Comparative evaluation of salivary bisphenol A levels in patients wearing vacuum-formed and Hawley retainers: An in-vivo study

•Retainers fabricated from thermoplastic materials could release BPA.•BPA in saliva was assessed with vacuum-formed, heat-, and chemical-cure retainers.•BPA levels increased in all groups after placement of the retainer.•BPA level in saliva was greatest for vacuum-formed retainers.•BPA level in salive was lowest for heat-cure Hawleys retainers.

IntroductionThe aims of the study were to evaluate and compare the bisphenol A (BPA) levels in saliva in patients using vacuum-formed retainers or Hawley retainers.MethodsForty-five patients who had completed their fixed orthodontic treatment and were entering the retention phase were randomly allocated into 1 of 3 groups: vacuum-formed retainer, Hawley retainer fabricated by heat cure, and Hawley retainer fabricated by chemical cure. Saliva samples were collected immediately before placement, within 1 hour after placement, 1 week and 1 month after placement. Statistical analyses were performed by using 2-way analysis of variance and post-hoc multiple-comparisons Tukey HSD tests.ResultsStatistically significant BPA levels in saliva were found for all groups (P ≤0.05). The highest levels were noted in the vacuum-formed retainer group, followed by Hawley retainers fabricated by chemical cure; the lowest levels were found with Hawley retainers fabricated by heat cure.ConclusionsWith many options available for removable retainers, clinicians should consider the BPA release from these retainers; a Hawley retainer fabricated by heat cure is a favorable choice.