This chapter discusses the unique properties of currently used impression materials and describes how these characteristics affect the quality of an impression and of the cast or model made from the impression. To produce accurate replicas of intra- and extraoral tissues, the impression materials should be (1) sufficiently fluid to adapt to the oral tissues, (2) viscous enough to be contained in a tray, (3) able to transform (set) into a rubbery or rigid solid in the mouth in a reasonable time (less than 7 min), (4) resistant to distortion or tearing when removed from the mouth, (5) dimensionally stable long enough to allow one or more casts to be poured, (6) biocompatible, and (7) cost-effective in terms of time as well as the expense of the associated processing equipment.Įnvironmental conditions and the type of tissue dictate the choice of materials, quality of the impression, and quality of the cast. Which of the seven criteria that ensure accurate impression making are related to the time the impression material is in the mouth? Which one is related primarily to the properties of a set impression?

Impression putty dental