Dimensional Stability and Weight Change of Orthodontic Clear Aligners Exposed to Hot and Cold Beverages: An In Vitro Study

Abstract

This study aims to find the influence of hot and cold beverages on single-layered (SL) and multilayered (ML) clear aligners in terms of dimensional stability, weight variations, and chemical characteristics by using attenuated total reflectance fourier-transform infrared (ATR-FTIR) spectroscopy and X-ray diffraction (XRD) technique. One hundred clear aligners were thermoformed, 50 per material, and subdivided into five groups (10 per group). The groups were coffee at 55°C, distilled water at 55°C, cola at 5°C, distilled water at 5°C, and distilled water at 37°C. The aligners were scanned and weighed along with chemical characterization, then immersed in the solutions for 45 min daily for 14 days. After finishing the immersion period, they were rescanned and weighed, and chemical characterization analyses were taken. Scans were superimposed by GeoMagic Control X software. The root mean square (RMS) of the deviations was used to compare dimensional changes. The results revealed significantly higher RMS in distilled water at 55°C and coffee than in other groups. The SL showed higher RMS values than ML groups; all aligners gained weight, and the rate was higher for hot solutions. In conclusion, hot beverages negatively impact clear aligners’ dimensional stability, and patients should avoid drinking them while wearing their aligners.