Physical and mechanical properties of 18 commercial light-activated composite resins were measured and the correlation between their properties was discussed. Hardness of the material, which was polymerized in accordance with the manufacturer's recommendation, increased considerably after exposure to light and reached approximately constant values after 24 hours. Hardness and elastic modulus were strongly dependent upon the filler fraction. On the other hand, there was no significant correlation between filler fraction and compressive strength. Most of the curing shrinkage was brought together at the bottom part of the cavity, as the light-activated composite resins polymerized from the surface exposed to light.
The resistance to toothbrush abrasion increased according to the increase of inorganic filler content level.