Geometically standardaized dental radiographs were taken. We prepared Digital Cu-Equivalent Image Analyzing System for quantitative assessment of mandible bone. Images of radographs were digitized by means of Quick scanner and personal Mcquintosh computer. NIH image as software was used for analyzing images. A stepwedge composed of 10 steps of 0.1mm copper foil in tickness was used for reference material.This study evaluated the effects of step numbers of copper wedge adopted for calculating equation, kVp and exposure time on the coefficient of determination(r2)of the equation for conversion to Cu-equivalent image and the coefficient of variation and Cu-Eq value(mm) measured at each copper step and alveolar bone of mandible. The results were as follows: 1. The coefficients of determination(r2) of 10 conversion equations ranged from 0.9996 to 0.9973(mean=0.9988) under 70kVp and 0.16 sec. exposure. The equation showed the highest r2 was Y=4.75614612-0.06300524x +0.00032367x2 -0.00000060x3. 2. The value of r2 became lower when the equation was calculated from the copper stepwedge including 1.0mm step. In case of including 0mm step for calculation, the value of r2 showed variability. 3. The coefficient of variation showed 0.11, 0.20 respectively at each copper step of 0.2, 0.1mm in thickness. Those of the other steps to 0.9 mm ranged from 0.06 to 0.09 in mean value. 4. The mean Cu-Eq value of alveolar bone was 0.14+/-0.02mm under optimal exposure. The values were lower than the mean under the exposures over 0.20sec. in 60kVp and over 0.16sec. in 70kVp . 5. Under the exposure condition of 60kVp 0.16sec., the coefficient of variation showed 0.03, 0.05 respectively at each copper-step of 0.3, 0.2mm in thickness. The value of r2 showed over 0.9991 from both 9 and 10 steps of copper. The Cu-Eq value and the coefficient of variation was 0.14+/-0.01mm and 0.07 at alveolar bone respectively. In summary, A clinical application of this system seemed to be useful for assessment of quantitative assessment of alveolar provided high coefficient of determination is obtained by the modified adoption of copper step numbers and the low coefficient of variation for the range of Cu-Equivalent value of alveolar bone from optimal kVp and exposure time for each x-ray machine.
Copper ; Humans ; Mandible ; Radiography* ; Ticks

PURPOSE: To evaluate the effect of variable scanning protocols of computed tomography for evaluation of pre-implant site of the mandible through the comparison of the reformatted cross-sectional images of helical CT scans obtained with various imaging parameters versus those of conventional CT scans. MATERIALS AND METHODS: A dry mandible was imaged using conventional nonoverlapped CT scans with 1 mm slice thickness and helical CT scans with 1 mm slice thickness and pitches of 1.0, 1.5, 2.0, 2.5 and 3.0. All helical images were reconstructed at reconstruction interval of 1 mm. DentaScan reformatted images were obtained to allow standardized visualization of cross-sectional images of the mandible. The reformatted images were reviewed and measured separately by 4 dental radiologists. The image qualities of continuity of cortical outline, trabecular bone structure and visibility of the mandibular canal were evaluated and the distance between anatomic structures were measured by 4 dental radiologists. RESULTS: On image qualities of continuity of cortical outline, trabecular bone structure and visibility of the mandibular canal and in horizontal measurement, there was no statistically significant difference among conventional and helical scans with pitches of 1.0, 1.5 and 2.0. In vertical measurement, there was no statistically significant difference among the conventional and all imaging parameters of helical CT scans with pitches of 1.0, 1.5, 2.0, 2.5 and 3.0. CONCLUSION: The images of helical CT scans with 1 mm slice thickness and pitches of 1.0, 1.5 and 2.0 are as good as those of conventional CT scans with 1 mm slice thickness for evaluation of pre-dental implant site of the mandible. Considering the radiation dose and patient comfort, helical CT scans with 1 mm slice thickness and pitch of 2.0 is recommended for evaluation of pre-implant site of the mandible.
Dental Implants ; Humans ; Mandible ; Tomography, Spiral Computed ; Tomography, X-Ray Computed

Magnetic resonance imaging with its superior soft tissue contrast resolution and absence of beam hardening artifacts, combined with its ability to perform multiplanar imaging, is now effective tool in diagnostic imagings. Magnetic resonance is primarily a phenomenon that involves atomic nuclei. It provides totally new clinical informations with no known hazards through the use of very weak interactions with endogenous stable magnetic atomic nuclei. This article briefly summarized the basic mechanism of generation and detection of the signals and general sorts of tissue properties which can influence the signals and thereby give rise to tissue contrast. It also describes how the machine-operating parameters can be used to manipulate the tissue contrast observed in the image.
Artifacts ; Magnetic Resonance Imaging*

