The aim of this study was to investigate and compare the leaching of four different clear aligner systems (Invisalign®, Eon®, SureSmile®, and Clarity®). Three sets of aligners as obtained from the four manufacturers were cut and immersed in glass vials containing ethanol with different solutions. The first was 100% ethanol, the second was 75% ethanol to 25% water, the third was 50% ethanol to water, the fourth was 25% ethanol to 75% water, and the last was 100% water. The samples were incubated for two weeks at 37 °C. Leached substances were detected by the gas chromatography-mass spectrometry (GC-MS). Eleven different chemical compounds were detected and confirmed. Benzene1,3-bis(1,1-dimethylethyl) was the only compound detected in all four systems at levels of 100% and 75% ethanol. Statistically, insignificant differences were detected among the different systems where leaching was confirmed. Eon® system was the only material to show statistically significant differences when comparing the number of leached substances among the immersion solution concentrations. The four included systems showed variable degrees of leaching. The lowest amount of leached chemicals was observed in relation to the Invisalign® system, while the highest number was found in the Eon® system. None of the included clear aligner systems leached detectable amounts of bisphenol-A (BPA).
Keywords: benzene; chemical compound; clear aligners; gas chromatography–mass spectrometry; leaching.