Evaluation of bisphenol release of different clear aligner materials using the liquid chromatography-mass spectrometry/mass spectrometry method.

Objectives: To evaluate the bisphenol release of different brands of clear aligner materials.

Materials and methods: Six different clear aligner materials were used in this study: Duran (Scheu-Dental GmbH, Iserlohn, Germany), Zendura Flx (Bay Materials LLC, Fremont, CA, USA), Zendura A (Bay Materials), Essix (Raintree Essix Inc., Metairie, LA, USA), Taglus Premium (Laxmi Dental Export Pvt. Ltd, Mumbai, India), and Smart Track (Align Technology, San Jose, CA, USA). The samples were kept in saline solution for 8 weeks in airtight test tubes at 37°C. The ratio between the weights of the samples and the volumes of the dilutions was prepared as 0.1 g/mL as suggested by International Standards Organization parameters. To evaluate the bisphenol release of materials, liquid chromatography-mass spectrometry/mass spectrometry analysis was performed. Data were analyzed with the Kruskal-Wallis test (α = 0.05).

Results: Bisphenol A (BPA) values in Smart Track were found to be significantly higher than the Zendura A and Zendura Flx groups (P = .02, P = .03, respectively). There was no statistically significant difference among the samples in terms of Bisphenol F (BPF) values (P = .108). In terms of Bisphenol S (BPS) values, a statistically significant difference was found (P = .002) indicating that Smart Track released significantly more BPS than Zendura A (P = .001).

Conclusions: Under the test conditions, the amounts of leached BPA, BPF, and BPS were less than the reference dose for daily intake. However, the cumulative effect of these appliances should not be underestimated.