• Restorative Dentistry and Endodontics
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• v.37 no.3
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• pp.155-159
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• 2012

Objectives: To investigate the effect of dentin moisture degree and air-drying time on dentin-bond strength of two different one-step self-etching adhesive systems. Materials and Methods: Twenty-four human third molars were used for microtensile bond strength testing of G-Bond and Clearfil $S^3$ Bond. The dentin surface was either blot-dried or air-dried before applying these adhesive agents. After application of the adhesive agent, three different air drying times were evaluated: 1, 5, and 10 sec. Composite resin was build up to 4 mm thickness and light cured for 40 sec with 2 separate layers. Then the tooth was sectioned and trimmed to measure the microtensile bond strength using a universal testing machine. The measured bond strengths were analyzed with three-way ANOVA and regression analysis was done (p = 0.05). Results: All three factors, materials, dentin wetness and air drying time, showed significant effect on the microtensile bond strength. Clearfil $S^3$ Bond, dry dentin surface and 10 sec air drying time showed higher bond strength. Conclusions: Within the limitation of this experiment, air drying time after the application of the one-step self-etching adhesive agent was the most significant factor affecting the bond strength, followed by the material difference and dentin moisture before applying the adhesive agent.

• Journal of Physiology & Pathology in Korean Medicine
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• v.20 no.2
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• pp.320-327
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• 2006

This study was written in order to help understanding of listening diagnosis to vocal sound and speech. The purpose of listening diagnosis is that we know states of essence(精), Qi(氣) and spirit(神). Vocal sound and speech are made by Qi and spirit. Vocal sound originates from the center of the abdominal region(丹田) and comes out through vocal organs, for example lung, larynx, nose, tongue, tooth, lip and so on. Speech is expressed by vocal sound and spirit. They are controled by the Five Vital organs(五臟). Various changes of vocal sound and speech observe the rules of yinyang. For example, if we consider patient likes to say or not, we can diagnose heat and coldness of illness. If we consider he speaks loudly or quietly, we can diagnose weak and severe of illness. If we consider he speaks clearly or thick, we can diagnose inside and outside of illness. If we consider he speaks damp or dry, we can diagnose yin and yang of illness. If we consider change of voice, we can diagnose new and old illness. Symptoms of changes of five voices, five sounds, dumbness and huskiness are due to abnormal vocal sound, and symptoms of changes of mad talk, mumble, sleep talking and so on are due to abnormal speech.

• The korean journal of orthodontics
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• v.21 no.3
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• pp.543-560
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• 1991

Practitioners are aware of the presence of friction between bracket system and archwire during sliding movement of teeth. Clinically a mesiodistally applied force must exceed the frictional force to produce a tooth movement. The objective of this study were to determine, on a dry condition, changes in magnitude of friction with respect to load, 3rd order inclination (Torque), archwire materials and ligature type. Three wire alloys (Stainless Steel, TMA, NiTi) in two wire sizes (.016, .016x, .022 inch) were examined respect to two bracket system (Straight, Standard), and two ligature type (Metal, Plastic ligature) at three levels of load (100g, 150g, 200g). The results were as follows; 1. Frictional resistance was found to increase with increasing load for S.S., TMA, NiTi. 2. The straight bracket system was exhibited more frictional force than standard bracket system for .016x, .022 S.S. tightly ligated metal ligature. But, torque difference did not increase friction for loose metal ligature & plastic ligature. 3. Regardless of the ligature type, torque and load, stainless steel wire sliding against stainless steel exhibited the lowest friction, and TMA sliding against stainless steel exhibited the highest friction. 4. The loose stainless steel ligature generated lower frictional resistance than plastic ligature in all experimental groups. 5. The following factors affected friction in decreasing order; wire material ligature type, and load.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.271.1-271.1
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• 2013

Titania is usually used in sun-screens, tooth paste, and other daily used objects as a pigment. However, scientists have focused on titania as photocatalyst due to its excellent activities. By fabricating vanadium doped TiO2 and CuOx co-catalyzed TiO2 nano-size filter, the degradation level of the volatile organic compound (VOC) concentration was tested using 365nm UV LED as light source in a closed chamber. Main purpose for this test is to evaluate the activities of various catalysts for degrading the VOCs which are detrimental to human body and toluene and p-xylene were chosen in the VOC removal test. Target gas materials were injected into the test chamber with dry air as carrier gas which was flowed into the gas washer bottle filled with liquid form of VOC substance. When the VOC gas flows into the chamber, it is circulated by 200 mm fan in order to contact with the set-up filter on the aluminum holder. Target gas concentration in the chamber was monitored using VOC detector (miniRae3000, Raesystems) which was also placed inside the chamber. With the measured concentration, the VOC degradation efficiency and the degradation rate were evaluated and used to compare the catalytic activities.

