The comparative detectability of the artificial periapical defects among Ektaspeed Plus film. digitized and digora images was evaluated. The artifical defects were made in the cancellous bone and cancellous-cortical junction with the size of 1.0×0.8mm², 1.4×1.1mm² and 2.8×2.2mm². The defects in cancellous-cortical junction extended into cortical bone with the depth of 0, 0.5 and 1.0 mm. The results were as follows : 1. In junctional defects Ektaspeed Plus film for 2.8×12.2mm² defect showed the highest detectability. But significant difference were only found between Ektaspeed Plus films and digitized images (p<0.05). 2. Almost all defects within cacellous bone were not detected except a few digitized and Digora images for the size of 2.8×2.2mm². Digora images for them showed significant differences with Ektaspeed Plus films and digitized images (p<0.05). 3. The sensitinity of all imaging modalities were 0.9 or 1.0 in junctional defects for the size of 1.4×2.2mm² and 2.8×2.2mm². For cancellous defects, Digora image showed the highest sensitivity of 0.6 for the size of 2.8×2.2mm². 4. Significant differences for change of exposure time were found in most group of Ektaspeed Plus films and digitized images (p<0.05) . But there was no significant differences in Digora images for cacellous defects.