Introduction: The frontal sinus is the most variable part of the paranasal sinuses in terms of symmetry, anatomical features and degree of development. The aim of this study was to assess the morphometric changes of the frontal sinus in CONE-BEAM COMPUTED TOMOGRAPHY (CBCT) images. Materials & Methods: In this cross-sectional study, 200 CBCT images were examined for anatomical variations such as the presence of frontal sinus, sinus symmetry, lateral frontal sinus extension (LFSE) to orbital roof, scalloping, septum and type of septum. Moreover, Crista Galli (CG) was divided into three equal segments of anterior, middle and posterior in order to have a precise criterion for determining the location of the frontal recess in coronal plane. The data were analyzed using ANOVA with T-test and Chi-square at significant level of P<0. 05. Results: Of 200 cases, 113 and 87 ones were male and female with the mean age of 18‒ 88 years. The results showed that frontal sinus was bilateral in all cases and symmetric in 113(57%) cases. The LFSE to orbital roof had a significant relationship with gender, so that at the external onethird, the LFSE was less frequent in women than men (P<0. 001). The most frequent location of the frontal recess was in the posterior one-third of CG (85 (43%)) with significant difference (P=0. 012). Conclusion: In this study, frontal sinuses were rather symmetric, and the use of the anatomical CG marker in multiplanar (MPR) images was not feasible method for rapid detection of the frontal recess location in coronal plane.

Background: Multislice COMPUTED TOMOGRAPHY (CT) angiography is a robust imaging method for noninvasive assessment of coronary artery diseases، which is associated with high radiation dose. Having knowledge of the various parameters used to estimate the dose plays an important role in increasing the understanding of dose delivered to patients and help operators and technologist to reduce the dose. In this research، the amounts of Weighted COMPUTED TOMOGRAPHY Dose Index (CTDIW) for coronary CT angiography exams were measured in Isfahan city, IranMethods: To calculate the dose، an ionization chamber (Piranha، X-ray Analyzer، RTI Electronics and Sweden) and acrylic body phantom were used. Common conditions of coronary CT angiography used in two centers were applied for this project. Finally, CTDIW of all the scans were calculated using the related formulation.Findings: The amount of mean CTDIW for calcium score exams in Sina and Alzahra hospitals were 0.468±0.190 and 2.354±0.610 mGy, respectively (P = 0.007); and for coronary CT angiography scans in Sina and Alzahra hospitals were 6.221±1.290 and 5.299±0.840 mGy, respectively (P=0.860).Conclusion: CTDIW for the calcium score was significantly different in the two centers، but there was not significant difference in the two centers for coronary CT angiography scans. In this study، the amount of CTDIW was much lower than the measured in other centers. Since scan parameters have an important effect on the dose value، training and precision of technologist result in dose reduction and patient radiation protection.

Background: Determining the incidence and anatomic features of accessory mental foramen (AMF) in the Iranian population is of vital importance. This study investigated the prevalence and anatomic characteristics of AMF using CONE-BEAM COMPUTED TOMOGRAPHY (CBCT) in a selected Iranian population. Methods: A total of 853 CBCT images from 440 women and 413 men were examined in this crosssectional retrospective study. The images were evaluated by two independent observers using reconstructed 3-dimensional, cross-sectional, and panoramic views. Several parameters were assessed, including the location of AMF relative to mental foramen (MF), size and the point of canal bifurcations, and the distance between the main and accessory canals. Finally, statistical differences in the AMF prevalence in terms of gender and direction and its location were evaluated by the MannWhitney U test (P < 0. 05). Results: The prevalence of AMF was 10. 55%, which was more frequently located in the posterior inferior area relative to the main MF, and its nerve was more frequently originated from the anterior loop (P = 0. 001). There were no statistically significant differences in gender (P = 0. 26) and direction (P = 0. 4). The mean distance of AMF was 7. 62 mm. The mean height of MF and the AMF vertical height were 13. 65 mm and 52. 12 mm in those with AMF on one side, respectively, and this difference was statistically significant (P = 0. 001). The sizes of the MF and AMF were 3. 2 mm (large diameter), 2. 3 mm (small diameter), and 1. 4 mm (large diameter), and 1. 1 mm (small diameter), respectively. Conclusions: Based on the findings of the present study, the prevalence of AMF according to hemimandibular was 5. 80% in the selected Iranian population. Thus, AMF might branch from any section of the inferior alveolar nerve and the mandibular canal.

The aim of this study was to describe a new strategy, consisting of the use of CONE-BEAM COMPUTED TOMOGRAPHY (CBCT) in the planning and intraoperative stages of root canal treatment (RCT), associated with the use of radiopaque gutta-percha markers, as an auxiliary tool in the location of severely calcified root canals. Three cases involving anterior and posterior teeth with severe calcification of the root canal were submitted to initial periapical radiographic and CBCT evaluations for diagnosis and planning of the operative steps. In a first intervention, when the location of the canal orifice was not successful, radiopaque markers were inserted in the suggested position of canal orifice with the aid of magnification and the use of ultrasonic devices, in order to perform an intraoperative CBCT analysis that allowed dynamic navigation through the static position of markers. The association of intraoperative CBCT with radiopaque markers allowed the location of the canal orifice and the following RCT execution. The use of CBCT in two different moments of RCT allowed the diagnosis of three-dimensional anatomical variations of root canal. Add, when associated with the use of radiopaque gutta-percha markers, acted as an auxiliary tool in the location of the canal orifice of calcified canals. Therefore, the presented strategy provides the clinician the precision that cases with calcification require and give an important contribution to treatment predictability.

Background and Objective: The aim of this study was to evaluate the diagnostic ability of CBCT to detect external root resorption.Subjects and Methods: External root resorption defects of different sizes and in different locations were simulated in 60 human mandibular incisors. Cavities simulating root resorption defects of small size (0.3´0.6 mm), medium (1.2´0.6 mm) and large (1.8´0.9 mm) were drilled in the cervical, medial and apical thirds of buccal surfaces. The teeth were divided in random groups and mounted in the mixture of acryle and dryed skull sheep powder. CBCT scan was used to evaluate external root resorption in 180 root thirds by two blinded observer. Statistical analysis was done with Kappa test.Results: Sensitivity of CBCT to detect external root resorption was 89% and the specificity was 99 %.The most defects that was detected were on the medial root thirds and the lowest defects that were detected were on the apical root. The percentage of small defects detection was 80%.Conclusion: CBCT technique is a very good method to evaluate external root resorption with high sensitivity and excellent specificity. It can detect the defects as small as 0.3mm.