Effect of application of a filter in digital radiography to detect root resorption

Digital radiography has proper characteristics in the diagnosis of external root resorption. The purpose of this study was to determine the accuracy of digital radiographs processed with a filter referred to as ‘compensation of x-ray attenuation and visual response’ in the assessment of apical root resorption. In this in vitro study 60 extracted mandibular premolars were selected. The teeth underwent digital periapical radiography using the parallel technique before and after artificial root resorption procedures. The measurement of resorptions was carried out with the use of a periodontal probe and considered as the gold standard. The digital images were processed once without filter processing and once by x-ray attenuation and visual response option in Dental Eye software. The results of the digitally processed image measurements were compared with the gold standard by Wilcoxon’s nonparametric analysis and Kendall correlation coefficient. To determine the accuracy of the algorithm, the results of the processed digital image measurements were compared with the results of the non-processed digital image measurements by Wilcoxon’s nonparametric analysis (α=0.05). Kendall correlation coefficient between the gold standard and measurements made on processed digital images in relation to apical root resorption was 88.3%. Based on Wilcoxon’s nonparametric analysis, there were no significant differences between the results of the processed digital image measurements and the gold standard (p value = 0.2); however, there were significant differences between measurements made on processed digital images and non-processed digital images (p value = 0.004). Under the limitations of the present study, it was concluded that x-ray attenuation compensation and visual response algorithms are effective in diagnosing the severity of apical root resorption.