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 (Ø 10mm × 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 (R) 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, R and color coordinates were remeasured. Color differences (ΔE) were calculated by using CIEDE2000 formula. One-way analysis of variance (ANOVA) and pairwise t-tests were used to analyze R and ΔE data, while repeated measures ANOVA test was used to compare baseline, after brush, and after disinfection R values (α = 0.05).

RESULTS

Brushing did not affect the R values of tested materials (P ≥ .08). Both before and after brushing, Merz and Conv had higher R values than Poli and Ava (P < .001). Among disinfectants, effervescent tablet led to the lowest R for Merz (P = .003) and the highest R for Poli (P ≤ .039). Only NaOCl resulted in significant differences among the R of materials (P < .001), as Merz and Conv had higher R values than Poli (P ≤ .002). Repeated measures ANOVA revealed that effervescent tablet disinfection of Merz led to lower R values than those of baseline and after brushing (P ≤ .042). After brushing, Ava and Conv had higher ΔE values compared with Merz and Poli (P ≤ .015). When compared with other disinfection protocols, effervescent tablet led to higher ΔE values for Merz and Poli (P < .001). Significant differences were observed among materials when NaOCl was used; Conv had higher ΔE 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.