فهرست مطالب داریوش گودرزی پور

In the panoramic images, palatoglossal space error develops when the patient is unable to put the tongue against the mouth roof. In the case of this error, the radiographic diagnosis of the area is made with some difficulties or ever the image may lose its diagnostic ability. The aim of the present study was to investigate the relationship between the palatoglossal space error of the panoramic images and skeletal relationship. In this descriptive cross-sectional trial, 494 panoramic images were selected at the orthodontic department of Tehran dental school archive and the existence of the palatoglossal space was determined. The palatoglossal space error was statistically analyzed using chi-square test regarding the patients’ gender, age and skeletal relationships. Of total panoramic images, 346 (70.0%) cases showed palatoglossal space error while 148 (30.0%) images were free from this error. Furthermore, 74.1% of male images and 66.9% of female images showed palatoglossal space error. In Cl I (1˂ANB≤3), Cl II and Cl III patients; 65.6%, 73.1% and 67.4% of the images demonstrated the error, respectively. The incidence of palatoglossal space error in 5-14 and 15 years old age or higher patients were 72.2% and 58.8%, respectively. It was concluded that n o significant difference w as noted between the incidences of the palatoglossal space error regarding the patients’ gender or their skeletal relationships. T he error frequency was significantly decreased with age.

Because of high prevalence of TMJ dysfunctions، increased promotion of diagnostic and treatment methods is necessary. In many cases، in addition to disc position، morphology of other joint components such as articular eminence can be changed and therefore the probable correlation between disc position and morphology of hard tissue components can be used for prediction of internal derangements. The aim of this study was to evaluate the correlation between the position of disc and morphology of articular eminence of TMD`s patients using magnetic resonance imaging (MRI). In this cross sectional study by evaluation of digital MRI files، ultimately 78 joint images were identified which had sufficient quality and resolution for review. Then the MRI images، were observed and evaluated by 3 oral and maxillofacial radiologists to determine the disc position (normal، anterior displacement with and without reduction، and posterior displacement) and morphology of articular eminence (Box، Sigmoid، Flattened). Ultimately the results that were reported at least by 2 observers were included as the final results and were recorded in the check list. Data were analyzed using Chi-Square test and Fisher test. In this study، no case of posterior disc displacement was found and therefore was excluded from the study. Articular eminence morphology (Flattened versus Sigmoid) showed statistically significant correlation with anterior disc displacement with and without reduction (P-values for anterior displacement with and without reduction were 0. 03 and 0. 002، respectively). No significant difference was found between the sigmoid and box types in relationship with disc displacement (P-values for anterior displacement with and without reduction were 0. 72 and 0. 70. In this study، no significant difference between the anterior disc displacement with reduction and anterior disc displacement without reduction in relationship with the morphological changes of articular eminence in any of the cases were found. The results showed that flattening of articular eminence had significant relationship with anterior disc displacement.

Internal derangement of the Temporomandibular joint (TMJ) is the most common form of Temporomandibular disorders, which represents an abnormal internal strucural and functional change of the disk, as well as an abnormal relationship of the disk to the condyle, glenoid fossa and articular eminence when the teeth are in the closed- mouth position. The aim of this study was to evaluate the correlation between eminence steepness and condyle disk movements in TMJs affected by internal derangements using magnetic resonance imaging (MRI). In this cross-sectional study, digital MRI files of 90 joints belong to 45 patients in open and closed-mouth positions were evaluated. Patients were subdivided into two groups: 64 individuals with anterior disk displacement with reduction and 26 individuals with anterior disk displacement without reduction. Appropriate oblique sagittal sections were selected and printed. Outlines of the fossa, eminence, condyle and disk were traced on matte acetate sheets and evaluated by an oral and maxillofacial radiologist and a postgraduate student of oral and maxillofacial radiology. Disk rotation, condyle rotation, condyle translation and eminence steepness were measured. The data were analyzed using T-test. In this study, no significant difference was found in measurements between the two groups, (for steepness P=0.64, for Disc rotation P=0.77, for condyle rotation P=0.28 and for condyle translation P=0.12). Disk rotation showed statistically significant correlation with eminence steepness in the anterior disk displacement with reduction group (P=0.034). Although this correlation was weak (r=0.27) no statistically significant correlations were found between other variables and eminence steepness in this group (for condyle rotation P=0.3 and for condyle translation P=0.98). Disk rotation and condyle translation had statistically significant relationship in the anterior disk displacement without reduction group (P=0.011, r=-0.49). In addition, a significant difference was found between disk rotation and condyle rotation in this group (P=0.004, r=0.54). The relationship between other variables and eminence steepness were not statistically significant (for disc rotation P=0.06, for condyle rotation P=0.72 and for condyle translation P=0.73). According to the results of the present study, there is no obvious relationship between eminence steepness and movements of the condyle- disk assembly in patients with TMJ internal derangements. Therefore, the hypothesis that a steep articular eminence of the TMJ is a predisposing factor for disk displacement without reduction could not be verified. Performing prophylactic Eminectomy as a part of patient treatment plan is doubtful and need further evaluations.