PURPOSE: To find out the effects that different tomographic angles have on the osteophytic lesion detectability of condyle head by comparison the individualized lateral tomographic image with the various tomographic angled images using SCANORA . MATERIALS AND METHODS: This study is performed to simulate osteophytic lesions by a series of dentin chips placed at six locations on condyle head. The control angle is 15 and from this angle, tomographic angle were varied with -10 , +10 , +20 . All the images with each sized dentin chip were scored by three dental radiologists with the use of confidence levels for presence or absence of the lesion, each examiner viewed one of the images twice. A rating scale from 0 to 2 (0, lesion definitely not present; 1, uncertain if lesion is present; 2, lesion definitely present). Responses were assessed by Tukey's multiple comparison method and kappa value. RESULTS: 1. The lesion size of 0.3 mm could not be detected in all the tomographic angles. As the size of the lesion increased the average value of lesion detectability also increased. Therefore the average value for the lesion size of 2.0 mm was the highest in every angle. 2. In the leson sizes of 0.7 mm there was statistically significant difference between the 15 control angle and the altered tomographic angles (p<0.05). In 1.0 mm lesion there was no significant difference in the 10 altered angles (p>0.05), but there was significant difference in the +20 altered angle (p<0.05). In the lesion sizes of 0.3 mm and 2.0 mm there was no significant difference between the 15 control angle and all the altered angles (p>0.05). 3. In the medial, superocentral, lateral area of the condyle there was no significant difference between the 15 control angle and all the altered angles (p>0.05). In the anteromedial, anterosuperior, anterolateral area there was no significant difference between the 15 control angle and the 10 altered angle (p>0.05), but in the comparison with the +20 alterd angle there was significant difference (p<0.05). CONCLUSION: When imaging the lateral tomography of the temporomandibular joint used by SCANORA , it can be considered that in the osteophytic lesion size of 2 mm and above, the tomographic angle difference within +20 to the horizontal angle of the condyle, has little effect on the lesion detectability. And in the lesion size of 1 mm, the altered angle within 10 also has little effect on the lesion detectability.
Dentin ; Head ; Mandibular Condyle* ; Radiography, Dental, Digital ; Temporomandibular Joint

PURPOSE: The purpose of this study was to compare the qualities of the four different processing chemicals(solutions). MATERIALS AND METHODS: With EP 21 films(Ektaspeed plus film, Kodak Co., USA), nine unexposed and nine exposed films of a step wedge were processed utilizing automatic film processor(XR 24, Durr Co., Germany) for 5 days. During 5 days, the total number of processed films including out-patient's intraoral films were about 400-500 for each brand. Base plus fog density, film density, contrast of processed films were measured with densitometer(model 07-443 digital densitometer, Victoreen Co., USA). These measurements were analyzed for comparison. RESULTS: The results were as follows, 1. For the base plus fog density, there was significant difference among the four chemicals (p<0.05). The sequence of the base plus fog densities was in ascending order by Kodak, X-dol 90, Agfa and Konica. 2. For the film density, all chemicals showed useful range of photographic densities(0.25-2.5). The sequence of the film densities was in ascending order by Kodak, X-dol 90, Konica and Agfa. But there was no statistically significant difference of film density between X-dol and Kodak (p<0.05). 3. The sequence of the contrasts was in ascending order by Konica, X-dol 90, Kodak and Agfa. But there was no statistically significant difference of contrast between X-dol and Konica (p<0.05). CONCLUSION: These results indicated that the four processing chemicals had the clinically useful film density and contrast, but only Kodak processing chemical had useful base plus fog density.
Dentistry* ; Weather

PURPOSE: To compare radiographic images of Digora system and Ektaspeed Plus film obtained from normal adults. MATERIALS AND METHODS: Storage phosphor plate(SPP) was placed in a film holder behind Ektaspeed Plus film package without lead foil. The effect of film on SPP was studied in a separate in vitro experiment. Forty-seven sets of images were prepared for the evaluaton. The regions of interest(ROI) for evaluation were designated at seven sites including normal anatomical structures. The image quality for each ROI was evaluated on enhanced and unenhanced storage phosphor(SP) images and Ektaspeed Plus film. RESULTS: Two film-SPP configurations showed significantly different grey levels at each step of the aluminum step wedge(p<0.05). The contrasts were comparable. Enhanced SP images were significantly superior to unenhaned images and film in all anatomical sturctures(p<0.01). The differences between unenhanced SP images and film were significant(p<0.05) except root canal and cortical bone on alveolar crest. For anatomical items, there were statistically significant difference among five observers(p<0.05). CONCLUSIONS: The image quality of enhanced SP images were superior to Ektaspeed Plus film, and Digora system is potentially applicable to clinical diagnosis.
Adult ; Aluminum ; Dental Pulp Cavity ; Diagnosis ; Humans ; Radiography, Dental, Digital

