محمد امین توکلی

One of the major challenges in dam engineering is the design of the discharge flow of the stepped spillway. The rate of energy dissipation in downstream currents is higher than that of skimming currents. To achieve this goal, the discharge and skimming slope of the spillway must be low, which makes it economically efficient and applicable. For this reason, in the design process of spillway discharge, flow is assumed to be skimming. In this study, after validation of the Flow-3D model, the discharge flow of the Siah Bishe spillway was simulated. For validation, the values of the flow-Ashle curve were evaluated, and the root means square error of 5.07 was obtained. According to the results of numerical simulation, the flow must be at least 17 m3/s for the discharge. As the flow rate increases, the flow will discharge and move into the state of transient flow, which will continue to flow with 37 cubic meters per second. Finally, for values of more than 60 cubic meters per second, the flow is definitely skimming.

Temporomandibular Joint disorders are relatively frequent in different societies. The purpose of the present study was to determine abnormal Temporomandibular Joint radiographic findings in patients referred to Dental School, Shahid Beheshti University.

This descriptive cross-sectional study was done on 400 patients with no marked symptoms of temporomandibular joint disorders who met criteria of the study. Mean age of patient was 38.38. The data was collected by taking patients history, clinical evaluation while the panoramic radiographies were taken in standard conditions viewing by means of black-colored sheets. for statistical evaluation data was analyzed by chi- square and exact fisher tests.

Flattening was the most observed abnormal finding with 16.3% incidence. Erosion, condylar hyperplasia, concavity, Bifid condyle,condylar hypoplasia and sclerosis respected were the most common abnormal findings in this study. There were no significant differences in the incidence of abnormal findings regarding the patient’s gender, dental status and occlusion, but the prevalence of abnormal radiographic findings was significantly uprising as the age of the patients increased (P<0.002).

The results demonstrated the incidence of abnormal radiographic findings in 34.4% of the patients referring to the studied center which shows a relatively high prevalence.

An accurate imaging technique has an important role in implantology. Presence of sinus in the posterior maxilla is a limiting factor for implant insertion in this area. Therefore it is necessary to evaluate the relationship between alveolar ridge and sinus. The aim of the present in vitro study was to compare the accuracy of Cranex Tome Spiral and ProMax linear tomography to assess bone quality for the preoperative planning of implants in the posterior maxilla. Tomographs were taken from 3 dry human skulls using both units. Three sites were selected in each side of posterior maxilla and marked with orthodontic wires meaning a total of 24 sites (12 sites for each unit). Bone height and width were measured first on the tomography and then on the skulls after sectioning. In order to compare the measurement values between both units and to compare them with the values obtained from gold the Intraclass Correlation Coefficient of reliability (ICC) was used. The minimum Intraclass correlation coefficient of reliability was 0.569 in two times measurements of width for ProMax, and the maximum of this coefficient was 0.950 in two times measurements of height for Spiral. The mean difference between the real measurements and the height measurements of both units were less than 0.3 mm and for the width measurements were less than 0.5 mm of the real measurements. This study showed in both units, the height measurements were more accurate than the width measurements and all the measurements by Spiral were more valid then those of ProMax. Generally quantitative accuracy of Spiral unit was found to be higher than ProMax unit. Both units proved to be sufficient for quantity measurements. Adjustment an individual imaging plane for each site of tomography increases the accuracy. The most distal sites of Spiral unit may need separate adjustment other than manufacturer demands.

Determining chronological age of individuals is an investigation key in legal medicine. The aim of this study was radiographic evaluation of correlation between chronological age of Iranian people and developmental status of third molar tooth based on Demirjian staging method. This cross-sectional and diagnostic study was accomplished in Radiology department, Dental School, Shahid Beheshti University of Medical Sciences in Tehran (2004-2005). 350 young adults, 15-25 year-old, attended the study. ID cards and radiographic evaluation were used for data collection. The radiographs were studied by a legal medicine resident and an oral and maxillofacial radiologist. Determining the developmental stages of third molar teeth was based on Demirjian method. Statistical calculations were carried out by Levene, t, Wilcoxon's signed rank, Mann-Whitney, Friedman tests and Kendal correlation coefficients (tau-b). The distribution of different development stages of Demirjian method increased by development of third molars. There was a significant statistical discrepancy between boys and girls for the lower left third molar tooth (P<0.001) males were in a higher development rank. According to Calton system, the relation between Demirjian method and age was average in maxillary third molar teeth and was strong in mandibular third molar teeth. The maxillary third molars were generally in a higher development rank compared to mandibular third molar teeth (Friedman test, X2 = 44.214, P<0.001). Among four molar teeth, only developmental stage of lower left third molar was diagnosed to be effective (R= 0.714, R2 = 0.51, adjusted R2 = 0.507, F = 209.047, P< 0.001). Only stage (H) of Demirjian method that the distal canal is closed can be predicted with %99 precision whether the person will be 18 or above 18 years old.

