Some parameters for testing deformation of elastomeric impression materials

Because of conflicting published data, the temperature rise in four elastomeric materials was measured with a thermistor during setting in the oral cavity and in metal and plastic moulds of varying shapes and volumes for ‘elastic set’ specimens. The clinical temperature rise was 2–3°C higher in the molar region than anteriorly, except for the polysiloxane. The temperature range attained in the set materials varied from 29°C to nearly 35°C for clinical and in vitro specimens. The average time taken by a group of operators to remove this type of impression from the mouth was five seconds. In a custom tray with light and heavy viscosity materials, the syringe material layer was only 0–0.15 mm thick and, essentially, the heavy viscosity material provided the elastic components for the impression. 1992 Australian Dental Association