Effect of simulated brushing and disinfection on the surface roughness and color stability of CAD-CAM denture base materials

Purpose: To evaluate the effect of simulated brushing and chemical disinfection on the surface roughness and color stability of CAD-CAM denture base materials and to compare with those of a heat-cured denture base material.Material and methods: Disk-shaped specimens (O 10mm x 2 mm) were prepared from 3 CAD-CAM denture base resins (AvaDent, Ava; Merz M-PM, Merz; Polident d.o.o, Poli) and a heat-cured polymethylmethacrylate resin (Promolux, Conv) (n = 30). After polishing, baseline surface roughness (Ra) and color coordinates were measured. The measurements were repeated after 20000 cycles of simulated brushing, and the specimens were divided into 3 groups according to disinfection protocol (distilled water, 1% sodium hypochlorite (NaOCl), and effervescent tablet) (n = 10). After 9 cleaning cycles over a period of 20 days, Ra and color coordinates were remeasured. Color differences (Delta E00) were calculated by using CIEDE2000 formula. One-way analysis of vari-ance (ANOVA) and pairwise t-tests were used to analyze Ra and Delta E00 data, while repeated measures ANOVA test was used to compare baseline, after brush, and after disinfection Ra values (alpha = 0.05).Results: Brushing did not affect the Ra values of tested materials (P >= .08). Both before and after brushing, Merz and Conv had higher Ra values than Poli and Ava (P < .001). Among disinfectants, effervescent tablet led to the lowest Ra for Merz (P = .003) and the highest Ra for Poli (P < .039). Only NaOCl resulted in significant dif-ferences among the Ra of materials (P < .001), as Merz and Conv had higher Ra values than Poli (P < .002). Repeated measures ANOVA revealed that effervescent tablet disinfection of Merz led to lower Ra values than those of baseline and after brushing (P < .042). After brushing, Ava and Conv had higher Delta E00 values compared with Merz and Poli (P < .015). When compared with other disinfection protocols, effervescent tablet led to higher Delta E00 values for Merz and Poli (P < .001). Significant differences were observed among materials when NaOCl was used; Conv had higher Delta E00 values than Ava and Merz (P = .004).Conclusions: Brushing did not increase the surface roughness of materials. Disinfection protocol's effect on the surface roughness varied. The effect of brushing on the color of materials varied; color of Ava and Conv was affected from brushing more than the other materials. Color stability of materials varied depending on the disinfection protocol. Effervescent tablet caused higher color change with Merz and Poli compared with other disinfectants. NaOCl led to small color change for Poli, Ava, and Merz materials.