الفهرس 
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Abstract
Objective: To investigate effect of Grape seed extract (GSE) on micro-tensile bond strength(µTBS) and resin-dentin bond durability of universal adhesive (UA) to dentin and evaluating resin-dentin interface using scanning electron microscope (SEM). Materials & Methods: Flat Occlusal dentin surfaces of eighty sound human molars were exposed and randomly assigned into two groups; Control and GSE groups then both were further divided into etch-and-rinse (E&R) subgroups and self-etch (SE) subgroups. Each subgroup had two divisions; immediately tested specimens(n=10) and delayed tested specimens(n=10). Regarding GSE group, 10% of GSE (GNC®) prepared in hot distilled water and used for 1 min pretreatment after etching(15sec) in E&R technique or before adhesive (Single Bond Universal- 3M ESPE) application in SE technique. Composite build ups made incrementally and teeth were sectioned then subjected to µTBS at baseline 24h(t0) and 6months(t6). Six-month beams were stored in artificial saliva then subjected to thermal cycling (500 cycle) then tested. Slabs obtained for SEM. Failure modes of fracture surfaces inspected (stereomicroscope). Statistical analysis performed using two-way Anova and Tukey’s test. Results: Both at t0 and t6, µTBS means of E&R subgroups were significantly higher than SE subgroups with or without GSE pretreatment. In each time point, there were no significant difference between GSE specimens compared to control except for E&R subgroup at t0 was significantly higher than GSE subgroup. Comparing t0 and t6 timepoints, significant reduction in µTBS in all groups compared with their respective controls after aging but percentage of bond loss due to aging in GSE pretreated groups were less than controls. Most failure modes were mixed. SEM evaluation showed optimum resin tags infiltration in control groups unlike GSE pretreated groups. Conclusion: 10% GSE pretreatment for 1 min -before adhesion of Single Bond Universal- enhanced durability of resin-dentin bond yet did not completely eliminate loss of bond strength.