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Residual monomer content and its release into water from denture base materials
P K Vallittu1, V Miettinen, P Alakuijala
1Department of Prosthetics and Stomatognathic Physiology, University of Kuopio, Finland.
Objectives:
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).
Significance:
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.