Dynamic viscoelastic properties and the age changes of long-term soft denture liners

The dynamic viscoelastic properties of long-term soft denture liners were m easured over a wide range of frequencies using a dynamic viscoelastometer b ased on a non-resonance-forced vibration principle. Changes in properties o ver a 3 yr period have also been monitored. One acrylic material, one fluor oelastomer, one heat cured silicone and one self-curing addition silicone w ere used. Complex dynamic tensile modulus (E*), tensile storage modulus (E' ), tensile loss modulus (E") and loss tangent (tan delta) were determined o ver the frequency range from 0.01 to 100 Hz on administration of a 0.27% st rain at 37 degrees C. The dynamic viscoelasticity of the acrylic and fluoro elastomer products was more sensitive to changes in frequency than that of silicone products. The acrylic material and fluoroelastomer exhibited visco elastic behaviour whilst silicones exhibited elastic behaviour. The silicon e products remained unchanged after soaking for 3 yr whilst the acrylic and fluoroelastomer products underwent significant change. (C) 2000 Elsevier S cience Ltd. All rights reserved.