Do clear aligners release toxic chemicals? - a systematic review

The use of advanced polymer materials in clear aligners, such as polyurethane and PET-G, has gained widespread acceptance due to their mechanical properties, biocompatibility and aesthetic appeal. However, concerns persist regarding their potential to release chemical compounds. Our goal is to understand the impact of the toxicity of clear aligners on oral cavity of orthodontic patients. An extensive systematic search was conducted in electronic databases PubMed, Scopus and Cochrane, to identify articles with relevant data. This systematic review will be conducted following the Preferred Reporting Items for Systematic reviews and Meta-analysis guidelines to answer a question formulated according to the Population, Intervention, Com-parison and Outcomes strategy. Four hundred and thirteen articles potentially relevant were identified and after applying PRISMA guidelines 7 articles were included in this review. Our results suggest that clear aligners are generally safe, concerns remain regarding the chemical leaching of thermoplastic materials, bacterial accumulation due to reduced saliva flow, and mild inflammatory responses. Our review empha-sizes that although most materials are biocompatible, some exhibit moderate cytotoxicity, underscoring the need for continued research and improvements in material composition.