Biological significance of long-term bisphenol A release in the saliva of patients wearing orthodontic appliances: A systematic review and meta-analysis

Orthodontic appliances contain Bisphenol A and are controversial due to its potential risks for human health. Thus, the aim of the present research was to identify the presence of Bisphenol A in the saliva of patients wearing orthodontic appliances. A systematic search of the literature was conducted in four electronic databases (PubMed, Embase, Scopus, and Web of Science) and a manual search of grey literature. Research was done up to March 2023, without language restrictions. Based on inclusion/exclusion criteria, data were extracted by two independent reviewers. A total of 2293 potentially eligible articles were identified, of which 8 were finally included. The studies included a total of 238 patients and showed a moderate quality in the PEDro scale. All the devices studied released Bisphenol A into the saliva, with the polycarbonate brackets being the ones that released it for a longer time. The most significant increase occurred in the first 30 minutes after bonding with composites, reaching 697 µg/g. with polycarbonate brackets. Although a statistically significant increase of Bisphenol A levels in the saliva of orthodontic patients were found, this increase does not exceed the maximum allowable daily intake. Thus, the use of these materials can be considered safe for human health. BPA, Bisphenol-A, cytotoxicity, Orthodontic materials, Composite resins.