Validation and comparison of volume measurements using 1 multidetector computed tomography and 5 cone-beam computed tomography protocols: An in vitro study.

Purpose: The purpose of this study was to compare volume measurements obtained using 2 image software packages on Digital Imaging and Communications in Medicine (DICOM) images acquired from 1 multidetector computed tomography and 5 cone-beam computed tomography devices, using different protocols for physical volume measurements. Materials and Methods: Four pieces of bovine leg were prepared. Marrow was removed from 3 pieces, leaving cortical bone exposed. The resulting space of 1 piece was filled with water, another was filled with propylene glycol, and the third was left unfilled. The marrow in the fourth sample was left fully intact. Volume measurements were obtained after importing DICOM images into the Dolphin Imaging 11.95 and ITK-SNAP software programs. Data were analyzed using 3-way analysis of variance with a generalized linear model to determine the effects of voxel size, software, and content on percentage mean volume differences between tomographic protocols. A significance level of 0.05 was used. Results: The intraclass correlation coefficients for intraobserver and interobserver reliability were, respectively, 0.915 and 0.764 for the Dolphin software and 0.894 and 0.766 for the ITK-SNAP software. Three sources of statistically significant variation were identified: the interaction between software and content (P=0.001), the main effect of content (P=0.014), and the main effect of software (P=0.001). Voxel size was not associated with statistically significant differences in volume measurements. Conclusion: Both content and software influenced the accuracy of volume measurements, especially when the content had gray values similar to those of the adjacent tissues.

Diagnostic efficacy of different cone beam computed tomography scanning protocols in the detection of chemically simulated external root resorption.

OBJECTIVES: The aim of this study was to evaluate the efficacy of different high-resolution cone beam computed tomography protocols in the diagnosis of chemically simulated external root resorption (ERR). STUDY DESIGN: ERR was simulated in 3 sizes by using an acid decalcification protocol in the cervical, middle, and apical thirds of 30 single-rooted premolars. Four scans of each tooth were acquired with different voxel sizes: 0.080, 0.085, 0.120, and 0.133 mm. The images were analyzed by 2 blinded evaluators for the presence of ERR. The evaluation of diagnostic performance was based on receiver operating characteristic (ROC) curve analysis. RESULTS: No statistically significant differences were found in the detection of ERR with regard to lesion sizes or the different root thirds. Areas under the ROC curve were 0.901, 0.892, 0.887, and 0.767 for voxel sizes of 0.080, 0.085, 0.120, and 0.133 mm, respectively. Voxel sizes of 0.080 and 0.085 mm presented significantly larger areas under the ROC curve compared with the voxel size of 0.133 mm. There were no statistically significant differences among the protocols with the use of voxel sizes of 0.080, 0.085, and 0.120 mm. CONCLUSIONS: Cone beam computed tomography examinations with higher-resolution protocols demonstrated better performance in the diagnosis of ERR. Further investigations using simulations that more closely resemble the actual ERR process are warranted.

Airway volume analysis: is there a correlation between two and three-dimensions?

Objectives: No consensus exists on the assessment of airway in CBCT scans. Two-dimensional measures remain the standard in the cephalometric analysis. This research aimed to evaluate linear and area measurements in two-dimensional views from specific airway regions of interest and compare these to the correspondent volume in CBCT exams. Materials and Methods: 250-selected CBCT scans were retrospectively analyzed. A trained and calibrated examiner performed the linear, area and volume measurements in specific sites for nasal cavity, nasopharynx and oropharynx compartments. Dolphin Software was used for the analysis. The correlations were performed using Pearson coefficient. Results: The highest positive correlations were observed in the nasopharynx and oropharynx sagittal areas and the most constricted area in the oropharynx. Nasopharynx linear measures and nasopharynx coronal area did not present correlation with whole volume. Two-dimensional measurements in the soft palate (width and sagittal area) showed very low positive correlations. Although nasal cavity presented highest volume means, changes in oropharynx contributed more to variations in total volume, compared with the other two sections. Conclusion: Airway sagittal areas, as well as the most constricted axial area in oropharynx remains a useful guide to correlate with airway volume in two-dimensional images.

Diagnostic accuracy of cone beam computed tomography sections with various thicknesses for detecting misfit between the tooth and restoration in metal-restored teeth.

OBJECTIVE: To evaluate the diagnostic accuracy of cone beam computed tomography (CBCT) sections with various reconstruction thicknesses for detecting misfit between tooth and restoration in metal-restored teeth. STUDY DESIGN: Eighty teeth (perfect fit, 40 of these used with 0.2 mm gap, and 40 with 0.4 mm gap), were imaged with large FOV i-CAT. Images were reconstructed in five thicknesses: 0.2 (voxel size), 1, 2, 5, and 10 mm. Four examiners assessed the presence of gaps using a 5-point scale. Area under the receiver operating characteristics curve (aucROC) for misfit detection was calculated for each variable. A multivariate logistic regression was performed by using misfit detection accuracy as the dependent variable. RESULTS: The score "cannot decide" decreased when the reconstruction thickness was increased. Mean aucROC ranged between 0.60 and 0.72. Logistic regression showed that the presence of a gap and reconstruction thickness had an impact on diagnostic accuracy. CONCLUSIONS: Diagnostic accuracy of CBCT sections was low for detecting misfit in metal-restored teeth.

