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.

Usually the oral manifestations of NHL are secondary to a more widespread involvement throughout the body, however, it can rarely present as a primary lesion in the oral cavity, having 0.1% -0.2% prevalence. In this paper we report a case of highly proliferative oral non-Hodgkin lymphoma which presented with very mild symptoms, but had a sudden and significant progression in less than two weeks with involvement of all four quadrants of the oral cavity.

PurposeVertical root fracture (VRF) is a common complication in endodontically treated teeth. Considering the poor prognosis of VRF, a reliable and valid detection method is necessary. Cone beam computed tomography (CBCT) has been reported to be a reliable tool for the detection of VRF; however, the presence of metallic intracanal posts can decrease the diagnostic values of CBCT systems. This study evaluated and compared the effects of intracanal stainless steel or titanium posts on the sensitivity, specificity, and accuracy of VRF detection using a NewTom VG CBCT system.Materials and MethodsEighty extracted single-rooted teeth were selected and sectioned at the cemento-enamel junction. The roots were divided into two groups of 40. Root fracture was induced in the test group by using an Instron machine, while the control group was kept intact. Roots were randomly embedded in acrylic blocks and radiographed with the NewTom VG, both with titanium and stainless steel posts and also without posts. Sensitivity, specificity, and accuracy values were calculated as compared to the gold standard.ResultsThe sensitivity, specificity, and accuracy of VRF diagnosis were significantly lower in teeth with stainless steel and titanium posts than in those without posts. Interobserver agreement was the highest in teeth without posts, followed by stainless steel posts, and then titanium posts.ConclusionIntracanal posts significantly decreased the VRF diagnostic values of CBCT. The stainless steel posts decreased the diagnostic values more than the titanium posts.

Background and Aim: Haller cells are one of the anatomical variations in the orbital area, which are important in endoscopic surgical procedures and have a role in the pathogenesis of some diseases including sinusitis and chronic craniofacial pain. The frequency of Haller cells has been reported in a wide range, which can be attributed to several factors. The purpose of this study was to determine the frequency and anatomical characteristics of Haller cells. Materials and Methods: This descriptive study was performed on 381 patients referring to a private oral and maxillofacial radiology clinic during 2015-2017. These patients needed cone-beam computed tomography (CBCT) for various reasons. All CBCT scans were observed by a radiologist. The results were statistically analyzed by Chi-square test using SPSS version 16.0 software. Results: From 381 patients, 34 patients (8.9%) had Haller cells. Sixteen patients (47.05%) had Haller cells on the right side, 15 patients (44.11%) showed these cells on the left side, while 3 patients (8.82%) had these cells on both sides. On the right side, the oval shape showed the highest frequency (n=9; 47.3%). 36.8% and 15.7% of the right-sided Haller cells were round (n=7) and pyramidal (n=3), respectively. On the left side, the circular shape had the highest frequency (n=8, 44.4%). Furthermore, 27.7%, 16.7%, and 11.1% of the left-sided Haller cells were oval (n=5), pyramidal (n=3), and teardrop-shaped (n=2), respectively. Conclusion: The prevalence of Haller cells in our study was 8.9%. Genetic and racial factors, radiographic techniques, and the age range of patients are some of the reasons for different results.