روشنک غفاری

 Due to the increased prevalence of third molar impaction and the complications and existence of disagreements regarding the predicting factors for the impaction of this tooth, the aim of this study was to evaluate the relationship between the position of the mandibular third molar with different vertical skeletal dimensions on the panoramic images.

This cross sectional study was carried out on lateral cephalogram and orthopantomogram records of 130 orthodontic patients visiting to Isfahan (Khorasgan) University Dental School. Age range of the sample was 20-35 years. Various facial forms were determined with mandibular plane angle (SN-GoGn), jarabak index and Y-axis; S-GN– Frankfort plane. Beta angle; which is the angle between intersecting long axis of mandibular second molar and mandibular third molar was measured to determine the angle of eruption of mandibular third molar. Eruption pattern was classified as per Pell & Gregory and winter’s system. The data were analyzed by Chi-square test (p value < 0.05).

There was a significant difference in the frequency distribution of growth pattern on the left side of the jaw (p value = 0.048). There was no significant difference in the frequency distribution of the eruption pattern in the right side of the jaw (p value = 0.11). There was no significant difference in the frequency distribution of eruption surface in the right face between different facial forms (p value = 0.49) But on the left side of the jaw there was a significant difference between the three facial forms (p value = 0.049). Frequency distribution of mandibular third molar impaction was significantly different between the three facial forms (p value = 0.03). There was no significant difference between the three facial forms in terms of frequency of eruption angle in the right side of the jaw (p value = 0.25) and also in the left side of the jaw (p value = 0.15).

The incidence of impaction was significantly more in patients with long face than in other two groups. The prevalence of surface and pattern of third molar eruption in only one side of jaw was significantly different between the three facial forms. There was no significant difference between the frequency of angle of eruption and facial skeletal types in both jaws.

 Impacted third molar reduces the bone level in the distal aspect of second molar, and sometimes it can lead to external root resorption of the adjacent second molar. The aim of this study was to evaluate the prevalence and quality of this resorption using cone-beam computed tomography scanning.

 In this descriptive study, CBCT images selected from 60 patients (including 107 maxillary & mandibular impacted third molars) were obtained from patients referring to maxillofacial radiology department of dental faculty of Islamic Azad University of Isfahan (Khorasgan) in 2016. Under observation of oral radiologist, the images were examined (two times with one-week interval) in axial, coronal, and sagittal sections and recorded to diagnose external root resorption in CBCT. The data were analyzed via descriptive statistics including contingency tables and relative abundance.

 The prevalence of external root resorption of second molar, adjacent to the third molar were 43.25%. The most common type of third molar impaction were mesioangular third molars (41.1%) and in the next level were the vertical (28.1%), and distoangular (18.7) and then horizontal (12.1). The most common location of resorption in mandibular second molar teeth was in 1.3 of cervical (62.5%), and then 1.3 of apical (20.8%) and 1.3 of the middle (12.5%). Also one of teeth resorptions (4.2%) was between the 1.3 of apical and 1.3 of the middle. The most common site of resorption in maxillary second molar teeth was at 1.3 of the apical (68.45%), and then at the 1.3 of the middle (17.35%) and 1.3 of cervical (8.7%). With regards to the severity of resorption; 78.96% of resorptions were mild, 12.03% severe, and 9.03 were moderate.

 The prevalence of this type of resorption is almost high and the most common position of impacted third molars that resulted in this type of resorption are mesioangular and horizontal. Most common site of resorption in the maxilla was 1.3 of the apical and in the mandible was 1.3 of the cervical, which were often mild in resorption.

Radiography is a valuable adjunct to the diagnosis of periodontal disease. This study aimed to compare the accuracy of two periapical radiographic and digital biting techniques in assessing bone resorption in posterior teeth of patients with chronic periodontitis.

This descriptive-analytical study was performed on 36 samples of interproximal surfaces of posterior teeth in patients with chronic periodontitis, candidate of flap surgery referring to the department of periodontitis, faculty of dentistry, Islamic Azad University of Isfahan (Khorasgan) in 2015. First two methods of imaging include periapical and digital bitewing were performed and the necessary distances were measured by a radiologist. Then, during surgery, and before the bone contour correction, the distance from the reference point to the alveolar bone shaft (gold standard) was measured by a Williams probe. Data were analyzed using Paired t-test. (α = 0.05).

