• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.32 no.4
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• pp.391-396
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• 2006

The CT number is called Hounsfield unit(HU). Generally HU has a score between +1000 from -1000, and it is standardized usingthe air(-1000), water(0), and compact bone(+1000). Hounsfield Unit to standardize the density in computed tomography using the air and water has been used to analysis of lesion in other medical field. Computed tomography is popular method to analysis of lesion in oral & maxillofacial field but the analysis about density of lesion by Hounsfield unit is still obscure. For this study, computed tomography taken in Dankook University Dental Hospital and Hounsfield unit was measured to compare the difference of jaw bone lesion as cystic lesion, benign tumor, malignant tumor.

• Journal of Technologic Dentistry
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• v.34 no.2
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• pp.95-103
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• 2012

Purpose: Fracture strength of all-ceramic 3-unit fixed partial dentures manufactured by CAD/CAM and copy-milling systems were evaluated. Methods: Zirconia cores were made by milling the pre-sintered zirconia block by CAD/CAM or copy milling method followed by subsequent sintering. By building-up the corresponding porcelains on the core, all-ceramic bridges were fabricated, and those were evaluated in comparison with PFM fixed partial denture. Results: During the flexural test of the 3-unit PFM bridge, the porcelain started to chip or break at 507.28(${\pm}62.82$)kgf and the metal framework did not break until the maximum load level of 800kgf which was set in the testing instrument of this study. However, among all-ceramic restoration test groups, Everest(EV) group showed a peeling off or breakage of the porcelain from 365.64(${\pm}64.96$)kgf and the core was broken at 491.77(${\pm}55.62$)kgf. Those values of Zirkonzahn(ZR) were 431.03(${\pm}58.47$)kgf and 602.74(${\pm}48.44$)kgf, respectively. The break strength of the porcelain of PFM(PM) group was significantly higher than that of EV (p<0.05) group and there was no significant difference when comparing to that of ZR (p>0.05). ZR group showed higher break strength than that of EV group however there was no significant difference (p>0.05). The break strength of cores were in the increasing order of EV < ZR < PM (p<0.05). Conclusion: We could find that even though the PM group fractured at much higher value than all-ceramic cores, the breakage values of the porcelain of PM group with crack formation or delamination, which will be regarded as clinical failure, was significantly higher than that of EV group and not significantly higher than that of ZR group at p-values of 0.05. The break strength of ZR group was higher than that of EV group at an insignificant level(p>0.05).

• The Journal of the Korean dental association
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• v.23 no.7 s.194
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• pp.577-583
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• 1985

The purpose of this investigation was to evaluate scanning electron micrographs of repeatedly cast base metal alloy. For this study two Ni-Cr-Be alloys were used; Rexillium III and Verabond. They were repeatedly cast without addition o new alloy melting with an electric resistant furnace (Castron 8, Yoshida dental equipment Mfg.Co.). They were etched with 10% H₂SO₄ Sol. at 300mA/㎠ for 3 minutes with the use of metal etching unit Oxyetch (OXY dental product Inc.), and ultrasonic cleaning in 18% HC1 Sol. was done. Etched surfaces were examined under a SEM at x 200 and x 750. The surfaces are shown in legends.

• Restorative Dentistry and Endodontics
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• v.35 no.5
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• pp.368-373
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• 2010

Objectives: This study investigated the effect of infection control barrier thickness on power density, wavelength, and light diffusion of light curing units. Materials and Methods: Infection control barrier (Cleanwrap) in one-fold, two-fold, four-fold, and eightfold, and a halogen light curing unit (Optilux 360) and a light emitting diode (LED) light curing unit (Elipar FreeLight 2) were used in this study. Power density of light curing units with infection control barriers covering the fiberoptic bundle was measured with a hand held dental radiometer (Cure Rite). Wavelength of light curing units fixed on a custom made optical breadboard was measured with a portable spectroradiometer (CS-1000). Light diffusion of light curing units was photographed with DSLR (Nikon D70s) as above. Results: Power density decreased significantly as the layer thickness of the infection control barrier increased, except the one-fold and two-fold in halogen light curing unit. Especially, when the barrier was four-fold and more in the halogen light curing unit, the decrease of power density was more prominent. The wavelength of light curing units was not affected by the barriers and almost no change was detected in the peak wavelength. Light diffusion of LED light curing unit was not affected by barriers, however, halogen light curing unit showed decrease in light diffusion angle when the barrier was four-fold and statistically different decrease when the barrier was eight-fold (p < 0.05). Conclusions: It could be assumed that the infection control barriers should be used as two-fold rather than one-fold to prevent tearing of the barriers and subsequent cross contamination between the patients.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.28 no.1
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• pp.54-60
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• 2019

