Influence of dentin acid-etching and NaOCl-treatment on bond strengths of self-etch adhesives.

PURPOSE

To determine the microtensile bond strength (microTBS) of one- and two-step self-etch adhesives bonded to sound dentin conditioned or not with phosphoric acid (H3PO4) and sodium hypochlorite (H3PO4 + NaOCl).

METHODS

Extracted human third molars had their crowns transversally sectioned to expose flat dentin surfaces that were divided into four groups, and bonded as follow: (1) according to the manufacturers' directions, (2) acid etched with 36% H3PO4, and (3) 10% NaOCl treated for 2 minutes, after H3PO4 etching. Two two-step self-etching primers (Clearfil SE Bond/SEB and Resulcin/RE), and two one-step adhesives (One-Up Bond F/OUB and Etch & Prime 3.0/EP) were examined. Composite build-ups were constructed incrementally with Tetric Ceram. The specimens were stored in humidity for 24 hours at 37 degrees C and sectioned into beams of 1.0 mm2 cross-sectional area. Each beam was tested in tension in an Instron machine at 0.5 mm/minute, and mean microTBS data (MPa) were analyzed by 2-way ANOVA and post-hoc multiple comparisons tests (P < 0.05).

RESULTS

The two-step adhesive SEB exhibited the highest bond strength when bonded to smear layer-covered dentin, whereas RE was not affected by all dentin surface conditions. H3PO4 and H3PO4 + NaOCl pretreatments significantly increased bonding efficacy of the one-step adhesives OUB and EP, respectively.