Influence of Home Bleaching on Bond Strength of Dentin Adhesives

Objectives: The aim of the present study was to evaluate the influence of a commercially available home bleaching agent (Perfect Bleach 17%, Voco, Germany) on microtensile bond strength of four different dentin adhesives (Syntac and AdheSE, Vivadent, Liechtenstein; XP Bond, Dentsply DeTrey, Germany; Futurabond NR, Voco, Germany) in class V cavities in vitro. Methods: 120 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 eight experimental groups of fifteen each: S: Syntac/ control; S17: Syntac/ Perfect Bleach; A: AdheSE/ control; A17: AdheSE/ Perfect Bleach; X: XP Bond/ control; X17: XP Bond/ Perfect Bleach; F: Futurabond NR/ control; F17: Futurabond NR/ Perfect Bleach. 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 test series following tensile bond strengths were evaluated (mean values and standard deviations in MPa):

Group	S	S17	A	A17	X	X17	F	F17
Bond Strength	25.89	21.44	24.32	18.97	22.15	18.99	16.25	12.95
+/-	2.97	2.05	6.93	2.80	3.53	2.96	1.72	1.74

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 AdheSE (p< 0.05, Tukeys test). Futurabond NR and XP Bond showed no significant decreased bond strength values after bleaching. 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.