Radiopacity of dental cements

The radiopacity of zinc phosphate, polycarboxylate and glass ionomer dental luting materials was determined and the values were compared with those of tooth substrates. The radiographs of the 2 mm thick specimens were taken together with tooth slices and pure aluminum step wedges. The radiographic density of the specimens was measured using a densitometer and expressed in terms of the equivalent thickness of aluminum per unit thickness of material. All the zinc phosphate and polycarboxylate cements showed radiopacity values greater than that of enamel (3.5), while one glass ionomer material showed a radiopacity value lower than that of dentin (2.0). A radiopacity value greater than 3.5 may be desirable for the detection of luting materials or for their distinction from decayed tooth structure on the dental radiograph.