Bond strength of composite to astringent-contaminated dentin using self-etching adhesives

To determine the effects of contamination by ferric sulfate and aluminum chloride astringents on the bond strength of composite bonded to superficial dentin using self-etching adhesives.

Freshly extracted human teeth were ground to expose superficial dentin and polished to 600 grit. One of three self-etching adhesive systems and restorative composites were bonded to the specimens, with contamination by one of three astringents and five surface conditions (no contamination, moist dentin control; contaminant, air, adhesive; contaminant, water rinse, air, adhesive; contaminant, water rinse, glycolic acid scrub, rinse, adhesive; contaminant, water rinse, chlorhexadine scrub, rinse, adhesive). Composite was bonded to the surfaces in the shape of an inverted, truncated cone (n = 5, 180 specimens total). Specimens were stored in water at 37 degrees C for 24 hours, then de-bonded in tension with a testing machine at a crosshead speed of 0.5 mm/minute. Tensile bond strengths (MPa) were calculated.

Means (SD) were compared using analysis of variance. Significant differences (Fisher's PLSD) were found among all variables. SE and ABF had the highest control values, but were affected most by astringent contamination. Ferric sulfate reduced bond strengths the greatest in most cases, and aluminum chloride putty reduced bond strengths the least. Chlorhexadine rinse was most effective in restoring bond strength values.