Effect of Different Bleaching Systems on Surface Roughness of Two Nano-hybrid Composite Resins

Objective: This research aimed to assess the impact of 40% hydrogen peroxide bleaching in the workplace and 16% carbamide peroxide bleaching at home on the composite's surface roughness based on Omnichroma and Evetric resin. Materials and Methods: 24-disc composite samples, each measuring 5 mm in diameter and 2 mm in height, were created for this in vitro experimental investigation using every kind of nano-hybrid resin composite material. All composite group's samples were randomly split into 3 subgroups (n=8). Samples in the control subgroup were kept for a week at 37°C in artificial saliva. 40% hydrogen peroxide was used to bleach in-office bleaching samples. Samples of home bleaching were be bleached by 16% carbamide peroxide. Measurements of surface roughness were made for every sample in every subgroup. Samples of control sub-group were be considered as base line data. Both parametric and non-parametric statistical analyses were performed at P≤0.05 using the SPSS software (version 25 for Windows). Results: For both studied materials, all subgroups' surface roughness levels dropped below the threshold point (Ra<0.2 μm). The Kruskal–Wallis test revealed a significant difference among the Omnichroma subgroups (p = 0.002). Additionally, the one-way ANOVA confirmed a significant difference among the Evetric subgroups (p=0.035). Conclusions: All tested subgroups of both Omnichroma and Evetric composites showed surface roughness degree below the clinically acceptable threshold (Ra < 0.2 µm). Bleaching with 40% H2O2 and 16% carbamide peroxide gels did not produce a clinically significant increase in surface roughness for either material.