Objective: To investigate the effect of some natural antioxidants on microshear bond strength to enamel bleached using chemical and laser assisted bleaching.
Methods: Sound human maxillary central incisors were used in the study. The labial surfaces were ground to obtain flat enamel surfaces. Bleached specimens were divided into 2 main groups according to the bleaching protocol; chemical bleaching and laser assisted bleaching. Each group was subdivided into 4 subgroups according to the antioxidant used; 10% Ascorbic acid, 10% Alpha-tocopherol, 10% Hesperidin and No antioxidant. Non-bleached specimens were prepared to be used as a control group. Bonding procedures were done 1h after bleaching. Microshear bond strength (µSBS) was tested using a universal testing machine. Data were tabulated and statistically analyzed using Two-way ANOVA followed by Bonferroni's post-hoc test.
Results: The control group showed the highest µSBS value. Using hesperidin and ascorbic acid with both bleaching protocols recorded no significant difference compared to the control group. Also, laser bleaching without antioxidant was statistically comparable to the control group. Regarding type of antioxidant, hesperidin showed the highest µSBS results followed by ascorbic acid while α-tocopherol showed the lowest values.
Conclusion: Hesperidin and ascorbic acid have the ability to regain microshear bond strength to bleached enamel with superior performance of hesperidin. Alpha tocopherol is not able to reverse compromised bond strength after tooth bleaching. Laser assisted bleaching could allow immediate bonding procedures without the need for antioxidant application.