Objective: This study investigated the radiopacity of six commercially available flowable composites by using a digital image analysis method to determine the mean gray values of the materials.
Methods: The flowable resin composites evaluated in this study were Clearfil Majesty Flow, Estelite Flow Q, Tetric N Flow, Esthet X Flow, Filtek Supreme XT Flow and Gradia Direct LoFlo. Ten sample discs (6 x 1 mm) for each group were prepared and 1-mm thick slices were obtained from freshly-extracted teeth for the control group. The mean gray values (MGVs) of each specimen and aluminum (Al) stepwedge were measured by using the histogram function of a computer graphics program. Analysis of variance (ANOVA) was used to investigate the significance of the differences among the groups. For pairwise comparisons, the Tukey test was applied (alpha=0.05).
Results: The radiopacity values of Gradia Direct LoFlo, dentin and Estelite Flow Q were close to that of 1 mm Al. Tetric N Flow and Cl Majesty Flow were more radiopaque than enamel, whereas Filtek Supreme XT Flow had a similar radiopacity to enamel.
Conclusion: The radiopacity of flowable composites varies considerably, and care must be taken when selecting an appropriate material to enable secondary caries detection under posterior composite restorations.