Thermal diffusivity of composite restorative materials.
The substantial increases in the filler volume fraction of the current generation of composite resins, and the incorporation of radiopacifying heavy elements in many of these fillers, constitute significant changes which may affect thermal transport properties. Thermal diffusivity has been determined for 21 of these composite materials recommended for anterior and posterior applications. For radiopaque hybrid and for microfine composites, there was, however, only a gradual trend to increased thermal diffusivity with increasing volume fraction of inorganic filler. The diffusivity values were not greatly in excess of the level observed for dentin. Nevertheless, a small group of materials, incorporating substantial amounts of quartz or silicon nitride filler particles, exhibited high rates of thermal diffusion, up to three times the level exhibited by dentin.