Surface properties of elastomeric impression materials.

This study investigated the wettability of commonly used elastomeric impression materials and their gypsum castability. The wettability was evaluated by determining the contact angles of drops of a CaSO4 aqueous solution on flat impression surfaces. Gypsum castability was determined by counting the number of voids formed in die stone casts made from impressions of a critical die. All specimens used in this study were exposed to saliva to simulate clinical conditions, where materials spontaneously acquire salivary origin biofilms. The results indicate that the condensation silicones and conventional addition silicones exhibited the largest contact angles and the highest number of voids. The new generation of 'hydrophilic' addition silicones had higher wettability than the conventional silicones and an improved gypsum castability, comparable to that of the polyether materials.