Age changes in the viscoelasticity of a temporary soft lining material

The viscoelastic properties of a widely used temporary soft lining material have been monitored in vivo and in vitro using a force distance probe. Over a period of 8 weeks' clinical use, Coe Soft demonstrated a significant and continued reduction in compliance with time, the reduction being particularly rapid over the first week. These changes were not associated with a reduction in measured lining thickness for which significant changes were not found. In vitro immersion in water, saline or artificial saliva was characterized by a rapid and significant reduction in compliance values over the first week. Further continued reductions in compliance values were only observed in artificial saliva over 8 weeks, and on prolonged immersion in distilled water over 96 weeks. All reductions in compliance were significantly less than those seen clinically.