Objective: The aim of this study was to evaluate color longevity after different bleaching techniques. Background: Laser-activated bleaching methods are gaining popularity due to decreased chair time and increased patient compliance. However, the longevity of such methods has not been stated clearly. Methods: Sixty patients were divided into the following three groups (n = 20); group 1: chemical bleaching with 35% hydrogen peroxide (HP) gel, group 2: bleaching with 35% HP gel with diode laser activation, and group 3: bleaching with 35% HP gel with Er,Cr:YSGG laser activation. Color changes (ΔE*) were calculated by using two different formulas: (i) CIELAB (ΔE_ab) and (ii) CIEDE2000 (ΔE₀₀) with a spectrophotometer before treatment, 24 h after treatment 3, 6, and 12 months after treatment. Evaluation of postoperative sensitivity was performed before and immediately after treatment, followed by re-evaluation 24 h and 1 week after treatment. Results: For ΔE_ab calculation, no significant difference was observed during both intra- and inter-group evaluations (p > 0.05). For ΔE₀₀ calculation, no significant intergroup difference was observed (p > 0.05), whereas significant intragroup differences between the values of after treatment, 6–12 months. In the chemical bleaching group, increased postoperative sensitivity was observed after 24 h (p < 0.001). In the diode-laser-activated group, postoperative hypersensitivity was detected at 24 h and 1 week. No significant hypersensitivity was observed in the Er,Cr:YSGG-laser-activated group (p > 0.05). Conclusions: All three techniques provided efficient bleaching. Chemical and diode-activated bleaching methods resulted in slight sensitivity after application, whereas Er,Cr:YSGG-laser-activated bleaching did not cause sensitivity.

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.