• 전자공학회논문지
• /
• 제50권5호
• /
• pp.262-266
• /
• 2013

신개념 치과용 X선 촬영장치인 강내형 X선 튜브에 대한 연구가 소개되었다. 이는 초소형의 X-선 튜브를 구강내 삽입하여 외부에서 검출기로 영상을 획득하는 새로운 시스템이다. 본 연구에서는 구내 치근단 촬영을 위해 사용하는 강내형 X선 튜브의 온도분포 및 선량 분포 특성을 조사하였다. X선 튜브의 온도특성을 파악하기 위하여 튜브 표면에 써머커플을 부착하여 튜브 표면에서부터 거리에 대한 온도를 측정하였으며, EBT 필름을 이용하여 튜브표면에서부터 거리에 따른 선량 분포를 측정하였다. 그 결과 냉각장치가 없는 튜브에서 2mm 이상 거리에서 온도는 $27^{\circ}C$로 일정하였으며, 튜브에서 3cm, 5cm일 때 선량분포가 3.14, 1.84mGy로 나타났다. 그 결과 제안한 시스템은 기존 시스템에 비해 낮은 선량에서 안전하게 촬영이 가능한 것으로 향후 구내 치근단 촬영장치에 새로운 변화를 가져올 수 있을 것으로 사료된다.

• Imaging Science in Dentistry
• /
• 제32권4호
• /
• pp.207-211
• /
• 2002

Purpose : The purpose of this study was to determine the prevalence, radiographic appearance, and characteristics of patients with zygomatic air cell defect (ZACD), and to give recommendations concerning radiographic evaluation and surgery. Materials and Methods: Routine panoramic radiographs of 1,400 patients admitted to the Kyungpook National University Hospital Dental Clinic, were retrospectively examined for the clinical and radiographic features of ZACD. Results: ZACD was found in 31 cases, representing a prevalence of 2.2%. Patients with ZACD had a mean age of 27.5 years and a range of 9-52 years. Most ZACD cases were in their thirties. ZACD showed a strong male prediliction, 22 of the 31 subjects were males and 9 were females. Twenty-four cases of ZACD (77.4%) were unilateral, with the half occurring on the right side. In seven cases (22.6%), ZACD was bilateral. Twenty-six (68.4%) of the defects were of unilocular, while twelve (31.6%) of the defects were multilocular. Conclusion: Knowledge of ZACD may be helpful in interpreting images, including panoramic radiographs, in planning surgical treatment of the TMJ and in understanding the spread of pathological processes into the joint.

• Imaging Science in Dentistry
• /
• 제33권1호
• /
• pp.35-41
• /
• 2003

Purpose: To aid in determining the volume of graft bone required before a maxillary sinus lift procedure and compare the alveolar bone height measurements taken by panoramic radiographs to those by CT images. Materials and Methods : Data obtained by both panoramic radiographs and CT examination of 25 patients were used in this study. Maxillary sinus volumes from the antral floor to heights of 5 mm, 10 mm, 15 mm, and 20 mm, were calculated. Alveolar bone height was measured on the panoramic images at each maxillary tooth site and corrected by magnification rate (PBH). Available bone height (ABH) and full bone height (FBH) was measured on reconstructed CT images. PBH was compared with ABH and FBH at the maxillary incisors, canines, premolars, and molars. Results: Volumes of the inferior portion of the sinuses were 0.55 ± 0041 ㎤ for 5 mm lifts, 2.11 ± 0.68 ㎤ for 10 mm, 4.26 ± 1.32 ㎤ for 15 mm, 6.95 ± 2.01 ㎤ for 20 mm. For the alveolar bone measurement, measurements by panoramic images were longer than available bone heights determined by CT images at the incisor and canine areas, and shorter than full bone heights on CT images at incisor, premolar, and molar areas (p<0.001). Conclusion: In bone grafting of the maxillary sinus floor, 0.96 ㎤ or more is required for a 5 mm-lift, 2.79 ㎤ or more for a 10 mm-lift, 5.58 ㎤ or more for a 15 mm-lift, and 8.96 ㎤ or more for a 20 mm-lift. Maxillary implant length determined using panoramic radiograph alone could result in underestimation or overestimation, according to the site involved.

• Imaging Science in Dentistry
• /
• 제33권1호
• /
• pp.43-49
• /
• 2003

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 (+ 100, 00 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 00 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.

