The effect of a shear load on the viscosities of 10 vinyl polysiloxane impression materials.

The viscosities of 10 vinyl polysiloxane impression materials with and without the effect of a shear load were studied. Samples of each impression material were divided into two groups. An initial shear load of 5.12 rpm was applied to group A samples for 10 seconds. No shear load was applied to group B samples during the same interval of time. The viscosities of two groups of samples were compared at 60 seconds. Results indicated that there were statistically significant differences among the group A or B samples of the impression materials. There were no statistically significant differences between the group A and B samples of five impression materials. The group A samples displayed significantly lower viscosities than group B samples for two impression materials. The group A samples also displayed significantly higher viscosities than group B samples for three impression materials. It was concluded that the effect of a shear load had no consistent effect on the viscosities of a group of vinyl polysiloxane impression materials.