Evaluation of conventional and digital radiography capacities for distinguishing dental materials on radiograms depending on the present radiopacifying agent

Bacgroun/Aim. The radiopacity of an endodontic material can considerably vary as measured on film and a digital sensor. Digital radiography offers numerous advantages over convential film-based radiography in dental clinical practice regarding both diagnostic capabilities and postintervention procedures. The aim of this study was to investigate the capacity of conventional and charge-conpled device (CCD) based digital radiography to detect material on radiograph depending on the radio-pacifying agent present in the material. Methods. Experimental cements were formulated by mixing Portland cement with the following radiopacifying agents: zinc oxide (ZnO), zirconium oxide (ZrO2), titanium dioxide (TiO2), barium sulphate (BaSO4), iodoform (CHI3), bismuth oxide (Bi2O3) and ytterbium trifluoride (YbF3). In addition, 5 endodontic materials comprising Endomethasone (R), Diaket (R), N-2 (R), Roth 801 (R) and Acroseal (R) were investigated to serve as control. Per three specimens of each material were radiographed alongside an aluminum step wedge on film (Eastman Kodak Company (R), Rochester, NY) and a CCD-based digital sensor (Trophy Radiologie (R), Cedex, France). Radiopacity values were calculated by converting the radiographic densities of the specimens expressed as a mean optical densities or mean grey scale values into equivalent thickness of aluminum. Results. Two-way ANOVA detected no significant differences with respect to the imaging system (p > 0.05), but the differences were significant with respect to radiopacifier (p < 0.001) and the interaction of the two factors (p < 0.05). Paired t-test revealed significant differences between the methods used for pure Portland cement, all concentrations of BaSO4 and CHI3, 10% and 20% additions of ZrO2 and Bi2O3 and 10% and 30% addition of YbF3 (p < 0.05). Conclusion. The materials which incorporate CHI3 or BaSO4 as radiopacifying agents are expected to be significantly more radiopaque on a digital sensor than on film. During clinical practice one should concern to the quality of contrast assessement obtained by digital according to conventional radiography.