Viscoelastic properties of some soft lining materials - I - effect of temperature

The time dependent, viscoelastic characteristics of a number of dental soft liners (occasionally called resilient liners) were investigated using a dy namic mechanical analyser (DMA). The materials consisted of eight commercia l products including methacrylate, silicone and phosphazine-based soft poly mers as well as two experimental formulations. The DMA used was of the forc ed vibrational variety. The test conditions, such as frequency and temperat ure, were chosen to mimic in use (masticatory) conditions. A wide variety o f behaviour was observed and accounted for. This included a seven fold rang e in the storage modulus (2.79-19.7 MPa) and a 50-fold range in the loss ta ngent (0.029-1.52) at 37 degrees C and 1 Hz. The materials could generally be divided into either rubbery behaviour with low modulus and loss tangent, i.e. the silicones, or leathery behaviour with both higher modulus and los s tangent, i.e. the methacrylates. A search of the literature did not find a universally preferred set of properties, although a possible link with re sidual ridge resorption is indicated. (C) 1999 Elsevier Science Ltd. All ri ghts reserved.