• Restorative Dentistry and Endodontics
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• v.6 no.1
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• pp.105-107
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• 1980

A total of 125 extracted maxillary first molars were used to study the configuration of the floor of the pulp chamber. The specimens were ground and the pulp chamber was examined with a magnifying glass and explored with sharp explorer. The study showed the shape of the pulp chamber, number of root canals, and type of canal orifice. The results were as follows; 1. In so far as observing the shape of the pulp chamber of the teeth, 50.4% of the teeth were trapezoid, 20.8% were inverted trapezoid, 18.4% were rectangle and 10.4% were triangle shape. 2. 71.2% of the specimens have 3 root canal orifices, and 28.8% have 4 root canal orifices. 3. 71.2% of the specimens have 1 mesiobuccal canal orifice, 23.2% have 2 mesio-buccal canal orifices joined by a groove, and 5.6% have 2 mesio-buccal canal orifices seperated each other.

• Restorative Dentistry and Endodontics
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• v.12 no.2
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• pp.11-15
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• 1987

Thirty maxillary second premolars were fixed, decalcified, washed and embedded in celloidin to observe the root canal size and morphology at apical 5mm area. The results were as follows: 1. Single canaled teeth and two canaled teeth were approximately equal numbered. 2. Single canaled teeth have round canal but two canaled teeth have long, slender buccal canal and ovoid lingual canal. 3. The canal size of single canaled teeth was $380{\pm}30{\mu}m,\;340{\pm}22{\mu}m$, but that of buccal canal of two canaled teeth was $360{\pm}32{\mu}m,\;240{\pm}28{\mu}m$, lingual canal was $330{\pm}28{\mu}m,\;280{\pm}20{\mu}m$.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.43 no.5
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• pp.287-287
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• 2017

• 대한치주과학회:학술대회논문집
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• 2009.05a
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• pp.36-36
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• 2009

• Proceedings of the PSK Conference
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• 2001.10a
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• pp.302.2-302.2
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• 2001

• Imaging Science in Dentistry
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• v.32 no.3
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• pp.141-145
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• 2002

Purpose : The purpose of this study was to propose standard values for alveolar and basal bone in normal adult mandibles, and radiologically analyze the remodeling process of the edentulous mandible by examining molar areas and comparing them to the established normal values. Materials and Methods : Panoramic and CT scans of mandible were performed on 20 normal adults and 20 edentulous or partially edentulous adults. In both groups, arch half diameter and distance of alveolar bone were measured. Also the distance from the mandibular canal to the caudal edges, the buccal and lingual external borders of basal bone, were measured. A statistical comparison between the mean values of normal and edentulous mandibles was carried out in the selected areas. Results : There was evidence of decreasing arch half diameter and distance in the edentulous mandible, but statistically no significant change was seen between the normal and edentulous alveolar bone. There was evidence of decreasing buccal basal bone and increasing in the lingual basal bone in the edentulous mandible. A statistically significant difference between normal and edentulous mandibles was noted in the buccal basal bone. Conclusion: There was an inward and forward atrophic change of the edentulous mandibular molar area compared to the control. CT scanning required the use of sophisticated and expensive procedures to analyze the remodeling process of edentulous mandibles. Consequently, the development and application of a more simplified and objective radiographic procedure for broad and long-term study of remodeling procedures of edentulous mandible was recommended.

• The Korean Journal of Cytopathology
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• v.11 no.2
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• pp.89-92
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• 2000

Adenoid cystic carcinoma constitutes 4 percent of ail benign and malignant epithelial salivary gland tumors and is a highly malignant tumor of the salivary glands. The cytologic presentation in aspirates is usually characteristic with spherical clusters(balls) of small tumor cells filled with hyaline material. But in case of the poorly differentiated variety(solid type), it is difficult to differentiate from other tumors because sheets of small, fairly monotonous malignant cells, with somewhat larger and more conspicuous nuclei are only seen. The cytologic findings of fine needle aspiration of solid type adenoid cystic carcinoma of buccal mucosa in a 51-year-old man are presented. On cytologic findings, solid sheets of monotonous tumor cells with focal necrosis was noted on a hemorrhagic background and the characteristic cytologic features of adenoid cystic carcinoma was absent.

