Nasrin Farhadian; Amirfarhang Miresmaeili; Reza Mahvelati; Ahmad Sajedi
Abstract
background and aims: Cone-beam computed tomography (CBCT) is becoming established as a superior radiographic technique to conventional radiography in orthodontics. However cephalometric analysis in conventional lateral cephalograms (LC) is still an important tool in treatment planning. The aim of this ...
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background and aims: Cone-beam computed tomography (CBCT) is becoming established as a superior radiographic technique to conventional radiography in orthodontics. However cephalometric analysis in conventional lateral cephalograms (LC) is still an important tool in treatment planning. The aim of this study was to compare cephalometric measurements performed on conventional cephalograms with those on CBCT generated images.Method and materials: 24 patients with both LC and volumetric CBCT imaging (Newtom 3G) were selected. Generated Lateral cephalograms (GLC) were produced from related DICOM files in Dolphin 3D. cephalometric analysis, consisted of fifteen angular measurements and fifteen linear measurements (Dolphin V.11.2) were performed on both LCs and GLCs. Paired T-Test was used to compare differences in measurements between the two image modalities. Results: According to paired t-test results no statistically significant differences were found between the two set of measurements except Articular Angle, Gonial Angle (Ar-Go-Me) and Ramus Height (Ar-Go) (P<0.05). Since in all cases the interval between LC and CBCT imaging was short (3.5 months ± 2) and treatment has began after CBCT imaging, neither growth nor treatment was the cause of these differences. It could be supposed that the technical positioning errors in LCs of some patients might be the cause. Conclusions: LC could successfully be replaced by GLC. Since we can select the best orientation of the skull before generating GLC from CBCT DICOM files, GLC could be more reliable than LC.
Shahriar Shahab; Amirfarhang Miresmaeili; Mehdi Esmaeili; Vahid Mollabashi; Nasrin Farhadian
Abstract
Aim: The main objective of this preliminary study was to introduce a new approach for the estimation of nasal cavity volume using two dimensional measurements in serial sections, as an alternative to planimetry volume measurements.
Materials and Methods: Ten CBCT images were studied in the coronal plane ...
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Aim: The main objective of this preliminary study was to introduce a new approach for the estimation of nasal cavity volume using two dimensional measurements in serial sections, as an alternative to planimetry volume measurements.
Materials and Methods: Ten CBCT images were studied in the coronal plane and the 4-mm thick sections were selected between Anterior and Posterior Nasal Spine. Real estimation of nasal cavity volume was computed using Cavalieri principle in conjunction with planimetry method. The outline of each slice was digitized and the resulted surface area was computed by AutoCAD software. In alternative method, a surface area estimate was measured by multiplying maximum width and maximum height in each slice. The sum of slices area in each method was named as Total Nasal Cavity Area (TNCA). Nasal cavity volume = TNCA × thickness of tomography slice. TNCA1 based on planimetry method, was compared with TNCA2 using to coordinates with linear regression analysis.Results: Regression analysis showed a powerful correlation between two methods measurements (r = 0.951). The following formula was proposed for volume estimation using the coordinate method: TNCA1 = 85.6±1.53 TNCA2.
Conclusions: In this pilot study, we substituted successfully two linear measurements instead of planimetry to estimate nasal cavity volume. This may help investigators to overcome inherent problems appearing in measurements of nasal cavity volume.
