Evaluating the Impact of Ultrasonic Cleaning on the Structural Integrity of Clear Aligners at Varying Temperature

This study aims to investigate the effects of ultrasonic cleaning at varying temperatures on the structural integrity, fit, and cleanliness of clear aligners made from different materials, including triple-layered polyurethane, single-layered polyurethane, and PET-G.

Three types of aligner materials were selected: triple-layered polyurethane, single-layered polyurethane, and PET-G. Aligner sets were manufactured and subjected to ultrasonic cleaning at temperatures ranging from 10°C to 60°C for 10 minutes. Following the cleaning process, the aligners were visually inspected for debris removal and checked for fit, shape, and structural changes. The aligners were also examined after multiple retrievals to assess durability and the impact of cleaning.

The ultrasonic cleaning process successfully removed debris and biofilm without causing visible damage. However, at higher temperatures (51–60°C), the fit of the PET-G and single-layered polyurethane aligners became loose, whereas the triple-layered polyurethane aligner maintained its fit and structural integrity. No cracks, shape distortions, or changes in mechanical properties were observed in any of the aligners after 60 retrievals.

Ultrasonic cleaning proves effective in removing contaminants and biofilm from clear aligners. However, material properties play a crucial role in determining the durability of aligners under different cleaning conditions. Triple-layered polyurethane aligners demonstrated enhanced resistance to temperature-induced degradation, making them a preferable choice for long-term use. These findings highlight the importance of selecting suitable cleaning methods and materials to preserve both the aesthetic and functional qualities of clear aligners.