The purpose of this study was to investigate the level of the radiopacity of composite resins, glass ionomers for filling and cements, and to determine the optimum level of radiopacity that is the most appropriate for the radiologic diagnosis of secondary caries. The experiments were performed in two parts.
In the first part, the radiopacities of specimens of seven composite resins, two glass ionomers and four cements were measured by densitometer and those of the combined specimens were also measured. In the second part, caries was simulated by grooves of the depth of 0.5, 1.0, 1.5, 2.0mm in aluminium blocks of 4mm. thick. Specimens of 2, 4, 6mm. thick were mounted on the caries simulation block, and the differences of radiopacities between caries portion and noncaries portion were analyzed.
The following results were obtained :
1. The radiopacity of dental materials at 2mm thickness displayed a wide range of radiopacity, from 1.14 to 11.70mm. aluminium equivalents.
2. Most of the cements showed significantly higher radiopacity values of 8.78 to 11.70mm. aluminium equivalents, and those of ZPC were higher than any other materials used in this study.
3. Filling materials with radiopacity similar to enamel showed a tendency to have a sufficient degree of contrast facilitate the detection of underlying recurrent caries.
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