Out of 36 specimens, respectively in bitewing and periapical radiographs 2 and 1 cases were equal with clinical and in 16 (44.4%) and 20 (55.6%) distances were more. The average difference of amount of bone resorption in bitewing was 0.2 ± 0.12 mm and there was no significant difference between estimated mean value (p value = 0.01). Average difference of amount of bone resorption in periapical to clinical method was 0.87 ± 0.26 it was significant difference (p value = 0.001).

According to result, the use of bitewing radiography to determine the rate of bone resorption in posterior teeth is preferable to periapical radiography.

Clivus forms the middle part of the skull base, and different anatomical and pathologies variations can be created in this structure. The aim of this study was to determine the morphological variations and anthropometric analysis of clivus in CBCT images.

In this descriptive analytical study, CBCT images of 130 men and women over the age of 18 were evaluated using On-Demand 3D software. The width, length as well as skull base and clivus angle were measured. Clivus was also examined for anatomical variations such as pneumatization, canalis basilaris medianus, basilar invagination, fossa navicular is magna. Data were analyzed through one-way ANOVA and T-test using SPSS 22 (α<0.05).

The mean length of clivus was significantly higher in men (45.72mm) than in women (41.56mm) (P<0.001). The mean skull base angle was significantly higher in males (118.39 degrees) than in females (113.4 degrees) (P<0.001).The mean width and angle of clivus had no significant difference between two genders, and none of the study variables was significantly different in various age groups. The mean skull base angle was significantly higher (120.06 degrees) in patients who had basilar invagination (BI) (P<0.001). In the study of variations, 3 (2.3%) cases of incomplete pneumatization, 7 (5.4%) cases canalis basilar medianus of which 6 (4.6%) cases had fossa navicularis magna with mean length of 7.07 mm and 19 cases of BI (14.6%) with mean length of 3.55 mm were observed.

Familiarity of the maxillofacial radiologist with the anatomical variations of clivus, which were also rare, is important to differentiate from lesions. In anthropometric analysis, the length and angle of the skull base may be used to determine gender.

Hyoid bone is a solitary bone, which is composed of a main body and two pairs of horns (greater, and lesser). This bone has an important function in respiration, swallowing, and speech. This study aimed to define the morphology and the frequency of fusion of hyoid bone and its relationship with age and sex on CBCT images.

In this cross-sectional descriptive analytical study, the CBCT images of 163 patients (92 females and 71 males) were analyzed using Type I OnDemand 3D software. In the axial cross-sections, the thickness and length of the hyoid body was measured; in coronal cross-sections, hyoid bone height was measured; and on the thick axial crosssections, the angle between the hyoid bone greater horn and the hyoid bone body midline was measured. The body and greater horn were classified into four categories in terms of fusion (non-fusion with a distance > 2.5 mm, non-fusion with a distance < 2.5 mm, partial fusion and complete fusion). The data were analyzed with Kolmogorov-Smirnov, chi-squared, and Fisher’s exact tests, paired t-test, and Kruskal-Wallis nonparametric test using SPSS 25 (α = 0.05).

In 79.7% of the patients the fusion was similar on both sides (p value = 0.806). There was no significant difference in hyoid bone fusion morphology between male and female groups and between the two sides (p value = 0.977). The most and least frequent types of hyoid bone fusion were type II (non-fusion with a distance < 2.5 mm) and type III (partial fusion), respectively. With the exception of the 10-19 year age group, type II category was the most common type, while type I was the most common in the 1–19-year age group. Hyoid bone fusion morphology varied significantly between the different age groups (p value < 0.05). Hyoid bone size (thickness, length, and height) was greater in men compared to women (p value < 0.05); however, the angle exhibited no significant difference between the male and female subjects (p value = 0.591). Of all the hyoid bone dimensions, only the length of its body was significantly different between the different age groups (p value < 0.05).

With advancing age, the distance between the body and the greater horn of the hyoid bone decreased, and its fusion frequency increased. Only the hyoid body length was different between the different age groups, and the other hyoid bone dimensions were the same. All the hyoid bone dimensions were greater in men compared to women, with the exception of the angle. It is possible to differentiate males from females based on the above-mentioned parameters. CBCT can help reconstruct the hyoid bone using its multiplanar reconstruction with lower radiation.

