Objectives : To determine the effect of developer age and file thickness on diagnostic accuracy of E and F- speed films in position assessment of file tip to radiographic apex., Study design: Endodontic files size 10 and 15 were placed in mandibular first molar and second premolar up to the root apex or 1.5 mm shorter. Ten series of radiographs were made with two types of film: Kodak insight (F-speed film) and Ektaspeed plus (E-speed film) in different positions of file in apex or 1.5 mm short. The films of each series were processed manually on each day, using Champion chemicals. The films were assessed by four endodontists. They rated the position of file tip to radiographic apex using a 3-point confidence scale in the questionnaires (tip to tip, 1.5 mm under, can not diagnose). The diagnostic performance of observers was compared with true diagnosis., Results : Mean Az value of E and F-speed films, that shows the diagnostic accuracy is 0.986 and 0.983 for E and F-speed films respectively, that was not significantly different (P = 0.777). Also diagnostic accuracy of films processed during 10 days was not statistically different (P = 0.726). Assessment of files tip size 10 and 15 in lower molar and premolar canals was not significantly different (P = 0.712)., Conclusion : The performance of the F-speed film was not statistically different from E-speed for assessment of file tip to radiographic apex. Because of less required exposure, we suggest to use Kodak insight (F-speed film) in clinical examination.

Key words: Diagnostic accuracy, Intra oral radiographic film, Working length