Direct digital radiography versus conventional radiography for estimation of canal length in curved canals

A recent development in direct digital radiography (DDR) has made it possib le to make additive multiple point (click) measurements of onscreen images. Canal length was examined using four estimation methods: measurement of a conventional D-speed film radiograph, and onscreen DDR allowing two clicks, six clicks, and an unlimited number of clicks of the measuring device. Thi rty extracted human teeth with root curvatures ranging from 7 degrees to 47 degrees (Schneider method) were examined. Actual canal length was measured using a millimeter rule and x2 magnification. Teeth were mounted and prepa red for conventional and DDR imaging. Estimated canal length was determined by three board-certified endodontists using each of the four techniques. A two-way analysis of variance indicated that all radiographic techniques re sulted in canal lengths that were significantly different from the true can al length, and there was no significant difference between experimental gro ups, regardless of the canal curvature.