Journal of Dental Medicine

Background and Aim: 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.

Materials and methods: 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.

Results: Our findings showed that prescription of panoramic radiographs were in accordance with FDA guidelines in 97.2% of cases.

Conclusion: 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.

Background and Aim: Accurate bone measurements are essential to determine the optimal size and length of dental implants. The magnification factor of radiographic images may vary with the imaging technique used. The purpose of this study was to compare the accuracy of linear tomography and panoramic radiography in vertical measurements, as well as the accuracy of linear tomography in mandibular width estimation.

Materials and Methods: In this test evaluation study, the vertical distances between the crest and the superior border of the inferior alveolar canal, marked with a metal ball, was measured by linear tomography and panoramic radiography in 23 sites of four dry mandible bones. Also the mandibular width was measured at the same sites. Then, the bones were sectioned through the marked spots and the radiographic measurements were compared with actual values.

Results: The vertical magnification factor in tomograms and panoramic radiographs was 1.79 (SD=0.17) and 1.69 (SD=0.23), respectively. The horizontal magnification of tomograms was 1.47 (SD=0.17). A significant correlation was found between the linear tomographic and actual values, regarding vertical dimensions (p<0.001, r=0.968) and width (p<0.001, r=0.813). The correlation was significant but lower in panoramic radiographs (p<0.001, r=0.795). Applying the magnification values suggested by the manufacturer, the mean difference of vertical measurements between the tomographic sections was 2.5 mm (SD=3.4) but 3.8 mm (SD=1.65) in panoramic radiographs. The mean of absolute difference in mandibular width between the tomographic sections and reality was 0.3mm (SD=1.13). In the linear tomograms, 4.3% of vertical and 56.5% of the width measurements were in the ±1mm error limit. Only 4.3% of the vertical measurements were within this range in the panthomographs. The linear regression equation between the actual values and those obtained by radiography in vertical dimensions showed that 87.5% of tomograms and 51.8% of panoramics were located in the ±1 mm error limit.

Conclusion: Based on the results of this study, the linear tomography is more accurate than panoramic radiography in mandibular height estimation. The accuracy of linear tomography in width estimation is within acceptable limits.

Background and Aim: Image distortion is one of the major problems in panoramic radiography. Horizontal and vertical correction factors could be determined for more efficient clinical applications. The purpose of this study was to determine horizontal and vertical correction factors in panoramic radiography.

Materials and Methods: In this test evaluation study in which an asymetric mandibular phantom was constructed by plexiglass and aluminium as soft and hard tissue equivalents. The right half was slightly shorter than the left half. Steel markers were installed to make vertical and horizontal measurments possible.The length of the markers as well as the intermarker distances were measured by Mitutoyo digital micrometer which was accurate within ±0.05mm. The phantom was then positioned in PM 2002 cc proline (Planmeca, Finland) panoramic machine and panoramic images were obtained. 8 times for each half of the phan. The same length and inter marker distances were measured on digitized panoramic images by Cygnus software, which was accurate whitin ±0.01 mm. Magnification and correction factors were determined for the vertical and horizontal dimensions in each region of pantomograms.

Results: The mean vertical correction factor was 0.77±0.02 (range: 0.75-0.80) in the right and 0.77±0.05 (range: 0.75-0.85) in the left half jaw. The mean horizontal correction factor was calculated as 0.98±0.15 (range: 0.76-1.18) in the right and 1.02±0.14 (range: 0.90-1.25) in the left half jaw.

Conclusion: Dissimilarity of vertical and horizontal correction factors among left and right half jaws and also in different regions of a half jaw is relatively considerable. However, a constant correction factor, specialy in horizontal aspect, could not be applicable. Comparing with horizontal correction factors the vertical correction factors showed less variations between different regions as well as different samples.

Background and Aim: Digital subtraction Radiography (DSR) is a method of accurate assessing condylar head changes. several studies have been carried out in applying DSR in dentistry, however there is a few number of studies in efficacy of DSR method in assesment of condylar head changes, The aim of this study was to compare panoramic radiography and DSR detecting simulated lesions of the mandibular condyl.

Materials and Methods: this was a process reaserch study, in which two dry human skulls with no obvious temporomandibular joint pathology were used. Osteophytic lesions were simulated using three sizes of bone chips that were placed on the medial portion of anterior and superolateral aspects of the condyle. Osteolytic lesions were simulated making 1 and 2 mm holes using round burr in the central portion of anterior aspect and Lateral pole of the condyle. Panoramic radiographs were prepared with and without the lesions in place. These paired radiographs were digitized and digital- subtraction images of the original panoramic images were obtained. Eight observers evaluated 155 images of each modality for the presence or absence and the type of simulated lesions of the mandibular condyle. Sensitivity, specificity, reliability and measure of agreement were analyzed using kappa test and crossed tables and qualitative variables were assess by chi-square and fisher's Exact test.

