The influence of cigarette smoke on colour stability and friction property of aesthetic orthodontic wires—In vitro study

Does the exposure to cigarette smoke influence the colour stability and mechanical properties of different orthodontic elastic ligatures? - in vitro study

OBJECTIVE

The aim of this study was to evaluate the colour stability and mechanical resistance of orthodontic elastic ligature exposed to cigarette smoke.

METHODS

Four commercial brands were used: Aditek® (GA), Eurodonto® (GE), Morelli® (GM) and Orthometric® (GO). Eight elastic ligature rings (for mechanical analysis) and eight 5×5mm fragments of the material (for colour stability analysis) were separated from each commercial brand for the control group (C) (n=64) and experimental group (E) (n=64). The control group was not exposed to cigarette smoke. Colourimetric status (CIEL*a*b* System) and light transmittance (% transmitted light) were evaluated using Vita Easyshade Compact and CM2600 spectrophotometers, respectively. The mechanical resistance was evaluated using a universal testing machine (EMIC DL), performing tensile testing (speed 5mm/min). The analyses occurred at the following times: T0, before exposure to the smoke; T1, after the 1st exposure; and T2, after the 2nd exposure to cigarette smoke. Comparison between the groups and evaluation of the time effect were performed with the ANOVA/Tukey (a=0.05) and ANOVA-MR tests with Bonferroni correction (α=0.016).

RESULTS

Significant differences were only observed for colour stability in the GA-E (NBS T2: 15.94±1.88) and GM-E (NBS T2: 16.11±4.54) groups (P<0.05); transmittance in the GA-E group (T2-T0: -9.07±5.01) (P<0.016) and mechanical resistance in the GA-C group (T2-T0: -0.95±0.61N) (P<0.016).

CONCLUSION

The orthodontic elastic ligatures were sensitive to the cigarette smoke exposure regarding to loss of mechanical strength properties and change in colour stability.