Determination of the resolution of a digital system for panoramic radiography based on CCD technology

Is Panoramic Radiography an Accurate Imaging Technique for the Detection of Endodontically Treated Asymptomatic Apical Periodontitis?

INTRODUCTION

This study aimed to evaluate the diagnostic accuracy of panoramic radiography (PAN) for the detection of clinically/surgically confirmed apical periodontitis (AP) in root canal-treated teeth using cone-beam computed tomographic (CBCT) imaging as the reference standard.

METHODS

Two hundred forty patients with endodontically treated AP (diseased group) were detected via CBCT imaging using the periapical index system. They were divided into groups of 20 each according to lesion size (2-4.5 mm and 4.6-7 mm) and anatomic area (incisor, canine/premolar, and molar) in both the upper and lower arches. Another 240 patients with root filling and a healthy periapex (healthy group) were selected. All diseased and healthy patients underwent PAN first and a CBCT scan within 40 days. The periapical index system was also used to assess AP using PAN. Sensitivity, specificity, diagnostic accuracy, positive predictive value, and negative predictive value for PAN images with respect to CBCT imaging were analyzed. The k value was calculated to assess both the interobserver reliability for PAN and the agreement between PAN and CBCT.

RESULTS

PAN showed low sensitivity (48.8), mediocre negative predictive value (64.7), good diagnostic accuracy (71.3), and high positive predictive value (88.6) and specificity (93.8). Both interobserver reliability for PAN and agreement between PAN and CBCT were moderate (k = 0.58 and 0.42, respectively). The best identified AP was located in the lower canine/premolar and molar areas, whereas the worst identified AP was located in the upper/lower incisor area and upper molar area.

CONCLUSIONS

PAN showed good diagnostic accuracy, high specificity, and low sensitivity for the detection of endodontically treated AP.

Perception of anatomical structures in digitally filtered and conventional panoramic radiographs: a clinical evaluation

OBJECTIVES

The aims of the study were to compare subjective image quality of clinical images obtained with a storage phosphor plate (SPP)-based digital and conventional film-based panoramic system for the visualization of various anatomical structures and to evaluate the effect of various processing algorithms on image interpretation.

METHODS

Panoramic radiographs were taken in 42 patients both with film and with a SPP system. SPP images were treated with shadow, sharpen, negative, greyscale sigma and greyscale exponential filters. Four observers subjectively evaluated films and unfiltered and filtered SPP images for the visibility of anatomical structures with various radiodensities as well as for overall image quality on a three-point rating scale. The statistical methods used were Kruskal-Wallis, odds ratio analysis and Cohen's kappa.

RESULTS

No statistically significant difference was found between film and unfiltered digital images except for low-contrast structures (P > 0.05). Film images were preferred for the visibility of low-contrast structures (P < 0.05). Best overall image quality was obtained with sharpened images (P < 0.05) followed by films and unfiltered digital images. Among all filtered images, sharpened ones received the highest ratings for the visibility of all anatomical structures (P < 0.05). The intra- and interobserver agreement ranged between moderate and substantial and between fair and moderate, respectively.

CONCLUSIONS

Film and unfiltered SPP-based panoramic images performed equally well in terms of overall quality; however, films were best for the perception of low-contrast structures. The sharpening filter may be recommended for enhancing SPP panoramic images to improve the visual perception of most of the anatomical structures as well as overall quality.