IIt is important to have proper knowledge about the blood supply of the maxillary sinus to prevent unnecessary complications during surgeries. The aim of the present study was to evaluate the posterior superior alveolar artery (PSAA) in subjects > 20 years of age using the CBCT technique. In this descriptive ‒ analytical study, CBCT scans of 135 patients, with a mean age of 34.4 years, were analyzed. The diameter, the distance to the medial wall of the sinus and the position of the artery within the sinus wall were evaluated on coronal sections. Data extracted from the SIDEXIS 3D software program were analyzed with SPSS 20, using independent T-test, Chi-squared test and one-way ANOVA (p value < 0.05). In 243 (90%) patients, PSAA was detected within the maxillary sinus, with no significant difference in distribution of the artery between females and males (p value = 0.33). The most and least frequent locations of the artery were in the first molar and the first premolar areas, respectively. The most common type of artery was intraosseous (type I). The maximum and minimum mean distances between the artery and the medial wall of the artery were found in the third molar and the first premolar areas, respectively. In addition, the mean distance between the artery and the medial wall and the mean vertical diameter decreased with aging (p value 0.001). CBCT can provide useful information about the anatomic structures inherent to the maxillary sinus and PSAA to prevent unnecessary complications during surgery.

TAll parts of the temporal bone might be pneumatized by mastoid air cells. The aim of this study was to determine of the prevalence of pneumatized articular eminence of the temporal bone on CBCT scans.
In this descriptive analytical study, 150 CBCT scans were evaluated for the presence or absence of pneumatization of articular eminence and other data such as age, sex and the involved side for each case were recorded in special datasheets. Data were analyzed with SPSS 20, using chi-squared test.
Pneumatized articular eminence (PAT) was observed in 9 cases (6%). The prevalence of PAT in males was 33.3%, with 66.7% in females, with no statistically significant differences. Unilateral involvement was more prevalent than the bilateral form. In seven patients (77.8%) PAT was multilocular, and two patients (22.2%) with PAT exhibited unilocular form on the scans.
Prevalence of PAT is higher than what has been reported to date; it has been reported less frequently due to the absence of clinical symptoms and signs.

Forensic odontologists are the specialists that can be asked to assist in estimating the age of persons who may or may not have reached the legal age. In this regard, selecting a practical method would be a priority. The present study aimed to measure the apices of third molar to discriminate between individuals who are or not 18 years of age or older and to fix a cutoff for evaluation of the age in these cases.

Panoramic radiographs belonging to 150 healthy individuals aged between14-23, were randomly selected. To evaluate the individuals, using Cameriere method, the third molar maturity index- I3M- of the left side was calculated as follows: The sum of the distances between the inner sides of the open apices divided by the tooth length to normalise the measurements. For the statistical assessment of the data, SAS software and Proc Logistic were used.

If an individual has I3M≤0/01, he is 18 or more and if I3M>0/01 it can be predicted that the probability of being 18 years or more using the calculated formula. According to the results, there was no significant correlation between gender and Cameriere method model.

Calculating the third molar maturity index is a practical method to estimate age in Iranian population. Concordant percentage of 89.3% and C factor 90% showed that this method is suitable to estimate the age of an individual of more or less than 18 years.

Non-pathological facial asymmetries are usually due to differences in sizes of the right and left sides. This study investigated normal facial asymmetry in individuals with Cl II and III malocclusion to clarify facial laterality and its relationship with the right-handedness or left-handedness.
In this cross-sectional descriptive-analytical study, frontal-view digital photographs were taken of 66 subjects (43 Cl II and 23 Cl III) referring to the Department of Orthodontics, Faculty of Dentistry, Khorasgan University. The patients were questioned about the main chewing function side and their right- or left-handedness. On the photographs, the facial midline and menton point on the chin were drawn; the distance between the midline and the left and right sides were measured on the photographs using Photoshop software program. In addition, the distance between the menton point and the midline was measured. Data were analyzed with independent t-test (α = 0.05).
In 51.2% of Cl II and 47.8% of Cl III subjects the right side of the face (p value = 0.85) was wider than the left side and in 48.8% of Cl II and 52.2% of Cl III subjects the left side of the face (p value = 0.79) was wider than the right side, with no significant relationship between dental occlusion and face width. In addition, 62.1% subjects exhibited deviation of the chin to the left side (p value Cl II and Cl III malocclusion exhibited no effect on face laterality and the facial half width; however, right-handedness and left-handedness affected face laterality.

