Comparison of some properties of polyether and polysulfide materials.

Based on the present measurements on working time, setting time, and compression set of polyether and polysulfide materials, the following observations were made: 1. The manufacturer recommends a working time for polyether that is approximately 40 seconds more than that indicated by the clinical or ADA test. 2. Clinically, if more working time is desired, polysulfide impression material should be used. 3. Polysulfide material is more sensitive to temperature change than the polyether material. 4. If the material is allowed to set longer, the percentage change in compression set decreases. 5. For polyether, an increase in setting time of 2 minutes will significantly reduce the distortion of the impression upon removal.