The scanora X-ray unit uses the principles of narrow beam radiography and spiral tomography. Starting with a panoramic overview as a scout image, multiple tomographic projection could be selected. This study evaluated the accuracy of spiral tomography in comparison to routine panoramic radiography for dental implant treatment planing. An experimental study was performed on a cadaver mandible to assess the accuracy of panoramic radiography and spiral tomography film images for measurement of metallic spheres. After radiographic images of the metallic spheres on the surgical stent were measured and corrected for a fixed magnification of radiographic images, following results were obtained. 1. In the optimal position of the mandible, the minimal horizontal and vertical distortion was evident in the panoramic radiography images. The mean horizontal and vertical magnification error in anterior sites was 5.25% and 0.75%, respectively. The mean horizontal and vertical magnification error in posterior sites was 0.50% and 1.50%, respectively. 2. In the displaced forward or in and eccentric position of the mandible, the magnification error of the panoramic radiography images increased significantly over the optimal position. Overall, the mean horizontal magnification error of the anterior site in the different position changed dramatically within a range of -17.25% to 39.00%, compared to the posterior range of -5.25% to 8.50%. However, the mean vertical magnification error stayed with the range of 0.5% to 3.75% for all the mandibular positions. 3. The magnification effects in the tomographic scans were nearly identical for the anterior and posterior with a range of 2.00% to 5.75% in the horizontal and 4.50% to 5.50% in the vertical dimension, respectively. 4. A statistically significant difference between the anterior and posterior measurements was found in the horizontal measurements of the panoramic radiography images of the displaced dorward and backward position of the mandiblw(P<0.05). also a significant difference between the optimal panoramic and tomographic projections was found only in the vertical measurement (P<0.05).
Cadaver ; Dental Implants ; Mandible ; Radiography ; Radiography, Dental, Digital ; Radiography, Panoramic ; Stents ; Vertical Dimension

The comparative detectability of the artificial periapical defects among Ektaspeed Plus film, digitized and digora images was evaluated. The artificail defects were made in the cancellous bone and cancellous-cortical junction with the size of 1.0x0.8mm2, 1.4x1.1mm2 and 2.8x2.2mm2. The defects in cancellous-cortical junction extended into cortical bone with the depth of 0, 0.5 and 1.0 mm. The results were as follows : 1. In junctional defects Ektaspeed Plus film for 2.8x12.2mm2 defect showed the highest detectability. But siginificant difference were only found between Ektaspeed Plus films and digitized images(p<0.05). 2. Almost all defects within cacellous bone were not detected except a few digitized and Digora images for the size of 2.8x2.2mm2. Digora images for them showed significant differences with Ektaspeed Plus films and digitized images(p<0.05). 3. The sensitinity of all imaging modalities were 0.9 or 1.0 in junctional defects for the size of 1.4x2.2mm2 and 2.8x2.2mm2. For cancellous defects, Digora image showed the highest sensitivity of 0.6 for the size of 2.8x2.2mm2. 4. Siginificant differences for change of exposure time were found in most group of Ektaspeed Plus films and digitized images(p<0.05). But there was no significant differences in Digora images for cacellous defects.
Radiography, Dental, Digital*

PURPOSE: To evaluate the effect of deviation of mandibular positioning, by changing the mandibular plane inclination, on the measured height and width of mandible in spiral conventional tomography. MATERIALS AND METHODS: By means of the Scanora multifunctional unit, cross-sectional tomograms were taken from two human dried mandibles at the mandibular angulations: -15 degrees, -10 degrees, -5 degrees, and 0 degree. Twenty-eight sites in two dried mandibles were imaged. One examiner measured the bone heights and widths at selected sites on the images and the actual bone heights were recorded. RESULTS: The bone heights at the four mandibular inclinations overestimated real bone heights and the mean difference between actual heights and image heights on 0 degree was the smallest (P< 0.01). The bone widths on -15 degrees were narrowest and there were significant differences between bone widths measured at the four mandibular inclinations (P< 0.001). We found statistically significant differences between both bone heights and widths as measured according to the mandibular plane angle for the posterior region (P< 0.01). CONCLUSION: The use of different mandibular positioning may result in discrepancies in heights and widths when measured from the cross-sectional tomographic images. It is suggested that the mandibular positioning may play a significant role in the measurement of mandibular heights and widths.
Dental Implants ; Humans ; Mandible ; Radiography, Dental, Digital

PURPOSE: To know whether there would be a difference among spiral tomograms of different slice thicknesses in the measurement of distances which are used for dental implant planning. MATERIALS AND METHODS: 10 dry mandibules and 40 metal balls are used to take total 120 Scanora tomograms with the slice thickness of 2 mm, 4 mm and 8 mm. 3 oral radiologists interpreted each tomogram to measure the distances from the mandibular canal to the alveoalr crest and buccal, lingual and inferior borders of mandible. 3 observers recorded grades of 0, 1 or 2 to evaluate the perceptibility of alveolar crest and the superior border of mandibular canal. For statistical analysis, ANOVA with repeated measure, Chi-square tests and intraclass correlation coefficient(R2, alpha) were used. RESULTS: There was not a statistically significant difference among spiral tomograms with different slice thicknesses in the measurement of the distances and in the perceptibility of alveolar crest and mandibular canal(p>0.05). All of them showed a good relationship in the reliability analysis. The perceptibility of alveolar crest and mandibular canal was almost similar and an excellent relationship was seen on all of them. CONCLUSIONS: There would be no significant difference, no matter which spiral tomogram of any slice thickness may be used in dental implant planning, considering the thickness of dental implant fixture.
Dental Implants* ; Mandible ; Radiography, Dental, Digital