Results: Specificity of panoramic and DSR methods were 15.4% and 66.7% respectively. Sensitivity of panoramic and DSR methods were 61.1% and 80.6% for osteophytic lesions and 37.5% and 83.3% for Osteolytic lesions. The percentage of correct decisions made in DSR method was significantly more than conventional panoramic method (82.6% vs 41.9%) (p<0.0001).

Conclusion: Based on the results of this study digital subtraction technique was significantly more accurate than the panoramic radiographs in detection of simulated lesions of the mandibular condyle.

Background and Aim: Dental pulp calcification may have the same pathogenesis as vascular calcifications. Pulp stones are calcified mass, which are commonly observed in usual dental radiographs. The purpose of this study was to evaluate the relationship between pulp stones and ischemic CVD.

Materials and Methods: This was a cross-sectional descriptive-analytic study on 20-25-year-old patients who had at least 8 intact teeth and were referred to Afshar hospital for cardiovascular examinations. Relationship between vascular stenosis and dental pulp stone was explored.

Results: Sixty one patients who had undergone angiography were studied. They included 32 male (52.5%) and 29 female (47.5%). 38 patients had at least one stenotic vessel (from one to three vessels) and the others (37.7%) showed normal angiographic findings. 73.8% (31 cases) of the patients with dental pulp stones suffered from coronary narrowing where as only 36.8% (7 cases) of the patients without dental pulp stones showed coronary vessels narrowing. Pulp stones were mostly seen in first and second Molar teeth.

Conclusion: According to the results, we can state that oral and maxillofacial radiology is helpful in screening of cardiovascular diseases.

Background and Aim: 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.
Materials and Methods: 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.
Results: 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%).
Conclusion: 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.

Background and Aims: 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.

Materials and Methods: 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 participants' 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.

Results: 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 patients' mouth side did not significantly influence the overlapping of the proximal surfaces in both panoramic techniques.

Conclusion: 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.

Background and Aims: The main purpose of orthodontic treatment is normal positioning of teeth in three dimensional plans, including the mesiodistal inclination. In this study, mesiodistal axial inclination of posterior teeth in skeletal class II was evaluated and compared with that of posterior teeth in skeletal class I.

Materials and Methods: Seventy-eight panoramic radiographs for subjects between 12 to 24 years old with skeletal class I and 78 panoramic radiographs for subjects between 12 to 19 years old with skeletal class II were selected. All of the subjects were in permanent dentition with no tooth missing, no tooth extraction, no impacted tooth, and no crowding in posterior teeth. Two reference lines were established over each radiograph: the upper one passing through the most inferior point of right and left orbits lower one passing through the right and left mental foramina. After that, the long axis of teeth was traced (the image of root canal in single-rooted teeth, mean image of buccal and palatal canals in upper premolars, mean image of mesial and distal canals in lower molars, and the image of palatal canal in upper molars.). The mean values for two skelotodental classes were analyzed using T-test.

Results: The results showed that there was significant difference between (P<0.05) mesiodistal axial inclination of teeth 15, 16, 17, 25, 26, and 27 in upper jaw in skeletal class II compared with that of the same teeth in skeletal class I, which was more mesially in skeletal class II. Mesiodistal axial inclination of teeth 36, 46, and 47 in lower jaw was more mesially in class II compared with that of the same teeth in class I. For other teeth there were no significant differences between two skeletodental classes (P>0.05).

Conclusion: The mesiodistal axial inclination of upper molars and second premolars and lower molars in class II was more mesially compared with that of the same teeth in class I.

Background and Aims: Conventional radiological equipments in our country are going to be converted to digital system 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.
Materials and Methods: 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.
Results: 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.
Conclusion: 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.

Background and Aims: Apical root resorption is an adverse side effect of fixed orthodontic treatment which cannot be repaired. The aim of this study was to use panoramic radiographs to compare the root resorption before and after the orthodontic treatment with standard edgewise .018 appliance.

Materials and Methods: The before and after treatment panoramic views of sixty-three patients needed fixed orthodontic treatment included 1520 teeth were categorized into 3 Grades (G0: without resorption, G1: mild resorption with blunt roots or ≤ 1/4 of root length, G2: moderate to severe resorption or > 1/4 to 1/2 of root length. Relationship between root resorption and sex and treatment duration was analyzed with Mann-whitney and  Spearman's correlation coefficient, respectively.

