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*

No anstract available.
Adolescent* ; Ameloblastoma* ; Child* ; Humans

The purpose of this study was to investigate whether a radiographic estimate of osseous fractal dimension and power spectrum of 2D discrete Fourier transform is useful in the characterization of structural changes in bone. Ten specimens of bone were decalcified in fresh 50 ml solutions of 0.1 N hydrochloric acid solution at cummulative timed periods of 0 and 90 minutes, and radiographed from 0 degree projection angle controlled by intraoral parelleling device. I performed one-dimensional variance, fractal analysis of bony profiles and 2D discrete Fourier transform. The results of this study indicate that variance and fractal dimension of scan line pixel intensities decreased significantly in decalcified groups but Fourier spectral analysis didn't discriminate well between control and decalcified specimens.
Fourier Analysis* ; Fractals* ; Hydrochloric Acid ; Osteoporosis

The authors examined the condylar position and shape of condylar process from the transcranial radiographs and polytomographs of the 130 temporomandibular joints of 65 patients who complained symptoms of temporomandibular disorder and the followings were obtained ; 1. The age and sex distribution of the 65 patients showed peak incidence in 2nd decade (27.7%) followed by 3rd (18.5%) and 4th decade (18.5%) and female predominance (87.7%). 2. In polytomography 64 joints (49.2%) showed consistent condylar position from lateral to medial and 39 joints (30.0%) of them showed agreement with those of transcranial radiographs. Among the 66 joints (50.8%) which showed changes in condylar position, 48 joints (36.9%) showed agreement with lateral and central tomographic and transcranial radiographic position. 41 joints (31.5%) showed disagreement in condylar position between the polytomographic and transcranial radiographic images. 3. When the condylar position was classified as anterior, central and posterior, the posterior position was the most frequent position, that is , 42.3% of the transcranial radiography and 42.3%, 49.2% and 38.5% of the lateral, central and medial polytomographic radiographs. 4. In polytomography 84 joints (64.6%) showed consistent condylar shape from lateral to medial and 74 joints (56.9%) of them showed agreement with those of transcranial radiographs. Among the 46 joints (35.4%) which showed changes in condylar shape, 40 joints (30.1%) showed agreement with lateral and central tomographic and transcranial radiographic shape. 41 joints (31.5%) showed disagreement in condylar shape between the polytomographic and transcranial radiographic images.
Female ; Humans ; Incidence ; Joints ; Radiography* ; Sex Distribution ; Temporomandibular Joint ; Temporomandibular Joint Disorders

The author examined bone changes from 1274 polytomographic images of 182 temporomandibular joints which showed symptoms of temporomandibular disorder and the following results were obtained ; 1. The number of temporomandibular joints which showed bone changes were 64 (35.2%) among 182 joints. 2. The age and sex distribution of 64 joints which had bone changes showed the prevalence of female (90.6%) and thrid decade (25.0%) followed by fourth (21.2%) and second decade (17.2%). 3. The 252 images which showed bone changes consisted of 56 images from lateral side (22.2%), 118 images from center (46.8%) and 78 images from medial side (30.9%). 4. The most frequently observed bone changes were flattening (22.7%) followed by sclerosis (19.3%) and cortical unsharpness (19.3%)
Female ; Humans ; Joints ; Prevalence ; Sclerosis ; Sex Distribution ; Temporomandibular Joint ; Temporomandibular Joint Disorders*

The following conclusions were obtained from the non-reconstructed and reconstructed subtraction images of the standard intraoral radiographs which were taken with paralleing technique with Rinn XCP only and with occlusal bite registration for geometric standardization using bilateral mandibular premolar and molar regions of two dry humad skulls. 1. The SD of the overall subtraction images of the premolars and molars of the non-reconstructed, tnat is, the manual superimposition showed statistically significant difference between the non-registered and registered groups. 2. In non-reconstructed and non-registered cases, the quality of the subtraction images were improved when superimposition was focally done and this was more evident in areas where the radiographic imaged tend to be distorted due to anatomic readons. 3. In non-restructed and registered cases, the subtraction images were consistent regardless of the anatomic site or the focus superimposition. This means that the geometric standardization with only occlusal bite registration could produce serial radiographs which is suitable for subtraction. 4. The SD of the overall subtraction images of the premolars and molars of the reconstructed, that is, the automatic superimposition showed statistically insignificant difference between the non-registered and registered groups. This means that using reconstruction, subtraction radiography is possible without occlusal bite registration. 5. In reconstructed and non-registered cases, compatible quality of the subtraction images were obtained regardless of the anatomic site or area of the corresponding points. 6. In reconstructed and registered cases, best subtraction images whose quality showed sensitivity to the areas of corresponding points were obtained.
Bicuspid ; Jaw Relation Record ; Molar ; Radiography* ; Skull

This study was designed to reveal the correlationship between the internal derangement state of TMJ and clinical characteristics including pain and mandibular dusfuntion. One hundred and twenty five subjects with TMJ signs and symptoms were chosen for two years. The level of pain and mandibular dysfuntion were evaluated by Visual Analog Scale(VAS) and Craniomandibular Index(CMI). The diagnostic categories of TMJ internal derangement were determined by arthrography and they included normal disc position, anterior disc displacement with reduction(ADDR), rotational disc displacement with reduction(RDDR), andterior disc displacement without reduction(ADDNR), and rotational disc displacement without reduction(RDDNR). Also disc perforation was used as a criteria to divide the diagnostic subgroups. The obtained results were as follows ; 1. The patient distribution of each group was 5 in normal disc position(4%), 40 in ADDR(32%), 30 in RDDR(24%), 34 in ADDNR(27%), and 16 in RDDNR(13%). 2. Perforation was observed in 8% of ADDR, 10% of RDDR, 32% of ADDNR, and 19% of RDDNR. 3. CMI of perforation group was higher than that of reduction or normal group(P<0.005), but vas showed no significant difference. 4. CMI of non-reduction group was higher than that of non-perforation group in reduction group(P<0.05). 5. There were no significant differences of CMI and VAS between anterior disc displacement group and rotational disc displacement group in both reduction and non-reduction group. 6. CMI of RDDNR group was higher than that of RDDR group(P<0.05). 7. There were no significant difference of CMI and VAS between bilateral involvement group and unilateral involvement group(p>0.05).
Arthrography ; Humans ; Temporomandibular Joint*

The purpose of this study was to perform the radiographic measurements and temporomandibular joint evaluation in mandibular asymmetry. For this study, thirty-two patients who have mandibular asymmetry were selected and submentovertex, panoramic and lateral corrected tomographic radiagraphs were taken. Horizontal and vertical analysis using various landmarks on these radiographs were performed. Also radiographic and clinical evaluation of temporomandibular joint were obtained. Ther results were as follows ; 1. On the submentovertex radiograph, the mean distance of Pogonion to midline was 5.0(+/-)3.8mm. 2. The mean distance of Pogonion to Gonion between the deviated and the contra-lateral side(P<0.001). 3. The distance difference of Pogonion to Gonion between the deviated and the contra-lateral side was significantly realated to the degree of asymmetry(P<0.001). 4. On panoramic radiagraph,the condylar height of the contral-lateral side was significantly longer than the one of the deviated side(P<0.001). 5. On lateral corrected tomogram, bony of temporomandibular joint was observed in 11 condyles of the deviated side and 9 condyles of the contra-lateral side. Erosion and ostephyte were the most common changes in both the deviated and the contra-lateral sides.
Humans ; Temporomandibular Joint