Effect of object position in the field of view and application of a metal artifact reduction algorithm on the detection of vertical root fractures on cone-beam computed tomography scans: An in vitro study

PURPOSE: To assess the effects of object position in the field of view (FOV) and application of a metal artifact reduction (MAR) algorithm on the diagnostic accuracy of cone-beam computed tomography (CBCT) for the detection of vertical root fractures (VRFs). MATERIALS AND METHODS: Sixty human single-canal premolars received root canal treatment. VRFs were induced in 30 endodontically treated teeth. The teeth were then divided into 4 groups, with 2 groups receiving metal posts and the remaining 2 only having an empty post space. The roots from different groups were mounted in a phantom made of cow rib bone, and CBCT scans were obtained for the 4 different groups. Three observers evaluated the images independently. RESULTS: The highest frequency of correct diagnoses of VRFs was obtained with the object positioned centrally in the FOV, using the MAR algorithm. Peripheral positioning of the object without the MAR algorithm yielded the highest sensitivity for the first observer (66.7%). For the second and third observers, a central position improved sensitivity, with or without the MAR algorithm. In the presence of metal posts, central positioning of the object in the FOV significantly increased the diagnostic sensitivity and accuracy compared to peripheral positioning. CONCLUSION: Diagnostic accuracy was higher with central positioning than with peripheral positioning, irrespective of whether the MAR algorithm was applied. However, the effect of the MAR algorithm was more significant with central positioning than with peripheral positioning of the object in the FOV. The clinical experience and expertise of the observers may serve as a confounder in this respect.

[ comparison between digital panoramic view and cone-beam computed tomography [CBCT] images in diagnosis of apical radiolucent lesions]

Panoramic radiography is used extensively in the field of dentistry as a screening method. In endodontic treatment, the diagnosis and evaluation of periapical area is very important. However, using advanced imaging such as cone beam computed tomography [CBCT] has increased diagnostic ability, but it must be used precisely and in special condition. The aim of this study was to compare diagnostic value of digital panoramic view and CBCT in diagnosis of apical lucent lesion. In this cross-sectional study, digital panoramic view and CBCT of 47 patients [573 apical portions of root] who had referred to maxillofacial radiology clinic for maxillary and or mandibular CBCT procedures were assessed. All of the selected patients needed these images as their treatment protocol. According to order of CBCT [maxilla, mandible and both], the teeth of the same jaw in digital panoramic radiography by a maxillofacial radiologist were evaluated. After data enterance, agreement, Sensitivity, specificity and likelihood ratio [positive and negative] were assessed totally and for each jaw separately with 95 percent confidence interval. 0.05 was established as a level of significant. Periapical radiolucency in 15.9% of apical areas in CBCT and in digital panoramic view in 4.2% of them was detected. Overall, sensitivity and specificity of digital panoramic view were 26.4% and 100% respectively. Sensitivity of panoramic view in diagnosis of periapical lucency in mandible was higher than maxilla. According to kappa analysis, the agreement level between panoramic and CBCT was assigned low [kappa=0.374]. Although panoramic is a routine screening method in field of dentistry, it is not accurate in diagnosis of the presence of periapical lesions. This limitation in maxilla is more than mandible

Comparison of high-resolution and standard zoom imaging modes in cone beam computed tomography for detection of longitudinal root fracture: An in vitro study

PURPOSE: The purpose of this study was to compare the efficacy of two imaging modes in a cone beam computed tomography (CBCT) system in detecting root fracture in endodontically-treated teeth with fiber posts or screw posts by selecting two fields of view. MATERIALS AND METHODS: In this study, 78 endodontically-treated single canal premolars were included. A post space was created in all of them. Then the teeth were randomly set in one of 6 artificial dental arches. In 39 of the 78 teeth set in the 6 dental arches, a root fracture was intentionally created. Next, a fiber post and a screw post were cemented into 26 teeth having equal the root fractures. High resolution (HiRes) and standard zoom images were provided by a CBCT device. Upon considering the reconstructed images, two observers in agreement with each other confirmed the presence or absence of root fracture. A McNemar test was used for comparing the results of the two modes. RESULTS: The frequency of making a correct diagnosis using the HiRes zoom imaging mode was 71.8% and in standard zoom was 59%. The overall sensitivity and specificity in diagnosing root fracture in the HiRes mode were 71.79% and 46.15% and in the standard zoom modes were 58.97% and 33.33%, respectively. CONCLUSION: There were no significant differences between the diagnostic values of the two imaging modes used in the diagnosis of root fracture or in the presence of root canal restorations. In both modes, the most true-positive results were reported in the post space group.

Diagnostic value of two modes of cone-beam computed tomography in evaluation of simulated external root resorption: an in vitro study

PURPOSE: Field of view and voxel resolution of cone beam computed tomography (CBCT) might affect the diagnostic capability. This study was performed to compare between the standard and HiRes zoom modes in the diagnosis of external root resorption (ERR) using CBCT. MATERIALS AND METHODS: Sixty three small cavities (0.25 mm depth and 0.5 mm diameter) were simulated on the buccal, lingual, and proximal surfaces at three different levels of 16 roots of teeth. After covering the root with nail varnish, the roots were inserted in the sockets and the model was placed in a water-containing lacuna. CBCT scans were taken in both standard and HiRes zoom modes using NewTom VG (QR srl Company, Verona, Italy). Then, an observer assessed the images to determine the presence or absence of the cavities. This process was repeated by increasing the size and depth of cavities to 0.5 mm depth and 1 mm diameter. Data were analyzed by McNemar test. The sensitivity, specificity, positive predictive value, negative predictive value, and likelihood ratio in evaluation of the simulated cavities were calculated. RESULTS: There was a significant difference between the two imaging modes in diagnosing the shallow cavities (p=0.02).The sensitivity of the standard zoom in detecting the shallow cavities was lower than that of the HiRes zoom. The likelihood ratio of the HiRes zoom was higher in the diagnosis of both cavity types. CONCLUSION: This study suggested that a smaller voxel size in the HiRes zoom mode of CBCT is preferred for diagnosis of ERR.