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.