Evaluation of Color Stability and Surface Roughness of Nanohybrid Resin Composites with Different Photoinitiator Systems After Staining and Home/Office Bleaching: An In Vitro Study

Aim: This in vitro study aimed to evaluate the color stability and surface roughness of different photoinitiator systems-based nanohybrid resin composites after staining and home or office bleaching. Materials and Methods: A total of 80 resin-based composite (RBC) discs with lucirin-TPO (Tetric EvoCeram, Ivoclar Vivadent) or champhoroquinon (CQ) (Grandio, Voco) were preperad (8x2mm). At baseline, post-coffee staining (12 days/37°C), and bleaching, color values (ΔE*Lab) using spectrophotometre and surface roughness (Ra) by profilometer were measured. Hydrogen peroxide gel 35% (Whiteness HP, FGM) for office bleaching and carbamide peroxide gel 16% (Whiteness Perfect, FGM) for home bleaching were used. One sample of each groups was evaluated under scanning electron microscopy. Statistical analyses were performed by one-way ANOVA with Tukey HSD, dependent t-test and non-parametric tests (p<0.05). Results: CQ-based RBC/home group moved closer to return to baseline color (p=0.016). Home bleaching provided more effective bleaching than office bleaching on tested composites (p<0.05). surface roughness of CQ-based RBC/home significantly increased compared to baseline (p=0.038). Ra values of tested composites exceeded the threshold value (0.2 μm) after both home and office bleaching. Conclusion: The home bleaching effectively bleached CQ-based RBC, while simultaneously leading to an increase in surface roughness. It is believed that the lucirin-TPO photoinitiator system due to its enhancing effect on polymerization, may increase the resistance to surface roughness caused by bleaching.