Shahab-ud Din, Muhammad Hassan, Sandra Parker, Mangala Patel.
Setting characteristics of three commercial vinyl polysiloxane impression materials measured by an oscillating rheometer.
Pak Oral Dental J Jan ;36(3):524-8.

The aim of this study was to determine the setting characteristics of three commercial vinyl polysiloxane (VPS) impression materials at two different temperatures (23ºC and 37ºC). The objects were to investigate the effect of temperature and to compare the setting profile of these materials with each other using an oscillating rheometer. The three commercial VPS used were Aquasil Ultra Monophase (Aq M), Elite HD Monophase (Elt M) and Extrude Medium bodied (Extr M). For each material (n=5), 2 g VPS was extruded on to the lower plate of the rheometer and then the upper plate was positioned on top. The temperature was controlled using a thermostatically controlled water bath. Working time was calculated as 95% of the full trace recorded and setting time when the trace became parallel. Increasing the temperature significantly decreased the working and setting time for all materials tested. At 23ºC there was no significant difference between the working time of Aq M and Extr M, which were significantly longer than Elt M. Extr M had the highest mean working time at 23ºC and Elt M had the lowest mean working time. At 37ºC the working time for Elt M was significantly shorter than Extr M and there was no significant difference with Aq M. The setting and working time for Elt M at 23ºC and 37ºC were significantly shorter compared with Aq M and Extr M. Aq M and Extr M at 23ºC showed no significant differences. The working and setting time of all the materials were temperature dependent.

PakMediNet -Pakistan's largest Database of Pakistani Medical Journals - http://www.pakmedinet.com