An investigation of the radiopacity of composite restorative materials.

The radiopacity of 33 commercially available composite materials was measured in terms of their equivalent thickness of an aluminum alloy per unit thickness of material. The theoretical significance of this definition was discussed. The radiopacities were found to vary by more than an order of magnitude. Although nearly 30 percent of the materials have radiopacities less than dentine, all materials claimed to be radiopaque were more so than dentine. The influence of operating potential, specimen thickness, X-ray generator type, film type, filtration and X-ray dose were investigated. The former two factors were found to have a large influence on the radiopacity.