The comparison of accuracy of conventional periapical and direct digital subtraction radiography

Abstract

Imaging techniques are a complimentary aid for clinical diagnosis. There is some limitation in conventional imaging. For example in periapical radiographs approximately 30%-40% of mineral loss/gain is necessary for detecting density changes. Lesions with less than 5% bone loss can be detected by Digital Subtraction Radiography (DSR), even minute changes in alveolar bone density can be detected and quantified. The aim of this study was to compare the accuracy of conventional periapical radiography and direct digital subtraction radiography with and without enhancement in diagnosing the density changes. Methods and Materials: In this descriptive analytic study 3 dry human skulls with unknown sex and age were used. Periapical and direct digital radiographs were taken from 3 regions of mandible. By adding AL sheets until the sheet dimensions were detectable in the image. The acquired direct digital images were subtracted from the initial image using Photoshop software. 3 observers observed the radiographs and subtracted images with contrast enhancement and without it, and wrote down the code of the film which the density changes were detectable. Results: One-way Variance analysis showed that in all samples (regardless the studied location) there was a statistically significant difference between periapical radiography and direct digital subtraction radiography with and without enhancement (P<0.001). There wasnEt a significant difference in posterior regions of all mandibles between direct digital radiographs with and without enhancement. But two methods of digital subtraction had statistical difference in anterior regions. Conclusion: DSR with and without enhancement was a better method for detecting smaller changes in density than conventional periapical radiography and density detection in DSR with enhancement in the anterior region was better than DSR without enhancement.