Radiographic detection of overhangs formed by resin composite luting agents

Objectives: An in vitro model was used to assess the ability of standard radiographic techniques to detect marginal overhangs of resin composite luting agents beside porcelain and resin composite inlays. Methods: The radiodensity of five commercially available luting resins was determined using ISO 4049 methodology. For four of the luting agents, artificial overhangs (0.5 × 0.5 × 2 mm) were created at the cervical margin of standard resin composite and porcelain inlays. Radiographs were recorded, using wax as a tissue equivalent, and the overhangs reduced incrementally in depth by 0.5 mm with serial images at each depth. The images were assessed in random sequence by three observers. Results: There were significant differences between the radiopacity of the luting resins. These correlated well with the ability of the observers to detect marginal overhangs adjacent to resin composite inlays. Conclusions: Even with the most radiopaque luting material, a substantial marginal ledge could not be detected in association with a radiopaque resin composite inlay. The threshold for detection of the overhang was lower when using a radiolucent porcelain inlay.