An in-vitro assessment of bisphenol a release from thermoplastic orthodontic appliances exposed to various beverages

Thermoplastic orthodontic appliances have been used as retention devices for years and gaining popularity as aligners, alternative to fixed orthodontic mechanics. This study aims to assess Bisphenol-A (BPA) release from thermoplastic orthodontic appliances exposed to different beverages.

The appliances in this study were enrolled from aligners of Invisalign, ClearCorrect, and thermoplastic retention device, Essix ACE. Five different beverages (pure water, whole milk, coke, orange juice, filtered coffee) were determined and 5 glass tubes containing 10 ml of each beverage formed experiment groups. Appliance samples from each brand (with 0.50 ± 0.0082 g weight) were inserted in glass tubes and left in room temperature for 1 h. Later, samples were removed and Flow Injection Liquid Chromatography/Mass-Mass Spectrometry (FIA-LC/MS-MS) analysis was performed to evaluate BPA release. Five glass tubes for each beverage group, which did not contain any appliance, were also analyzed with the same technique to detect the possible pre-existing BPA levels in the liquids.

FIA-LC/MS-MS analysis showed no measurable amount of BPA in pure water and any beverage group. BPA was also not detected in samples without appliances.

BPA release was not detected from thermoplastic orthodontic appliances after 1 h of incubation in beverages. Within the limitations, different types of beverages were not found to affect BPA release from thermoplastic orthodontic materials. From a clinical perspective, further in-vivo studies will be useful with larger samples and longer term investigations.