Objectives: To compare radiographic densitometry with indirect digital image analysis for evaluating the radiopacity of dental materials and structures. Methods: Samples of 6 polymeric materials measuring 5.0 mm in diameter and 2.9 mm thick were prepared in duplicate from a stainless steel matrix. Additional samples of amalgam and discs of human teeth of the same thickness were obtained. The samples were arranged on a Insight dental film (Kodak) and radiographed (Spectro, Dabi Atlante) at 70 kV, 10 mA for an exposure time of 1 s. After development, the optical densitiy of all the materials was determined by digital transmission photodensitometer (MRA, Brazil) and by an image analysis program (Adobe Photoshop 6.0), using the histogram function after scanning (HP Deskjet 4C/T) and digitalization of all radiographs (n=12). Regression analysis was used to correlate radiopacity readings obtained from the two methods. Results: Overall radiopacity indexes of the two methods were highly correlated (R²=0.99, p<0.0001). Radiopacity ranking of the materials was the same for both methods. Correlations for individual materials were as follow: Film Base R²=0.012, Permit C/SDI R²=0.028, Durafill VS/Kulzer R²=0.096, Enamel R²=0.476, Freedom/SDI R²=0.585, Z-100/3M R²=0.593, Dentin R²=0.623, Prodigy/Kerr R²=0.627, Fill Magic/Vigodent R²=0.744, ArtGlass/Kulzer R²=0.787. Conclusions: Both methods were able to distinguish and rank different degrees of radiopacity between materials, however lower correlations were found at the extremes of the radiopacity spectrum.

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