Influence of cigarette smoke on enamel color stability after orthodontic debonding: an in vitro study.

Objective: The aim of this study was to evaluate the color stability of dental enamel exposed to cigarette smoke after orthodontic debonding. Methods: Thirty-two bovine incisors were allocated into control (C1 and C2) and experimental groups (n=8) according to distinct bonding protocols: with adhesive (B1) and without adhesive (B2) and exposure to cigarette smoke. Samples from B1, B2 and C2 were exposed to ten cycles of smoke in a specific and hermetic chamber while the C1 remained stored in artificial saliva. Color analysis was performed with a spectrophotometer according to the L*a*b* system. Intergroup comparisons and effect of time were estimated with ANOVA/Tukey and paired Student t tests, respectively (a=0.05). Results: Statistically significant color changes have not been observed in C1 (L*: -0.69 ± 0.80; a*: 0.36 ± 0.23; b*: 0.17 ± 0.50) and without adhesive (B2) (L*: -3.74 ± 2.85; a*: 0.93 ± 0,73; b*: 1.13 ± 1.16) through the study time (p>0,05). However, the group with adhesive (B1) presented significant color changes in L*:-5.55 ± 2.28, a*: 2.33 ± 0.77 and b*: 3.30 ± 1.37, what means, darker, greener and more yellow, respectively (p<0,05) and the control group that was exposed to the cigarette smoke (C2) presented significant color changes in L*: -1.72 ± 0.28 e b*: 1.82 ± 0.22, what means, darker and more yellow, respectively. Conclusion: Enamel color stability was affected by exposure to cigarette smoke after orthodontic debonding, especially when bonding protocolcomprised the application of primer adhesive.