The use of E-speed film for root canal length determination.

This study compared the use of D-speed and E-speed dental X-ray film for assessing the working length of root canals. Root canal files of varying size (ISO 06, 08, 10 and 15) were placed in the root canals of a maxillary molar and a mandibular molar in a dried skull and mandible. Files were set at various lengths relative to the radiographic apex. The X-ray projections were kept constant. Exposure settings for the two film types that gave comparable radiographic density were selected. Films were developed manually under standardized conditions. A total of 48 films of each type were examined at various magnifications by four trained examiners for the estimation of distance between the file tip and radiographic apex. There were no differences between examiners in estimating working length. The effect of file size, root and magnification were also not significant. The differences between the film types were not significant (P > 0.05). It is concluded that clinicians should use E-speed film instead of D-speed film for root canal length measurement, because the exposure time was reduced by over 40% but the quality of the radiographic image was not significantly different.