The purpose of this study was to investigate the rheological properties of a syringe type agar impression material, a zinc oxide eugenol impression patste and 6 types of elastomeric impression materials.
Boiled agar impression material was cooled from 80℃ to 32℃, and its viscosity was measured during the temperature decrease at three different shearing rates. Viscosities of unmixed impression pastes were measured at three different temperature
conditions ad three different shearing rates. Impression materials were mixed at 23 and 30℃, and the viscosities were measured as a function of elapsed time from mixing. At 30℃ mixing condition, viscosities of condensation silicone rubger
impression
materials were measured with the variation of base/catalyst ratio, and viscosities of addition silicone rubber impression material with the varying amounts of retarder were measured.
@ES The results are as follow:
@EN 1. In all impression materials, viscosity values were decreased as the shear rate increased (P<0.05).
2. Viscosity of agar impression material was increased rapidly when the temperature decreased below 42℃ (P<0.05).
3. Viscosities of unmixed impression materials were decreased by the increased temperature. Condensation and addition silicone rubber impression materials showed low viscosities, and polysulfide impression materials showed moderate viscosities,
and
polyether and zinc oxide eugenol impression materials showed much higher viscosities than other impression materials.
4. As the room temperature increased, the mixed impression materials showed significantly rapid increase of viscosities during the same lapse of time (P<0.05).
Polysulfide rubber and zinc oxide eugenol impression materials retained low viscosities for longer time in the course of setting. Ramitec, polyether rubber for bite registration, attained high viscosity within short elapsed time. On the other
hand,
Impregum-F polyether rubber impression material showed slower increase of viscosity than condensation and addition silicone rubber impression materials.
5. Viscosities of condensation silicone rubber impression material reacted sensitively with the variation of base/catalyst ratio (P<0.05).
6. Addition silicone rubber impression material mixed with 2 drops of retarder per 5 cm pastes showed no significant difference in viscosity compared with normal mixing condition (P>0.05), but 4 drop-added mix showed significant decrease in
viscosity
compared with normal mixing group (P<0.05)
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