Effect of prolonged brushing with different agents on surface characteristics of conventional and 3D-printed denture resins

Given the increasing use of three-dimensional (3D) technology, evaluating the effects of prolonged brushing on denture base resins is necessary. This study evaluated the influence of long-term brushing with cleaning/disinfection agents on the surface properties of heat-cured and 3D-printed denture base resins. Resin discs were produced and randomly divided into groups: T0: no brushing; T1: simulated 1-year brushing; T2: simulated 2-year brushing. A soft-bristled toothbrush was used with one of the solutions: dentifrice (Colgate TOTAL®), disinfectant soap (Lifebuoy®), or distilled water (negative control group). Color stability, roughness and hardness (n = 9 each) tests were performed. Surface topography was analyzed by Scanning Electron Microscopy (n = 2). Data were analyzed using the Mann-Whitney U test (α = 5%). For comparison between the resins, the mean values and standard deviations of the variables for the types of resin and brushing times were obtained, controlling the solutions, using two-way ANOVA with Tukey's Post Hoc Test. For both resins, a statistically significant change in color stability was observed in the groups brushed with dentifrice after 2 years. There was an increased roughness in the samples brushed with the same solution. Concerning hardness, a decrease was observed regardless of the solution and the resin, after 2 years of brushing. Differences between resins were found in relation to color change and hardness. Both resins, heat-cured and 3D-printed, presented changes in color stability, increased roughness and decreased hardness after 2 years of brushing with dentifrice. Brushing with disinfectant soap caused the smallest changes in surface properties, which can be an option for brushing dentures.