In vitro evaluation of the citotoxic effects and bisphenol release of different clear aligner materials used during active and retension therapy in orthodontics

Clear aligners used in active orthodontic treatment and retention period are produced from polymers such as polyethylene (PE), polyethylene terephalate (PET), polyethylene terephalate glycol (PETG), polyurethane (PU) and polypropylene (PP). The interaction of these materials with teeth, gingiva and intraoral fluids during the treatment makes it important to evaluate their cytotoxic effects and their harmful effects in terms of Bisphenol A (BPA), Bisphenol F (BPF) and Bisphenol S (BPS) releases. In our study, 6 different clear aligner brands [Duran (ScheuDental GmbH, Iserlohn, Germany), Zendura Flx (Bay Materials LLC, Fremont, CA, USA), Taglus (Laxmi Dental Export Pvt. Ltd, Mumbai, India) and Smart Track (Align Technology San Jose, CA, USA), Zendura (Bay Materials LLC, Fremont, CA, USA), Essix C+ (Dentsply, FL, USA)] determined using the human gingival fibroblast cell line using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) method and the X CElligence real-time cell analysis system. Liquid chromatography/mass spectrometry (LC/MS-MS) device was used in the evaluation of bisphenol releases. When the cell proliferation percentages obtained by MTT method were examined, the proliferation percentages of the Smart Track and Zendura groups were found to be significantly lower (p= .028, p= .028). When the X-Celligence method data were compared, no statistically significant difference was found (p= .063). When BPA releases were compared, Smart Track values were found to be statistically significantly higher than the Zendura and Zendura Flx groups (p= .02, p= .03, respectively). While there was no statistically significant difference between the groups in terms of BPF values (p= .108), a statistically significant difference was found between the groups in BPS values (p= .002) and it was observed that the BPS values of the Smart Track group were significantly higher than the Zendura group (p= .001, p= .001).