Hamadan University of Medical Sciences Avicenna Journal of Dental Research 2423-7582 8 2 2016 03 01 Using Periapical Radiography to Differentiate Periapical Granuloma and Radicular Cysts 7 7 10.17795/ajdr-30882 EN Farrokh Farhadi Seyed Sina Mirinezhad Ali Zarandi Journal Article 10.17795/ajdr-30882 2015 06 22 2016 01 18 Background: The distinction between radicular cysts and apical granulomas is important in treatment decision. Objectives: The current study aimed to differentiate these two lesions based on radiography images. Patients and Methods: The material consisted of 138 radiographs obtained using Kodak E -speed, in patients aged 29 to 47, divided into two groups: 109 granulomas and 29 radicular cysts. Size of radiography images was measured; the tooth then was extracted and examined in pathologist lab. The results were analyzed by SPSS.15 and ROC curve was created to find cut-off point to differentiate periapical granuloma and radicular cysts. Results: Average size of radiography in periapical granuloma was 7.4 mm and for a radicular cyst was 11.1 mm. Cut-off point was 8.2 mm and the area under curve (AUC) was 0.63. Also, the tests were 83% sensitive and 79% specific. Conclusions: Based on 8.2 mm cut-off point could differentiate 83% periapical granulomas and 79% radicular cysts from radiography images.