It can be concluded that the majority of dentists in the study group did not select the proper method, material and equipment in order to minimize the exposure of their patient to unnecessary radiation in dental radiography.
PurposeInsufficient knowledge of the anatomy of the maxillary sinuses prior to sinus graft surgery may lead to perioperative or postoperative complications. This study sought to characterize the position of the posterior superior alveolar artery (PSAA) within the maxillary sinuses using cone-beam computed tomography (CBCT).Materials and MethodsA total of 300 patients with edentulous posterior maxillae, including 138 females and 162 males with an age range of 33-86 years, who presented to a radiology clinic between 2013 and 2015 were enrolled in this retrospective cross-sectional study. The distance from the inferior border of the PSAA to the alveolar crest according to the residual ridge classification by Lekholm and Zarb, the distance from the PSAA to the nasal septum and zygomatic arch, and the diameter and position of the PSAA were all assessed on patients' CBCT scans. The data were analyzed using the Mann-Whitney test and the t-test.ResultsThe PSAA was detected on the CBCT scans of 87% of the patients; it was located beneath the sinus membrane in 47% of cases and was intraosseous in 47% of cases. The diameter of the artery was between 1 and 2 mm in most patients (72%). The mean diameter of the artery was 1.29±0.39 mm, and the mean distances from the PSAA to the zygomatic arch, nasal septum, and alveolar crest were 22.59±4.89 mm, 26.51±3.52 mm, and 16.7±3.96 mm, respectively.ConclusionThe likelihood of detecting the PSAA on CBCT scans is high; its location is intraosseous or beneath the sinus membrane in most patients. Determining the exact location of the PSAA on CBCT scans preoperatively can help prevent it from being damaged during surgery.
The mean thickness of the labial alveolar bone overlying maxillary anterior teeth was found to be between 1 to 1.2 mm and between 0.5 to 0.8 mm for mandibular anterior teeth at the first 5 mm from bone crest in a Persian population.
PurposeThis study was performed to evaluate the effect of changing the orientation of a reconstructed image on the accuracy of linear measurements using cone-beam computed tomography (CBCT).Materials and MethodsForty-two titanium pins were inserted in seven dry sheep mandibles. The length of these pins was measured using a digital caliper with readability of 0.01 mm. Mandibles were radiographed using a CBCT device. When the CBCT images were reconstructed, the orientation of slices was adjusted to parallel (i.e., 0°), +10°, +12°, -12°, and -10° with respect to the occlusal plane. The length of the pins was measured by three radiologists, and the accuracy of these measurements was reported using descriptive statistics and one-way analysis of variance (ANOVA); p<0.05 was considered statistically significant.ResultsThe differences in radiographic measurements ranged from -0.64 to +0.06 at the orientation of -12°, -0.66 to -0.11 at -10°, -0.51 to +0.19 at 0°, -0.64 to +0.08 at +10°, and -0.64 to +0.1 at +12°. The mean absolute values of the errors were greater at negative orientations than at the parallel position or at positive orientations. The observers underestimated most of the variables by 0.5-0.1 mm (83.6%). In the second set of observations, the reproducibility at all orientations was greater than 0.9.ConclusionChanging the slice orientation in the range of -12° to +12° reduced the accuracy of linear measurements obtained using CBCT. However, the error value was smaller than 0.5 mm and was, therefore, clinically acceptable.
Background. The upper airway volume is among the factors that affect orthodontic treatment plans. Cone-beam computed tomography (CBCT), as an accurate diagnostic modality, can help assess anatomical structures associated with the upper airway volume.Objectives. This study aimed to use CBCT to determine if there are differences in the upper airway volume between different sagittal and vertical skeletal patterns, considering the hyoid bone position, palatal depth, nasal septum deviation (NSD), and concha bullosa.
Material and methods.From among 105 initial CBCT samples retrieved from the archive of a private radiology clinic in Tehran, Iran, 90 CBCT scans of 27 males and 63 females aged 17-65 years were considered in the study according to the inclusion criteria. The upper airway volume was assessed with regard to Angle's classification (using the A point-nasion-B point angle (ANB)), the vertical skeletal dimension (using the sella-nasion plane to mandibular plane angle (SN-MP)), the hyoid bone position, palatal depth, NSD, and concha bullosa, using CBCT and the NNT ® software. The one-way analysis of variance (ANOVA), Levene's test and the t test were used to analyze the data with the SPSS Statistics for Windows software, v. 17.0.Results. The upper airway volume was significantly smaller in long-face cases (p = 0.037). There was no significant correlation between the upper airway volume and Angle's classification, the hyoid bone position, palatal depth, NSD, and concha bullosa.Conclusions. The vertical skeletal dimension was the only parameter that was related to the upper airway volume. The results of this study can be considered while preparing orthodontic treatment plans.
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