Diagnostic accuracy of conventional and digital radiography for detecting misfit between the tooth and restoration in metal-restored teeth.

STATEMENT OF PROBLEM: Although the postprocessing of digital images with enhancement filters could lead to the presence of artifacts and result in false-positive diagnoses, no study has analyzed whether the use of digital radiographs and/or postprocessing of digital images interferes with the diagnosis of marginal adaptation in metal-restored teeth. PURPOSE: The purpose of this study was to compare the diagnostic accuracy of conventional and digital radiographic images with and without filters for detecting a misfit between the tooth and restoration in metal-restored teeth. MATERIAL AND METHODS: Forty teeth with mesial-occlusal-distal inlays and 40 with complete crowns (each with a perfect fit, 20 with a 0.2-mm gap and 20 with a 0.4-mm gap) were imaged with conventional film and digital phosphor plate systems. Digital radiographs were exported as original images and with edge enhancement (high and low), inversion, and pseudo-3-dimensional filters. Four examiners assessed the presence of gaps by using a categorical scale (fit, misfit, cannot decide). Sensitivity, specificity, and overall accuracy were calculated for each variable. In addition, time spent scoring the images was recorded. A multivariate logistic regression was performed with accuracy as the dependent variable. RESULTS: Of the images, 6.2% received the score "cannot decide," most of them with a high edge enhancement filter and in the crown group. A tendency for higher sensitivity (range 0.67-0.83), specificity (range 0.81-0.92), and accuracy (range 0.73-0.86) values was found in conventional and digital original images. Results of a logistic regression found that restoration type, gap size, and high enhancement and inversion filters had a statistically significant impact on accuracy (P<.05). CONCLUSIONS: Original nonfiltered images should be used to assess teeth with metal restorations. High enhancement filters and image inversion should be avoided, especially when metal crowns are present.

Development of a new in vitro methodology to simulate internal root resorption.

INTRODUCTION: Studies to evaluate the diagnostic power of imaging examinations to detect root resorption have been based on simulations produced by burs. Standardized, round, and well-outlined access cavities do not reproduce the characteristics of physiological lesions and may facilitate diagnosis, masking the true accuracy of imaging techniques. A methodology to simulate internal root resorption by using acid demineralization was developed. METHODS: Eleven extracted single-rooted teeth were mesiodistally sectioned into homologous halves. Root canals were labeled to ensure restricted and controlled action of fluids. The protocol was composed of 24-hour cycles (5% nitric acid for 12 hours, rinsing with deionized water, and 8% sodium hypochlorite for 10 minutes). At the end of each cycle 1 tooth was removed from treatment, defining an exposure time that cumulated to the last tooth. Electron microscopy imaging was assessed to determine lesion area and depth. RESULTS: Minimum and maximum and areas and depths were 3.14 mm² and 10.34 mm² and 0.22 mm and 1.59 mm, respectively. Resorption simulated by the protocol proposed reproduced lesions of different sizes. CONCLUSIONS: The irregular shape and larger diameter:depth ratio suggest that these lesions are more similar to in vivo internal root resorption, compared with bur-induced lesions.

Detection of vertical root fractures by conventional radiographic examination and cone beam computed tomography - an in vitro analysis.

OBJECTIVES: This study compared the ability of conventional radiographic and cone beam computed tomography (CBCT) examinations to detect vertical root fractures (VRF) in teeth with or without root canal treatment and metallic posts. Furthermore, the influence of using different voxel sizes from CBCT images was assessed. METHODOLOGY: Sixty single-rooted human teeth were randomly divided into two groups: experimental and control. Twenty teeth were endodontically prepared and obturated with gutta-percha, twenty had a metallic postcemented after the filling, and twenty had no preparation. The teeth from the experimental group were fractured. All teeth were radiographed with three different horizontal angles, and after, CBCT images were acquired following three protocols in which the variation was the voxel resolution (0.4, 0.3, and 0.2 mm). Three calibrated examiners assessed the images. RESULTS: Chi-squared test showed no statistical difference among the images in detecting VRFs. The results of the diagnostic performance tests presented similar ability to detect VRFs when conventional radiographic examination was compared with 0.2 and 0.3-voxel CBCTs scans, in roots without endodontic treatment and metallic post. Moreover, specificity, sensitivity, and accuracy findings were similar for both 0.2 and 0.3-voxel resolution scans for teeth that are not root filled. However, it was observed that in teeth with root canal treatment and a post, the accuracy was higher when 0.2-mm voxel resolution was used. CONCLUSION: The radiographic examination with horizontal angle variation should be encouraged as the first complementary approach to assess the presence of VRFs. If conventional imaging is not capable to provide adequate information, CBCT can be indicated if a root fracture is strongly suspected. The root condition should then guide the voxel resolution choice, selecting 0.3-voxel for not root filled teeth and 0.2-voxel for teeth with filling and/or a post.