Physical Alterations of Enamel and Composites Brushed With Whitening Dentifrices

Objectives: To evaluate the color and surface roughness stability of enamel and composites brushed with whitening dentifrices.
Methods: Thirty specimens (6mm diameter X 2mm thick) were made of each composite (Z250, Z350 – 3M ESPE – and Tetric N-Ceram, Ivoclar-Vivadent). One specimen of each composite was fixed on the molars buccal surfaces of 30 participants, selected according to inclusion criteria (Ethical Comitee approval Protocol: 05501312.20000.5419). The subjects received soft toothbrush and dentifrice Sorriso Dentes Brancos (SDB, no whitening, control), and were instructed to use these products for 7 days. After this, initial color (Easyshade, VITA) and surface roughness (Surfcorder SE 1700, Kosakalab) readouts were taken from the specimens and also from the participant´s upper central incisor enamel. For roughness readings, replicas of polyurethane resin obtained after molding (Express, 3M ESPE) both, tooth and specimens were used. Participants were separated in 3 groups (n=10), according to dentifrice used: Group 1) SDB; Group 2) Colgate Luminous White (CLW, Colgate-Palmolive) and Group 3) Close up White Now (CWN, Unilever). New color and surface roughness readings were taken after 7, 30 and 90 days of brushing.
Results: After analysis (2-way ANOVA, repeated measures, Tukey, p<.05), it was observed that there is no effect of SDB on color of any studied substrate, in any time (p>.05). Tetric N- Ceram showed that the longer the time of brushing, the greater the color and surface roughness changes (p<.05) after brushing with CLW. The same occurred with Z350, when brushed with CWN (p<.05). Regarding Z250, there was no color alteration (p>.05) independent of time and dentifrice used, however, there was a decrease in surface roughness when CLW was used.
Conclusions: Brushing time with whitening dentifrices may cause color and surface roughness alterations of composites and there is no effect of this variables on enamel.