Efficacy of Image Processing Filters in the Detection of Proximal Caries in Digital Bitewing Radiograph

Document Type : Original Article


1 Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.

2 Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Ahvaz Jundishapur University of Medical Sciences, Ahvaz,


Background and Objectives: Image processing filters are supposed to improve the diagnostic performance of digital images. Thus, the aim of present study was to compare the performance of digital radiography with and without image processing filters in the detection of proximal caries lesions.
Subjects and Methods: In this in vitro studystandardized digital radiographs of 100 approximal surfaces were acquired. Unfiltered and filtered images (low sharpen, intermediate sharpen, high sharpen and inversion filters) on the Scanora® (version 4.3.1) software were assessed by 2 observers. The teeth were sectioned and the caries detector used subsequently to determine the gold standard.
Results: Sensitivity, specificity and overall accuracy evaluated with sub curve analysis of ROC (Az) and compared using ANOVA/Tukey test. The Spearman test was used for intra-observers agreement. The sensitivity, specificity and overall accuracy of the low sharpen, inversion and unfiltered images were significantly higher than the intermediate sharpen and high sharpen filter images (P<0.05). The difference between unfiltered images, the low sharpen and inversion filter images were not significant (P˃0.05). The low sharpen filter images had the highest sensitivity and overall accuracy, and unfiltered images had the highest specificity. The high sharpen filter images had the lowest sensitivity, specificity and overall accuracy.
Conclusion: The low sharpen filter may be an acceptable processing filter for detection of the caries lesions; because it showed the highest sensitivity and overall accuracy. The intermediate sharpen and high sharpen filters are not recommended for detection of the caries lesions.


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