PURPOSE: The objective of this study was to compare clinical examination of of dental caries and secondary caries with panoramic examination, and to examine bone lesions and dental anomaly of unerupted state. MATERIALS AND METHODS: In this study, clinical records and panoramic radiographs were available for 89 first grade students in elementary school. Dental caries of occlusal surfaces, proximal surfaces, and buccolingual surfaces were examined . Secondary caries was examined too. In addition, the central lesion and dental anomaly of unerupted state were examined in panoramic radiographs. RESULTS: The obtained results were as followed : 1. Carious detectability of clinical examination in occlusal and buccolingual surface was higher than that of panoramic examination, but it is statistically insignificant(p>0.05). In proximal surface, carious detectability of panoramic examination was higher than that of clinical examination, and it is statistically significant(p<0.01). 2. In contrast to clinical examination only, when the two examination methods were combined, there was additional detection of dental caries(26.7% in occlusal surface, 48.2% in proximal surface, 33.3% in buccolingual surface, and 38.3% totally). 3. In detection of secondary caries, panoramic examination had lower ability than clinical examination in all three surfaces, but in case that both methods were combined, totally 36.0% extra carious lesions were detected. 4. In panoramic examination, detectability of secodary caries in upper teeth is lower than lower teeth. 5. In panoramic examination, it was possible to detect the central lesions and dental anomalies of unerupted state which cannot be detected in clinical examination. CONCLUSION: It is useful to combine the panoramic examination with clinical examination in order to increase carious detectability and to evaluate the central lesions and dental anomalies of unerupted state
Dental Caries* ; Diagnosis* ; Humans ; Radiography, Panoramic* ; Tooth

OBJECTIVES: The purpose of this study was to evaluate the optimal distance and angle of observers by modulation transfer functions(MTFs) and receiver operating characteristics(ROCs). MATERIALS AND METHODS: Digital periapical radiograms were taken from 43 patients who have dental diseases(19 patients : dental caries, 12 patients : periapical lesions, 12 patients : periodontal diseases). Segmental images(4x4cm) were evaluated by 4 MTFs and ROC analysis. RESULTS: The optimal distance(magnification) using MTF by Mannos & Sakrison was 12.97, and those by Nill, Ngan and Rao were 8.39, 4.78, 5.84 respectively. The optimal distance obtained from 4 radiologists by ROC analysis was 32cm(Az value : 0.89), and it was 40cm(Az value : 0.78) from 4 non-radiologists. There were significant differences of Az values between 4 radiologists and 4 non-radiologists at 24, 32 and 40cm (p<0.05). No significant differences of optimal distances were observed using 4 MTFs among +20, +10, 0, -10, -20 degrees(p>0.05). The optimal angle obtained from 4 radiologists by ROC analysis was +20 degrees (Az value : 0.91), and no significant differences of Az values were observed among +20, +10, 0, -10 and 20 degrees(p>0.05). The optimal angle obtained from 4 non-radiologists by ROC analysis was 0 degree(Az value : 0.81), and no significant differences of Az values were observed among +20, +10, 0, -10 and 20 degrees(p>0.05). And there was significant difference of Az value between 4 radiologists and 4 non-radiologists at +20 degree(p<0.05), but no significant differences of Az values were observed among +10, 0, -10 and -20 degrees(p>0.05).
Dental Caries ; Humans ; ROC Curve

PURPOSE: The objective of this study was to evaluate the possibility of substitution of the zonography for the full-mouth periapical radiography in aspect of radiation protection. MATERIALS AND METHODS: Rando phantom and LiF TLD chips were used for dosimetry. The absorbed doses at brain, skin above the TMJ, parotid gland, bone marrow in the mandibular body, and thyroid gland during the full-mouth periapical radiography, panoramic radiography, and zonography were measured. RESULTS: From the zonography, the absorbed doses to the brain, the skin over the TMJ, and the parotid gland were relatively high, but the absorbed doses to the bone marrow in the mandibular body and, especially, the thyroid gland were very low. CONCLUSION: The zonography can be an alternative to the full-mouth periapical radiography in aspect of radiation protection.
Bone Marrow ; Brain ; Parotid Gland ; Radiation Protection ; Radiography* ; Radiography, Panoramic* ; Skin ; Temporomandibular Joint ; Thyroid Gland ; Tomography, X-Ray*

The purpose of this study was to investigate whether a radiometric analysis of radicular cysts and periapical granulomas is useful in the differential diagnosis. In this experiment, twenty-nine periapical radiographs of the radicular cyst and those periapical granuloma were used. The periapical radiography was taken by intraoral paralleling device. The X-ray film was digitized and digitally filtered to reduce film-grain noise. We estimated density difference of the inner/outer area, roundness or circularity, bone profile or scan line of the margin and cumulative percentage frequency curve of radicular cyst & periapical granuloma. The obtained results were as follows ; 1. The differences in density between ROIs of inner and outer area of radicular cysts were smaller than those of periapical granulomas. 2. The equivalent circular diameter was over 6.3mm, there was significant difference between periapical cyst and periapical granuloma. 3. In differential diagnosis of radicular cyst and periapical granuloma using bone profile, sensitivity, spicificity and accuracy were considerably high(0.83, 0.86, 0.86) respectively. 4. Cumulative percentage frequency curve of the radicular cyst was closer to the pseudo-pixel value of 50 than average curve, whereas periapical granuloma was closer to that of 0. Hence we conclude that digital radiometric features might be useful in the differential diagnosis between radicular cyst and periapical granuloma.
Diagnosis, Differential ; Noise ; Periapical Granuloma* ; Radicular Cyst* ; Radiography ; X-Ray Film