Colorimetric Evaluation of Various Orthodontic Thermoformed Retainers Exposed to Different Staining Agents and Cleaning Techniques

Abstract

Abstract Aims: The aim of this in vitro study was to evaluate the color changes in the retainers by different manufacturers (Essix ACE, Forestadent, Leone, and Bioart) after exposure to various beverage solutions (coke, tea, coffee, and artificial saliva) and also to assess the stain removal potential of different cleansing agents [listerine (L) and retainer brite (RB)]. Materials and Methods: A total of 320 specimens (80 samples in each group) of thermoformed retainers from four different manufacturers were tested. All retainers were thermoformed and were immersed in different beverages (black tea, coffee, and cola) and artificial saliva as a control group for 7 and 14 days. These were then cleaned by either L or RB crystals. The color changes (ΔE) in several retainers were assessed following a 7-day exposure (T1–T0), a 14-day exposure (T2–T0), and following cleaning (T3–T1 and T3–T2). The CIELAB color space approach was utilized to obtain the ΔE measurements. To statistically evaluate the data, t test, analysis of variance, Tukey’s range test, and Levene’s test were employed. Results: On intragroup comparison, all groups were stained by tea with significant differences at 7 and 14 days (P < 0.05). Significant differences in color change after cleaning by L at the 7-day interval (P < 0.05) were noted in group A for immersion in cola. No significant difference was noted for groups B and C (P > 0.05). Significant differences in color change after cleaning with RB for tea stains in group D (P < 0.05) were noted. Significant intergroup differences in staining were noted for tea at 7- and 14-day intervals (P < 0.05) with maximum staining in group D. For coffee, significant intergroup differences were noted with maximum staining in group A (P < 0.05) at both 7- and 14-day intervals. Significant intergroup differences in cleaning were noted at the 12- h interval in group A for tea stains by RB (P < 0.05) and cola stains by L (P < 0.05). Conclusions: Tea exhibited the greatest staining potential among all staining agents at 7-and 14-day intervals for Forestadent, Leone, and Bioart retainers, while coffee stained Essix ACE retainers the most. Among the four different retainer brands, Bioart exhibited the least staining with the various staining agents at 7- and 14-day intervals. RB eliminated tea stains better, whereas cola and coffee stains were better removed by L.