Heraldo Luis Dias da Silveira

Influence of Voxel Size in the Diagnostic Ability of Cone Beam Tomography to Evaluate Simulated External Root Resorption

This study assessed in vitro the diagnostic ability of cone beam computed tomography (CBCT) scans with different voxel resolutions in the detection of simulated external root resorption (ERR). For that purpose, 59 teeth were viewed through iCAT tomography (Imaging Sciences International, Inc, Hatfield, PA) following three protocols in which the variation was the voxel resolution (0.4, 0.3, and 0.2mm). A calibrated examiner blinded to the protocol assessed the images through the i-CAT View software (Imaging Sciences International, Inc). The chi-square statistical analysis did not show associations between voxel resolution, section plane, size of cavity, and radicular third. Sensitivity and specificity values were similar. However, likelihood ratio values of 6.4 for a 0.4-mm voxel, 16 for a 0.3-mm voxel, and 12 for a 0.2-mm voxel were found. It was concluded that CBCT is a reliable method for the investigation of simulated ERR, and a 0.3-mm voxel appeared to be the best protocol, associating good diagnostic performance with lower X-ray exposure.

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.

A comparative study of lateral cephalograms and cone-beam computed tomographic images in upper airway assessment

The purpose of this study was to evaluate the accuracy of airway measurements from lateral cephalograms, cone-beam computed tomographic (CBCT) lateral reconstructions, and CBCT axial planes, as well as to correlate these findings with area measurements acquired with the latter imaging method. Landmarks were defined for the measurements of naso- and oropharynx of 30 patients (12 males and 18 females, mean age 17.5 years), for different planes, using linear antero-posterior measurements and the corresponding area. Analysis of variance showed significant differences in the linear measurements of the oropharynx between the two methods, although all measurements assessed corresponded to the respective areas. The linear measurements of the airway space obtained using the different techniques correlated positively with the respective area measurements, which demonstrate the reliability of the investigated techniques.

Reproducibility of Cephalometric Measurements Made by Three Radiology Clinics

The purpose of this study was to assess reproducibility of cephalometric measurements in cephalograms obtained by three dentomaxillofacial radiology clinics. Forty lateral cephalometric radiographs were selected and sent at different times to three different clinics for cephalometric analyses. Each clinic digitized the radiographs with the same resolution, and landmarks were located with the mouse pointer directly on the digitized radiographic image on the screen. Three cephalograms were obtained from each radiograph, totaling 120 analyses. Data were analyzed with analysis of variance. Of the 32 factors studied, reproducibility of results was satisfactory for only four factors: position of maxilla relative to anterior cranial base, inclination of occlusal plane relative to anterior cranial base, position of lower incisor relative to nasion-pogonion line, and soft-tissue profile of face (P < .05). Differences in cephalometric measurements were present and such differences were significant for most factors analyzed. The different cephalometric measurements obtained by the three dental radiology clinics were not reproducible.

Comparison between two tomographic sections in the diagnosis of external root resorption

Objectives To assess the accuracy of coronal and sagittal CT sections to detect cavities simulating root resorption. Material and Methods 60 mandibular incisors were embedded in plaster bases, and cavities with 0.6, 1.2 or 1.8 mm in diameter and 0.3, 0.6 or 0.9 mm in depth (small, medium and large cavities) were drilled on the buccal surfaces with high-speed round burs with diameters of 0.6, 1.2 and 1.8 mm to simulate external inflammatory root resorption. Simulations in the cervical, middle and apical thirds of each tooth root were made randomly. The Dental Scan software was used to obtain 1-mm-thick axial images from direct scanning, which were reconstructed in the coronal and sagittal planes using 3D software (Syngo FastView). Each series was loaded into the software. Fourteen images of each tooth were reconstructed in the coronal plane and 14 in the sagittal plane. A total of 1,652 images were obtained for analysis. Series information, tooth number and the plane reconstructed were stored. The images generated were saved on a CD-ROM together with the visualization software (Syngo FastView). Images were analyzed by a previously calibrated blinded, radiologist. Cochran’s Q test was conducted separately for each region analyzed followed by pair-wise comparison by the McNemar test (p=0.05). Results No statistically significant difference (p>0.05) was observed in the diagnosis of simulated resorption between the apical, middle, and coronal thirds. When the axial plane was assessed separately, diagnoses were statistically different (p<0.05) among the three root thirds. The apical third differed significantly (p<0.05) from the cervical and middle thirds. Diagnostic errors were more often observed in the apical third compared to the cervical and middle thirds. Mid-sized cavities revealed no statistically significant differences (p>0.05) between planes, irrespective of the third in which the resorptions were located. Conclusion When tomographic sections are requested for the diagnosis of buccal or lingual external root resorption, sagittal sections afford the best image characterization of the resorption process.