The maxillary sinus septa are a major problem in sinus lift procedures, resulting in an increase in sinus membrane perforation. The aim of this study was to determine the frequency, location and size of maxillary sinus septa on CBCT images in an adult population.
In this descriptive-analytical study, CBCT images of 75 patients >18 years of age were evaluated. Then the frequency, location and size of maxillary sinus septa were determined. The patients were divided into three groups (n=25) based on the number of teeth: posterior complete edentulism, posterior partial edentulism and posterior complete dentition. The images were evaluated in terms of the location of septa in three areas: the anterior (premolar region), middle (distal to the second premolar to distal to the second molar) and posterior (distal to the second molar). The septa sizes and locations were evaluated using Ondemand 3D software program. Data were analyzed with ANOVA and chi-squared, McNemar and Kruskal-Wallis tests (α = 0.05).
In 150 maxillary sinuses, CBCT images showed 86 septa (57.3%). Most septa (53%) were located in the middle region of maxillary sinuses. Sinus septa were present in 30% of posterior totally edentulous subjects, 37% of posterior partially edentulous subjects and 33% of patients dentate in the posterior region, with no significant differences between the three groups (p value = 0.37). The mean height of the septa was 5.9±3.6 mm.
Most septa were located in the middle region of maxillary sinuses, with no statistically significant differences between the three groups. CBCT might provide useful information during sinus lift procedures, considering wide anatomic variations in the frequency, size, location and morphology of maxillary sinus septa.

Infraorbital ethmoid air cells are such anatomical variations may result sinusitis. CT scan is commonly used for imaging infraorbital ethmoid cells but panoramic radiographs often show infraorbital ethmoid cells. This study aim to determaine the prevalence of infraorbital ethmoid cells on panoramic radiographs in cases older than 4 years referred to Dental School of Islamic Azad University Khorasgan Branch.
In this descriptive and analytical study, 416 panoramic radiographs (235 wemen and 181 men) were examinded for infraobital ethmoid cells and were recorded hallers cell and characteristics of cell in questionnaire form. Data analysis were done by Chi-square test.
Prevalence of infraorbital ethmoid (hallers) cells on panoramic radiographs in the patients older than 4 years referred to Dental School of Islamic Azad University Khorasgan was 17.8% (14.4% for men and 20.4% for wemen). There was satisically significant differences between men and wemen. The most frequency related to the patients who were between 20-29 years old (28.3%) and the least frequent age was between 40-49 years old (13.5%), but there was no satistically significant differences in several ages. There was no relationship between taller’s cells and cell shape. 11 patients (14.9%) with hallers cell had history or symptoms of sinusitis and 4 patients (5.4%) with hallers cell had sinus disorder (retention cyst) in panoramic radiographs.
In this study, the prevalence of infraorbite ethmoid cells on panoramic radiographs was efficient for first diagnosis. Identification of hallers cells on panoramic radiographs can help dental professional to make differential diagnosis of orofcial pain of sinus origin.

The retromolar canal is an anatomical structure of the mandible and a type of bifid inferior alveolar canal. The retromolar canal might conduct accessory innervation to the mandibular molars or contain an aberrant buccal nerve; thus, this canal is of clinical significance. The aim of this study was to evaluate the prevalence of retromolar canal on cone-beam computed tomography (CBCT) scans. In this descriptive-analytical study, 151 retromolar canalsin 102 patients (102 unilateral and 49 bilateral) with third molar teethrequiring CBCT were evaluated. The scans were evaluated for presence of the retromolar canal and linear measurements (distance to second molar, height and width) were made. The data were analyzed by independent t-test and chi square test. The prevalence of retromolar canal was 7.3% (n=11).With regard to linear measurements, the mean distance from the retromolar canal to the second molar was 12.76± 4.3mm. The mean height of the canal was 6.66 ±2.18mm, and the mean width was 1.7± 0.6mm. The presence of retromolar canal was not statistically correlated withsex, side of the jaw or age (P=0.146). The prevalence of retromolar canal on CBCT scans was 7.3%.

