Color Stability and Surface Properties of PMMA/ZrO2 Nanocomposite Denture Base Material after Using Denture Cleanser

Abstract

Statement of Problem. Novel polymethyl methacrylate (PMMA) containing zirconium dioxide nanoparticles (nano-ZrO2) was suggested as a denture base material but there is a lack of information regarding denture cleanser effects. Objectives. This study aimed to evaluate denture cleanser effects on color stability, surface roughness, and hardness of PMMA denture base resin reinforced with nano-ZrO2. Materials and Methods. A total of 420 specimens were fabricated of unreinforced and nano-ZrO2 reinforced acrylic resin at 2.5% and 5%, resulting in 3 main groups. These groups were further subdivided (n = 10) according to immersion solution (distilled water, Corega, sodium hypochlorite, and Renew) and immersion duration. Surface roughness, hardness, and color were measured at baseline (2 days-T0) in distilled water and then after 180 and 365 days of immersion (T1 & T2) in water or denture cleansing solutions. Data was collected and analyzed using two-way ANOVA followed by Bonferroni post hoc test (α = 0.05). Results. Surface roughness increased significantly after denture cleanser immersion of unmodified and nano-ZrO2-modified PMMA materials while hardness decreased ( $P<0.001$ ). The denture cleansers significantly affected the color of both PMMA denture bases ( $P<0.001$ ). The immersion time in denture cleansers significantly affected all tested properties ( $P<0.001$ ). Within denture cleansers, NaOCl showed the highest adverse effects ( $P<0.05$ ) while Renew showed the least adverse effects. Conclusion. Denture cleansers can significantly result in color change and alter the surface roughness and hardness of denture base resin even with ZrO2 nanoparticles addition. Therefore, they should be carefully used.