Effects of various cleaning methods on thermoplastic orthodontic retainer material: An in vitro study

• Author Details:   
• Rani Jain ^*
• Sowmya K S
• Shashaka P Kumar
• Bharath Reddy
• Vedavathi H K

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Background: Thermoplastic vacuum-formed retainers (VFRs) are widely used for orthodontic retention due to their aesthetics and comfort. Their mechanical and optical qualities, however, might be impacted by regular cleaning procedures. This study assessed the effect of four different cleaning techniques on the flexural modulus and light transmittance of thermoplastic orthodontic retainer materials over a 12-month simulation.

Materials & Methods: Four groups (n=14) of fifty-six specimens of thermoformed sheets (50 mm × 15 mm × 1 mm) were selected based on four different cleaning techniques: chlorhexidine mouthwash, alcohol-based mouthwash, alcohol-free mouthwash, and toothbrushing with tap water. Samples were kept at 37°C in artificial saliva and cleaned twice a week using the designated technique. A universal testing machine was used to measure the flexural modulus, and UV-visible spectrophotometry was employed to determine light transmittance at 0, 4, 8, and 12 months. The Bonferroni, and repeated measures ANOVA tests were used in the statistical analysis.

Result: Over time, all cleaning techniques produced notable changes (p < 0.001). The earliest and most reliable increase in flexural modulus was brought on by tooth brushing. Alcohol-based mouthwash exhibited the highest reduction in light transmittance. Mouthwashes without alcohol and chlorhexidine had relatively mild effects.

Conclusion: The physical characteristics of retainers may be negatively impacted by mechanical brushing and cleaning solutions with alcohol. Mouthwashes without alcohol or chlorhexidine provide superior retainer integrity preservation.