• Imaging Science in Dentistry
• /
• 제35권2호
• /
• pp.77-82
• /
• 2005

Purpose : To reveal what is the distinct differential diagnostic differences between unicystic ameloblastoma and solid or multicystic ameloblastoma. Materials and Methods : 56 cases of ameloblastoma were retrospectively reviewed and evaluated among the patients who had taken CT scans at the department of Oral & Maxillofacial Radiology in Yonsei University Dental Hospital from January 1996 to December 2003. Results : In 56 cases, 21 cases $(37.5\%)$ were unicystic ameloblastoma, 35 cases $(62.5\%)$ were solid or multicystic ameloblastoma. Only 1 case $(4.8\%)$ of unicystic ameloblastoma and 4 cases $(11.4\%)$ of solid or multicystic ameloblastoma were occurred in maxilla. 13 cases $(61.9\%)$ of unicystic ameloblastoma were observed as unilocular, and 8 cases $(38.1\%)$ as lobulated. 5 cases $(14.3\%)$ of solid or multicystic ameloblastoma were observed as unilocular, 13 cases $(37.1\%)$ as lobulated, and 17 cases $(48.6\%)$ as multilocular. Tn the results from the measurements after correction of the buccolingual widths and heights to the mesiodistal lengths, there is a statistically significant difference between unicystic ameloblastoma and solid or multicystic ameloblastoma in ANCOVA test (p<0.05). Hounsfield units in the lesion were $24.9{\pm}8.8\;HU$ in unicystic ameloblastoma, $31.2{\pm}11.5\;HU$ in solid or multicystic ameloblastoma. There is no statistically significant difference (p>0.05). Conclusion : Characteristic differences between unicystic ameloblastoma and solid or multicystic ameloblastoma is that there is higher prevalence of solid or multicystic ameloblastoma that have lobulated or multilocular patterns. To measure the Hounsfield units in the lesion is helpful, but it is not a differential diagnostic point between unicystic ameloblastoma and solid or multicystic ameloblastoma.

• Imaging Science in Dentistry
• /
• 제46권2호
• /
• pp.117-125
• /
• 2016

Purpose: This study evaluated and compared interradicular distances and cortical bone thickness in Thai patients with Class I and Class II skeletal patterns, using cone-beam computed tomography (CBCT). Materials and Methods: Pretreatment CBCT images of 24 Thai orthodontic patients with Class I and Class II skeletal patterns were included in the study. Three measurements were chosen for investigation: the mesiodistal distance between the roots, the width of the buccolingual alveolar process, and buccal cortical bone thickness. All distances were recorded at five different levels from the cementoenamel junction (CEJ). Descriptive statistical analysis and t-tests were performed, with the significance level for all tests set at p<0.05. Results: Patients with a Class II skeletal pattern showed significantly greater maxillary mesiodistal distances (between the first and second premolars) and widths of the buccolingual alveolar process (between the first and second molars) than Class I skeletal pattern patients at 10 mm above the CEJ. The maxillary buccal cortical bone thicknesses between the second premolar and first molar at 8 mm above the CEJ in Class II patients were likewise significantly greater than in Class I patients. Patients with a Class I skeletal pattern showed significantly wider mandibular buccolingual alveolar processes than did Class II patients (between the first and second molars) at 4, 6, and 8 mm below the CEJ. Conclusion: In both the maxilla and mandible, the mesiodistal distances, the width of the buccolingual alveolar process, and buccal cortical bone thickness tended to increase from the CEJ to the apex in both Class I and Class II skeletal patterns.

• Imaging Science in Dentistry
• /
• 제46권2호
• /
• pp.87-92
• /
• 2016

Purpose: The aim of this study was to assess and compare the diagnostic performance of panoramic and occlusal radiographs in detecting submandibular sialoliths. Materials and Methods: A total of 40 patients (20 cases and 20 controls) were included in this retrospective study. Cases were defined as subjects with a submandibular sialolith confirmed by computed tomography (CT), whereas controls did not have any submandibular calcifications. Three observers with different expertise levels assessed panoramic and occlusal radiographs of all subjects for the presence of sialoliths. Intraobserver and interobserver agreement were assessed using the kappa test. Sensitivity, specificity, accuracy, positive and negative predictive values, and the diagnostic odds ratio of panoramic and occlusal radiographs in screening for submandibular sialoliths were calculated for each observer. Results: The sensitivity and specificity values for occlusal and panoramic radiographs all ranged from 80% to 100%. The lowest values of sensitivity and specificity observed among the observers were 82.6% and 80%, respectively (P=0.001). Intraobserver and interobserver agreement were higher for occlusal radiographs than for panoramic radiographs, although panoramic radiographs demonstrated a higher overall accuracy. Conclusion: Both panoramic and occlusal radiographic techniques displayed satisfactory diagnostic performance and should be considered before using a CT scan to detect submandibular sialoliths.

