Composition of and Leachable Products from Polymer Based Orthodontic Materials

Methods: The materials included in the projects were pre-polymerized plates (Essix Embrace, Essix A, Biocryl C), light cured material (Triad VLC), and powder and liquid type (Orthocryl). The composition of the materials was determined by gas chromatography/mass spectrometry (GC/MS) and high pressure liquid chromatography (HPLC). Cured/processed specimens were immersed in extraction vehicles for 7 days at 37 °C, and the leachable components were identified.

Results: Comparing our results with the information given in the Material Safety Data Sheets (MSDS), additional monomers and additives were found in the orthodontic materials that were not declared in the MSDS. Several of the identified components are potentially hazardous and listed as mutagenic, tumorigenic, irritant, and/or reproductive toxicant in the RTECS data base (Registry of Toxic Effects of Chemical Substances, National Institute for Occupational Safety and Health, USA). It was found that the number and amount of leachable components from pre-polymerized materials were small. In contrast, several components leached out from the light cured and the powder and liquid based materials, among them 2-hydroxyethyl methacrylate (2-HEMA), urethane dimethacrylate (UEDMA), methyl methacrylate (MMA) and N,N-dimethyl-p-toluidine. More leachables were identified in the surfactant solution than in water.

Conclusions: Material Safety Data Sheets are of limited value in terms of understanding the composition of a material. The use of pre-polymerized orthodontic base plate material is favourable in reducing the risk of adverse reactions caused by chemicals leaching from the materials.

This study was funded by the Norwegian Directorate for Health and Social affairs.