Color change and surface degradation of esthetic brackets after exposure to cigarette smoke and two cleaning treatments.

AIM: During orthodontic treatment, the presence of brackets increases the accumulation of biofilm, which can increase the surface degradation of brackets. Thus, cleaning methods must address removal of both biofilm and stains, specially acquired due to cigarette smoke. Therefore, color change and surface texture of esthetic brackets subjected to cigarette smoke were evaluated before and after use of different cleaning treatments. MATERIALS AND METHODS: Three types of conventional esthetic brackets (slot size 0.022" x 0.028" and Roth prescription) were evaluated: polycarbonate/P (Composite/Morelli), polycrystalline ceramic/PC (Iceram/Orthometric) and monocrystalline ceramic/MC (Iceram-S/Orthometric). They were exposed to cigarette smoke (Marlboro Red Box) for 5 days in a machine that simulated the oral conditions of a smoker. Then, they were assigned to one of two different cleaning treatments (n=10): a) bicarbonate jet (sodium bicarbonate particles 4 microm in diameter, at pressure 2.3 bar, distance 5 mm, for 10 seconds), or b) Robinson brush, pumice stone and water. Color analyses (CIEL*a*b*, WID, DeltaEab, DeltaE00 and DeltaWID) and surface micromorphology (500 x magnification) were performed before and after exposure to smoke, and after the cleaning treatments. RESULTS: Mixed generalized linear models (alpha=0.05) showed that after exposure to smoke, all brackets showed a significant decrease in L* (p<0.0001) and WID (p<0.0001), and a significant increase in a* (p<0.05) and b* (p<0.0001), with greater staining for the P brackets (p<0.0001). CONCLUSIONS: After the cleaning treatments, it was not possible to recover the initial color of the P brackets with the use of a Robinson brush. Although the cleaning treatment partially or completely removed the surface staining, the P brackets showed more extensive surface degradation, especially with use of the bicarbonate jet.