Dynamic Viscoelastic Properties in Torsion of Four Commercially Available Resins for Crown and Bridge.

Abstract

In order to clarify the viscoelastic properties of four commercial resins for crown and bridge, the dynamic shear modulus (G'), Knoop hardness (KHN), filler content, quantity of unreacted substance and thermal expansion were measured. The results were as follows. The G' (37•Ž) of each material ranged from 2.61•`11.1GPa, and gradually decreased with increasing temperature. KHN (23•Ž) ranged from 29.4 to 120, and the most significant correlation (0.999) was found between G' and KHN. Of the relationship among G', filler content and unreacted substance, there was a highly significant correlation (0.980) between G' and filler content. The coefficient of linear-thermal expansion (ƒ¿) also ranged from 17.9•`65.0•~10-6/•Ž (25-60•Ž), and gether with an increase in temperature. Key words: Viscoelastic property, Resin for crown and bridge, Thermal expansion VISCOELASTIC PROPERTIES OF CROWN RESIN to those of resin composites because of the similar ingredients and composition. Furthermore, it is generally known that resins for crown and bridge are viscoelastic, and that viscoelastic properties are affected remarkably by experimental conditions such

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