Background. The present study was undertaken to compare the Hounsfield Unit (HU) in computed tomography (CT) with the gray level in CBCT in human tissues. Methods. In this study, 25 different soft and hard tissues were evaluated in 21 patients. CBCT images were taken with Newtom VGi machine (Verona, Italy) and CT images were prepared with Somatom Sensation unit (Siemens, Germany). The HU values of soft and hard tissues were compared with the gray level values of CBCT images. Results. There was a strong correlation between the HU in CT and the gray level in CBCT in soft tissues (P<0.001, R2 = 0.85) and hard tissues (P<0.001, R2 = 0.74) and in general (P<0.001, R2 = 0.91). Conclusion. A high degree of agreement was seen between HU in CT and gray level in CBCT in both hard and soft tissues. Since the gray level in CBCT was similar to HU in CT and can be used as a parameter determine bone density in implant treatment and also to determine the bone type, the CBCT technique is recommended in such cases due to its low radiation dose, short time and low cost compared to CT.

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Background. Various factors such as aging, sex hormones and the distribution pattern of occlusal forces affect the morphology and osseous components of the temporomandibular joint (TMJ). Recognition of the effects of these factors on the anatomy of the area results in the differentiation of normal variations from abnormal cases. Objectives. The aim of the present study was to evaluate the relationship between the condyle and other hard components of TMJ, and age, gender and the number of remaining teeth. Material and methods. In the present descriptive-analytical study, a total of 145 cone-beam computed tomography (CBCT) images were evaluated. The condyle morphology, the thickness of the glenoid fossa roof, and the height and slope of the eminence were evaluated. Results. There were significant differences between the right and left sides only in terms of the height of the articular eminence (p = 0.008 and p ≤ 0.001 on the right and left side, respectively). There were significant differences between both sides in the slope of articular eminence depending on the number of teeth (p = 0.01 and p = 0.008 on the right and left side, respectively). The height of the articular eminence on the left side differed significantly depending on age (p = 0.005) and the number of remaining teeth (p = 0.02). There were no significant differences in any other cases. Conclusions. No significant relationship was found between the thickness of the glenoid fossa roof and the articular eminence, and the condyle morphology in all 3 cross-sections regarding gender, age and the number of remaining teeth.

Objectives: One of the most important problems of cone-beam computed tomography (CBCT) imaging technique is the presence of dense objects, such as implants, amalgam fillings, and metal veneers, which result in beam-hardening artifacts. With an increase in the application of CBCT images and considering the problems in relation to cupping artifacts, some algorithms have been presented to reduce these artifacts. The aim was to present an algorithm to eliminate cupping artifacts from axial and other reconstructed CBCT images. Materials and Methods: We used CBCT images of NewTom VG imaging system (Verona, Italy, at Dentistry Faculty, Medical Sciences University, Tabriz, Iran) in which every image has a resolution of 366 × 320 in DICOM format. 50 images of patients with cupping artifacts were selected. Using Sobel edge detector and nonlinear gamma correction coefficient, the difference was calculated between the density of axial images in the main image and the image resulting from nonlinear gamma correction at the exact location of the radiopaque dental materials detected by Sobel. The points at which this density difference was out of a definite limit were treated as image artifacts and were eliminated from the main image by the inpainting method. Results: The resultant axial images, for producing reconstructed cross-sectional, panoramic images without cupping artifacts, were imported into NTT viewer V5.6 and utilized. Conclusions: With comparison, acquired images observed that the offering algorithm is practical and effective for reducing the cupping artifacts and preserving the quality of the reconstructed images. This algorithm does not need any additional equipment.

Background: Nasal septum deviation might disrupt the integrity of nasal septum components, resulting in deformity. Such changes might affect the morphology of adjacent structures. The aim of the present study was to evaluate the dimensions of the palate in subjects with and without nasal septum deviation on cone-beam computed tomography (CBCT) images in an Iranian population. Methods: In the present cross-sectional study, the CBCT images of subjects with and without nasal septum deviation were evaluated in two groups (n=107) referred to the Department of Oral and Maxillofacial Radiology, Tabriz Faculty of Dentistry in 2017. The presence or absence of nasal septum deviation and its severity were evaluated in association with palatal dimensions. Data were analyzed by SPSS. Independent samples t test was used to compare the dimensions of the palate. Finally, the Mann-Whitney U test was employed to compare palatal arch depth (PAD)/palatal interalveolar length (PIL) ratios. Results: There were no significant differences between the two groups in terms of the palatal depth (P=0.967), palatal width (P=0.223), and palatal depth/palatal width ratio (P=0.644). However, the results demonstrated significant differences in palatal depth (P<0.001) and palatal width (P=0.05) between male and female subjects. Conclusions: Overall, no significant differences were observed in the dimensions of the palate (depth and width) and their ratios between subjects with and without nasal septum deviation, although greater palatal dimensions (depth and width) were detected in males compared to females.