Effect of Mesoporous Zinc Oxide Nanoparticle Incorporation on the Bond Strength of Resin-Modified Glass Ionomer Cement to Enamel and Dentin: An In Vitro Study.

Objective: The purpose of this in vitro study was to evaluate the microshear bond strength (µSBS) of resin-modified glass ionomer cement (RMGIC) to enamel and dentin, with and without the inclusion of zinc oxide nanoparticles (ZnO NPs) and mesoporous ZnO NPs. Materials and Methods: 140 extracted human third molars were used, categorized into two primary groups based on the substrate-enamel or dentin-and further divided into seven subgroups (n = 10). The groups consisted of RMGIC alone, and RMGIC enhanced with either 3%, 5%, or 7% of conventional ZnO NPs or mesoporous ZnO NPs. µSBS testing was performed, followed by statistical evaluation. Results: The type of substrate and the incorporation of NPs significantly affected bond strength (p < 0.001), with enamel showing superior µSBS compared to dentin (p < 0.001). The subgroup containing 5% mesoporous ZnO NPs demonstrated the highest bond strength overall (p < 0.001), while no significant variations were detected among the other groups (p > 0.05). Conclusion: Enhancing RMGIC with 5 wt.% mesoporous ZnO NPs markedly improved adhesion to both enamel and dentin. Increasing the (nanoparticle) NP concentration beyond 5% did not further enhance bonding performance. Enamel exhibited consistently better bonding than dentin in all subgroups. These results highlight the potential of 5% mesoporous ZnO NPs in improving the clinical efficacy of RMGIC.