Purpose: The aim of the present study was to clarify the influence of early setting conditions on the properties of self curing addition silicone resilient denture lining materials.
Methods: Four auto-mix types of commercial self curing addition silicone resilient denture lining materials were used. Agar plates containing various concentrations of methyl mercaptan (MMP) were prepared and cylindrical specimens (10mm in height and 10mm in diameter) of silicone liners were set on the agar plate. The Shore A hardness of the agar-contacted surface of the specimen was measured at 0, 1, 7 and 28 days after stored in 37 degrees C water. The viscoelastic properties (instantaneous elastic modulus, coefficient of viscosity and permanent deformation) of two silicone liners, which showed a great decrease in the Shore A hardness by agar contact, were determined by a creep meter.
Results: The Shore A hardness, coefficient of viscosity, and instantaneous elastic modulus deceased when the specimen was set on the MMP containing agar plate, but the permanent deformation of these specimens increased.
Conclusion: The exposure to MMP at the early setting stage influenced the properties of self curing addition silicone resilient denture lining materials.