Effect of the application time of phosphoric acid and self-etch adhesive systems to sclerotic dentin

Objectives: to evaluate the effect of application time on the resin-dentin bond strength (μtbs) and etching pattern of adhesive systems applied on sclerotic dentine. material and methods: a total of forty-two bovine incisors had their roots removed. the 1-step self-etch go (sdi),the 2-step self-etch adper se bond (3mespe) and the 35% phosphoric acid (3mespe) from the 2-step etch-and-rinse adper single bond 2 (3mespe) were applied on the bovine incisal surfaces according to the manufacturer's instructions or duplicating the recommended conditioning time. after adhesive application,thirty teeth were restored with composite resin,stored for 24 h in distilled water at 37°c,and sectioned into resin-dentin bonded sticks (0.8 mm2) and tested according to the μtbs at 0.5 mm/min. the etching pattern of the remaining twelve teeth (n=4 for each material) was examined under scanning electron microscopy. each tooth was divided into a buccal-to-lingual direction into three thirds,and each third randomly assigned to the groups: control (no treatment),according to the manufacturers' instructions and duplicating the recommended application time. the jtbs and the relative percentage of the tubule area opening were evaluated by two-way repeated measures anova and tukey's tests (α=0.05). results: the duplication of the conditioning time favored only the go adhesive (p<0.05). both application methods significantly increased the tubule area opening (p<0.05) compared to the controls. conclusions: the efficacy of duplicating the conditioning time was only effective for the 1-step self-etch adhesive system tested.