title: Residual monomer content and its release into water from denture base materials.
abstract: OBJECTIVE
  The aim of this study was to determine the content and amount of residual monomer released from heat-cured and chemical-cured polymethyl methacrylate (PMMA) during storage in water.
  
  
  METHODS
  Residual monomer was extracted from ground PMMA with tetrahydrofuran and from the storage water with n-hexane. Samples were analyzed by using HPLC-chromatography. Duration of the storage period in water was up to 8 wk at temperatures of +22 degrees C and +37 degrees C.
  
  
  RESULTS
  Residual monomer content of chemical-cured PMMA was higher than that of heat-cured PMMA. The effect of storage temperature was significant (p<0.001). During the first day of storage at +37 degrees C, the monomer release from chemical-cured PMMA was 1906.7 ppm and from the heat-cured PMMA 34.5 ppm and that release was higher at +37 degrees C than at +22 degrees C (p<0.001).
  
  
  CONCLUSIONS
  This study suggests that the amount of released monomer can be diminished by storing the PMMA product in water for at least 1 d before use, preferably at +37 degrees C.
authors.affiliation: Department of Prosthetics and Stomatognathic Physiology, University of Kuopio, Finland.
authors.forename: P K
authors.initials: PK
authors.lastname: Vallittu
authors.forename: V
authors.initials: V
authors.lastname: Miettinen
authors.forename: P
authors.initials: P
authors.lastname: Alakuijala
mesh_terms: D000704:Analysis of Variance; D003819:Denture Bases; D004356:Drug Storage; D006358:Hot Temperature; D008768:Methylmethacrylates / Q000032:analysis / Q000737:chemistry*; D013997:Time Factors; D014867:Water
chemical_list: D008768:Methylmethacrylates; D014867:Water