The influence of admixing microfiller to small-particle composite resin on wear, tensile strength, hardness, and surface roughness.

A series of photo-initiated composite resins, with a Bis-GMA-TEGDMA resin matrix, was investigated in vitro for occlusal wear, surface roughness, diametral tensile strength, and hardness. The materials contained mixtures of ground quartz (macrofiller, 3 microns) and colloidal silica (microfiller, 0.04 micron), with total filler being constant at 68.5% by volume. The study was conducted to determine the influence of an increasing ratio of micro to macrofiller in the mixtures. When the macrofiller was gradually replaced by 3, 5, 7.5, 10, 15, and 20 vol% of microfiller, wear resistance increased substantially, ultimately to a constant level. Any influence on surface roughness or tensile strength and hardness could not be demonstrated.