Evaluation of viscoelastic properties, hardness, and glass transition temperature of soft denture liners and tissue conditioner

This study assessed methods for the evaluation of the viscoelasticity and glass transition temperature (Tg) of the silicone permanent soft liner, acrylic permanent soft liner, and tissue conditioner. Three rheological parameters of storage modulus (E′), loss modulus (E′′), and loss tangent (\(\tan \delta\)),Tg, and hardness were determined using dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and the Shore A0 hardness test. Five specimens were measured for each material. The time –temperature superposition principle was applied to produce master curves ofE′,E′′, and\(\tan \delta\) for the tested materials at a reference temperature of 37  °C. The acrylic permanent soft liner and tissue conditioner exhibited viscoelastic behavior and sensitivity to frequency, especially at lower frequencies. The silicone permanent soft liner showed elastic behavior and was frequency-independent.Tg for the acrylic permanent soft liner was higher than that for the tissue conditioner, which in turn was higher than that for the silicone  permanent soft liner for both DMA and DSC. In DMA, a higher frequency led to higherTg values. A positive linear relationship was found between Shore A0 hardness andE′ values, but notE′′ and\(\tan \delta\) values. Shore hardness reflects elasticity, but not viscosity. The results of the present study can be used to improve methods for evaluating the viscoelasticity andTg of soft denture liners and tissue conditione...

Source: Odontology - December 4, 2019 Category: Dentistry Source Type: research