Novel coating materials for glassionomer cement: formulation characteristics, surface adhesion and impact on microhardness

The study aimed to assess the characteristics of new formulations as substitutes for petroleum jelly in coating glass ionomer cement (GIC) and the effect on its microhardness. Methodology: Three formulations were produced with different food coloring and essences: Formulation-1(F1) was olive-oil-based, Formulation-2(F2) was coconut-oil-based, and Formulation-3(F3) comprised starch and a lower dose of petroleum jelly as main ingredients. The formulations underwent characterization tests on mechanical, and rheological properties. Surface adherence was tested using methylene-blue added formulations and petroleum jelly on GIC samples subjected to mechanical stimulations. Microscopic imaging at 10x magnification was performed at five-time intervals in 60 min, and the remaining formulation percentages were analyzed using Fiji-Image-J software. The Vickers microhardness was measured on 25 disc-shaped GIC (Fuji IX-GP) specimens coated with formulations, vaseline, and no-coating after 24 h, 7 and 30 days at 37 °C, 100% humidity. In addition, the biocompatibility was evaluated on fibroblast cells using the MTS assay after 24 h exposure to the conditioned media obtained from formulation. Data were analyzed using ANOVA and Tukey’s test. Results: All formulations exhibited pseudoplastic flow and appropriate viscosity suitable for oral application. Surface adhesion of the tested materials showed a statistically insignificant difference, with significant reduction of the materials over time. A statistically significant difference was found in microhardness between olive-oil-based-F1 and other groups, with coconut-oil-based-F2 and uncoated group after 24 h with no difference among formulations and vaseline after 7 and 30 days. Biocompatibility testing showed that all formulations (F1–F3) maintained over 95% fibroblast viability at dilutions of 1:10, 1:100 and 1:1000, supporting their safety for intraoral application. Conclusions: Olive-oil-based-F1 formulation presents a promising superior alternative to petroleum jelly for coating glass ionomer cement. Clinical Relevance: Clinically, the novel surface coating formulations offer a safer, petroleum-free, and patient-friendly alternative to routine products, with the olive oil-based formulation being a promising substitute for vaseline.