PURPOSE: To evaluate the differences in bone height, bone width, and visibility of posterior spiral tomographic images according to various exposure directions, image layer thickness, and inclination of the mandibular inferior border. MATERIALS AND METHODS: Six partially and completely edentulous dry mandibles were radiographed using Scanora spiral tomography. Spiral tomography was performed at different exposure directions (dentotangential and maxillotangential projection), image layer thicknesses (2 mm, 4 mm and 8 mm), and at various inclinations to the mandibular border (+/-10, 0 and -10 ). The bone height and width was measured using selected tomographic images. The visibility of mandibular canal, crestal bone, and buccal and lingual surfaces were graded as 0, 1, or 2. RESULTS: The bone width at the maxillo-tangential projection was wider than at the dento-tangential projection (p< 0.05). The visibility of buccal and lingual surface at the maxillo-tangential projection was higher than at the dento-tangential projection (p< 0.05). Thinner image layer thicknesses resulted in greater visibility of buccal and lingual surfaces (p< 0.05). Bone height was greatest in the -10 group, and at the same time the bone width of the same group was the narrowest (p< 0.05). The visibility of alveolar crest and buccal surface of the+/-10 group was the highest, while the visibility of the mandibular canal was greatest in the 0 group. CONCLUSION: When spiral tomography is performed at the mandibular posterior portion for visualization prior to implant surgery, it is important that the inferior border of mandible be positioned as parallel as possible to the floor. A greater improvement of visibility can be achieved by maintaining a thin image layer thickness when performing spiral tomography.
Dental Implants ; Mandible* ; Radiography, Dental, Digital

The purpose of this study was to evaluate the accuracy and usefulness of spiral tomography through the comparison and analysis of SCANORA cross-sectional tomographs and DentaScan computed tomographic images of dry mandibles taken by a SCANORA spiral tomographic machine and a computed tomographic machine. Thirty-one dry mandibles with full or partial edentulous areas were used. To evaluate the possible effect of location in the edentulous area, it was divided into 4 regions of Me (region of mental foramen), M1 (the midportion between Me and M2), M2 (the midportion between mental foramen and mandibular foramen) and S (the midportion of the mandibular symphysis). A ZPC column (sized 4 mm X 5 mm) was seated on the edentulous regions of Me, M1, M2 and S using the acrylic stent. Then SCANORA spiral tomography and computed tomography were taken on the edentulous regions which contained the ZPC column. The ZPC columns and cross-sectional images of the mandible were measured in the radiographs by three observers and the differences between the two imaging modalities were analysed. The results were as follows: 1. In comparing the actual measurements of the ZPC column and measurements in the radiographs, the mean error of the DentaScan computed tomography was 0.07 mm in vertical direction and -0.06 mm in horizontal direction, while the mean error of the SCANORA spiral tomography was 0.06 mm in vertical direction and -0.12 mm in horizontal direction. There was a significant difference between the two radiographic techniques in the horizontal measurement of the ZPC column of the symphysis region (p<0.05). but there was no significant difference in the measurements of other regions>0.05). 2. In measurements of the distance from the alveolar crest to the inferior border of the mandible (H), and of the distance from the alveolar crest to the superior border of the mandibular canal (Y), there was no significant difference between the two radiographic techniques (p>0.05). 3. In measurements of the distance from the lingual border of the mandible to the buccal border of the mandible (W), and of the distance from the lingual border of the mandible to the lingual border of the mandibular canal (X), there was a significant difference between the two radiographic techniques in measurements of the midportion between the mental foramen and the mandibular foramen (M2) (p<0.05). but there were no significant differences in measurements of the other regions of symphysis>0.05). 4. Considering the mean range of measurements between observers, the measurements of SCANORA spiral tomography showed higher value than those of DentaScan computed tomography, except in measurements of symphysis (S). 5. On the detectability of the mandibular canal, there was no significant difference between the two radiographic techniques (p>0.05). In conclusion, SCANORA spiral tomography demonstrated a higher interobserver variance than that of DentaScan computed tomography for implant site measurements in the posterior edentulous area of the mandible. These differences were mainly the result of difficulty in the detection of the border of the mandible in SCANORA spiral tomography. But considering the cost and the radiation exposure, SCANORA spiral tomography can be said to be relatively good radiographic technique for implant site measurement.
Mandible* ; Radiography, Dental, Digital ; Stents

