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.

Introduction: The inferior alveolar canal is an important anatomical structure in the field of dentistry implants and CONE BEAM COMPUTED TOMOGRAPHY (CBCT) is an important diagnostic technique. The aim of this study was to evaluate the prevalence of anatomical variations of the mandibular canal observed in CBCT images. Materials & Methods: In this descriptive-analytic study 384 inferior alveolar canals were evaluated in 192 patients, who were referred to the radiology department of Isfahan Azad University in 1396 for a CONE-BEAM COMPUTED TOMOGRAPHY. Radiographs were performed to assess the frequency of different left and right mandibular canal segregations by sex in terms of upper and lower position, baccolingual position, shape of the general canal. The frequency and different types of existing mandibular plug canals were also evaluated. Data were analyzed by Chi Square, independent T Test, paired t-test. (p value < 0. 05). Results: The mandibular canal was 2. 1% of the lower position, 11. 9% of the upper position and 86% of the middle position. Statistically significant differences were observed between the frequency distributions of canal positions and gender (p value = 0. 004). The prevalence of Bifid mandibular canals was 14. 8%. There was no significant relationship between the shape of the general channel path and gender. There was no significant difference between the mean distance between the mandibular canal and the buccal cortex in both Molar and Ramus with the sex of the subjects and the side of the canal (p value < 0. 05). Conclusion: The highest frequency of mandibular canal in most subjects was on the right in the intermediate position. The mean distance between mandibular canal and buccal cortex in Ramos and Molars area on both right and left sides was not significantly different between men and women.

Introduction & Objective: The mental foramen is a part of lower jaw which has neurovascular bundles and also is important in biology. 3D imaging of this area by CONE BEAM COMPUTED TOMOGRAPHY (CBCT) before surgery can prevent some problems. This study aims to evaluate the anatomic position and geometrical shape of the mental foramen by CBCT images.Materials & Methods: In this research, the CBCT images (by NewTom and Planmeca promax 3D set) of 85 patients referred to dentistry school clinic or other clinics in Hamadan city were studied. These patients did not have their first and second premolar teeth extracted in both right and left sides. The geometrical shape of mental foramen, the canal angle connecting to mental foramen compared to the buccal plate of lower jaw, distance from the lower border of mental foramen to the lower border of lower jaw, position of mental foramen relating to the root of adjacent tooth and the incidence of accessory mental foramen were studied.Results: The means of canal angle connecting to mental foramen in the right side in men and women were 123.3 and 130.1 and in the left side were 123.8 and 133.7, respectively. The mean distance from the lower border of mental foramen to the lower border of lower jaw in the right side in men and women were: 12.4 and 13.3 mm and in the left side were: 12.7 and 13.6 mm, respectively. Also, there is a meaningful statistical relation between gender and the angle of canal of mental foramen, regarding to the buccal plate in both sides.Conclusion: Regarding to the variations in the position and shape of mental foramen and the angle connecting to the mental foramen related to the buccal plate and accessory mental foramen, investigation of CBCT images before placement of implants is necessary.

Background and Objective: Many surgeries are performed on anterior region of mandible. Incisive branch of the inferior alveolar nerve is located in the anterior region of mandible. The identification of various form of nerve is important for diagnosis and treatment plan. This study was carried out to the assessment of visibility and extension rate of incisive branch of the inferior alveolar nerve in CONE BEAM COMPUTED TOMOGRAPHY (CBCT) imagings.Methods: This descriptive- analytic study was performed on 105 CBCT images. The presences or absence of incisive branch of the inferior alveolar nerve and assessment of visibility and extension rate of mandibular incisive canal were studied.Results: In 79% extension of the incisive branch of the inferior alveolar nerve were observed. 18.07% of extensions were observed in one-side and 78.31% were bilateral. Extension of the incisive branch of the inferior alveolar nerve was observed to central, lateral and canine tooth in 59%, 26.5% and 14.5% respectively. There was no significant relation beween gender and age of subjects with extension of the incisive branch of the inferior alveolar nerve.Conclusion: Regarding the high visibility of the incisive nerve branches in the lower dental CBCT images this method can be used to evaluate the anterior region of mandible.

Introduction & Objective: Study of bone quality before treatment is very important. The aims of this study were to assess bone quality with density values obtained by CONE-BEAM COMPUTED TOMOGRAPHY (CBCT) and to determine the correlations between bone density and primary stability of dental implants.Materials & Methods: In this experimental in vitro study 32 implants were inserted into fresh sheep bone. The bone densities of implant recipient sites were determined by CBCT. The maximum insertion torque value of each implant was recorded and stability was measured by Osstell. Spearman’s correlation coefficient was used to evaluate the correlations among the variables.Results: The mean density value, insertion torque, and Osstell value were 1481.78±166.614, 74.69±16.33 and 73.78±4.025 N/cm2 respectively. Statistically no significant correlations were found among the variables.Conclusion: The bone quality evaluated by CBCT showed no correlation with the primary stability of the implants.

Introduction: Bleeding is an important complication during implant placement. The aim of this study was to evaluate the anatomic situation of the posterior superior alveolar artery (PSAA) in CONE-BEAM COMPUTED TOMOGRAPHY (CBCT) images in maxillary molar region in an Iranian population. Methods: In this descriptive cross-sectional study, CBCT scans of the edentulous regions of the posterior maxilla were participants to examine the location and anatomical features of the PSAA. 300 CBCT scans of patients with the mean age of 48. 79 years were used. The CBCT scans had been obtained by Scanora 3D (Soredex, Tuusula, Finland). The diameter and the PSAA distance to the alveolar crest was measured by OnDemand 3D software on cross sectional and coronal sections. Data were analyzed through the Chi-Square, T-Test, ANOVA and Exact Fisher tests using the SPSS software (version 23). Results: Out of 300 images, the PSAA was observed in 203 (67. 6%) ones. The artery was slightly more observable in males (68. 8%) compared to females (66. 4%). Although the difference was not significant (pvalue: 0. 711). The mean artery diameter and distance to alveolar crest were higher in males (1. 33±, 0. 64 mm,18. 016±, 4. 78 mm, respectively) compared to females (1. 12 ±, 0. 47 mm,17. 885±, 4. 31 mm). Only the difference between the diameters was significant (p-value: 0. 008). Conclusion: According to this study, with the increase of age, the diameter and distance of the artery to bone crest decreases. The mean artery diameter and distance to bone crest is higher in males compared to females.