It has been reported that some patients with multiple sclerosis may develop trigeminal neuralgia (TN) that may cause the loss of patient’s intact teeth when incorrectly diagnosed by dentists. This study was conducted with the aim of assessing the frequency of trigeminal neuralgia in MS patients who were referred to the Iranian MS Association during 2004-2005. This descriptive cross-sectional study was conducted on 179 MS patients whose diagnosis was confirmed by MRI protocol. Patients were selected randomly among those who participated in educational courses at the Iranian MS Association. The data was collected by questionnaire, interview and clinical examinations. The collected information was analyzed by student-t and fisher’s exact tests. The study showed that 7.8% of MS patients to have definitive signs of TN while detection of such involvement was not so clear in 2.8% of cases. About 76.5% of all patients were females and the rest (23.5%) were males. About 36.8% of TN patients showed some manifestations in the maxilla, 31.6% in the eye region, and 21.1% in the mandible. About 10.5% of the manifestations have occurred in the right side, 47.4% in the left and 42.1% in both sides. Seven patients (36.8%) demonstrated with trigger zones. Only about 10.6% of studied MS patients demonstrated trigeminal neuralgia. The ratio of TN development in patients with history of Baclofen usage was less than nonusers.

Trauma, as one of the most prevalent tooth accidents in all stages of life, has received a lot of attention. Increasing knowledge about trauma can reduce and prevent its harmful consequences as well as the related costs. The aim of this study was to evaluate treatment prognosis of anterior traumatized teeth among patients referred to endodontics and pediatrics of Shaheed Beheshti and Tehran dental faculties during 1995-2000. In this descriptive and exsisting data study, a written questionnaire was used for data collection. Files of patients with completed treatment, in endodontics and pediatrics departments of both dental faculties were investigated. The colleefed data were analyzed by SPSS software. 84% of the studied teeth were maxillary central teeth. The most prevalent etiology for trauma was falling down and the most prevalent type of fracture was that of enamel and dentin without pulpal involvement. The most reported treatment was pulpal and periapical treatment. traumatized anterior teeth, was acceptable. Treatment procedures conducted on the traumatized anterior teeth, was acceptable.

The cephalometric analysis should be done for patients seeking orthognathic surgical treatments to diagnose dentoalveolar relationships properly. Finding a landmark for the analysis must be time consuming and depends on individual experience or errors and further needs more training. The aim of this study was to develop and evaluate a software for automatically locating of the cephalometric landmarks. Methods & Materials: A software was designed and developed by programmers group using 140 cephalometric radiographs as databases. Further to cephalograms were grabbed by a digital camera (Sony cybershot 1000X1200) in JPEG format and displayed on LCD monitor (Toshiba, 1600X1200 UXGA) for three expert orthodontists and asked them to locate 10 landmarks. The statistic analysis was based on Paired t test. The results showed 51% of the assigned points by software locating were within 1mm accuracy, 63% within 2 mm and 92% within 4mm accuracy. The mean distance from reference (the mean distance of three observers’ points) of seven out of ten points was less than maximum difference between observers. For B point the mean distance difference in computer locating (0.4mm) was less than mean distance observers’ points (3.1mm). For S point the mean distance difference from reference point was 3.4mm in computer locating which was greater than the mean distance difference between observers (0.6mm). The study showed that landmark locating errors by computer were not greater than errors of individuals so, perhaps, computer could be a proper substitute for individuals for locating and analysis of cephalometric landmarks.

