AGE-CHANGES IN THE VISCOELASTICITY OF PERMANENT SOFT LINING MATERIALS

Age-related changes in the viscoelasticity of an acrylic-based (Palasi v 62) and silicone (Molloplast-B) permanent soft lining material were evaluated in parallel clinical and laboratory longitudinal studies usi ng a force/distance probe. Changes in the viscoclastic properties of P alasiv 62 in clinical use were characterized by a significant and cont inued reduction in both initial and delayed compliance. That is, the m aterial became harder whilst still retaining the underlying pattern of viscoelasticity seen at baseline. Laboratory immersion in distilled w ater resulted in significant reductions in compliance values. These re ductions were cumulatively similar to those seen clinically but did no t occur as rapidly. There was evidence of small. continued reductions in the measured thickness of clinical linings of Palasiv 62. The clini cal and laboratory compliance of Molloplast-B remained stable over tim e. Ageing did not affect the essential elasticity of this material.