The Effect of Enamel Etching with Different Acids on the Bond Strength of Brackets

The purpose of this study was to compare the bond strengths of metallic brackets on human enamel etched with different acid solutions including (1) 37% phosphoric acid, (2) 10% maleic acid, (3) 37% phosphoric acid with i.23% NaF addition, (4) 10% maleic acid with 1.23% NaF addition to reveal if this caries prevention modalities adversely affect the clinical success of bonding procedure. All the groups had stainless steel brackets bonded to the buccal surface of each tooth with no-mix adhesive. An Instron testine machine was used to determine tensile bond strengths. The mean bond strength values of the groups were as follows: phosphoric acid group 9.17 ± 4.59 MPa; maleic acid group 8.46 ± 3.89 MPa; NaF added phosphoric acid group 2.33 ±2.19 MPa; NaF added maleic acid group 2.02 ± 1.43 MPa. The statistical analysis was done by an analysis of variance and Duncan multiple range tests. Bond strengths that the two “only acid” groups yie fded were significantly higher than NaF added groups (P0.05). The current findings indicate that 10% maleic acid alone may produce similar bond strengths to 37% phosphoric acid however, 1.23% NaF addition to either phosphoric or maleic acids to increase caries resistance results in significantly lower bond strengths and should not be advocated for clinical use as an enamel conditioner