Physical and Mechanical Properties of Denture Base Soft Lining Materials

Abstract

The working time and setting time, viscosity, elastic recovery, elastic modulus, hardness(H_DA)and dimensional change of 10 commercial denture base soft lining materials(5 acrylates, 3 silicones, 1 fluoro polymer and 1 olefin polymer)were measured.The working time for the six materials examined ranged from 2.5 to 17.0 min, the setting time ranged from 3.8 to 14.3 min.In the case of two silicones, the viscosity was markedly increased after the start of measurement.Six materials reached above 90% of elastic recovery at 2〜9 min after the start of mixing.The elastic recovery for two silicones at 30 min was nearly 100%.The elastic modulus ranged from 1.51×10⁶ to 2.74×10⁶dyne/cm².These values were lower than those obtained for the oral soft tissue(0.7〜4.4×10⁷dyne/cm²).Olefin polymer and one acrylate(heat cured)had a higher hardness value than the other materials.For acrylates, the values of elastic modulus and hardness increased with time(30 day).In dimensional change, four acrylates showed expansion for 2〜5 hr after the start of mixing.