# Bisphenol A Release from Fiber-Reinforced vs. Conventional Stainless-Steel Fixed Retainers: An In Vitro Study

## TL;DR

This study compares bisphenol A (BPA) release from different types of dental retainers in a lab setting.

## Contribution

It is the first in vitro study comparing BPA release from fiber-reinforced and stainless-steel retainers over a month.

## Key findings

- Polyethylene and glass fiber retainers released higher BPA levels than stainless-steel retainers.
- BPA concentrations were highest after one month, but differences between retainer types were not statistically significant.
- The study used liquid chromatography–tandem mass spectrometry to measure BPA release at multiple time points.

## Abstract

Objectives: The objectives of this study were to investigate in vitro BPA release from two common fiberglass fixed lingual canine-to-canine retainers and to compare these amounts with those released from a conventional multistranded stainless-steel orthodontic retainer. Methods: Fifty-four recently extracted teeth were divided into groups of six teeth each, formed in an arch shape. Three different retainer types were evaluated: Ribbond, EverStick Ortho and Wildcut wire. Three identical specimens were constructed for each retainer type. BPA release was determined with validated the liquid chromatography–tandem mass spectrometry method at 1 and 24 h, as well as at 7, 14 and 30 days. The method’s limits of detection and quantification were 0.32 ng/mL and 0.96 ng/mL, respectively. A two-way mixed, repeated-measures analysis of variance with Greenhouse–Geisser correction was employed to verify the existence of any significant differences. Results: Higher levels of BPA were released from the polyethylene fiber and glass fiber retainer in comparison with the conventional retainer in the present study. The differences between the systems over time were not statistically significant at the 95% confidence level. Conclusions: In vitro BPA release during the first month did not differ between the examined retainer types. The highest BPA concentrations were observed at 1 month.