Comparison of enamel colour changes associated with orthodontic bonding using two different adhesives

The purpose of this study was to evaluate the enamel colour changes associa ted with bonding of brackets with a no-mix (one-phase) adhesive resin (Unit e) and a glass-ionomer adhesive (GC Fuji Ortho). Thirty recently extracted premolars were used in the investigation. Black rectangular pieces of adhes ive tape with a 3-mm diameter window were used to standardize the enamel su rface intended for analysis. The teeth were divided into two groups of 15 t eeth each, brackets (Starfire TMB) were bonded with the two adhesives, and the enamel surfaces were colourimetrically evaluated at three time interval s: (a) before bonding (baseline), (b) following debonding and cleaning, and (c) after artificial photo-ageing for 24 hours. The CIE colour parameters (L*, a*, b*) were recorded and averaged for each material, interval group, and the corresponding colour differences (DeltaE) were calculated. The resu lts were statistically analysed using two-way ANOVA repeated measures, and Scheffe multiple range test at alpha = 0.05 level of significance. All differences noted exceeded the threshold for clin ica I detection (Delt aE = 3.7). The highest differences were recorded for the baseline-debonding interval for both adhesives used. No difference was found with respect to DeltaE between etching-mediated and no etching-mediated bonding implying th at the debonding cleaning process involving adhesive grinding may be more i nvasive relative to acid etching with regard to enamel colour alterations.