Measuring the radiopacity of direct restorative materials to tooth structure using a digital radiography system

Objectives: The aim of this study was to evaluate and compare the radiopacity of conventional resin composites, flowable resin composites, glass ionomer cements, luting cements and endodontic sealers with sound tooth structure and to values reported by the manufacturers.
Methods: Disc shaped specimens (n=4) of direct restorative materials were fabricate in two thicknesses (2 and 3 mm). Digital radiographs were taken together with tooth slice, aluminum step wedge and disk specimens of different materials. Radiopacity values of either enamel or dentin of 2mm thick tooth section was considered as the reference control value. Gray values were obtained from the radiographic images and radiopacity was analyzed using two way ANOVA and Tukey’s test and p < 0.05 was consider statistically significant.
Results: The values of radiopacity for materials ranged from 0.5 to 12.9 for different restorative materials. The radiopacity values of majority selected restorative materials were above the dentin reference radiopacity value. However, some specimens had significantly lower radiopacity values than enamel (p < 0.05). The radiopacity values of different resin-based composites were not very different in contract to luting materials which varies considerably.
Conclusions: Majority of the materials are more radiopaque than enamel and would help in radiographic diagnosis of secondary caries. However, manufacturers’ claims are not always reliable.