Assessment of external root resorption using digital subtraction radiography.

Digital subtraction radiography was investigated for its capability to detect and quantify experimentally produced external root resorptive defects in teeth. Using a long source to object X-ray technique and E-speed film, serial radiographs of teeth with artificial lesions in a dry human skull (soft tissue simulated) were obtained. Receiver operating characteristic analysis was used to evaluate the diagnostic performance for each imaging system (conventional versus subtraction). To explore the quantitative assessment potential of digital subtraction radiography, images were produced after sequential demineralization by HCl. The acid solution was analyzed for calcium concentration by atomic absorption spectrophotometry. Three-dimensional histogram quantification for each subtracted image was performed. In overall performance for detecting experimentally produced external root resorption, digital subtraction radiography was found to be significantly superior to conventional radiography. In addition, digital subtraction radiography can provide quantification of experimentally produced external root resorptive defects.