• Journal of Periodontal and Implant Science
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• v.34 no.2
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• pp.281-292
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• 2004

Periodontal defects of the furcation are characterized by several inherent anatomic factors that can make successful periodontal therapy difficult and results unpredictable. The severity and rate of occurrence of periodontal disease are directly related to the location of the furcation relative to the cementa-enamel junction and anatomical form of the root by limiting the accessibility and effectiveness of the periodontal instrumentation. This study investigated the reliability and accuracy of panoramic radiograph diagnoses of the periodontal state of mandibular molars, particularly regarding the diagnosis of furcation area periodontal defects, treatment planning, and prognosis prediction. This study examined a total of 110 teeth belonging to 33 subjects (19 male, 14 female) presenting with incipient to moderate periodontitis 4-7mmpocket depth. The alveolar bone level, length and width of the root trunk, and root separation angle were measured using the panoramic radiograph and compared to the results taken directly by retracting a full-thickness flap. The results of the study are as follows: 1. Data regarding the alveolar bone level of the mandibular first molar showed that the directly taken surgical measurements resulted in $5.1{\pm}0.9mm$ that was slightly deeper than the corresponding panoramic measurement resulted in $4.8{\pm}0.8mm$, but these differences were statistically insignificant (p>0.05). 2. The data of the directly taken surgical measurement of the mandibular second molar $(5.1{\pm}1.1mm)$ was slightly deeper than the corresponding panoramic measurement $(4.7{\pm}1.2mm)$, but these differences were statistically insignificant (p>0.05). 3. The measured values of the length and width of the mandibular first molar root trunks were determined to be $4.1{\pm}0.6mm$ and $7.3{\pm}0.9mm$, respectively, while the values of the mandibular second molar root trunks were determined to be $4.6{\pm}1.3mm$ and $7.6{\pm}0.9mm$ respectively. The differences between these values were found to be statistically significant (p<0.01). 4. The measured values of the root separation angle showed that the mandibular first molars averaged $34.5{\pm}4.4^{\circ}$, while the mandibular second molars averaged $23.0{\pm}10.0^{\circ}$. The differences between these values were found to be statistically significant (p<0.01).

• The korean journal of orthodontics
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• v.41 no.4
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• pp.255-267
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• 2011

Objective: The purpose of this study was to confirm the reliability of a cone beam computed tomography (CBCT)-generated panoramic view based on a CBCT 3D image and to find the most helpful 2D panoramic image compared with CBCT 3D image when examining the mesiodistal tooth axis. Methods: A test model was constructed according to cephalometric norms. The test model was repeatedly repositioned for CBCT and panoramic radiographic imaging. Panoramic radiographs were acquired at each of the following 3 occlusal plane positions: $-5^{\circ}$, $0^{\circ}$, and $+5^{\circ}$. Measurements of mesiodistal tooth axis in CBCT 3D image, CBCT-generated panoramic view, and panoramic radiographs were compared. Results: Compared with the CBCT-generated panoramic view, CBCT 3D image showed significant difference in the mesiodistal tooth axis in the premolars and no significant difference in the mesiodistal tooth axis in the incisors and canines. Mesiodistal tooth axis on the CBCT-generated panoramic view was significantly different from that on panoramic radiographs. Conclusions: CBCT-generated panoramic view can be a useful tool for evaluating mesiodistal tooth axis.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.248-251
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• 2002

The intensity modulated radiation therapy (IMRT) with a multileaf collimator (MLC) requires the conversion of a radiation fluence map into a leaf sequence file that controls the movement of the MLC during radiation treatment of patients. Patient dose verification is clinically one of the most important parts in the treatment delivery of the radiation therapy. The three dimensional (3D) reconstruction of dose distribution delivered to the target helps to verify patient dose and to determine the physical characteristics of beams used in IMRT. A new method is presented for the pretreatment dosimetric verification of two dimensional distributions of photon intensity by means of Beam Intensity Scanner System (BISS) as a radiation detector with a custom-made software for dose calculation of fluorescence signals from scintillator. The scintillator is used to produce fluorescence from the irradiation of 6MV photons on a Varian Clinac 21EX. The BISS reproduces 3D- relative dose distribution from the digitized fluoroscopic signals obtained by digital video camera-based scintillator(DVCS) device in the IMRT. For the intensity modulated beams (IMBs), the calculations of absorbed dose are performed in absolute beam fluence profiles which are used for calculation of the patient dose distribution. The 3D-dose profiles of the IMBs with the BISS were demonstrated by relative measurements of photon beams and shown good agreement with radiographic film. The mechanical and dosimetric properties of the collimating of dynamic and/or step MLC system alter the generated intensity. This is mostly due to leaf transmission, leaf penumbra and geometry of leaves. The variations of output according to the multileaf opening during the irradiation need to be accounted for as well. These phenomena result in a fluence distribution that can be substantially different from the initial and calculative intensity modulation and therefore, should be taken into account by the treatment planning for accurate dose calculations delivered to the target volume in IMRT.

