Cytotoxicity assessment of different clear aligner systems: An in vitro study.

OBJECTIVES: To evaluate and compare the cytotoxicity of multiple clear aligner systems (Invisalign, Eon, SureSmile, and Clarity).

MATERIALS AND METHODS: A cytotoxicity assessment was carried out by immersing three sets of aligners from the included four systems in normal saline for 1 month at 37°C. The solutions were then diluted to three different concentrations (5%, 10%, and 20% volume/volume). Gingival fibroblasts were exposed to the solution after being seeded to 96-well microplates for 48 hours, and the medium was substituted with an MTT solution (MTT: 3-[4,5-dime- thylthiazol-2-yl]-2,5-diphenyltetrazolium bromide). Optical density was then measured to determine cell viability and evaluate cytotoxicity subsequently.

RESULTS: Cytotoxicity comparison showed no statistically significant difference among the four included systems. However, when cell viability of each system was compared with the control, a significant difference was reported at the 10% and 20% solution concentrations. The Clarity system had the lowest toxicity across all solution concentrations.

CONCLUSIONS: The thermoplastic materials used by all tested systems (Invisalign, Eon, SureSmile, and Clarity) presented some degree of toxicity (slight to moderate), with statistically significant mean differences compared with the control.