using computed radiology (CR) technology. If we know the accuracy of digital panoramic radiography for detection of small defects in tooth, it will be useful in cases with difficulty for taking the intraoral radiographs. The aim of this study was to evaluate sensitivity and specificity of digital panoramic radiography for detection of proximal caries compared with the bitewing radiography. One-hundred patients who had been ordered for taking both bitewing and panoramic radiography were included in this study. Panoramic and then bitewing radiographs were observed by a maxillofacial radiologist and interproximal caries were recorded. Sensitivity and specificity of digital panoramic radiography (CI=95%) was calculated compared with the bitewing radiography as a gold standard. This study showed that the values for sensitivity and specificity were 62.7% (CI 95%=57.7%-67.5%) and 91.0% (CI 95%=89.2%-92.5%), respectively. Sensitivity of digital panoramic is less than bitewing radiography even with processing before printing. Therefore, bitewing radiography is superior for detection of inter proximal caries.

Caries and bone loss are the most common diseases in oral cavity. The prevalence of these diseases will be reduced by controlling their risk factors. In this study, bitewing radiographs of patients were examined to illustrate the relationship between caries and bone loss. One-hundred and fifty bitewing radiographs of 86 patients were evaluated. In these radiographs, caries and distance between alveolar crest and CEJ were measured. In addition, confounding variables (contact type, tooth type, tooth surface) were assessed. Furthermore, patients were asked about the use of other possible risk factors of bone loss like smoking, brushing, and flossing. The data were analyzed using Regression analysis. Findings of this study showed that the relationship between caries and bone loss was significant (P=0.02). Also, there were significant relationships between flossing (P=0.03), tooth type (P=0.0001) tooth surface (P=0.02) and bone loss. Finally the multivariate analyses considering confounding variables illustrate significant relationship between caries and bone loss (P=0.0001). Caries and bone loss have important roles as the risk factors for each other. Thus, it is necessary to prevent these risk factors and treat them as soon as possible to reduce these diseases.

Overlapping of the proximal surfaces of posterior teeth in the panoramic radiography is a major concern. Therefore, an option has been developed in the panoramic unit of Planmeca Promax, namely improved interproximal mode. This mode causes lower horizental angle with the teeth contact region during the unit rotation decreasing overlapping of the panoramic images of the posterior teeth especially premolar teeth. The present study was done to compare the overlapping of posterior teeth using two techniques of improved interproximal panoramic program and standard panoramic. In this diagnostic study, 32 patients requiring panoramic radiographies at their posterior teeth during their routine diagnosis and treatment process with the mean age of 27.3 years were participated. No patients showed crowding of posterior teeth or missed and restored posterior teeth. The participant's panoramic radiographies were randomly taken by two techniques of improved interproximal panoramic and standard panoramic using Planmeca Promax device. The overlapping of the panoramic images was blindly assessed by an oral radiologist. The overlapping in both techniques was reported by frequency and percentage. The comparisons were done by Chi-square test between two techniques and the odds ratio of overlapping was estimated using regression analysis. In standard panoramic techniques, 38.5% (148 contacts of 384 contacts) of the proximal surfaces overlapped while the overlapping of the proximal surfaces was observed in 18.8% (72 contacts of 384 overall contacts) in improved interproximal technique. Significant differences were noted between two techniques regarding overlapping (P<0.001). Also 66.4% and 39.1% of 4-5 teeth contacts overlapped in standard and improved techniques. The values were reported to be 39.1% and 12.5% in contacts of 5-6 teeth and 10.2% and 4.7% in the contacts of 6-7 teeth in both techniques, respectively. The overlapping odds ratio in improved technique as compared to standard techniques was 2.72 more. While the odds ratio of overlapping in the contact regions of 4-5 and 5-6 teeth was 16.4 and 4.61 as compared to the contact region of 6-7 teeth (all: P<0.001). The lower or upper jaw with the patient's mouth side did not significantly influence the overlapping of the proximal surfaces in both panoramic techniques. Under the limitations of this study, improved interproximal panoramic significantly reduced the overlapping of proximal surfaces in the panoramic radiographies of posterior teeth as compared to the standard panoramic technique. Therefore, it can be used to detect proximal caries in the posterior teeth as a diagnostic tool. Using this option may affect other part of panoramic image which should be investigated in other research.

Impaction of maxillary cuspids is the most common after third molars with 1% to 3% prevalence. Localization of these impacted teeth may affect orthodontic or surgical treatment plan. Therefore, different techniques have been introduced to localize impacted canines. The present study was conducted to compare the accuracy of panoramic, tube shift and panoramic plus palpation in determination of the position of maxillary impacted canine. 47 patients (20 females, 27 males) with the age of more than 12 years (mean age of 25.4 years old) whom referred to Dental School, Tehran University of Medical Sciences, with at least one impacted maxillary canine included. An oral and maxillofacial radiologist localized impacted canine first by using panoramic then tube shift technique blindly. After that, an oral and maxillofacial surgeon localized the canine by panoramic and palpation of the area before surgery. Data obtained from radiologist and surgeon were compared with true location of canine after surgery. Statistical analysis was done using sensitivity and specificity. Among total 47 impacted maxillary canines, 11 cases (23.4%) showed buccal impactions and 36 cases (76.6%) palatal impactions. Sensitivity (ability of technique to localize palatal impaction) of all of the techniques were same (100%) but specificity (ability of technique to localize buccal impaction) of tube shift (100%) was more than two others (0%). The tube shift technique was the most accurate technique to localize maxillary unerupted canines compared to the others. Due to the ability of panoramic and panoramic with palpation in prediction of palatal canine impactions and failure of these techniques to predict buccal impactions, both methods are not suitable in localization of impacted maxillary canines and they must be used as adjunctive techniques.

