Abstract
The working and setting times, viscosity, elastic recovery, elastic modulus, hardness and dimensional change of ten denture base soft lining materials were measured. The endurance of these materials was examined using a thermal cycling test. Moreover, effects of voids caught in the material on these physical and mechanical properties and endurance were investigated.
The working time was 2.5 to 17.0 min, the setting time 3.8 to 14.3 min. For two silicones, the viscosity was markedly increased after the start of measurement. Six materials showed a more than 90% elastic recovery at 2-9 min after the start of mixture. The elastic modulus for acrylates and silicones was 3.57×106 to 9.01×106 dyne/cm2. These values were nearly equal or lower than that for oral soft tissue(0.7-4.4×107 dyne/cm2). In dimensional change, four acrylates showed expansion. The materials with no voids had a higher elastic modulus and hardness, and lower dimensional change than those of the materials with a large number of voids. After the thermal cycling test, the surface roughness, weight change and gel strength change of acrylates and silicones with a large number of voids were larger than those of materials with no voids. These findings show that the presence of voids affects the endurance of materials.
