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.