Enamel colour changes at debonding and after finishing procedures using five different adhesives.

The purpose of this study was to evaluate enamel colour alteration of five different orthodontic bonding adhesives by means of digital measurements after exposure to photoageing in order to simulate discolouration of adhesives in vivo. Seventy-five non-carious premolars were randomly divided into five equal groups. The brackets were bonded with five different adhesives (Transbond XT, Eagle Bond, Light Bond, Blugloo, Unite) and subjected to artificial accelerated photoageing for 24 hours. The enamel surfaces were colourimetrically evaluated before bonding, following debonding and cleaning with a tungsten carbide bur, after polishing with Stainbuster, and after photoageing of the debonded enamel surface. The Commission Internationale de l'Eclairage(CIE) colour parameters (L*a*b*) were recorded and colour differences (DeltaE) were calculated. The results were statistically analyzed using the Kruskall-Wallis test. Further investigation among subgroups was performed using Dunn's multiple correlation test (P < 0.05). The clinical detection threshold for DeltaE value was set at 3.7 units. DeltaE values between the first and second measurements showed an increase in the Transbond XT, Eagle Bond, and Light Bond groups. The highest DeltaE value was 1.51 +/- 1.15 in the Transbond XT group. No clinically significant DeltaE value was observed. Colour changes of orthodontic bonding systems induced by photoageing cannot be clinically observed. Polishing with Stainbuster eliminates enamel surface roughness, which may improve light reflection.