Abstract:
During working time the flow properties of elastomeric impression materials are essentially influenced by their storage and material temperature, respectively.
The purpose of this work was to study the influence of temperature on the setting of the respective impression material and the presentation in flow diagrams. The tests have been realized by means of the so-called Shark Fin device, modified by integration in a test-setup with a laser distance-measure device. Three A-silicones- and one polyether have been tested. Test series were carried out at 6 times (start of measurement 30, 60, 90, 120, 150 and 180 s) after the start of mixing, each at storage and material temperature, respectively, of 18, 21, 25 and 28 °C. During polymerization the flow properties of the impression materials were written in flow diagramms (shark fin mold depending on time). As a definition for maximum working time, a limit for a minimum flow time (sinking time of the shark fin mold into the paste) of 2 s was taken.
The study confirmed the high influence of the material temperature on the flow properties and the polymerization, respectively. Clinically relevant is the fact, that the working time (defined by limit values at 21 °C) of the tested three A-silicones is below 120 s and of the polyether above 180 s.