Comparison of two methods for radiometric evaluation of resin-based restorative materials

Objectives: To compare radiographic densitometry with indirect digital image analysis for evaluating the radiopacity of nine different resin-based restorative materials. Methods: Discs of amalgam and nine different resin-based restorative material, 10 mm in diameter and 2 mm thick. were radiographed together with 2 mm thick discs of intact and carious human teeth and an aluminium stepwedge. Density was evaluated by digital transmission densitometry and with the histogram function of an image analysis programme (Image Tool 1.27, University of Texas Health Sciences Center, Texas, USA) following the digitization of the radiographs with a drum scanner. Results: The two methods produced essentially similar results. With both methods, Dyract (Dentsply De Trey, Konstanz, Germany) had the highest radiodensity and Estilux Hybrid (Kulzer, Werheim, Germany) the lowest. Conclusion: Digital image analysis is a suitable alternative to transmission densitometry for evaluation of the radiopacity of restorative materials.