Influence of roughening and EDTA application on shear bond strength to sclerotic dentin: in vitro study

This study evaluated two different adhesive systems (Adper Single Bond 2 - SB2; Palfique Bond - PALF) to bovine sclerotic dentin with and without dentin pretreatments. For this purpose, 200 incisors were randomly distributed into eight groups (n = 25), according to the pretreatment (none; diamond bur roughening - BUR; EDTA application - EDTA; and BUR + EDTA) and adhesive system (SB2 and PALF). A flat dentin area was obtained through wet polishing with 200, 320, 400, and 600-grit SiC paper after the teeth were embedded in chemically activated resin, with the exposed dentin surfaces parallel to the horizontal plane. Each dentin surface received two or three cylinders of flowable resin (Opalis Flow; FGM). The resin cylinders were made directly on the sclerotic dentin surface after each specific micro shear bond strength test (mu SBS) treatment. The results were recorded, and the failure patterns were classified through stereomicroscopy. Parallelly, 16 bovine teeth were selected and treated according to each group, sectioned in a precision cutting machine, and analyzed using scanning electron microscopy. Results were analyzed by two-way ANOVA and Tukey's test (alpha = 0.05). There were statistically significant differences among the mu SBS values (p < 0.05). Groups with pretreatment showed values significantly higher (p < 0.05). Cohesive failure was prevalent within the adhesives. PALF produced thinner hybrid layers when compared to SB2, but diamond bur roughening was capable of enhancing its thickness. In conclusion, the pretreatments of sclerotic dentin evaluated in this study resulted in better mu SBS results in both tested adhesives systems.