Accuracy of Digital Subtraction Radiography in detection of artificial external root resorption (in vitro)

External root resorption refers to the loss of cementum and/or dentin from the rootof the teeth. 40% mineral loss occur in conventional radiographies but digital subtractionradiography is capable of localizing a lesion with only 1-5% mineral loss. This in vitro study aimedto determine the accuracy of digital subtraction radiography in diagnosis of simulated external rootresorption.Methods and Materials: Ten premolar teeth with clinically intact roots were used were fixed insuitable place between the X-ray tube and CCD sensor. Direct digital radiographs were obtainedbefore and after each lesion was created by 1/2, 1, 2, 4 and 6 round dental burs at facial andproximal surfaces; then digital subtraction images were obtained and observers evaluated all of theimages and sensitivity and specificity and accuracy were calculated. Results were compared by J2test. The sensitivity of digital subtraction and direct digital methods in detecting proximaldefects were 97.34% and 93.92% respectively (p value = 0.16). The sensitivity of digital subtractionand direct digital radiography in facial surfaces were 98% and 92.6% respectively (p value =0.03). The specificity of direct digital and subtraction methods in proximal surfaces were 91.92%and 96.52% (p value = 0.08) and in facial surfaces were 91.92% and 99.26% respectively (p value= 0.002). The accuracy of digital subtraction radiography in detecting facial lesion wassignificantly superior to direct digital radiography. Digital subtraction radiography was superior to direct digital radiography indetecting small external root resorptive defects.