The loss of residual monomer from acrylic orthodontic resins

The paper studies the loss of residual monomer from 6 acrylic orthodontic resins. Gas chromatography was used for the determination of residual monomer in the resin, and ultraviolet spectroscopy for the determination of methylmethacrylate in water. The results showed that high levels of residual monomer were present in orthodontic resins. There was a rapid loss of monomer in the first 24 h of soaking of the specimens in water. This loss continued but shows that high levels of residual monomer remain. It is recommended that in any future Standards Specification there should be an upper limit of residual monomer that is agreed as acceptable.