Radiographic interpretation of the periapical region is considered to be inconsistent, with a wide variation between observers. Toward improving the interpretation of this important region, the influence of 18 radiographic features on the consistency and reliability of interpretation of this are was investigated. Fifty-six radiographs of healthy and pulp diseased (vital and nonvital pulps) teeth were interpreted by 10 dentists. Results indicated that the pattern, size, and density of bone trabeculae are the best radiographic features for identifying "healthy" teeth. The lamina dura's continuity and shape and the periodontal ligament's width and shape were the most consistent features for diagnosis of teenth with nonvital pulps. Radiographic interruptions in the continuity of the lamina dura were detected by all observers; nevertheless, this important finding was not strongly considered in the overall interpretation assessment. Variations in interpretation were found among observers; however, these variations were decreased by using mean observers' opinions for interpretation. In addition, interpreting independently the lamina dura continuity, shape and density, and the periodontal ligament width and shape proved to be the best radiographic features reducing interobserver variations and provided the dentist with a more constant and correct diagnosis.