Orthodontic mini-implants are widely placed in the palate. Cortical bone and soft tissue thickness of the palate are important factors for determining the location of mini-implants. The present study investigated the palatal cortical bone thickness using cone-beam computed tomography (CBCT). In this descriptive-analytical trial, 150 eligible CBCTs were selected from males and females in two 19‒40 and 8‒18 age groups. Cortical bone thickness was measured on 8 coronal slices (with 3-mm distances from the incisive foramen) at 0 (midline), and 3- and 6-mm distances from the palatal midline using On Demand 3D software. Data were analyzed with Student’s t-test between two age groups and genders while repeated measures ANOVA was used to analyze data on anterior, middle and posterior areas of the palate (α=0.05). Cortical bone thickness means were 1.38±0.28, 1.1±0.33 and 1.16±0.43 mm in the anterior, middle and posterior regions, respectively (p value < 0.001). Cortical bone was thicker in males at 3-mm distance from the midline compared to females (p value < 0.001) and in the 19‒40 age group compared to the 8‒18 age group (p value < 0.03). There were no significant differences between the two age groups and genders in cortical bone thickness at midline and at 6-mm distance from the midline. Under the limitations of the present study, the anterior region of the palate exhibited the thickest cortical bone; however, mini-implants can be placed in the posterior areas due to the adequate bone thickness.

Frontal sinus and nasal septum have different forms in different people. Frontal sinuses are different in shape even in monozygotic twins. The aim of this study was to determine the prevalence of different combined patterns of frontal sinus and nasal septum in men and women referring to a treatment center in Isfahan. In this descriptive/analytical study Water’s views of 198 subjects aged 20‒40 were collected. The particulars of frontal sinuses in relation to the presence or absence of the sinus proper, symmetry or asymmetry, the form of the septum and the superior border outline of the sinus and the form of the nasal septum were evaluated and recorded. Data were analyzed with chi-squared test (α= 0.05). Bilateral presence of frontal sinus was observed in 100% of the subjects. There were no relations between sex and the presence of a septum within the frontal sinus (p value = 0.53), sinus symmetry (p value = 0.35), and form of the nasal septum (p value = 0.89). There was a significant relation between sex and the presence of a scalloped superior border outline of frontal sinuses (p value < 0.05), with more scalloped borders in men compared to women. Under the limitations of the present study, it was concluded that the combined patterns of frontal sinuses and nasal septa on radiographs cannot be used to distinguish males from females.

Digital radiography systems can be used to detect dental caries. These systems have the advantage of reducing patient dose. The purpose of this study was to compare digital photostimulable phosphor plate, charge coupled device and cone-beam computed tomography systems in detection of interproximal demineralization.

In this cross-sectional analytical laboratory study, sixty extracted human teeth with sound mesial and distal surfaces were selected. Using a ¼ round bur (0.5 mm in diameter) cavities were prepared to a depth of 0.25 mm just apical to the interproximal contact point on 15 surfaces of teeth. A ½ round bur (0.6 mm in diameter) was used to prepare cavities to a depth of 0.3 mm on 15 surfaces and a #1 round bur was used to prepare cavities 0.4 mm in depth on 15 surfaces. The teeth were mounted in groups of three in wax blocks. The images were captured by digital CBCT, PSP and CCD systems under a standard condition. One oral radiologist observed the images to detect interproximal defects twice three weeks apart. Then, sensitivity and specificity were calculated and Cochran test was used for statistical analysis with SPSS 20).α=0.05).

The sensitivity rates of CBCT, PSP and CCD systems for the detection of lesions measuring 0.25 mm in depth (incipient caries) were 100%, 93.3% and 86.7%, respectively (p value = 0.22); there was no differences between the systems in the detection of deeper lesions (100%). There was a high agreement rate between the radiographic systems evaluated and the gold standard in the detection of lesions with varying depths (CCD=94.4% and CBCT/PSP=100%). Specificity of all the systems was 100%.

Under the limitations of this study, there were no significant differences between CBCT, PSP and CCD digital radiographic systems in the detection of interproximal demineralization. The specificity of all the three systems was the same.

