Working time of synthetic elastomeric impression material.

This study will introduce a new method for measuring the working time of elastomeric impression materials, taking into account the perceived shortcomings of existing systems for evaluating these times. The working times of various commercially available polysulfide, addition reaction silicones and polyethers were determined at room temperature (20 degrees C), following storage in a refrigerator (6 degrees C), and at mouth temperature (35 degrees C). At room temperature, the polysulfides demonstrated the longest working times and the silicones the shortest. Both the polysulfides and the silicones had longer working times following storage at 6 degrees C for 24 hours. However, the polyethers were found to be unusable at this temperature. All the impression materials had shorter working times when placed into the testing apparatus, which had been heated to mouth temperature.