Effectiveness and SEM-EDX analysis following bleaching with an experimental bleaching gel containing titanium dioxide and/or chitosan.

The aim of this study was to evaluate the bleaching effectiveness and mineral alterations following the use of experimental bleaching gels that included 6% hydrogen peroxide (HP), titanium dioxide (TiO2) and/or chitosan in comparison with the routinely used 35% HP bleaching gel. Thirty-six maxillary anterior teeth were divided into three groups according to bleaching agent as follows: Group 1: 6% HP + TiO2, Group 2: 6% HP + TiO2 + chitosan, Group 3: 35% HP. Tooth colour was measured with a spectrophotometer before bleaching and after sessions one and two on days 14 and 30, respectively. Colour changes were assessed with the CIEDE2000 and CIELab formulas. Mineral analysis was performed with a scanning electron microscopy-energy dispersive X-ray (SEM-EDX) device before and 14 days after application. The enamel surfaces of randomly selected samples from each group were analysed by SEM. Two-way ANOVA was used to compare differences between groups. All tested materials resulted in significantly increased bleaching compared to the initial colour values (p < 0.05). Group 3 showed significantly more whitening compared to the other groups after the first and second sessions (p < 0.05). However, Group 2 presented prolonged whitening efficiency and reached a bleaching level similar to the 35% HP treatment after 14 and 30 days. The results of the CIEDE2000 and CIELab formulas were found to be correlated (r > 0.6). The increases in Ca were similar in Groups 2 and 3 (p > 0.05) and were significantly higher than that in Group 1 (p < 0.05). p was similarly decreased among all groups (p > 0.05). The combination of 6% HP, chitosan and TiO2 appears to constitute a promising material for tooth whitening, showing good bleaching efficiency and acceptable mineral alterations.

Evaluation of the cytotoxic and genotoxic effects of different universal adhesive systems.

OBJECTIVES: The objective of this study was to evaluate and compare the cytotoxicity and genotoxicity of different universal adhesive systems in the mouse fibroblast cell line L929. MATERIALS AND METHODS: L929 (mouse fibroblast) cells were exposed to G-Premio Bond (GPB) (GC Europe, Belgium), Prime&Bond Universal (Dentsply Sirona, USA), Universal Bond Quick (Kuraray, USA), Single Bond (SB) Universal (3M ESPE, USA), and Tokuyama Universal Bond (TB) (Tokuyama, USA). Cell viability was assessed by the 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide test, whereas oxidative DNA damage was assessed by determining the 8-hydroxydeoxyguanosine level using an enzyme-linked immunoassay kit. Statistical analysis was performed by one-way analysis of variance, followed by Bonferroni post hoc tests. RESULTS: Cytotoxic and genotoxic effects of TB and SB Universal groups were significantly higher than the other groups (P < 0.05). Among the adhesives tested, GPB (93.0 ± 1.3) had the least cytotoxicity, while TB (67.3 ± 3.0) had the most cytotoxic effect. In terms of genotoxicity, GPB (2.2 ± 0.3) had the least genotoxic effect, while Tokuyama Bond Universal (4.17 ± 0.4) had the most genotoxic effect. CONCLUSIONS: Universal adhesive systems used in dentistry have cytotoxic and genotoxic effects in live cells. Universal adhesive systems should, therefore, be used with caution due to their cytotoxic and genotoxic effects in clinical applications.