Enamel loss and superficial aspect during bonding and debonding of metallic brackets

To evaluate the cumulative enamel loss during bonding and debonding procedures of orthodontic metallic brackets and to analyze the enamel superficial roughness. Forty-seven maxillary first premolars were obtained for quantitative and qualitative analysis. For quantitative analysis, forty premolars were weighed at each stage of treatment and the equivalent thickness of enamel loss was measured. The amount of tooth mass loss in each stage was divided by the density value to obtain the corresponding enamel volume lost. Subsequently, these volumes were divided by a circular area with a diameter of 7 mm, thus obtaining the equivalent thickness of enamel loss. They were assessed under the following conditions: as sound enamel, after acid conditioning, following the removal of residual resin composite, after final polishing with high or low-speed, and with or without water refrigeration. A rugosimeter was used to obtain a graphic registration of the enamel superficial roughness before and after acid conditioning. The data were analyzed with the Quantikov software and the Shapiro Wilk's and Wilcoxon statistical tests were used to evaluate enamel superficial roughness. The one-way ANOVA followed by Bonferroni Post-Hoc tests were used to analyze the amount of enamel loss. For qualitative analysis, scanning electron microscopy (SEM) of the enamel surfaces was performed on seven premolars, one in each step. Acid conditioning significantly increased enamel surface roughness (p