Raising knowledge about skeletal and soft tissue changes with aging has been highly essential due to an increasing demand for esthetic facial surgery due to aging. The aim of this study was to evaluate the three-dimensional computed tomography images to assess changes in the orbit with aging. In this analytical-descriptive study facial bone computed tomography (CT) scans were obtained from 66 subjects (33 females, 33 males). The subjects consisted of 11 males and 11 females in each of the three age categories: 20-40, 41‒60 and over 60. Each CT image was reinforced by using the Volume Viewer three-dimensional analysis software program. Linear measurements were carried out using Workstation GE 403 software program. Orbital aperture width was measured as a line drawn from the posterior lacrimal crest to the fronto-zygomatic suture. This line was then used as the x-axis from which the distances to the superior and inferior orbital rim at nine equal increments (labeled 1 to 9) were obtained. The height of the orbit was measured at 10 locations. Data were analyzed using one-way ANOVA and post hoc LSD tests (α=0.05). In both genders there were significant changes in the orbital width (p value < 0.001) with aging. There was an increase in the height of superior orbital rim in both genders (p value < 0.05), except for location 8, i.e. the most lateral point, in males (p value = 0.3). In addition, there was an increase in the height of the inferior orbital rim in both genders (p value < 0.05), except for location 1 (the most medial point) in males (p value = 0.2), suggesting that the inferior and superior orbital rims receded with age. Under the limitations of the present study, recession takes place in the width and height of the orbit with advancing age in both males and females. Knowledge about these senile changes might prove useful in esthetic surgeries, facial reconstructions and reconstruction of facial changes.

Frontal sinuses are valuable for human identification especially when there are not other identification methods. The aim of the study is evaluation of frontal sinus indexes in Isfahanian population samples for identifying unknown persons. In this study paranasal sinus images of 103 cases in the age range of 12-81 were collected. Then presence or absence, symmetry or asymmetry, kind of septum and superior border outline form of frontal sinuses were evaluated and FSS classification system was used for classification of indexes. Furthermore, total width of two sinuses, the distance between the highest points of the two sinuses and the distance of each sinus to its maximum lateral limit, were measured; then, the data were analyzed. Bilateral and unilateral absences of frontal sinus were observed respectively 2.9% and 1.9%. Also, there were no relation between age and sex with frontal sinus presence. Most dimensions of men were larger than women. There was no relation between the age and the measurements. Probability of the frontal sinus uniqueness was 75% in our samples; though, it was increased 100% by adding measurements. The success rate of 75% implying the classification method could be useful for practical purposes of identification especially by adding measurements to it.

Background and Digital radiography has led to many improvements in radiology. Despite many advantages there are different ideas in determining anatomical landmarks which results in some errors in cephalometric analyses. The aim of this study was to determine the degree of identification differences of anatomical landmarks by conventional and digital lateral cephalometric techniques using manual tracing of human skulls. This descriptive-analytical study was conducted in 17 cases of human skulls in which metal radiopaque markers were attached to 9 landmarks as follows: N, S, ANS, PNS, A, B, Pog, the most inferior point of lower mandibular border, and Go. Conventional and digital lateral cephalograms were obtained from each skull with and without markers. The two cephalograms without markers were traced for landmarks by three orthodontists. Any difference between these landmarks and those of cephalograms with markers, were recorded and analyzed by student t-test. The level of differences in S point was not statistically significant along both x and y coordinates. The measurement differences for the ANS and PNS points obtained by both radiographic methods were significant along the x coordinate but not significant along the y coordinate. Also, the measurement differences for the most inferior point of lower mandibular border, A, B, and Go points along both x and y coordinates were observed to be statistically significant. The measurement difference obtained for the Pog point was significant along the y coordinate and non-significant along the x coordinate. The difference in landmark identification between the two digital and conventional lateral cephalometric techniques was statistically significant for some points on both dimensions, however, the difference was not clinically significant.

