Abstract
Ca(OH)2 has been used commonly as root canal filling material, liner and pulp capping material, and its pathological characteristics have been well studied previously.But its physical properties, which influence the handling of this material significantly, were not studied very much in the past.So, in order to accumulate fundamental data on the fluid behavior of Ca(OH)2-H2O system, the relation between shear rate and shear stress of this system was studied.Ca(OH)2 and H2O were mixed at the following rate:0.80g/ml, 0.75g/ml, 0.70g/ml, 0.65g/ml:and were measured at the temperatures 20℃, 30℃ and 37℃.When the Ca(OH)2-H2O system was given constant shear rate, the shear stress decreased gradually as the time elapsed.Then the shear rate was varied to 5rpm, 10rpm, 20rpm, 50rpm, and 100rpm, and the shear stress was measured respectively.From these result, a hysteresis loop was plotted according to Umeya's method, and the loop showed thixotropy.The strength of this flow increased as the amount of Ca(OH)2 increased, and decreased as the temperature rose.Thixotropy was influenced largely by the amount of Ca(OH)2 and slightly by the change of temperature.
