Synthetic phenolic antioxidants, including butylated hydroxytoluene (BHT), in resin-based dental sealants

Resin-based dental sealants (also referred to as pit-and-fissure sealants) have been studied for their contribution to bisphenol A (BPA) exposure in children. Nevertheless, little attention has been paid to the occurrence of other potentially toxic chemicals in dental sealants. In this study, the occurrence of six synthetic phenolic antioxidants (SPAs), including 2,6-di-tert-butyl-4-hydroxytoluene (BHT), 2,6-di-tert-butyl-4-(hydroxyethyl)phenol (BHT-OH), 3,5-di-tert-butyl-4-hydroxy-benzaldehyde (BHT-CHO), 2,6-di-tert-butylcyclohexa-2,5-diene-1,4-dione (BHT-Q), 3,5-di-tert-butyl-4-hydroxybenzoic acid (BHT-COOH) and 2-tert-butyl-4-methoxyphenol (BHA), was examined in 63 dental sealant products purchased from the U.S. market. BHT was found in all dental sealants at median and maximum concentrations of 56.8 and 1020 µg/g, respectively. The metabolites of BHT and BHA were detected in 39–67% of samples, at concentration ranges of <LOQ to 242 µg/g. BHT is likely used in sealants to inhibit oxidative reactions, remove free radicals, and inhibit potential polymerization, which would eventually prolong the shelf-life of the products. The estimated daily intake (EDI) of BHT, following sealant placement, based on a worst-case scenario (application on eight teeth at 8 mg each tooth), was 930 and 6510 ng/kg bw/d for adults and children, respectively. The EDI of BHT from dental sealants was several orders of magnitude lower than the current acceptable daily intake (ADI) proposed by the European Food Safety Authority (EFSA). - Highlights: • Synthetic phenolic antioxidants (SPAs) were detected in dental sealants. • 2,6-di-tert-butyl-4-hydroxytoluene (BHT) concentration of up to 1020 µg/g was found. • Estimated daily intake of BHT after sealant placement was up to 9.52 µg/kg bw/d. • Daily intake of BHT through dental sealant application was below the acceptable daily intake.