# Effect of Cleansing Agents on the Color Stability of Stained Clear Aligners: An In Vitro Study

## TL;DR

This study found that black coffee causes the most discoloration in clear orthodontic aligners, and common cleaning agents are not very effective at removing the stains.

## Contribution

The study provides empirical evidence on the staining potential of beverages and the limited effectiveness of cleansing agents on clear aligners.

## Key findings

- Black coffee caused the highest and most consistent color change in aligners.
- Cleansing agents showed no significant difference in stain removal effectiveness.
- Color changes in aligners increased progressively over time.

## Abstract

Aim

This study aims to assess the discoloration of clear orthodontic aligners caused by commonly consumed beverages and to compare the effectiveness of various cleaning agents in stain removal.

Materials and methods

A total of 100 clear orthodontic aligners were immersed for seven days in four commonly consumed beverages, specifically black coffee, black coffee with milk, kombucha, and a green smoothie, as well as in distilled water, which served as the control solution. Following this immersion period, 20 aligners from each beverage group were cleaned using four different cleansing agents: Bluem Aligner Foam, Curaprox BDC 100 Denture Gel Daily, IsoDent Ortho Cleaner, and 3% hydrogen peroxide. The VITA Easy-Shade compact spectrophotometer used the CIELAB (Commission Internationale de L'Eclairage L*a*b* colour system) scheme to evaluate the color change of the aligners at four intervals: T0 (before immersion), T1 (after 24 hours), T2 (after 48 hours), T3 (after seven days), and T4 (after cleaning with cleansing agents). The color values were converted into National Bureau of Standards (NBS) units to quantify the degree of color change. Statistical analysis was performed using IBM SPSS Statistics for Windows, Version 29 (Released 2022; IBM Corp., Armonk, New York, United States), employing non-parametric methods to assess differences between groups and across time intervals.

Results

A significant color change in aligners was observed after immersion in the stated solutions (p < 0.001). Among the staining agents, black coffee induced the highest and most consistent colour change at T0-T3 ΔE = 8.867 (8.553-9.22), followed by coffee with milk ΔE = 3.325 (3.259-3.544), kombucha ΔE = 2.45 (2.272-3.094), and green smoothie ΔE = 1.581 (1.463-1.723) (p < 0.001). Intergroup and intragroup comparisons of cleansing agents revealed no significant differences among groups.

Conclusion

The study demonstrated significant differences in the staining potential of various beverages on clear aligners, with black coffee inducing the most pronounced discoloration. All aligners exhibited progressive color changes over time. The cleansing agents tested showed limited efficacy, with no statistically significant ability to reverse the discoloration.