In Vitro Evaluation of Resilient Liner after Brushing with Conventional and Experimental Ricinus communis-Based Dentifrices

Purpose To evaluate the effect of experimental (Ricinus communis) and commercial dentifrices used for denture cleaning on abrasiveness (gravimetric method; roughness), hardness, and color stability of a resilient relining material. Materials and Methods Sixty circular (15 x 3 mm) specimens were distributed into four groups: C (control; brushing with water); CO (brushing with Colgate - for natural teeth); CB (brushing with Corega Brite - for complete dentures); RC (brushing with experimental dentifrice). Brushing was performed in a toothbrushing machine with a soft brush and a dentifrice suspension for 50 minutes, calculated to correspond to 1 year of regular brushing. Variables were measured initially and after the trial period. For the gravimetric method, the difference in mass was considered. The surface roughness was measured by a rugosimeter, and the hardness test was performed by a Shore A durometer. Color changes (Delta E; CIE L*a*b* and NBS systems) were measured by a portable spectrophotometer. Results were analyzed by ANOVA/Tukey's test (alpha = 0.05). Results The largest mass variation (mu g; p < 0.0001) occurred in C (-6.21 +/- 3.18). Concerning roughness, CB (0.26 +/- 0.04) showed the lowest value, followed by RC (0.29 +/- 0.08) and CO (0.34 +/- 0.24) (p < 0.0001). Group C produced the greatest surface roughness (0.72 +/- 0.25). Hardness values decreased after brushing with water (p = 0.014). No significant differences were found among RC (50.31 +/- 1.03), CO (49.11 +/- 1.31), CB (49.17 +/- 1.23), and C (48.02 +/- 1.26). Color stability was similar in all groups (p = 0.135; C: 2.3 +/- 0.77; CO: 2.6 +/- 0.54; CB: 2.2 +/- 0.44; RC: 2.9 +/- 1.56). Conclusions The use of experimental dentifrice could be indicated, as it showed similar results to the specific dentifrice, keeping the resilient material properties within acceptable values.