Influence of Bleaching Agents on Microtensile Bond Strength of Adhesives

Objectives: The aim of the present study was to evaluate the influence of different bleaching agents and concentrations on microtensile bond strength of different dentin adhesives in class V cavities in vitro. Methods: 135 freshly extracted third molars were included in this study. In all teeth cervical class V dentinal cavities were prepared also allowing the simulation of dentin perfusion. The specimens were randomly assigned to nine experimental groups of fifteen each: S0: Syntac/ control; S17: Syntac/ Perfect Bleach 17%; S38: Syntac/ Opalescence Xtra Boost 38%: X0: XP Bond/ control; X17: XP Bond/ Perfect Bleach 17%; X38: XP Bond/ Opalescence Xtra Boost 38%; F0: Futurabond NR/ control; F17: Futurabond NR/ Perfect Bleach 17%; F38: Futurabond NR/ Opalescence Xtra Boost 38%. Bleaching was performed 8 hours at 36°C for 7 days. Microtensile bond strength of the above mentioned bonding agents was measured using an universal testing machine. Results: For the nine test series following tensile bond strengths were evaluated (mean values and standard deviations in MPa):

Statistical analysis showed a significant influence of the used dentin bonding agent and the bleaching agent on microtensile bond strength (p< 0.001, ANOVA). Pairwise comparison showed a significant reduction of bond strength in specimen treated with bleaching materials compared to the untreated control groups. In the case of Syntac and XP Bond a significant reduction in bond strength between both bleaching materials could be observed (p< 0.05, Tukeys test). Conclusions: Within the limitations of an in vitro investigation it can be concluded that the pretreatment of dentin using high concentrated bleaching agents might affect tensile bond strength of the dentin adhesives tested.