Optical X-ray density of composite resin luting agents.

This study verified the optical density of four composite resin luting agents - RelyX ARC (RY), Enforce (E), C&B Cement (CB) and Flow it (FI), at thicknesses of 2, 3, and 4 mm. The optical density of the luting agents was compared with that of enamel and dentin at the same thicknesses. Fifteen tooth crowns were embedded in PVC cylinders with self-cured acrylic resin. In addition, acrylic resin was poured into 5 PVC cylinders and four equidistant 5 mm diameter holes were prepared, with one luting material inserted in each. A laboratory cutting machine was used to prepare 4-, 3- and 2-mm thick slices of the tooth crowns and materials. Digital images were obtained with a Digora system. Three radiographs of each thickness were obtained, totalizing 135 radiographs of the crowns and 45 of the materials. Three readings were carried out on each radiograph: three in enamel, three in dentin and three in each material, totalizing 1350. According to Students t-test (p<O.05), the materials RY and CB did not differ statistically from enamel at any thickness, but differed from E and FI, which had statistically higher results. RYdid not differ statistically from dentin, presenting a lower value than enamel and lower than the other materials at all thicknesses. The composite resin luting agents E and FI can be distinguished from dental structures, while the CB and RY are not easily distinguished.