Dynamic mechanical thermal analysis of denture soft lining materials.

The purpose of this study was to characterize the deformation properties of a range of long-term denture soft lining materials using dynamic mechanical thermal analysis. Specimens were subjected to sinusoidal shear deformation at a frequency of 1 Hz and a strain of 64 microns peak to peak over a temperature range of 30-70 degrees C. The technique simulated the type and rate of deformation soft lining materials would experience clinically, thus producing more relevant results than previously used methods. Shear modulus G', dissipative modulus G' and mechanical loss tangent G'/G' were obtained for each material. With increasing temperature the moduli of the acrylic materials decreased, indicating an increased compliance and greater deformation. The silicone (Molloplast B) and alternative formulation (Novus) properties were generally insensitive to temperature over the range chosen. The mechanical loss tangent values of the acrylics fell continuously with temperature, suggesting that the plasticization process lowered the Tg values below 30 degrees C, the lowest temperature of testing.