Radiographic evaluation of endodontic therapy and the influence of observer variation

In radiographic evaluation of the results of endodontic therapy the development or persistence of periapical radiolucencies often serve as criteria for therapeutic failure. In the present study the influence of inter- and intraexaminer variation on these results was investigated. Three endodontists and three radiologists interpreted periapical conditions and quality of root filling seal in radiographs of 119 endodontically treated roots. Consensus on the presence of periapical lesion was reached in 27% of cases classified as pathologic. In 6% reports of increased width of the periodontal membrane space accorded. The examiners agreed completely on normal periapical conditions in 37% of the cases. On assessing the quality of root filling seal the opinions of observers differed even more. Complete agreement on cases with adequate and defective seal was reached in 25% and 12%, respectively. For the individual examiner the widened periodontal membrane space was the diagnosis most difficult to reproduce. The present study indicates that the large variation noted among clinical and radiographic studies on the results of endodontic therapy could partly be explained by difficulties in defining and maintaining criteria for radiological evidence of periapical disease.