Dental age plays an important role in age estimation. It has often been used together with skeletal age to improve the accuracy of age estimation abroad, but seldom performed in China. As a noninvasive technology, dental radiological imaging has been widely used in age estimation. By observing the age-related changes such as the pulp cavity and development of crown and root on radiographs. Gleiser and Hunt, as well as Demirjian have developed different methods to determine the age of human. Demirjian's method has been proved to be more accurate but with limitation when used in persons of eighteen and above. The accuracy and reliability of the measurements on pulp cavity could be improved as the development of computed tomography with its high resolution and intelligent software. As a convenient and accurate method, age estimation from dental computed tomographs would be more promising in the future for forensic scientists and anthropologists.
Age Determination by Teeth/methods* ; Dental Pulp/diagnostic imaging* ; Forensic Dentistry ; Humans ; Radiography, Panoramic/methods* ; Tomography, X-Ray Computed/methods*

PURPOSE: This study was performed to evaluate the reliability of the identification of anatomical landmarks in panoramic and lateral cephalometric radiographs on a standard medical grade picture archiving communication system (PACS) monitor and a tablet computer (iPad 5). MATERIALS AND METHODS: A total of 1000 radiographs, including 500 panoramic and 500 lateral cephalometric radiographs, were retrieved from the de-identified dataset of the archive of the Section of Oral and Maxillofacial Radiology of the University Of Connecticut School Of Dental Medicine. Major radiographic anatomical landmarks were independently reviewed by two examiners on both displays. The examiners initially reviewed ten panoramic and ten lateral cephalometric radiographs using each imaging system, in order to verify interoperator agreement in landmark identification. The images were scored on a four-point scale reflecting the diagnostic image quality and exposure level of the images. RESULTS: Statistical analysis showed no significant difference between the two displays regarding the visibility and clarity of the landmarks in either the panoramic or cephalometric radiographs. CONCLUSION: Tablet computers can reliably show anatomical landmarks in panoramic and lateral cephalometric radiographs.
Archives ; Connecticut ; Dataset ; Humans ; Radiography, Dental, Digital ; Radiography, Panoramic ; Radiology Information Systems

PURPOSE: This study aimed to provide comparative measurements of the effective dose from direct and indirect digital panoramic units according to phantoms and exposure parameters. MATERIALS AND METHODS: Dose measurements were carried out using a head phantom representing an average man (175 cm tall, 73.5 kg male) and a limbless whole body phantom representing an average woman (155 cm tall, 50 kg female). Lithium fluoride thermoluminescent dosimeter (TLD) chips were used for the dosimeter. Two direct and 2 indirect digital panoramic units were evaluated in this study. Effective doses were derived using 2007 International Commission on Radiological Protection (ICRP) recommendations. RESULTS: The effective doses of the 4 digital panoramic units ranged between 8.9 microSv and 37.8 microSv. By using the head phantom, the effective doses from the direct digital panoramic units (37.8 microSv, 27.6 microSv) were higher than those from the indirect units (8.9 microSv, 15.9 microSv). The same panoramic unit showed the difference in effective doses according to the gender of the phantom, numbers and locations of TLDs, and kVp. CONCLUSION: To reasonably assess the radiation risk from various dental radiographic units, the effective doses should be obtained with the same numbers and locations of TLDs, and with standard hospital exposure. After that, it is necessary to survey the effective doses from various dental radiographic units according to the gender with the corresponding phantom.
Female ; Fluorides ; Head ; Humans ; Lithium ; Lithium Compounds ; Radiation Dosage ; Radiography, Dental, Digital ; Radiography, Panoramic

PURPOSE: This study was performed to evaluate relationship between the inferior alveolar nerve injury and the findings of panoramic and tomographic images for preventing inferior alveolar nerve injury after the 3rd molar extraction. MATERIAL AND METHOD: From April, 2005 to June, 2005, The 190 patients who visited in the Department of Oral and Maxillofacia Surgery, Chonnam National University Hospital and the panoramic radiographies were taken for extraction of the mandibular third molar, was selected. Among 215 mandibular third molars, Scanora tomographic imagings were taken in the 90 teeth which were overlaped to the mandibular canal in the panoramic imagies. In panoramic radiographies, the angulation, the level, the root morphology, and the superimposition sign of the mandibular third molars with the mandibular canal were evaluated. In the tomographic radiographies, the location and distance of the mandibular third molar from the canal were also evaluated. The relationships between these findings and the inferior alveolar nerve injury were examined. RESULTS: In the panoramic findings, the inferior alveolar nerve injuries were occurred in the darkened roots (5 molars, 7%), the uncontinuous radiopaque image (3 molars, 7%), and the depositioned mandibular canal (2 molars, 10%). In the tomographic findings of 90 molars, 20 molars also had the superimposition imagies. Five molars in those molars (25%) had the inferior alveolar nerve injury after extraction. There were 10 patients who had the inferior alveolar nerve injury. The sensory was began to be recovered in 9 patients, except 1 patient, within 2 weeks, then fully recovered within 3 months. CONCLUSION: These results indicate that the depth mandibular third molar and the superimposition sign may be related with the risk of the inferior alveolar nerve injury after extraction.
Humans ; Jeollanam-do ; Mandibular Nerve* ; Molar ; Molar, Third* ; Radiography, Dental, Digital ; Radiography, Panoramic ; Tooth