Effect of Slice Thickness on the Accuracy of Linear Measurements Made on Cone Beam Computed Tomography Images (InVitro)

Objective: Cone beam computed tomography (CBCT) is applied for the imaging of the maxillofacial and dental structures, particularly for surgical treatments and dental implants. The aim of this study was to assess the effect of slice thickness on the accuracy of CBCT linear measurements. Methods: In this diagnostic accuracy study, forty-two titanium pins with the same dimensions were inserted into seven dry sheep mandibles. The length of the pins before the insertion was carefully measured by a digital caliper, (0.01mm accuracy). Imaging of the mandible performed using CBCT New Tom VGi. After image reconstruction by NNT Viewer, linear measurements were made on cross-sectional slices (thicknesses of 0.125, 0.5, 1 and 2mm) by three radiologists. The accuracy of measurements assessed using descriptive indices and compared between different slice thicknesses by repeated measures ANOVA.Results: Repeated measures ANOVA showed a significant difference between different slice thicknesses (P=0.024). According to the least significant difference (LSD) test, the difference in absolute errors was significant in all thicknesses (P=0.024). Measurements at 0.125 mm thickness were significantly different from others, with a higher error rate (mean absolute error=0.17). Measurements at 0.5mm thickness showed a significant difference with those at 0.125 and 2mm (mean absolute error=0.15). Measurements at 2mm thickness were significantly different from those at 0.125 mm thickness (mean absolute error=0.13).The average error rate was lower in 2mm thickness and the measurements were more accurate.Conclusion: A statistically significant difference was seam between CBCT measurements and actual sizes in different slice thicknesses. The differences were below 1mm, and clinically acceptable

Diagnostic Accuracy of Digitized Images Using Different Resolution Settings of Digital Camera in Detection of Proximal Caries

Objective: When none of digital systems and scanners is accessible and it is essential to have digitized images of conventional radiographs, digital cameras can be used. The Aim of this study  was to investigate whether digital images obtained by different resolutions of a digital camera are matched to the original radiographs in evaluation of caries.Methods: In this diagnostic accuracy in vitro study the conventional radiographs of168 proximal surfaces of 84 teeth were produced, Then they were digitized with digital camera in three different resolutions; high (2048x1536), medium (1600x1200) and low resolution (480x460). Images were stored in Photoshop7.0 software, and were evaluated by5 observers to show the presence and depth of the caries. Cronbach’s α calculated inter-observers agreement and in order to calculate the agreement with original conventional radiographs Kappa index was used.Results: In assessing the presence of caries, the agreement between low, medium and high resolutions with original radiographs were 0.286, 0.235 and 0 respectively. Also, assessing the depth of the caries agreement was reported0.21, 0.338 and 0.412 respectively. In most instances, there was a fair agreement between the different resolutions and original radiographs. The highest inter- observer’s agreement was reported in diagnosis of the presence of the caries with using high resolution (α=0.837) and the lowest inter-observer’s agreement was reported in diagnosis of the  depth of the caries with medium resolution (α=0.762).There was no significant difference reported in observations of different resolutions and original images.Conclusion: Using of high-resolution cameras did not show a significant difference with medium and low resolutions in caries evaluations. Therefore, considering the increase in the file size and difficulties in cameras selection, using of high-resolution digital cameras is not necessary in order to increase the diagnostic accuracy of digitized images

Anatomical Variations of the Greater Palatine Canal and Greater Palatine Foramen in an Iranian Subpopulation Using Cone-Beam Computed Tomography: CBCT Evaluation of Greater Palatine Canal

Objectives This study aimed to assess the anatomical variations of the greater palatine canal (GPC) and greater palatine foramen (GPF) in an Iranian subpopulation using cone-beam computed tomography (CBCT). Methods This cross-sectional study was conducted on 193 CBCT scans of adults (94 males, 99 females) taken between 2017-2021 that were retrieved from a radiology clinic in Urmia, Iran. Axial sections were used to assess the position, diameter, and shape of GPF, and sagittal sections were used to assess the length and path of GPC. Data were analyzed by paired and independent t-test, Wilcoxon test, Mann-Whitney test, and Chi-square test (alpha=0.05). Results In most cases (97.34% of males and 98.49% of females), GPF was located distal to the maxillary first molar. The mean distance between the GPF and midpalatal suture was significantly greater in males than females (15.2±1.8 vs. 14.3±1.5 mm; P=0.002). The mean diameter of GFP was significantly larger in males than females in both mesiodistal (2.34±0.64 vs. 1.96±0.63 mm, P<0.05) and anteroposterior (4.69±1.17 vs. 4.07±1.20 mm, P=0.001) dimensions. The mean length of GPC in males was significantly higher than that in females (28.55±2.62 vs. 26.90±3.31 mm, P<0.05). The most common form of GPF and GPC (on sagittal sections) was oval, and sigmoid, and curve, respectively. The most common GPC path was anterior-inferior (65.96% of males and 64.65% of females). Conclusion The present results provided valuable information regarding the anatomical variations of GPF and GPC in Iranian population. CBCT was proven to be a valuable tool for assessment of maxillofacial anatomical landmark

Effect of Developer Age and Film Speed on Diagnostic Accuracy of Endodontic File Length Measurement on Radiographs

Background and Aim: Radiography has extensive applications in root canal treatment and the developer age plays an important role in making a definite diagnosis. The present study examined the effect of developer age on the diagnostic accuracy of endodontic file length measurement using D-speed, E-speed and E/F-speed films. Materials and Methods: In this diagnostic study, radiographs were processed weekly by a developer aged for up to 6 weeks. Radiographs were viewed by 5 postgraduate students of endodontics and oral radiology. They determined the file tip position using a 3-point confidence scale. The area under the curve (Az) was calculated and used as a diagnostic accuracy scale. The effects of film type and endodontic file size were analyzed by one-way ANOVA, Tukey’s post hoc test and Student’s t test. Results: E-speed and D-speed films had similar diagnostic accuracy higher than that of E/F speed film (p<0.0001). The Az values of D, E and E/F speed films were 0.5882, 0.5538 and 0.3578, in fresh developer, 0.5782, 0.5718 and 0.3498 in 2-week old develop-er and 0.6196, 0.6724 and 0.2080, in 4-week old developer solution, respectively. Devel-oper age did not decrease the diagnostic accuracy of D and E-speed films but decreased that of E/F films at 4 weeks. Radiographs processed with 6 weeks old developer were not readable. All observers showed higher diagnostic accuracy determining the size of file # 15 than 10 (p<0.0001). The mean Az values for endodontic file sizes 10 and 15 using fresh, 2-week and 4-week old developers were 0.3984 and 0.6016, 0.3732, and 0.6268 and 0.2774 and 0.7226, respectively. Conclusion: The developer aged for up to 4 weeks did not significantly affect the diag-nostic accuracy of D-speed and E-speed films. E/F speed films cannot be used with de-velopers older than 2 weeks and their usage was associated with lower accuracy compared to E and D-speed films