• Imaging Science in Dentistry
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• v.50 no.2
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• pp.133-139
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• 2020

Purpose: This study compared 2 cone-beam computed tomography (CBCT) systems in the detection of mechanically simulated peri-implant buccal bone defects in dry human mandibles. Materials and Methods: Twenty-four implants were placed in 7 dry human mandibles. Peri-implant bone defects were created in the buccal plates of 16 implants using spherical burs. All mandibles were scanned using 2 CBCT systems with their commonly used acquisition protocols: i-CAT Gendex CB-500 (Imaging Sciences, Hatfield, PA, USA; field of view [FOV], 8 cm×8 cm; voxel size, 0.125 mm; 120 kVp; 5 mA; 23 s) and Orthopantomograph OP300 (Intrumentarium, Tuusula, Finland; FOV, 6 cm×8 cm; voxel size, 0.085 mm; 90 kVp; 6.3 mA; 13 s). Two oral and maxillofacial radiologists assessed the CBCT images for the presence of a defect and measured the depth of the bone defects. Diagnostic performance was compared in terms of the area under the curve (AUC), accuracy, sensitivity, specificity, and intraclass correlation coefficient. Results: High intraobserver and interobserver agreement was found (P<0.05). The OP300 showed slightly better diagnostic performance and higher detection rates than the CB-500 (AUC, 0.56±0.03), with a mean accuracy of 75.0%, sensitivity of 81.2%, and specificity of 62.5%. Higher contrast was observed with the CB-500, whereas the OP300 formed more artifacts. Conclusion: Within the limitations of this study, the present results suggest that the choice of CBCT systems with their respective commonly used acquisition protocols does not significantly affect diagnostic performance in detecting and measuring buccal peri-implant bone loss.

• Journal of The Korean Society of Integrative Medicine
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• v.5 no.4
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• pp.103-112
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• 2017

Purpose : This study was conducted to improve cognitive oral healthcare care by analyzing the correlation between oral health behavior and oral health status Korean adolescents. The subjects were 65,528 youths in 798 schools monitored in the Twelfth Korea Youth Risk Behavior Web-based Survey in 2016. Methods : The general characteristics consisted of 9 items including sex, grade, and academic performance. The academic performance and economic status were restructured into "upper, middle, lower". Subjective health perception and subjective oral health perception were reorganized as "health", "normal", "no health". The sub-areas of oral health behavior include five times of daily brushing during the day yesterday. The number of brushing times was "0", "1-2", "3", "more than 4" After lunch at school, brushing was restructured as "always," "sometimes," "not." The oral health status subscale consisted of 6 items including tooth breakage and toothache at the time of eating. Result : Tooth fracture(43.7 %), pain in mastication(43.7 %), tooth tingling(47.4 %), gum pain and bleeding(45 %), pain in buccal mucosa(43.8 %) and halitosis(46.6 %) were rare in adolescent having healthy oral health status cognitively(P<.001). Nosymptom adolescents without dental sealant showed low tooth fracture(0.64 times), pain in mastication(0.67 times), tooth tingling(0.59 times), gum pain and bleeding(0.84 times), pain in buccal mucosa(0.76 times), and halitosis(0.90 times). Nosymptom adolescents without scaling showed low tooth fracture(0.88 times), pain in mastication(1.03 times), tooth tingling(0.82 times), gum pain and bleeding(0.64 times), pain in buccal mucosa(0.70 times) and halitosis(0.82 times). Conclusion : This study revealed that oral health status is correlated with oral health behavior. Development of educational media and program, and aggressive promotion required to establish oral health Korean adolescent.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.4
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• pp.615-643
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• 1998

The purpose of this study was to evaluate the effect of cantilever length, load, and implant number on the stress distribution of implant supported fixed prosthesis. In the replica of an edentulous human mandible, four or five implants were placed and spaced evenly between the mental foramina and symmetrical gold alloy cast superstructures with cantilever were fabricated. Strain gauges were placed in buccal and lingual side of implants. 9, 15, 21kg of loads at varying cantilever lengths were applied to the occlusal surface of fixed prostheses. The strains were recorded from each gauge and principal stresses were calculated The results were as follows : 1. Increasing the length of the cantilever increased the stresses on the bone supporting implants. and the ratio of increase became high as increasing the load. 2. In the model with four implants, the highest compressive stress was measured on lingual side of the first implants nearest loading point and the highest tensile stress was measured on buccal side of the second implants. 3. In the model with five implants, the highest compressive stress was measured on lingual side of the first implants nearest loading point. And the highest tensile stress was measured on buccal side of the second implants, and lingual side of the third implants. 4. There was no significant change of the magnitude of stress on the most distal imp]ant of non cantilevered side as increasing the cantilever length or load. 5. In general, the superstructure supported by five implants reduced the stress and was less affected by cantilever length compared to the support provided by four implants.