Shear Bond Strengths of New Enamel Etchants

Many dental adhesive systems now rely on simultaneous etching of enamel and dentin. Instead of the traditional 35-40% phosphoric acid, new etchants (including 10% maleic acid, 10% phosphoric acid, and oxalic acid/aluminum nitrate) are used. This in vitro study determined the shear bond strengths of resin composite to enamel which was etched with these agents according to manufacturers' instructions. The control etchant, 35% phosphoric acid, gave a mean bond strength of 24.5 MPa. 10% maleic acid and 10% phosphoric acid had significantly lower shear bond strengths (13.2 MPa). Gluma 1 & 2 Conditioner (oxalic acid/aluminum nitrate) had a mean bond strength of 6.3 MPa, which was significantly less than the other etchants. Bond strengths for each etchant were not affected by the type of unfilled resin used.