Variations of radiographic images of dental luting cements and composite posts depending on their composition and radiographic system used

Objectives. According to the International Standard Organization (ISO), the radiopacity of luting cements and dental posts should be equal to or greater than that of aluminum. The aims of these in vitro studies were: to determine the radiopacity of 13 commercially available dental luting cements and compare it with that of human enamel and dentin, to investigate the capacity of various radiopacifying agents to produce the difference in radiopacity on film and a CCD - based digital sensor, to evaluate the radiopacity of seven commercially available dental posts and determine the minimum radiopacity value necessitated for their clinical evaluation and to determine the threshold radiopacity value for detection of small thicknesses of dental luting cements in adjacent to implant abutment. Materials and Methods. Five classes of luting cements were evaluated: zinc phosphate (Cegal N and Harvard Zinc Phosphate), zinc polycarboxylate (Harvard Polycarboxylate and Hoffmann’s Carboxylate), glass ionomers (Ketac Cem Easymix, Ketac Cem Radiopaque and Fuji I), resin-modified glass ionomer (Rely X Luting), and resin cements (Multilink Automix, Variolink II, Speed CEM, Rely X Unicem Automix and Variolink Veneer). Teeth slices served as controls. Five specimens of each material measuring 8 mm in diameter and 1 mm thick were prepared and radiographed alongside tooth slices and an aluminum stepwedge using a Trophy Radiovisiography (RVG) sensor (Trophy Radiology, Cedex, France). The radiopacity values were expressed in mm Al and analyzed by the ANOVA and Tukey tests (P 0,05). Zinc phosphate, zinc polycarboxylate, and three of the resin cements presented radiopacity values that were significantly greater than that of enamel (P 0,05), but it was significant with respect to radiopacifier (P 0,05). Minimum radiopacity value of cement excess required for visualization of 0,1 mm thick cement overhang was 2,2 mm Al on conventional radiography and 1,7 mm Al on digital sensor. Conclusions. Almost all the investigated dental cements presented an acceptable radiopacity. Radiopacity of dental cements seems to depend more on the presence of elements with high atomic numbers than on the type of the material. Materials which incorporate CHI3 or BaSO4 as a radiopacifying agent are expected to be significantly more radiopaque on digital sensor than on film. All examined posts exceed the minimum ISO guideline of 1 mm of aluminum per millimeter of material and can be considered sufficiently rad