The effects of developer age on diagnostic accuracy: a study using assessment of endodontic file length

Objectives: To examine the effects of developer age on image quality. Methods: Endodontic files, size 10 and 15, were placed in upper and lower molars and premolars up to the root apex or 1.5 mm short. A series of radiographs were made with each of three film types: Dentus M2 (Agfa-Gevaert, Mortsel, Belgium). Ektaspeed Plus and Ultra-speed (Kodak Eastman Co, Rochester, USA). The films were processed bi-weekly using the same Agfa chemicals (Heraeus Kulzer, Dormagen, Germany) over a 6-week period. An additional set of Dentus M2 films was processed using Periomat chemicals (Durr Dental, Bietigheim-Bissingen, Germany). The films were viewed by eight dentists who rated the position of the tip of the file using a 5-point confidence scale. ROC data were analysed by means of analysis of variance. A(z) value was the dependent variable, whereas observer age group was entered as between subject factor. The null hypothesis was rejected when P<0.05. Results: The diagnostic accuracies of the three films were comparable during the first 4 weeks. In the sixth week Ultra-speed was significantly better than the other two films (P=0.046). The Periomat chemicals showed significantly greater consistency than the Agfa chemicals (P=0.004). Developer exhaustion significantly affected the performance of the older observers (P=0.008), especially when Agfa chemicals and file size 10 were used. Conclusion: Agfa chemicals older than 4 weeks significantly affect the assessment of endodontic file length. In earlier stages there are no significant differences between the three films tested. Dentus M2 and Ektaspeed Plus films should be used as they require lower exposures.