SHEAR MODULUS - MEASUREMENT METHODOLOGY WITH APPLICATION TO LIGHT-CURED RESIN COMPOSITES

Objectives. This study was conducted to test a novel methodology for s hear modulus determination of light-cured resin composites. Methods. U sing a butterfly-shaped specimen, a special loading device was able to apply pure uniform shear stress on a significant region of the specim en. Validation of the method was proven by photoelastic experiments. S hear modulus was directly obtained through shear stress-strain curve w here the strains were measured by a shear strain gauge rosette. The co mposite materials analyzed were one microfill (Silux Plus, 3M Dental P roducts) and four hybrids (Brilliant, Coltene; Herculite XRV, Kerr; Z- 100, 3M Dental Products; Graft LC, GC). An analysis of variance was us ed to evaluate the G modulus (p < 0.01). Results. Modulus values varie d between 2.54-8.01 GPa. The microfilled material presented the lowest value, and Graft LC presented the highest value. A statistically sign ificant difference was found between all materials (p < 0.01). Signifi cance. The described methodology can also be applied to other restorat ive materials, as well as to adhesion strength measurements.