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.

Introduction: Due to the possible association between chronic sinusitis and anatomical variations of the area, the present study was performed to determine the prevalence of concha bullosa and nasal septal deviation and their association with chronic sinusitis to increase the success rate of nasal endoscopic surgery by eliminating the predisposing factors. Materials & Methods: In this cross-sectional study, (CBCT) images of maxilla from 100 patients referred to the radiology department of Hamadan Dental School in the year 2016-2017 were examined. Pneumatization of middle concha (concha bullosa) on sides, nasal septum deviation, and mucosal thickening were recorded. Data were analyzed by Chi-square test based on gender and age (p value ≤,0. 05). Results: The results showed that there was no significant difference between the mean age and sex with the presence of concha bullosa (p value > 0. 05). 50% of the samples had nasal septum deviation and 42% had chronic sinusitis displaying no significant difference between men and women (p value > 0. 05),Also, there was no significant difference between nasal deviation and chronic sinusitis (p value > 0. 05), although chronic sinusitis was significantly higher in people with concha bullosa and while concha Bullosa was significantly higher in people with nasal septal deviation (p value < 0. 05). Conclusion: According to the results of the study, concha bullose can be considered as a predisposing factor for chronic sinusitis.

Background. This study aimed to develop a classification for the sagittal root positioning (SRP) of mandibular anterior teeth in terms of their anterior buccal bone for use before placing immediate implants. Methods. A retrospective review of (CBCT) images was conducted on 150 patients (75 males and 75 females; mean age: 47. 5 years) who met the inclusion criteria. The root position of the tooth samples was classified as buccal, middle, or lingual types according to their respective sagittal position and subtypes a, b, c, or d, according to the morphology of their osseous housing. Results. The frequencies of the root positions of each classified group of the sample teeth were as follows: 14% buccal type, 77% middle type, and 8% lingual type; 18. 0% subtype a, 4. 33% subtype b, 75. 55% subtype c, and 2. 11% subtype d. As a complementary procedure for data collection, the sagittal position of the apex was classified into Class I (buccally angulated apex: 4. 6%), Class II (apex with no angulation: 78. 2%), Class III (lingually angulated apex: 0. 7%) and Class IV (exposed root: 16. 3%). In addition, the results of the examination of the buccal undercut showed that in 1. 6%, 32. 0%, and 66. 3% of the sample teeth, the undercut was located coronally, medially, and apically, respectively. Conclusion. Considering these results, the newly proposed SRP classification system can be used to study the mandibular anterior buccal bone morphology as a diagnostic tool for immediate implant treatment.

Background and Aims: There is a risk of nerve injury during the extraction of the impacted third molars, in cases with proximity of the inferior alveolar nerve and this tooth. The aim of this study was to evaluate the effect of different various factors on the degree of vulnerability using (CBCT) (Cone Beam COMPUTED TOMOGRAPHY) imaging technique.Materials and Methods: (CBCT) images of 191 patients referred for the exact assessment of the relationship between the mandibular canal and impacted mandibular third molars were selected. The position of these anatomical structures was evaluated at their contact point. The possible effect of gender, impaction form of the third molars, anatomical relationship between the third molars and the mandibular canal and the age differences were studied. Data were analyzed using Chi-square and Student’s t-test.Results: There was a close relationship between the mandibular canal and impacted third molars in 81.7% of the patients. The contacts were shown to be significantly higher in females than males (P=0.01) and in the cases with the lingually position of the third molar and the mandibular canal (P<0.001). However, age and impaction form of the teeth did not have a significant influence.Conclusion: The risk of nerve damage or exposure will be increased in females and lingual position of the mandibular canal to the third molar in cases with higher proximity between these 2 structures in panoramic radiographs using (CBCT) images. Therefore, the surgeon must pay enough attention in these cases of third molar extraction.