• Journal of Periodontal and Implant Science
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• v.46 no.6
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• pp.372-381
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• 2016

Purpose: The aim of this study was to determine the relationship between buccal bone thickness and gingival thickness by means of a noninvasive and relatively accurate digital registration method. Methods: In 20 periodontally healthy subjects, cone-beam computed tomographic images and intraoral scanned files were obtained. Measurements of buccal bone thickness and gingival thickness at the central incisors, lateral incisors, and canines were performed at points 0-5 mm from the alveolar crest on the superimposed images. The Friedman test was used to compare buccal bone and gingival thickness for each depth between the 3 tooth types. Spearman's correlation coefficient was calculated to assess the correlation between buccal bone thickness and gingival thickness. Results: Of the central incisors, 77% of all sites had a buccal thickness of 0.5-1.0 mm, and 23% had a thickness of 1.0-1.5 mm. Of the lateral incisors, 71% of sites demonstrated a buccal bone thickness <1.0 mm, as did 63% of the canine sites. For gingival thickness, the proportion of sites <1.0 mm was 88%, 82%, and 91% for the central incisors, lateral incisors, and canines, respectively. Significant differences were observed in gingival thickness at the alveolar crest level (G0) between the central incisors and canines (P=0.032) and between the central incisors and lateral incisors (P=0.013). At 1 mm inferior to the alveolar crest, a difference was found between the central incisors and canines (P=0.025). The lateral incisors and canines showed a significant difference for buccal bone thickness 5 mm under the alveolar crest (P=0.025). Conclusions: The gingiva and buccal bone of the anterior maxillary teeth were found to be relatively thin (<1 mm) overall. A tendency was found for gingival thickness to increase and bone thickness to decrease toward the root apex. Differences were found between teeth at some positions, although the correlation between buccal bone thickness and soft tissue thickness was generally not significant.

• Journal of Periodontal and Implant Science
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• v.28 no.1
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• pp.37-56
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• 1998

The purpose of this study was to evaluate the clinical and microbiological outcomes following the use of 30% minocycline-loaded polycaprolacton film and 2% minocycline-loaded gel that was applied locally into pockets combined with scaling and root planing. 25 human subjects who were non-pregnant, non-lactating, aged 20-50 and diagnosed as moderate to advanced adult periodontitis were enrolled. Subjects were excluded if they had a history of severe acute or chronic systemic disease, if they required antibiotic prophylaxis for dental treatment for any reason, or if they reported a history suggestive of hypersensitivity reactions to minocycline or tetracycline. 4quadrants that had several teeth with a 5-8mm probing pocket depth and radiographic evidence of alveolar bone loss for each patient were selected and divided into test sites and control sites according to the split-mouth design. Scaling and root planing was done for each site at baseline(0week). Test sites received the minocycline gel and strip and control sites had saline irrigation. The patients received both treatments simyltaneously. Subgingival irrigation of sterile saline was applied to the control sites for approximately 30 seconds. Minocycline strip and gel was applied into the periodontal pocket at 1, 2, 3, 4 weeks each after scaling and root planing in the test sites. The clinical and microbiological measurements were made at baseline and at the follow-up visits 6, 10, 14, 20 weeks. The results of this study were as follows; 1. The sulcular bleeding index, probing pocket depth and Periocheck test was significantly reduced and the relative proportions of spirochetes and motile rods were significantly reduced and the proportion of cocci was correspondingly increased, in locally delivered minocycline strip group compared to saline irrigation group. 2. In locally delivered minocycline gel group, The effect was the same with minocycline strip group as compared with saline irrigation therapy. 3. There was no significant differences between minocycline strip group and minocycline gelgroup. In conclusion, minocycline HCl local drug delivery combined with scaling and root planing may provide added improvement of clinical and microbiological responses by inhibiting bacterial recolonization of treated sites. It is suggested that the local administration of minocycline-HCl in the periodontal pocket is effective when combined with subgingival mechanical debridement.

