Abstract
Introduction
By-products of hydrogen peroxide degradation released during dental bleaching influence the polymerization of adhesive systems and composite resins, causing a reduction in shear bond strength to the tooth.
Objective
the aim of this article was to evaluate the effect of 10% sodium bicarbonate (SB), applied for different lengths of time, on the shear bond strength to enamel and dentin after bleaching.
Material and method
Enamel and dentin blocks were divided into groups (n=10): (1) control: no bleaching; (2) immediate: bleaching immediately followed by restoration; (3) 14-day: bleaching, restoration 14 days later; (4) SB for 10 minutes: bleaching, SB gel for 10 minutes, immediately followed by restoration; (5) SB for 20 minutes: bleaching, SB gel for 20 minutes, immediately followed by restoration. A 38% hydrogen peroxide gel (Opalescence Boost/Ultradent) was used. After application of the adhesive system, composite resin cylinders were mounted on the surface of the substrates in order to test shear bond strength. Result: ANOVA and Tukey tests showed significantly higher mean enamel bond strength values for the 14-day follow-up group and without significant differences for control group. Mean bond strength values obtained for the other groups were intermediate. When testing dentin, the Tukey test revealed a significantly higher mean bond strength value for the 14-day follow-up group when compared with application of SB for 20 minutes.
Conclusion
SB gel applied was unable to reverse the low bond strength to enamel and dentin after bleaching treatment.
Descriptors:
Tooth bleaching; hydrogen peroxide; shear strength; sodium bicarbonate