Evaluation of oxidizable substance interaction associated with orthodontic clear aligners and an acrylic material: A preliminary in vitro study

Abstract

Objective: This study aimed to comparatively evaluate the interactions of oxidizable substances associated with different orthodontic aligner materials using potassium permanganate (KMnO4 ). Methods: In this study, materials from three different clear-aligner manufacturers (SmartTrack, ClearQuartz, and Scheu Dental CA Pro+) and one acrylic block were used. The materials were mechanically fragmented and exposed to KMnO4 , a strong oxidizing agent. Potassium permanganate solutions were prepared at six concentrations (1.24 mM, 0.62 mM, 0.31 mM, 0.16 mM, 0.08 mM, 0.04 mM) to establish a calibration curve (R²=0.9999). Based on this calibration, 0.2 mM and 1 mM solutions were selected for the experimental phase. The color change was evaluated spectrophotometrically at 1, 4, and 24 hours to assess interactions with oxidizable substances. Results: The amount of oxidizable substances interacting with KMnO4 was estimated in mM. Oxidizable substances were detected in all samples (Acrylic Block 0.0723 mM, ClearQuartz 0.0826 mM, Scheu Dental CA Pro+ 0.0584 mM, SmartTrack 0.0271 mM); however, the estimated levels of oxidizable-substance interaction varied among samples. The highest level was observed in ClearQuartz at 24 hours. Conclusion: Orthodontic aligner materials exhibit varying levels of interaction with oxidizable substances, particularly during the first 24 hours. The method may serve as a simple preliminary screening tool. Future studies should investigate the composition of the released substances using more sensitive analytical methods.