The goal of dental treatment is to improve oral hygiene, to maintain teeth and minimize the risk of diseases. Although data obtained from radiographs has distinct advantages to patients, the radiation side effects should be considered as well. FDA has developed a guideline for prescribing radiographs in the middle of the eighties. The aim of this study was to evaluate the reasons of ordering panoramic radiographs and their accordance with FDA guidelines in Tehran dental school. This descriptive study was carried out on 250 patients referred from different departments of Tehran dental school to radiology department for panoramic radiography. Chief complaints and clinical findings of patients were recorded in a check list and compared with the FDA guidelines prescribed. Our findings showed that prescription of panoramic radiographs were in accordance with FDA guidelines in 97.2% of cases. Based of the results of this study, the trend of panoramic radiography ordering in the dental school of Tehran university is adequate. This may be attributed to the academic field of this study.

Proper shaping and cleaning of the root canal system is one of the most important aspects of endodontic treatment. To estimate the canal length before instrumentation in endodontic treatment, traditionally, conventional radiographic techniques and recently Direct Digital Radiography (DDR) are applied. The application of computer technology to radiography has allowed less exposure time, image acquisition, manipulation, storage, retrieval, and transmission to remote sites in a digital format, elimination of wet processing and considerable reduction in the time lapse between image acquisition and display. The purpose of this study was to compare the accuracy of DDR versus conventional radiography in estimating endodontic file lengths of curved canals in first mandibular molars. In this test evaluation study, fourty extracted human first mandibular molars with root curvature were selected.Samples were divided into two groups: With root curvature less than 25 and more than 25. Samples were mounted in plaster blocks and canal lengths were estimated by using DDR and conventional radiographs. Regression analysis and correlation coefficient were used to calculate statistical differences between the groups with P<0.05 as the limit of significance. Conventional radiography was more precise in canals with less than 25 degrees curvature (P=0.160). While, DDR was more precise for canals with curvature more than 25 degrees (P=0.605). However, these differences were not statistically significant. The image quality of DDR system has improved to the point that it can now be used for estimating canal lengths, even for curved canals, with accuracy comparable to that of conventional radiography.

Statement of Problem: A few decades have past from using radiographic technology as an accurate paraclinical method and always protective measurements is applicated against ionizing radiation. As dental radiography is a routine procedure in dentistry the importance of protective strategies is clear.Propose: The aim of this descriptive study is to evaluate the protection principles in centers which have intraoral radiographic devices in Yazd. We have considered all three aspects of practitioner, environment and patient protection using questionnaire and visiting those centers. 33/7% of dental offices, 10 clinics, 3 institution and faculty of dentistry had intraoral radiographic equipments. Stablishment of protection principles for radiographer was favorable. 7.7% of centers had x-ray room with leaded walls, 23.1% had curtain, in 69/2% of centers radiographers stood in correct position and distance while taking radiograph. Regarding to protection of environment, beams leakage control in 23.1% dental offices, 70% of clinics, all institution and faculty of dentistry have done. Non of the centers used rectangular localizator, thyroid shield, film holder and just some centers used leaded apron in specific circumstances. We have concluded that patient protection constitute less consideration. Generally lack of protective consideration is related to deficient knowledge of operators. Lack of information about protection equipments causes decrease of demanding of these tools and ultimately lack of these equipments in the market.

Statement of Problem: One of the dental lesions which is mainly diagnosed by periapical radiography is apical root resorption Diagnosis of the presence and extension of this lesion can put some effects on its treatment plan and prognosis. The aim of the present study was to evaluate the efficacy of periapical radiography on apical root resorption diagnosis. In this experimental study, sixty extracted teeth were examined radiographic and histological regarding the presence and extension of apical root resorption. It should be noted that periapical radiographs were taken before extraction of all mentioned teeth. The results were analyzed by Fisher’s exact test. The results of this study showed significant differences between radiological and histological examinations (P=0.0003). Significant correlation between these two observations was seen only in 53.33% of cases comprising 23% of teeth with root resouption. Non-correlation was found in 46% of samples. Moreover, there was no significant difference in the prevalence of apical root resorption between maxillary and mandibular teeth (P=0.233). Sensitivity of periapical radiographs in apical root resorption diagnosis was determined 57.3%. According to the findings of the present study, it seems that periapical radiography technique does not possess desirable efficacy in diagnosis of apical root resorption and its limitation should be considered by clinicians.