Bifid uvula is the mildest form of cleft palate. The size of the cleft may vary from minimal to complete separation of the uvula into two lobes. The prevalence is %0.3-2.2 and is greater in males than in females (M/F:2.5/1). The disturbance appears to be autosomal dominant. This developmental defect may occur in syndromes such as Marfan, Crouzon, Apert and Pierre Robin. Case Report: In this report, the patient was a 29 years old man whoever referred for dental restoration and scaling. He had Bifid uvula, dome – shaped palate, malocclusion and limited movement of mandibule. He didn’t have any systemic problems and syndrome.

Root fracture is a clinical problem which often is difficult to detect and diagnose. As the root fracture detection is based on demonstration of a fracture line or lines, radiographic examination is important. The aim of this study was to compare diagnostic efficacy of direct digital radiography with conventional radiography for detecting experimental root fractures. This study was based on observational diagnostic method which eighty one extracted single rooted human teeth were endodontically instrumented and divided into two groups, a control group of 40 teeth and a fractured group of 41 teeth in which root fractures were produced with Instron machine. Each tooth was imaged using the parallel technique with a CCD-based digital system and E-speed film. The images were interpreted by three experienced oral and maxillofacial radiologists without prior knowledge of the distribution of the root fractures. Three image groups were taken: conventional film, digital images and enhanced digital images. Sensitivity, specificity, false negative and false positive percentage, accuracy of each method in comparison with golden standard (visual examination of fractured and intact teeth) were analyzed. The degree of agreement in detecting root fractures with each imaging system compared with each other was expressed as the kappa value. The sensitivity, specificity and accuracy for root fractures in conventional radiography were 73.2%, 87.5% and 80.2% respectively, in direct digital radiography were 78%, 77.5% and 77.8% respectively and in enhanced direct digital radiography were 82.9%, 85% and 84% respectively. The most sensitive was enhanced direct digital radiography and the most specific was conventional radiography. There was fair to good agreement between conventional radiography and digital radiography (k=0.68), fair to good agreement between enhanced digital radiography and conventional radiography (k=0.73) and excellent agreement between digital radiography and enhanced digital radiography (k=0.90). The diagnostic efficacy of Conventional radiography, digital radiography and enhanced digital radiography in detecting root fractures was comparable with each other.

The aim of this research is assessment off radiation protection in Shahid Beheshti dental offices. Method & Material: This descriptive study was performed in 200 dental offices in 7 parts of Tehran under supervision of Shahid Beheshti University which were selected randomly in 2002. From these offices, 94% didn’t use Lead shielded wall, 75.5% didn’t use Lead partition, and in all of them distance between practitioner and x-ray unit was acceptable, in 1% rectangular collimator was used. The knowledge of dentists about radiation protection rules and methods were very poor and it is essential to emphasize on the radiation effects and x - ray risk and radiation protection guidelines in continuing education lectures.

This investigation was designed to evaluate upper airway spaces in patients with skeletal anteroposterior and vertical malocclusions. Methods and Materials: Ninty lateral cephalograms of patients were traced with Cl I, Cl II and Cl III malocclusions having normal bite, openbite and deepbite were traced. Hypopharyngeal, nasopharyngeal and oropharyngeal depths were measured considering a magnification of 1.1. Chisquare and ANOVA tests were used to analyse the data. Hypopharyngeal depth was found to be at 17.3±3.7mm in Cl I, 16.0±3 in Cl II and 16.7±4 in Cl III 17.4±0.1 in normal bite, 16.4±3.2 in openbite and 17.1±3.5 in deepbite. The mean oropharyngeal depth was 10.4±2.4 in ClI, 9.8±2.4 in ClII, 11.3±3.3mm in ClIII 10.9±3.1 in normal bite, 9.7±2 in openbite and 11±3.1mm in deepbite cases. Nasopharyngeal depth was found to be at 23.8±3.3 in ClI, 22:7±3.3 in Cl II: 21±4 mm in Cl III: 23±4.7 in normal bite, 22.1±3.5 in openbite and 22.4±3.1 in deepbite cases. No significant difference was found between hypopharyngeal and oropharyngeal depths of three vertical and sagittal malocclusions. However, nasopharyngeal depth showed a significant difference between Cl II and Cl III malocclusions and also between Cl I and Cl III malocclusions (P<0.05). No significant difference was found between different groups in vertical malocclusions too.