SURFACE-PROPERTIES OF ELASTOMERIC IMPRESSION MATERIALS

This study investigated the wettability of commonly used elastomeric i mpression materials and their gypsum castability. The wettability was evaluated by determining the contact angles of drops of a CaSO4 aqueou s solution on flat impression surfaces. Gypsum castability was determi ned by counting the number of voids formed in die stone casts made fro m impressions of a critical die. All specimens used in this study were exposed to saliva to simulate clinical conditions, where materials sp ontaneously acquire salivary origin biofilms. The results indicate tha t the condensation silicones and conventional addition silicones exhib ited the largest contact angles and the highest number of voids. The n ew generation of 'hydrophilic' addition silicones had higher wettabili ty than the conventional silicones and an improved gypsum castability, comparable to that of the polyether materials.