Endodontic recall radiographs: how reliable is our interpretation of endodontic success or failure and what factors affect our reliability?

Three hundred thirty cases were selected from an endodontic practice. Postoperative and recall radiographs of each case were examined by four endodontists for an interpretation of treatment success or failure. One hundred eighteen cases were examined a second time by each endodontist. Initial analysis showed substantial inconsistency in both inter- and intraobserver interpretation. The cases were then categorized by average radiographic density differences within radiograph sets, anatomic location of the treated tooth, technical compatibility within radiograph sets, and by length of time between postoperative and recall radiographs. It appears that these factors do not affect reliability of success/failure interpretation.