Radiopacity of fiber-reinforced resins

To investigate the radiopacity of three fiber-reinforced composite (FRC) materials using digital analysis to determine the mean gray values (MGVs) of the materials. The FRC materials tested were everStick, Interling, and Ribbond. Five sample discs of 5-mm internal diameter and 2-mm depth were prepared for each group, and 2-mm-thick tooth slices were cut transversally from five freshly extracted, intact human molar teeth. All samples, including dentin discs, were exposed to a 99% pure aluminum (Al) step-wedge with five 2-mm incremental steps. The films were scanned, and on each image, a 50 x 50 pixel region of interest was selected at the center of each test sample and on each step of the step-wedge. The MGV of each sample and the Al step-wedges were measured by using the histogram function of the software. Then, the mean MGV of each sample was calculated. In total, 180 readings were analyzed with ANOVA and Tukey's test. In all tests, alpha was set at 0.05. The differences among all test materials were statistically significant (p < 0.001). The radiopacities of everStick, Interling, and Ribbond were equal to that of 1.10, 0.87, and 0.65 mm Al, respectively. All materials were less radiopaque than 2-mm-thick Al and dentin. It is known that the radiodensity of a resin-based restorative material should be higher than that of dentine and similar to or slightly greater than that of enamel. Unfortunately, none of the materials tested in the present study satisfied these requirements.