Effects of different orthodontic adhesives and resin removal techniques on enamel color alteration

Objective: To investigate the color alterations in enamel following the use of different orthodontic bonding resins and adhesive residue removal burs. Materials and Methods: Metal brackets were bonded to extracted human premolars (n = 175) by using an etch-and-rinse adhesive system, a self-etch adhesive system (SEP), or a resin-modified glass ionomer cement (RMGIC). After 24 hours of photoaging, the brackets were removed and the adhesive residue on the tooth surfaces was cleaned with either a tungsten carbide bur or a Stainbuster bur. Tooth colors were measured with a spectrophotometer at baseline, after adhesive removal, and after additional photoaging. Color evaluation was made, and color differences induced by photoaging were calculated. Statistical evaluation was made using the Kruskal-Wallis test and the Mann-Whitney U-test, with Bonferroni correction. Results: All specimens showed discoloration at varying levels. The highest color change was observed in the etch-and-rinse adhesive/tungsten carbide bur group. When the etch-and-rinse and self-etch adhesives were used, adhesive-remnant removal with Stainbuster burs resulted in significantly lower discoloration. The type of bur did not affect the extent of enamel discoloration in the RMGIC group. Conclusions: Orthodontic treatment alters the original color of enamel, and both the adhesive system and the resin-removal methods are responsible for this change. When brackets are bonded with the etch-and-rinse system or the SEP, cleaning the adhesive residuals with Stainbuster burs is recommended for minimal change. RMGIC can be safely cleaned with tungsten carbide burs.