11-4 predominantly resulted in cohesive failure, whereas SDF and nHAP primarily exhibited adhesive failure. Conclusions Among the three remineralizing agents tested, SAP P11-4 demonstrated the highest shear bond strength to demineralized dentin. Its superior performance highlights its potential to enhance the longevity and durability of resin-based restorations in minimally invasive dentistry. The predominance of cohesive failure further supports its effectiveness in creating a strong, integrated bond between the composite resin and dentin substrate.