Comparative Effectiveness of Microwave, Chemical, and Herbal Disinfectants on Surface Microhardness of Heat Cured Acrylic Resin- An in vitro Study

Background and Aims: Disinfection of acrylic dentures is essential to prevent pathogen transmission; however, its effect on the surface microhardness of denture base resins remains unclear. This study aimed to evaluate and compare the effects of chemical, microwave, and herbal disinfection methods on the microhardness of heat-cured acrylic denture base resin. Methods: In this in vitro study, 200 rectangular specimens were fabricated and divided into four groups (n=50): control (Group X), chemical (Group C), microwave (Group M), and herbal (Group H). Each experimental group was further split into two subgroups based on disinfection duration—one cycle (7 days) and three (21 days) cycles. Surface microhardness was measured using Vickers hardness testing (50 g force for 10 seconds). Data were analyzed using Kruskal-Wallis, Dunn post hoc, and Wilcoxon signed-rank tests (p<0.05). Results: After 7 days, the microwave group showed the highest microhardness, followed by the chemical, control, and herbal groups. At 21 days, chemical disinfection resulted in the highest microhardness, followed by microwave, control, and herbal groups. Statistically significant differences were observed between groups for both time points. Conclusion: Microwave and chemical disinfection had the most favorable effects on the surface microhardness of heat-cured acrylic resins at 7 and 21 days, respectively, while herbal disinfection consistently showed the lowest values. Key words: Denture cleansers, denture cleansing methods, denture-based resins, microhardness