Software system for calibrating examiners in cephalometric point identification.

INTRODUCTION The literature has shown that subjective concepts lead to interobserver variations in the definitions and identifications of cephalometric landmarks. Observers must be trained and calibrated to conduct scientific research using cephalometric comparisons. In this study, we aimed to develop and test a computational model called Cyclops cephalometry in radiographic cephalometry training and calibration. METHODS This system uses the concepts of evaluation process managers, examiners, and testers, thus affording uniformity in cephalometric evaluations. The system was tested with 5 orthodontists and 5 postgraduate students who located 28 landmarks in 10 lateral cephalometric radiographs before and after training. RESULTS Before training, the Student t test showed significant differences (P <0.05) in accuracy between the orthodontists and the students (71.4% and 54.9%, respectively). However, considerable improvement in accuracy was observed after training in both groups (86.5% and 83%, respectively), without significant differences (P = 0.30) between groups. Users of the system agreed about its usability aspects such as effectiveness, efficiency, and satisfaction. CONCLUSIONS This model was shown to be a useful and efficient tool in the calibration process, and might be helpful in various comparative cephalometric investigations.

Dental findings in GAPO syndrome: case report

This article reports the case of a young female adult with GAPO syndrome who presented as a peculiar dental finding unerupted primary and permanent dentitions, which resembled total anodontia on clinical examination. A cephalometric analysis was performed to investigate the alterations in facial bone development. This is the 9th GAPO syndrome case reported in a Brazilian patient.

Clinical variability in KBG syndrome: report of three unrelated families.

The KBG syndrome is characterized by short stature, macrodontia, a specific combination of minor anomalies, developmental delay, and/or mental retardation. We reported on four patients from three unrelated families. The most frequent clinical findings were: atypical face, long/flat philtrum, thin upper lip, macrodontia, dental malposition, enamel hypoplasia, and cleft teeth. Skeletal anomalies such as cervical ribs and vertebral abnormalities were also noted. Hand anomalies were observed in three patients. Mental retardation and developmental delay were present in three of the four patients. There is wide clinical variability in the expression of this syndrome. The males are usually more severely affected then the females, suggesting possible X‐linked inheritance in some cases.

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.

Buccal-lingual localization of the mandibular canal in relationship with the third molar using the lateral oblique technique

Aim: The aim of this study was to evaluate the use of lateral oblique radiography (LOR) at two different incidence angles for the bucco-lingual topographic localization of the mandibular canal with respect to the lower third molars. Materials And Method: A total of 24 dry jaws bearing at least one third molar were subject to LOR at vertical incidence angles of 0° and -30°. A trained and calibrated examiner measured the distance between the top of the mandibular canal to the most apical point of the third molar, using a digital calliper and individual light box for the radiographs. Based on the analysis of the two measurements (incidence angles of 0° and -30°) and considering the buccal object rule, the observer estimated the location of the mandibular canal, which was classified as lingual, central or buccal to the corresponding third molar. Results were compared with the computerized tomography images (gold standard). Results: The statistical analysis included sensitivity, specificity and accuracy tests. These results showed that LOR (0° e -30°) could be used to determine the bucco-lingual location of the mandibular canal with respect to the third molar. Conclusion: In spite of the magnification, LOR images demonstrated that the technique could be used for this study proposal.