Micro-CT assessment of comparative radiopacity of adhesive/composite materials in a cylindrical cavity.

This study was performed to evaluate the comparative radiopacity of adhesive/resin composite materials in cylindrical cavities using micro-computed X-ray tomography (muCT). The two-step self-etch adhesive systems, Clearfil SE Bond (SE) and FL-Bond II (FL), and flowable resin composites, Beautifil Flow F10 (BF) and Clearfil Majesty ES Flow High (MJ), were used. The radiopacity of bovine tooth structures and restorative materials was measured by muCT. In addition, cylindrical cavities prepared in bovine teeth were restored with the following adhesive/composite combinations: SE-BF, SE-MJ, FL-BF, and FL-MJ. The mean gray values of the composite restorations were calculated. The threshold values of the muCT images were evaluated using the Otsu's thresholding method. The current results show that the comparative radiopacity of the materials and tooth structure varied, which affected distinguishing the muCT images of the composite restorations in the cylindrical cavity. The proper combination of restorative materials should be considered when conducting in vitro muCT assessments of composite restorations.