• Journal of Periodontal and Implant Science
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• v.36 no.2
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• pp.461-471
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• 2006

In order to achieve a satisfactory esthetic result of periodontal surgery or implant in maxillary anterior area, periodontists must be aware of normal alveolar bone anatomy. The purpose of this study was to evaluate the relationship of alveolar bone morphology to tooth shape and form. 78(mean age : 25 yrs) periodontally healthy volunteers participated in this study. Two maxillary central incisor and one lateral incisor were selected to study. With minimal local anesthesia, gutta-percha cone inserted to labial gingival sulcus of selected teeth just after bone sounding with periodontal probe. Metal ball (4mm diameter) attached to palatal fossa of central incisor. Then, periapical radiograph was taken according to long cone paralleling technique. After film scan, labial alveolar bone profile reproduced along interproximal bone and apical ends of gutta-percha cones on computer screen. By utilizing computer program, the distance from height of interproximal bone to the labial bone crest in central incisor-central incisor and central incisor-lateral incisor area was measured and converted to real distance by using vertical length of metal ball on film. After measuring crown length & width of central incisor, the 10 individuals ranked lowest GW/L ratio (crown width/length ratio) and the 10 ranked highest were selected as having a long-narrow(group N), or a short-wide(group W) form of the central incisors. Means of the distance from height of interproximal bone to the labial bone crest of group N, W were calculated and compared by means of independent t-test. The results were as follows: 1. Mean distance from the height of the interproximal bone to the labial bone crest was $3.5{\pm}0.7mm$ between two central incisor, and $2.8{\pm}0.6mm$ between central and lateral incisor. 2. Mean GW/L ratio of group N was 0.57, and group W was 0.8. Mean distance from the height of the interproximal bone to the labial bone crest of group N was higher than group W in both measured area(measurements of group N, W were $3.9{\pm0.2mm$ and $3.5{\pm}0.2mm$ between two central incisor, $3.0{\pm}0.2mm$ and $2.8{\pm}0.2mm$ between central and lateral incisor), but there were no statistically significant differences when the groups were compared. Within the limits of the present study, there was a tendency that subjects with long-narrow teeth have more scalloped alveolar bone profile than subjects with short-wide teeth in upper anterior area, but no statistically significant differences were found.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.1
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• pp.225-233
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• 1998

The purpose of this study was to determine the thickness of the cortical bone at the mandibular angle in children and adolescents. The subjects were composed of 153 subjects who were 3 to 17 years of age that had not been history of bone disease or metabolic disease and no dental caries or tooth loss on mandibular molars. The subjects were divided into three age groups, group I (preschool children) was 3 to 5 years of age and grouop II (school children) was 6 to 11 years of age and group III (adolescence) was 12 to 17 years of age. Panoramic radiographs of these patients were collected and measurements of the thickness of the cortical bone were obtained at the mandibular angle. The average thickness of the cortical bone in the group I was 1.01$\pm$0.18 mm in boys and 1.07$\pm$0.22 mm in girls. In the group II was 1.23$\pm$0.18 mm in boys and 1.32$\pm$0.18 mm in girls. In the group III was 1.60$\pm$0.23 mm in boys and 1.58$\pm$0.20 mm in girls. Statistical analyses did not reveal any significant difference between the right or left side of the mandible but difference was exist between the same age groups by sex, especially in group II (p<0.01), except in group III. The greater thickness of cortical bone in the older age group was shown to be statistically significant. The correlation coefficient between age and the thickness of the cortical bone at the mandibular angle showed a high value of r=0.76.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.1
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• pp.32-38
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• 2018

