Effects on shear bond strength and the enamel surface with an enamel bonding agent

Introduction: The purpose of this study was to evaluate the shear bond strength of orthodontic brackets and the effect of an enamel bonding agent (EBA) on enamel surface after debonding. Methods: Seventy-five extracted maxillary premolars were collected and randomly divided into 3 groups of 25. The enamel cracks were surveyed with a stereomicroscope. In the first group, 1 layer of EBA was applied before the adhesive resin. In the second group, 2 layers of EBA were used; in the third group, no EBA was used. Bonding was followed by incubation for 48 hours at 37 degrees C and thermocycling for 1000 cycles. Debonding was performed with a shear force. The surfaces of the teeth were evaluated, and the length, depth, direction of cracks, and adhesive remnants on the enamel surface were recorded. Data were analyzed by using analysis of variance and paired samples t tests. Results: There were no significant differences between the shear bond strengths (P = 0.341) of the 3 groups, or in the direction, length, and depth of the cracks before and after debonding (P > 0.05). There was a significant increase in the number of cracks after debonding in the 3 groups (P < 0.05). The evaluation of adhesive remaining on the surface of the teeth indicated that most bond failures occurred at the resin-bracket interface. Conclusions: The use of EBA does not enhance bond strength or provide greater protection to the enamel surface during debonding. (Am J Orthod Dentofacial Orthop 2010; 137: 375-8)