Effect of Zinc Oxide Nanoparticles on Optical Characteristics and Surface Roughness of Polymethyl Methacrylate

This research aims to assess the impact of different concentrations of ZnO nanoparticle powder on the surface roughness, opacity, and color parameters of polymethyl methacrylate denture resins.Ninety Six specimens were made of heat-cured and cold-cured PMMA with different ZnO NP concentrations (0%, 2.5%, 5% and 7.5%), then distributed into 8 groups (n=6) by ZnO NP concentrations. The surface roughness of 48 specimens (4 groups) were measured using a surface roughness tester. The color (L*a*b*) and opacity of 48 specimens (4 groups) were assessed using chromameter. Color differences between specimens (CIE ΔEab Lab*) were calculated. Statistical analysis were prosessed with two-way ANOVA followed by Games-Howell and LSD post hoc tests. Type of PMMA and ZnO NP concentration significantly affected surface roughness and opacity (p=0.001). Type of PMMA and ZnO NP concentration also had significant effects on all color parameters, that are L*, a*, b*, and CIE ΔEab (Lab*) (p=0.001). Incorporating ZnO NPs (2.5% to 7.5%) into heat-cured and cold-cured PMMA effectively reduces surface roughness while increasing opacity and inducing color changes. The surface roughness and color stability of heat-cured PMMA were superior to those of coldcured PMMA.