Purpose: The purpose of present study was to retrospectively analyze the survival rate of narrow diameter implant less than 3.6 mm by initial stability and radiographic measurements. Materials and Methods: In total, 24 patients who received 38 narrow diameter implants (${\leq}3.6mm$ in diameter, ${\geq}7mm$ in length) were enrolled in this retrospective study. The cumulative survival rate was calculated and various factors were investigated according to the implant platform diameter, body diameter, length, position, concomitant use of guided bone regeneration in implant placement and final prosthesis type. Initial stability was investigated with implant stability quotient (ISQ) value. The mesial and distal marginal bone level (MBL) change was calculated with radiography. Results: The overall survival rate was 92.11%. Mean ISQ value and MBL change of survival implants was 66.26 and $0.14{\pm}0.31mm$, respectively. None of the implants with platform diameters larger than the body diameter failed. Conclusion: In conclusion, the findings of present study suggest that narrow diameter implant could be predictable treatment in narrow alveolar ridge.

• Journal of radiological science and technology
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• v.21 no.1
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• pp.52-58
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• 1998

We can and must improve the diagnostic images using available knowledge and technology. At the same time we must strive to reduce the patient's integral and entrance radiation dose. Reducing the integral dose to the patient during the radiologic procedure is a primary concern of the patient, especially the pediatric patient, the radiologist and the technologist. A 100cm focal film distance generally is used for most over-table radiography. The early x-ray tubes and screen film combinations required long exposures, which often resulted in motion artifacts. But nowaday, we have the generators and x-ray tubes that can deliver the energy necessary in a very short time and the receptors that can record the information just as rapidly. And, we performed this studies to evaluate the patient exposure dose and the image quality by increasing focal film distance in diagnostic radiography. There are many factors which affected to exposure factor, but we studied to verify of FFD increase, only. Effect of increasing the focal film distance to a 140 cm distance was tested as follows; 1. The focal film distances were set at 100, 120, and 140cm. 2. A 18cm acryl(tissue equivalent) phantom was placed on the table top. 3. An Capintec 192 electrometer with PM 05 ion chamber was placed at the entrance surface of the phantom, and exposure were made at each focal film distances. 4. The procedure was repeated in the same manner as above except the ion chamber was placed beneath the phantom at the film plane. 5. Exit exposure were normalize to 8mR for each portions of the experiment. Based on the success of the empirical measurements, a detailed mathematical analysis of the dose reduction was performed using the percent depth dose data. The results of this study can be summerized as followings ; 1) Increasing FFD from 100 cm to 140 cm, we would create a situation that would have a significant effect on the overall quality of radiograph and achive the 17.42% reduction of entrance dose and the 18.95% reduction of integral dose that the patient receives. 2) Thickness of Al step wedge for equal film density increased with the long distance. 3) Increasing FFD, Magnification of image was lowered. 4) Resolution of image also increased with the FFD. As the results described above, we strongly recommend using the long FFD to provide better information for our patients and profession in abdomen radiographic studies.

• Journal of radiological science and technology
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• v.35 no.2
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• pp.109-117
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• 2012

The purpose of this work was to evaluate an amorphous silicon cesium iodide based indirect flat-panel detector (FPD) in terms of their modulation transfer function (MTF), Wiener spectrum (WS, or noise power spectrum, NPS), and detective quantum efficiency (DQE). Measurements were made on flat-panel detector using the International Electrotechnical Commission (IEC) defined RQA3, RQA5, RQA7, and RQA9 radiographic technique. The MTFs of the systems were measured using an edge method. The WS(NPS) of the systems were determined for a range of exposure levels by two-dimensional (2D). Fourier analysis of uniformly exposed radiographs. The DQEs were assessed from the measured MTF, WS(NPS), exposure, and estimated ideal signal-to-noise ratios. Characteristic curve in the RQA3 showed difference in the characteristic curve from RQA5, RQA7, RQA9. MTFs were not differences according to x-ray beam quality. WS(NPS) was reduced with increasing dose, and RQA 3, RQA5, RQA7, RQA9 as the order is reduced. DQE represented the best in the 1mR, RQA 3, RQA5, RQA7, RQA9 decrease in the order. The physical imaging characteristics of FPD may also differ from input beam quality. This study gives an initial motivation that the physical imaging characteristics of FPD is an important issue for the right use of digital radiography system.