The optimum level of radiopacity in posterior composite resins.

Radiopacity is an indispensable property of composite resins for clinical diagnosis. The level of radiopacity that is most compatible with the radiographic diagnosis of recurrent caries was studied in a two-part experiment. In the first part, 16 composities were evaluated and divided into four groups based on their levels of radiopacity compared with an aluminum stepwedge. In the second part, caries was simulated by grooves of increasing depth in aluminum blocks of a thickness equivalent in radiopacity to enamel and the detectability assessed beneath differing thicknesses of three representative composite resins, P-30, Brilliant Lux and Occlusin. The relative radiographic density was measured and P-30 found to have the greater contrast. It is proposed that composite materials with a radiopacity similar to enamel are best for the detection of recurrent caries.