Mandibular third molar impaction can sometimes be associated with pathological phenomena such as caries, pericoronitis and cystic lesions. The aim of this study was determination of some anatomic factors, including gonial, alpha and beta angles and Ganss ratio for predicting mandibular third molar impaction. In this cross-sectional descriptive/analytical study, 98 panoramic radiographs of patients, aged 20‒30, were divided into two groups of erupted and mesioangularly impacted third molars. Inclination of the third molar to the second molar (beta angle), third molar angle to the base of the mandible (alpha angle), the distance between the most distal point of the second molar to the anterior border of the ramus (Ganss ratio), and the angle between the posterior border of the ramus and lower border of mandible (gonial angle) were recorded. Data were analyzed by t-test using SPSS 11.5 (α=0.05). Means of gonial angles in the mesioangularly impacted and erupted groups were 122.8° and 122.5°, respectively, with no significant differences (p value = 0.66). Means of beta and alpha angles and Ganss ratios in the erupted group on the right side were 42.64°, 86.11° and 1.24 and in the mesioangularly impacted group they were 21.48°, 70.85° and 0.82. Means of beta and alpha angles and Ganss ratio on the left side in the erupted group were 9.26° and 94.1° and 1.22 and in the impacted group they were 25.7° and 71.25° and 0.82 (p value < 0.001). Alpha and beta angles and Ganss ratios were appropriate discriminative factors for predicting impaction of mandibular third molars. The means of Ganss ratios and beta angle were higher in the impacted group and the alpha angle was greater in the erupted group. Gonial angle could not be a suitable discriminative factor for predicting the impaction of third molars. It appears by determining alpha and beta angles and Ganss ratio on panoramic radiographs at 20 years of age it is possible to predict eruption status of third molars.

The accuracy of Willems and Demirjian’s methods can be affected by different patterns of calcifications of molars and premolars. In this descriptive-cross sectional study, 152 panoramic radiographs of 47 boys and 105 girls aged 3 to 18 were used. The dental age of samples was determined by Willems and Demirjian’s methods. Based on the developmental of first and second premolars and second molar the following ranking was made: 1. The development stage of the first premolar and the second premolar is the same. 2. The development stage of the first premolar is earlier than the second premolar. 3. The development stage of the second premolar and the second molar is the same. 4. The development stage of the second premolar is earlier than the second molar. Data were entered into SPSS 17 software and analysed by paired t-test. Demirjianʼs method overestimated the age of the teeth (0.5 years) and Willmsʼ method under estimated the age of the teeth (0.2 years) that shows the higher accuracy of the Wilelmsʼ method. The Willems method in the first group of the whole population,in the girls of the first group and in the boys of the second group showed the highest accuracy. Demirjian’s method in the whole population and in the girls of the second group and in the boys of the third group showed the highest accuracy. This research showed that the accuracy of Willemʼs method is higher than Demirjianʼs, and different patterns of tooth development affect the accuracy of these methods and will help the forensic dentist to be more ensured.

The aim of the present study was to assess the effect of mandibular inclination on accuracy of linear measurements performed on CBCT scans. In this descriptive analytical study، 12 linear dimensions between anatomical landmarks were measured on a dried human mandible. The measurements were obtained with a digital caliper three times by two observers. The mandible was scanned using a cone-beam CT (scanora 3D) with the base of mandible positioned in 5 different inclinations: horizontal، tilted downwards، tilted upwards، laterally tilted and rotated. Computer measurements of the dimensions were obtained twice by two observers، three times at each session. Then، the inclinations were corrected by the software and all the measurements were repeated. Paired T-test and Pearson correlation test were used to analyze the data. In 88. 4% of the samples، the mean computer measurements were smaller than the mean manual caliper measurements. The mean difference was 0. 01-2. 65 mm for different inclinations. The percentage error was below 10% (except for 6 cases) which is considered to be the safe margin in studies. Following correction of the inclinations، the mean absolute error exceeding 1 mm was observed in only one case and the percentage error was less than 8%. Regarding the reproducibility high inter and intra examiner correlation was observed (r>0. 9). High inter and intra examiner correlation was observed with respect to the reproducibility of the results (r>0. 9). Head orientation during CBCT scanning is not as crucial as in CT scan especially when the inclinations are corrected via software before the measurements.

The use of hand-held portable x-ray units is on the rise in dentistry. X-ray equipment operators are worried about being exposed to radiation-induced risks. The aim of this study was to determine the amount of scattered radiation around PORT-XII portable dental radiography device.

In this descriptive study radiation dose measurement was carried out at 6 positions around the PORT-XII radiography unit (over، under، right، left، behind and front at a distance of 1 meter from the unit). Dosimetry was carried out by the Geiger-Muller counter. The setting for all the exposures consisted of 60 kVp، 2 mA، and 0. 3 s and Primax (class E) films. In the current study 15 patients were evaluated. Study data was compared to the annual maximum permissible dose. Data were analyzed by paired t-test and one-way ANOVA using SPSS 18 (α = 0. 05).

