Powell-Cullingford A W, Pitt Ford T R
Department of Conservative Dental Surgery, United Medical and Dental School, Guy's Hospital, London, UK.
Int Endod J. 1993 Sep;26(5):268-72. doi: 10.1111/j.1365-2591.1993.tb00571.x.
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.
本研究比较了D速和E速牙科X线胶片在评估根管工作长度方面的应用。将不同尺寸（ISO 06、08、10和15）的根管锉置于干燥颅骨和下颌骨中的上颌磨牙和下颌磨牙的根管内。根管锉相对于影像学根尖设置在不同长度处。X线投照条件保持恒定。选择两种胶片类型中能产生可比影像学密度的曝光设置。胶片在标准化条件下手工显影。四名经过培训的检查人员在不同放大倍数下对每种类型的48张胶片进行检查，以估计根管锉尖端与影像学根尖之间的距离。检查人员在估计工作长度方面没有差异。根管锉尺寸、牙根和放大倍数的影响也不显著。两种胶片类型之间的差异不显著（P>0.05）。结论是，临床医生在根管长度测量中应使用E速胶片而非D速胶片，因为曝光时间减少了40%以上，但影像学图像质量没有显著差异。
