Effects of a Newly Developed Experimental Bleaching Agent on Tooth Color and Shear Bond Strength of Composite Resins

Purpose: To evaluate the bleaching efficacy and shear bond strength (SBS) of composite restorations performed immediately after bleaching with a newly developed experimental bleaching agent, including 6% hydrogen peroxide (HP), titanium dioxide (TiO2), and/or chitosan (CS). Materials and Methods: We randomly divided 132 maxillary anterior teeth into 2 study groups, 60 teeth for color analysis and 72 teeth for the SBS test. For color analysis, teeth were divided into 5 subgroups. For SBS analysis, teeth were divided into 6 subgroups according to bleaching agent: group C (control): no bleaching; group 35HP: whiteness 35% HP; group 6HP: 6% HP; group HPC: 6% HP+CS; group HPT: 6% HP+TiO2; group HPTC: 6% HP+ TiO2+CS. The teeth were measured with a spectrophotometer before and 24 h after the bleaching, and calculated with the CIEDE2000 formula. SBS test was evaluated in composite restorations immediately after bleaching, using a universal testing machine. Statistical analysis was performed using ANOVA. Results: The highest ∆E00 values were observed in group 35HP (4.2 ± 1.2); the lowest value was observed in group 6HP (1.7 ± 0.6) (p 0.05). The values for groups HPC and HPT were similar to each other and significantly lower than the value for 35HP (p 0.05 and p > 0.05, respectively). Group HPTC was similar to 35 HP (p > 0.05). For SBS, all groups except those containing chitosan showed significantly decreased bond strength compared to the control (p 0.05), while groups HPC and HPTC had values similar to the control (p > 0.05). Group C (28.02 ± 6.81) had the highest value, while group 35HP (17.02 ± 7.79) had the lowest SBS value. Conclusion: With the newly developed agent, the bond strength immediately after bleaching was found to be similar to the control group. Its bleaching efficacy was similar to that of routinely used bleaching agents. Keywords: hydrogen peroxide, titanium dioxide, chitosan, tooth bleaching