Abstract
In orthodontic bonding, it is crucial to obtain optimal marginal integrity between tooth surface and bonding adhesive. Undermining the intimate contact create gaps at the enamel-adhesive interface, these gaps may affect the bond strength and predispose the enamel to white spot lesions. This study evaluated the effect of leaving excess adhesive resin around orthodontic brackets on marginal integrity in vitro. In this in vitro experimental trial, 24 intact premolars were bonded with a stainless-steel orthodontic bracket using Transbond XT light cure adhesive composites mixed with Rhodamine B fluorescent dye. After positioning the bracket and before light curing, excess adhesive was removed according to the test groups. Group 1: the entire adhesive around the bracket was removed. Group 2, only 1-mm excess around the bracket was left. Group 3, only 2-mm excess around the bracket was left. The angle between enamel surface and bonding adhesive was measured using confocal laser scanning microscopy and data were analyzed by one way analysis of variance and post hoc Tukey test. The presence of excess adhesive significantly increased the angle (p<0.05), group 1 (0mm excess) presented a more favorable marginal integrity (4.5 degrees +/- 1.5 degrees) compared to groups 2 (14.65 degrees +/- 2.5 degrees) and 3 (19.44 degrees +/- 4 degrees). Excess adhesive around orthodontic brackets did not improve the marginal integrity.