Temperature Effects on the Rheological Properties of Elastomeric Impression Materials

Objectives: Working and setting time of impression materials are important factors for its clinical acting. This study, based on results for storage module (G'), verified the working and setting time of four elastomeric impression materials of regular consistence: Impregum Soft (I), Permlastic (P), Express (R) and Oranwash (O), varying the temperature (15°, 25° and 35°C). Methods: The materials were mixed in a glass plate according to the manufacturers' instructions (n=3) and inserted in the device (a stress-controled rheometer – ARES – Rheometrics) where the test was conducted during the time of 900s. The experiments were conducted with a frequency value of 1.0Hz and strain taxes of 0.1 for Impregum, 1.0 for Permlastic, 0.1 for Express and of 1.0 for Oranwash. Results: The mean values of working time at the temperatures of 35°, 25° and 15°C, respectively, were: I – 54.6s, 55.6s and 130s; for P – 116.3s, 117.6s and 167s; E – 44.6s, 135s and 160s; O – 96.3s, 216.6s and 331.0s. The mean values for setting time at the temperatures of 35°, 25° and 15°C, respectively, were: I - 729s, 855.6s and it did not happen at the temperature of 15°C during the study conducted time; P-645.6s, 869.3s and it didn't happen at 15°C; E - 309s, 574.3s and it did not happen at 15°C; and O - 712.3s, 834.6s and it did not happen at 15°C.

Conclusion: All the materials presented working and setting time altered by the variation in the temperature, and the lowest temperatures turned the cure process slower. By the analysis of the graph of the rheologic behavior, addition silicon was the material that presented the more stable results of setting time