The measured backscattered radiation at 6 positions around the PORT-XII unit at a distance of 1 meter far from the equipment was below the annual maximum permissible dose of 50 msv. The backscattered radiation behind the PORT-XII unit was less than other sides and the mean was 0. 98 ×10-3 msv، demonstrating a significant difference from other sides (p value < 0. 001). However، other sides were not significantly different from each other (p value = 0. 169). The mean of the measured dose was 0. 002 msv near the unit and 0. 004 mR 1 meter away from the unit.

Based on the results of the present study، the measured dose around PORT-XII unit was well below MPD.

An important step before establishing CBCT as a common orthodontic diagnostic approach is to assess landmark reliability. The purpose of the present study was to evaluate intra- and inter observer reliability in 3D landmark identification using CBCT images.

A total of 30 CBCT images were selected for this experimental study. Working independently، two observers identified 14 landmarks، twice in the CBCT images. Selecting the most appropriate slice in the axial، coronal، and sagittal views، the position of the landmark was recorded in millimeters for the X، Y، and Z coordinates respectively. Intra- and inter observer reliability values were determined using Pearson’s correlation test.

The Intra class correlation (ICC) was >0. 7 for 97. 6% of intra observer assessments and 92. 8% of inter observer assessments. None of the ICCs were <0. 6. The ICC was ≥0. 9 for 25 (59. 5%) of the intra observer assessments. The ICC was ≥0. 9 for 28 (66. 67%) of the inter observer assessments. The mean differences between the two observers in 95. 2% of the cases were less than 2 millimeters.

Considering the limitations and the results of the present study، the intra- and inter observer reliability was high. With proper training of the operator، the three-dimensional landmark identification using CBCT can offer consistent and reproducible data.

The relationship of the mandible to the cranial base influences both sagittal and vertical facial disharmonies. The aim of the present study was to analyze the relationship between facial height and sagittal position of the glenoid fossa in subjects with Class II malocclusion associated with mandibular retrusion.

This descriptive-analytical study was carried out on 60 subjects (21 males and 39 females, aged 7‒12 years), with Class II malocclusion associated with mandibular retrusion, who had different facial heights (normal, short, long). The cephalometric measurements were carried out based on three parameters of GF-S on FH, GF-PTM on FH and GF-FMN. Data were analyzed by SPSS16 using one-way ANOVA and Duncan analysis (α = 0.05).

The means of GF-FMN distances in subjects with short, normal and long faces were 72.6 mm, 70.4 mm and 69 mm, respectively. The means of GF-S distances on FH in the three groups were 11.6 mm, 12.7 mm and 11.27 mm, respectively and the means of GF-PTM distances on FH were 30.09 mm, 28.6 mm and 28 mm, respectively. There were no statistically significant differences in the sagittal position of glenoid fossa between the three groups (p values < 0.05). There were significant differences between long and short faces in the GF-FMN distance (p value = 0.048).

Under the limitations of this study there was no significant relationship between facial height and the sagittal position of glenoid fossa in subjects with Class II malocclusion associated with mandibular retrusion.

Backgroung: The most prevalent method for determining the dental age is the Demirjian method. But, different studies have been showing that this method overestimates the age so, Willems has presented a newer method. Willems has used (ANOVA) system to adapt Demirjian method to Belgian Caucasian race. The result was new tables in sex separated. Calculating the overall maturity score by summing the adapted scores for the seven mandibular teeth directly results in the estimated dental age. The purpose of this study is to determine the accuracy of Willems Method in age estimation of children by radiography of developing teeth in Esfahan. In this descriptive, cross –Sectional study, 151 panoramic radiographies belong to 54 boys and 97 girls at the age of 3 to 18 years old, were used. The samples of chronological age was obtained by subtraction of birth date from the radiography performance date. The sample of dental age which was determined by both Demirjian and Willems methods were entered to SPSS software (Ver 17) and differences with the chronological age were analysed by using a t-test and ANOVA. Fingings: The Demirjian method resulted in an overestimation of 0.63 year (boys 0.94 year and girls 0.47 year). The new adapted method resulted in a smaller overestimation of 0.11 year (boys 0.22 year and girls 0.06 year). In different age groups, the minimum difference has been in the range of 11 to 12 years old and it was 0.01 year. The maximum difference has been in the range of 17 to 18 years old and it was 1.2 year. The statistical difference between chronological age and Willems method is not significant. The adapted method was resulted in more accurate dental age estimations in this population