Hydrophobic Resin – Effect on 6-month Bond Strengths of Universal Adhesives

Objectives: To test the influence of a hydrophobic resin coating (HC) on the immediate (24h) and 6-month (6m) microtensile dentin bond strengths (μTBS) and nanoleakage (NL) of three universal adhesives applied in self-etch (SE) or in etch-and-rinse (ER) mode.
Methods: Sixty extracted third molars were assigned to 12 groups resulting from the combination of the factors “adhesive system” (Scotchbond Universal Adhesive [SBU], 3M ESPE; All-Bond Universal [ABU], Bisco Inc.; and G-Bond Plus [GBP], GC Corporation); “adhesive strategy” (SE or ER); “hydrophobic resin coating” [HC] (with or without Heliobond, Ivoclar Vivadent); and “storage time” (24h or 6m). Specimens were prepared for μTBS:(24h) half of the beams were immediately tested; and (6m) the other half was stored in distilled water (37ºC) prior to testing. For each tooth, two beams were randomly selected for NL for (24h) and (6m). Data were analyzed for each adhesive using ANOVA and Tukey’s post-hoc test (α=0.05).
Results: µTBS(24h): In SE, HC resulted in statistically greater mean µTBS for all adhesives; µTBS(6m): Mean µTBS for SBU/ER, ABU/ER, GBP/ER and SBU/SE decreased significantly without HC (Table).
NL(24h): SBU/ER, ABU/ER and GBP/SE resulted in a significant reduction in NL when HC was applied; (NL6m):No significant reduction was observed for SBU/ER or SBU/SE regardless of the use of HC.
Conclusions: The application of a HC improved the immediate and the 6-month performance of all three universal adhesives in SE mode.