Evaluation of effects of nanocoating on color changes of clear orthodontic appliances

Abstract

Background and Aim: Among the existing orthodontic appliances, adults prefer transparent orthodontic appliance for their beauty and convenience. Also, Color stability and transparency of transparent retainers should persist for a long period of retention. On the other hand, the self-cleaning properties of nanoparticles, such as TiO2, have been proven. For this purpose, the effect of Different percentages TiO2 nanoparticles on color variation of Transparent Retainer sheets was investigated.

Materials and Methods: The first, 25 pieces of sheets of transparent retiners in dimensions 1×3 cm2 ,in Five groups of five were dissolved in a solution of trifluoroacetic acid and mixed with TiO2 at ratios of 2.5,5,10 and 20 mg. After preparing sheets of transparent retiners and TiO2 with different ratios, samples were placed in distilled water solutions for 1 day with a control sample and their colors were first recorded by spectrophotometer. Then the samples were placed in artificial saliva and cola solution for 30 days. After 30 days, the color of the samples were re-recorded. Kolmogorov-Smirnov analysis was used for analyzing of the normal distribution of data. Also, Wilcoxon nonParametric Analysis was used for comparing of the color factors before and after and Kruskal-Wallis analysis used for Color variation (ΔE) investigation among five groups. Result and Discussion: The results showed that the highest mean of color change was in the group without nano coatings with a mean of 5.97 ± 3.39 and the lowest mean of color change was reported in the group with a concentration of 20 mg with a mean of 3.41 ± 0.70. Results showed that there was no normal distribution in some groups. As at comparing the color factors of before and after, and the color change (ΔE) between the five groups, the results showed that although the color change there is in the all groups among before and after But, level of variation of color between the five groups is not significant that due to the small number of specimens.

Conclusion: However, in the group with concentration of 20 mg from TiO2, the change of L* factor was at least, but level of ΔE between the groups did not have significant difference.