Results: The findings showed that 345 teeth were categorized as Grade 1.  Grade 2 of root resorption was not found in this study. The highest amount of root resorption was recorded for the mandibular lateral incisor. In both gender, the root resorption of the mandible was more than that of the maxilla. The males showed significantly higher rate of resorption than the females (P<0.05). Root resorption was not significantly related to the treatment duration and the side of the jaws (P>0.05).

Conclusion: The mandible and male patients showed higher amount of root resorption. In addition, root resorption was not related to the treatment duration and the side of the jaws.

Background and Aims: The Panoramic radiography is one of the routine techniques in implant imaging. Although there are some limitations with this technique, panoramic radiography is radiographic choice for basic evaluation for implant treatment. Many studies have been designed to determine magnification in panoramic images but most of them were performed on dry skulls or radiographic phantoms. In recent studies CT or CBCT are used as gold standard. The aim of this study was to determine vertical magnification of panoramic images using renovated CT sections in anterior and posterior regions of both jaws.

Materials and Methods: 30 panoramic radiographs (Planmeca EC or CC Proline) were selected from patients of implant department and Particular anatomic landmarks were selected in those images. Vertical dimensions of these landmarks were measured in both panoramic and renovated cross sectional CT images by a digital caliper and vertical magnification was calculated as the ratio of image dimensions to the real dimensions.

Results: The mean vertical magnification of panoramic radiographs in anterior and posterior maxillae were 1.22±0.02 and 1.16±0.02, respectively. The mean vertical magnification of panoramic radiograph in anterior and posterior mandible were 1.20±0.02 and 1.13±0.02, respectively. The differences between magnification in mandible and maxillae were significant (P<0.001). The differences between magnification in anterior and posterior regions of both jaws were not significant (P=0.11).

Conclusion: Vertical magnification of panoramic images (Planmeca EC or CC Proline) in different regions in both jaws were between 1.13 to 1.22.

  Background and Aims: Impacted third molar reduces the bone level in the distal aspect of second molar, and sometimes it can lead to root resorption of the adjacent tooth. The purpose of this study was to determine this resorption using panoramic and periapical radiographs.

  Materials and Methods: In this cross-sectional descriptive study 54 patient (28 men, 26 women) above 15 years old with the average of 22 years in Oral and Maxillofacial Department of Tehran University were studied. A periapical radiography from the third molar and a panoramic radiograph were taken from each patient (Because of their routine use and evaluation of accuracy of panoramic compared with periapical), and the magnitude of the root resorption for the second molar was determined by 2 observers and written in a questionnaire. Data were analyzed using Fisher test.

  Results: The prevalence of the root resorption of the second molar adjacent to the impacted third molar in the panoramic and the periapical radiographies, with respect to the limitation of the sample size were 46.3% and 31.5%, respectively, with 95% confidence(P>0.05). Most of these resorptions were in the cervical third of the second molar roots and in cases in which the third molars were mesially oriented or horizontal. There was also no significant difference between panoramic and periapical radiographs.

  Conclusion: Due to the increased risk of the resorption of the second molar adjacent to the third molar, extraction of the impacted third molars, especiall y mesially oriented or horizontal ones are recommended.

  Background and Aims: It is crucial to verify the relationship between root apices and maxillary sinus floor in some surgical procedures like extraction and implant placement or in orthodontic movements like intrusion. Protrusion of roots into the sinus increases the risk of post extraction pneumatization which in turn decreases the available bone at the implant or denture sites. The aim of this study was to determine the panoramic radiology accuracy for defining the relationship between posterior root apices and the maxillary sinus floor by Cone Beam CT (CBCT).

  Materials and Methods: Paired panoramic radiographs and CBCT images of 117 subjects were examined. 452 posterior maxillary roots including second premolar, first and second molar were classified by the means of the relationship with maxillary sinus floor. CBCT was used as Gold standard method, and the agreement of panoramic findings with CBCT was examined statistically. Data were analyzed using Chi-square and Multiple logistic regressions.

  Results: Agreement of the panoramic and CBCT results were seen in 57.7% of all cases. Roots which had no contacts with the sinus floor (class 0) showed a high agreement of 89.5% between two imaging techniques. Roots in contact with sinus floor (class 1) showed 58.8 % and cases with root protrusion into sinus cavity (class 3, 4) showed 50% of agreement (P<0.001). Also in 36% of cases with no protrusion into the sinus cavity (class 0, 1, 2), panoramic showed protrusion. The agreement for the premolar was higher than molars (P<0.001)

  Conclusion: The majority of roots which their images were projected on the sinus cavity had no vertical protrusion in CBCT cuts. Considering the results, in these cases CBCT can be recommended.

  Background and Aims: 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.

  Materials and Methods: 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.

  Results: 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.

  Conclusion: 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 .