An investigation of the rheological properties of 10 vinyl-polysiloxane impression materials.

PURPOSE

The time required for 10 vinyl-polysiloxane impression materials to reach a viscosity of 5000 poise (Tcv) was estimated. This viscosity was selected based on previous work that suggested that an impression material might not be workable if its viscosity exceeded this limit. The effect of variations in the time of placement of the impression materials into a simulated oral-temperature environment was also studied.

MATERIALS AND METHODS

The change in the viscosity of the impression materials was recorded with a viscometer at oral temperature. Impression materials were placed at either 20 seconds, 30 seconds, or 40 seconds from the start of mixing.

RESULTS

There were statistically significant differences in Tcv among various impression materials. Variations in placement time significantly affected the Tcv of six impression materials.

CONCLUSIONS

Knowledge of the viscosity change of an impression material is beneficial in the clinical selection of an impression material.