In vitro spectrophotometric evaluation of Vivera clear thermoplastic retainer discolouration.

Aims: To investigate the in vitro effect of different staining solutions on the colour stability of Vivera retainers.

Methods: Thirty flat specimens fabricated using the Vivera material (Align Technology Inc., CA, USA) were assigned into five Groups (A, B, C, D and E) and immersed at 37 degrees C in solutions of distilled water (control), coffee, tea, red wine, and Coca-Cola. The CIE colour parameters (L*, a*, b*) of each specimen were measured before immersion (T0) and after 12 hours (T1), three days (T2) and seven days (T3) of solution exposure. Colour differences (AE) between the interval groups were calculated. Results: Significant differences were observed concerning (i) L* between T, and T0, Ti and T2 for Group B; (ii) a* between To and T,, T, and T3 for Groups B, C, D and E, as well as between T1 and T2 for Group C; and (iii) b* between To and T,, T2 and T3 for Group B and between T0 and T2 and T1 for Group C. The differences between δE(T1-T0), δE(T2-T0) and δE(T3-T0) were statistically significant for Groups B and C, as well as the difference between δE(T1-T0) and δE(T2-T0) for Group D.

Conclusions: Coffee, tea and red wine caused visible changes in the retainers' colour.