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Evaluation of digital and geometric unsharpness in dental radiographs using an endodontic file model
1Section of Oral and Maxillofacial Radiology, School of Dentistry, Division of Diagnostic and Surgical Services, University of California, Los Angeles 90095-1658, USA. elhamr@dent.ucla.edu
Objective:
We sought to compare the effects of geometric and digital unsharpness.
Study Design:
Endodontic files of sizes 6, 8, 10, and 15 were placed in the root canal of an extracted lower incisor in 3 different positions at 2-mm increments. Radiographs were taken with a GE 100 x-ray unit at magnification factors of 1.0, 1.1, 1.2, and 1.3. With the use of a flatbed scanner, each radiograph was digitized at resolutions of 75, 150, 300, and 600 dpi. Ten observers viewed the digital images and identified the positions of the end of the files and the end of the roots, as well as assessed image quality.
Results:
No significant differences were found between the resolutions of 300 and 600 dpi, nor between the magnifications of 1.0 and 1.1. Significant differences were found between the magnification of 1.3 and the others and the resolution of 75 dpi and the others for all of the files.
Conclusion:
Geometric unsharpness has little relevance in clinical dental radiography. Increasing scanning resolution to 600 dpi did not improve accuracy with respect to recognizing the position of endodontic files.
