Effects of Different Adhesive Systems and Orthodontic Bracket Material on Enamel Surface Discoloration: An In Vitro Study

The aim of this in vitro study was to assess the effect of the type of orthodontic brackets and adhesive systems on enamel discoloration. The baseline color of the buccal surfaces of 50 extracted human premolars was recorded using a spectrophotometer according to the CIE Lab system. The teeth were randomly divided into five groups according to the bracket type and adhesive system used: Group A: metal brackets + a Three-step etch and rinse adhesive (E&R); Group B: metal brackets + a two-step self-adhesive adhesive (SE); Group C: ceramic brackets + (E&R); Group D: ceramic brackets + (SE); Group E: no bracket bonding, serving as a control. All teeth were thermocycled, the brackets were debonded, and the enamel surfaces were finished and polished. The tooth color was then re-assessed, and the change in color (∆E*) was calculated. Pairwise comparisons revealed significant differences in favor of ceramic brackets (ΔE = 3.77 ± 3.60; p = 0.009) and (E&R) (ΔE= 3.52 ± 2.45; p = 0.008). A significant difference was found among the different groups, with group C having the least change in color (ΔE = 2.00 ± 0.89) and group B having the highest (ΔE = 8.42 ± 5.66). Both the type of orthodontic bracket and adhesive system influenced tooth color change. The teeth bonded with ceramic and E&R had the least effect on color changes, whereas teeth bonded with metal and SE showed the highest color changes after debonding.