Evaluation of enamel color changes during orthodontic treatment

The purpose of orthodontics is to prevent the occurrence of a malocclusion, to correct the development of the malocclusion with simple approaches at an early phase, to provide a good function and aesthetics by treating and to maintain the corrected condition. In today?s world, individuals do not only settle with healthy and correctly aligned teeth but also want to have a perfect smile. However, roughening the enamel surface during etching, removal of the brackets and cleaning of the enamel surfaces cause physical and aesthetic changes on the tooth enamel. For this reason, keeping the integrity of the the enamel surface in its original condition when the orthodontic treatment is completed is an important target. In the literature, a few in-vitro studies evaluated the discoloration of orthodontic adhesives and the color alterations of enamel surfaces after finishing and polishing procedures. The purpose of this study was to investigate enamel color alterations of three different orthodontic bonding adhesives and two different finishing burs by means of digital measurement after exposure to photoageing.175 upper and lower first and second premolars were used in this study. After selecting 25 teeth as the control group, the remaining teeth were separated into 3 groups of 50 teeth depending on the difference of the adhesive system. Thereafter, every experiment group was divided into 2 sub-groups of 25 teeth depending on the difference of the bur used for cleaning the adhesive residuals on the tooth surface. Brackets were bonded to the teeth in the experiment groups by using total-etch adhesive system, self-etch adhesive system and resin-modified glass-ionomer cement. After then 24 hours of photoageing was applied to all of the teeth. Afterwards, the brackets were removed and the adhesive residuals on tooth enamel were cleaned with tungsten carbide and stainbuster burs. The teeth in the experiment groups were then applied a second photoageing of 24 hours. Tooth colors were measured with a spectrophotometer at the beginning of the treatment, after the enamel surfaces were cleaned and after the second photoageing. Color evaluation was made according to the CIE L* a* b* color system and ?E values were calculated.Discoloration at ?12 level in the control group was obtained above the clinic threshold (?E=3,7) and this discoloration was found similar to the RMGIC-tungsten carbide bur, RMGIC-stainbuster bur and self-etch adhesive system-stainbuster bur groups. Coloring values of the teeth in tungsten carbide bur sub-groups due to the orthodontic treatment were found above the clinic threshold. Discoloration values due to the orthodontic treatment in both the total-etch adhesive system and the self-etch adhesive system groups were found higher than the values in RMGIC group. But for the total coloring, the values in the total-etch adhesive system group were found higher than the values in both the self-etch adhesive system and the RMGIC groups. Coloring values due to the orthodontic treatment in only the self-etch adhesive system group among the stainbuster drill sub-groups were obtained above the clinic threshold. Discoloration values due to the orthodontic treatment in the self-etch adhesive system group were found higher than the values in both the total-etch adhesive system and RMGIC groups. But for the total coloring, the values in RMGIC group were found higher than the values in the total-etch adhesive system group. For the coloring that only occurred after orthodontic treatment, the values in RMGIC group were higher than the values in both the total-etch and self-etch adhesive system groups.In conclusion, orthodontic treatment causes teeth discoloration. The adhesive system and the resin removal techniques are effective for this color alteration. Total-etch adhesive system-stainbuster bur combination is advised for minimum color change due to the orthodontic treatment.