Objective: Dental fear is a feeling of anxiety and fear without intervention during a dental visit, mainly due to past negative dental treatment experiences, and in adults, despite the recognition of the need for dental treatment, it can lead to avoidance of dental treatment, which may cause deterioration of oral health. Therefore, this study was conducted to measure dental fear and anxiety level in some adults, and to identify related factors and their causes. Methods: This study used Kleinknecht's Dental Fear Survey scale and the SPSS 21 program (IBM SPSS Statistics 21) was used for analysis. Result: When the dental fear was the higher, the "access to the dental clinic" was found to be the highest, followed by "sitting in dental unit chair" and "smell of dental clinic" in that order. Conclusions: Dentists and dental hygienists should be able to understand the fear, anxiety, and concerns of the dentist office and to find various ways to provide systematic medical services.

• Journal of Korean society of Dental Hygiene
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• v.14 no.3
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• pp.327-332
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• 2014

Objectives : The purpose of the study is to investigate the self awareness of oral health, dental calculus and gingivitis according to smoking in soldiers. Methods : A self-reported questionnaire was filled out by 601 soldiers in Jeonnam military unit from April 7 to 23, 2013. The screening for oral examination was performed in the soldiers. The data were analyzed for frequency analysis and chi-square test by using SPSS 21.0 program. Results : The self awareness of smoking on oral health accounted for 27.0% in good status in nonsmokers, 23.5% of the past smokers answered good, and 16.5% of the smokers answered good. Approximately, 68.7% had dental calculus(p<0.05). The smokers tended to have more gingivitis than the nonsmokers and the past smokers(p<0.05). Conclusions : Smokers had low level of self awareness of oral health than the nonsmokers and the past smokers.

• Journal of Dental Anesthesia and Pain Medicine
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• v.19 no.4
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• pp.191-199
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• 2019

Background: Patients with special health care needs are more likely to develop health problems, including dental problems. Dental treatments require a good level of communication with the patient. Therefore, in these patients, sedation and general anesthesia are an extremely humanistic approach for comfortable and successful treatment. In patients with special needs, there is no standard anesthetic approach due to varying clinical conditions. The aim of this study was to provide literature content about the anesthetic approaches used by us in patients with special needs. Methods: The medical records of 710 patients with special health care needs treated under general anesthesia or sedation were reviewed retrospectively. Demographic data, the American Society of Anesthesiologists classification, Mallampati score, anesthesia duration, anesthesia type, anesthetic and analgesic agents used, dental treatment performed, secondary diseases, and complications in the perioperative period were recorded. Patients were evaluated under five groups: Down syndrome, other syndromes, psychiatric disorders, physical disabilities, and complicated medical story. Results: Among the patients evaluated, 47.5% were females and 52.5% were males (mean age $15.76{\pm}11.17$ years), and general anesthesia and sedation were administered in 72.9% and 22.1% patients, respectively. The mean duration of anesthesia was $43.20{\pm}35.85$ min. Simple dental treatments were performed in all groups, and the most common complications were observed in the other syndromes group. Conclusion: Complications can be reduced by utilizing the appropriate anesthetic approach and taking serious precautions in patients with special needs.

• The Journal of the Korean dental association
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• v.50 no.1
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• pp.13-21
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• 2012

In an edentulous situation, the dentist must make several determinations when constructing artificial teeth. These include vertical and horizontal relationships of mandible with respect to the maxilla, occlusal form and position, vertical dimension, occlusal relationships during both centric closure and eccentric excursive movements. Artificial teeth are attached to a movable base resting on movable and displaceable living tissue subject to damage. They act as a unit; therefore, they must be arranged to function as a unit. Bilateral balanced occlusion is that stability of the denture is attained when bilateral contacts ex ist throughout all dynamic and static states of the denture during function. Lateral excursion in a balanced scheme implies simultaneous working side and nonworking side contact, while occlusal contacts are maintained on both anterior and posterior teeth as the mandible moves anteriorly into protrusion.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.277-282
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• 2010

Imported vane type air motor and-piece is used widely in the domestic dental services. The imported hand-pieces are more than 90 percent in the domestic market. The air-motor unit of the hand-piece had not been developed inside of the country yet. Therefore it needs some research works. Purpose of this study is to design the air motor of the hand-piece for better performance. The geometry of the air-motor is based on product of NSK Company. The airflow of the air motor unit is simulated by Computational Fluid Dynamics. The performance analysis of the air motor units is investigated. ANSYS 12.0 CFX is used to analysis of the flowfield. Torque changes depends on spin calculated by the immersed solid method.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.49 no.4
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• pp.223-227
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• 2023

A midline or median cleft lip is rare, and a midline cleft associated with a unilateral cleft and a proboscis-like structure is rarer still. We present a case managed at our center in which a 5-year-old male had a median cleft of the upper lip with an associated 'proboscis' and a microform unilateral cleft lip.