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

Introduction: 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.Results: 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.Conclusion: Digital subtraction radiography was superior to direct digital radiography indetecting small external root resorptive defects.Key words: External root resorption, Digital subtraction radiography, Direct digital radiograph