1994 Volume 13 Issue 6 Pages 552-557
Dynamic viscoelastic properties of commercial resins for crown and bridge were determined using a torsion pendulum apparatus at temperatures ranging fron room temperature(23℃)to 200℃.Dynamic torsional shear moduli(G's)of the materials measured at individual temperatures of 37 and 80℃ were in the ranges of 1.27〜3.85 and 0.72〜3.24GPa, respectively.The G's of each material decreased relative to the increase in temperature, and the reduction in G's(80℃)was in the range of 15.8〜54.9% compared with G's(37℃).When a second run was repeated on the same specimen, G's(37℃)were approximately 1.07〜3.13 times higher than that in the first run.This was due to the decrease in the amount of unreacted substances, as each specimen was heated.The correlation between the Knoop hardnesses 24h from the start of irradiation and G's(37℃)of each material was relatively high(r=0.89).However, there was not an adequate correlation(r=0.41)between the inorganic filler contents(wt%)and G's(37℃).