• Imaging Science in Dentistry
• /
• 제42권3호
• /
• pp.147-154
• /
• 2012

Purpose: This study was performed to evaluate the incidence and degree of external apical root resorption of maxillary incisors after orthodontic treatment and to evaluate particular associated factors related to external apical root resorption. Materials and Methods: The records and maxillary incisor periapical radiographs of 181 patients were investigated. Crown and root lengths were measured and compared on the pre- and post-treatment periapical radiographs. Crown length was measured from the center of the incisal edge to the midpoint of the cemento-enamel junction (CEJ). Root length was measured from the CEJ midpoint to the root apex. A correction factor for the enlargement difference was used to calculate root resorption. Results: The periapical radiographs of 564 teeth showed that the average root resorption was $1.39{\pm}1.27$ ($8.24{\pm}7.22$%) and $1.69{\pm}1.14$ mm ($10.16{\pm}6.78%$) for the maxillary central and lateral incisors, respectively. The results showed that the dilacerated or pointed roots, maxillary premolar extraction cases, and treatment duration were highly significant factors for root resorption (p<0.001). Allergic condition was a significant factor at p<0.01. Age at the start of treatment, large overjet, and history of facial trauma were also factors significantly associated with root resorption (p<0.05). There was no statistically significant difference in root resorption among the factors of gender, overbite, tongue-thrusting habit, types of malocclusion, and types of bracket. Conclusion: These results suggested that orthodontic treatment should be carefully performed in pre-treatment extraction patients who have pointed or dilacerated roots and need long treatment duration.

• Imaging Science in Dentistry
• /
• 제42권4호
• /
• pp.225-229
• /
• 2012

Purpose: This study aimed to evaluate the trabecular bone changes after alveolar bone grafting in unilateral cleft lip and palate (UCLP) patients using a computer-aided diagnosis (CAD) system. Materials and Methods: The occlusal radiographs taken from 50 UCLP patients were surveyed retrospectively. The images were categorized as: 50 images in group 0 (before bone grafting), 33 images in group 1 (one month after bone grafting), 24 images in group 2 (2-4 months after bone grafting), 15 images in group 3 (5-7 months after bone grafting), and 21 images in group 4 (8 or more months after bone grafting). Each image was grouped as either "non-cleft side" or "cleft side". The CAD system was used five times for each side to calculate the pixel area based on the mathematical morphology. Significant differences were found using a Wilcoxon signed ranks test or paired samples t test. Results: The pixel area showed a significant difference between the "non-cleft side" and "cleft side" in group 0 ($404.27{\pm}103.72/117.73{\pm}92.25$; p=0.00), group 1 ($434.29{\pm}86.70/388.31{\pm}109.51$; p=0.01), and group 4 ($430.98{\pm}98.11/366.71{\pm}154.59$; p=0.02). No significant differences were found in group 2 ($423.57{\pm}98.12/383.47{\pm}135.88$; p=0.06) or group 3 ($433.02{\pm}116.07/384.16{\pm}146.55$; p=0.19). Conclusion: Based on the design of this study, alveolar bone grafting was similar to normal bone within 2-7 months postoperatively.

• Imaging Science in Dentistry
• /
• 제40권4호
• /
• pp.159-163
• /
• 2010

Purpose : This retrospective study was performed to investigate the prevalence of the idiopathic osteosclerosis (IO) in Korean malocclusion patients according to age, sex, and the Angle's classification of malocclusion. Materials and Methods : This study consisted of 2,001 randomly selected patients from the Department of Orthodontics at the Gangneung-Wonju National University Dental Hospital, Korea. The prevalence of IO in Korean malocclusion patients was recorded using their panoramic radiographs, and the following parameters were surveyed; age, sex, and the Angle's classification of malocclusion. The chi-square test was analyzed to determine the statistical significance of differences in the prevalence of IO between age, sex, and the Angle's classification of malocclusion. Results : The prevalence of IO in the jaws was 6.7% in a total of 2,001 examined orthodontic patients. The majority of IO was found in the mandible (96.58%). The 30-39 age group showed the highest prevalence of IO (9.60%). There was a higher prevalence in females (6.89%) than in males (6.45%). The prevalence of IO in Angle Class I group (7.07%) was the most frequent, followed by Angle Class II group (6.72%), and Angle Class III group (6.40%). However, there was no statistical significance in sex and Angle's classification of malocclusion. Conclusion : The prevalence of IO in malocclusion patients showed the differences between various age groups and most of them were found in the mandibular posterior area. However, sex and the type of malocclusion are not to be considered as a contributing factor of IO.