• Journal of The Korean Society of Grassland and Forage Science
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• v.6 no.2
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• pp.119-123
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• 1986

In order to find out the effect of sowing time on establishment, survival and yield of pasture species when hoof and tooth cultivation was applied, this experiment was conducted from 1982 to 1984 at the comfound of Alpine Experiment Station. The results obtained are as follows: 1. Grasses establishment of 15 April, 15 May, 1 August and 30 August plots was 11.1%, 9.8%, 12.4% and 3.1%, resulting in 10% establishment in all plots except 30 August. The establishment of legumes in spring sowing was about 30%, showing significant difference (P < 0.05) than that of autumn sowing. 2. Botanical composition of sown pasture in all plots 2 years after sowing ranged from 66% to 80%. There was no significant difference between treatment in terms of DM Production 3 years after sowing although there was the difference in establishment and survival of sown pasture at the beginning of grassland establishment. It indicates that appropriate fertilization and grazing management after sowing play an important role in grassland improvement when hoof and tooth cultivation is applied. 3. The utilization of forages in plot 2 years after seeding was from 45 to 53%.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.2
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• pp.192-203
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• 2007

This study histologically assessed the effect of topical alendronate application on periodontal healing in replanted teeth in fifty four SD Rats. Upper first molars in rat were extracted and replanted after dried during 15 minutes or 60 minutes in the air. In Group I, all teeth were replanted after 15 minutes of dry storage without any other treatment. In Group II and III, the pulps were removed and all teeth were replanted after soaking 10 min in Hank's balanced salt solution with/without alendronate, followed by 60 minutes of dry storage. the rats were sacrificed after 7, 15 and 30 days. The histological parameters studied were healed PDL, surface inflammatory and replacement resorption, and inflammatory severity. The following conclusions could be drawn from the present investigation. 1. Group I showed lower inflammatory root resorption and inflammation severity rate, compared to Group II and Group III. In Group I there showed effective for reattachment and regeneration of PDL. 2. In Group II, inflammatory root resorption were more severe and faster than other groups. There were extensive root resorption in the rats sacrificed after 30 days. 3 In Group III, there were localized inflammatory resorption in several areas, but extensive resorption did not occur Group III showed increase in root resorption rate, compared to Group I. However this difference was not statistically significant. 4. There were no difference between sacrificed days in replacement root resorption in all groups.

• Restorative Dentistry and Endodontics
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• v.34 no.6
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• pp.467-476
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• 2009

The aim of this study was to measure the dentinal tubular fluid flow (DFF) during and after amalgam and composite restorations. A newly designed fluid flow measurement instrument was made. A third molar cut at 3 mm apical from the CEJ was connected to the flow measuring device under a hydrostatic pressure of 15 $cmH_2O$. Class I cavity was prepared and restored with either amalgam (Copalite varnish and Bestaloy) or composite (Z-250 with ScotchBond MultiPurpose: MP, Single Bond 2: SB, Clearfil SE Bond: CE and Easy Bond: EB as bonding systems). The DFF was measured from the intact tooth state through restoration procedures to 30 minutes after restoration, and re-measured at 3 and 7days after restoration. Inward fluid flow (IF) during cavity preparation was followed by outward flow (OF) after preparation, In amalgam restoration, the OF changed to IF during amalgam filling and slight OF followed after finishing. In composite restoration, application CE and EB showed a continuous OF and air-dry increased rapidly the OF until light-curing, whereas in MP and SB, rinse and dry caused IF and OF, respectively. Application of hydrophobic bonding resin in MP and CE caused a decrease in flow rate or even slight IF. Light-curing of adhesive and composite showed an abrupt IF. There was no statistically significant difference in the reduction of DFF among the materials at 30 min. 3 and 7 days after restoration (p > 0.05).

• Journal of Korean society of Dental Hygiene
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• v.19 no.1
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• pp.55-64
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• 2019

Objectives: The purpose of this study was to compare the differences in oral health-related quality of life among elderly people aged over 65 years, in terms of physical, mental and oral health status and to analyze factors affecting their oral health-related quality of life. Methods: From May 9 to June 23, 2017, we randomly visited aged-care community centers in the metropolitan area, and recruited 222 elderly, aged 65 or older. First, each participant completed a questionnaire consisting of 4 general items: 1 systematic disease, and 3 subjective oral conditions. Afterwards, the researchers interviewed the participants to assess their mental status, using MMSE-DS and recorded the responses. Finally, an oral examination was performed to determine the number of remaining teeth. The average oral health-related quality of life according to each characteristic was analyzed by t-test and ANOVA. Hierarchical multiple regression analysis and Pearson's correlation coefficient analysis were used to analyze the correlations between factors and the factors affecting oral health-related quality of life. Results: The mean oral health-related quality of life was 4.15. Participants with 20 or more remaining teeth demonstrated better oral health-related quality of life than those with 19 or less teeth. Higher oral health-related quality of life was also found among elderly without gingival bleeding, self-reported halitosis and dry mouth. In addition, positive correlation with the number of remaining teeth and negative correlation with gingival bleeding, self-reported halitosis and dry mouth, were noted. Finally, the results of the hierarchical multiple regression analysis indicated that remaining teeth, gingival bleeding, self-reported halitosis and education were influential factors in determining the oral health-related quality of life among the elderly. Conclusions: The results of this study confirmed the necessity of better policy support, and the importance of implementing delivered, elderly-centered oral health education program by professionals to prevent tooth loss and manage periodontal diseases.

• Journal of dental hygiene science
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• v.19 no.4
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• pp.279-287
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• 2019

Background: Increasing age and loss of teeth weaken oral muscle strength. This study aimed to investigate the positive effects of orofacial myofunctional training on elderly people. Methods: Thirty six elderly individuals in a welfare center and a senior citizen center were included in this study. A survey regarding lip and tongue strength suvsequent to orofacial myofunctional training and oral health-related quality of life was conducted from April to June, 2019. Data were analyzed using PASW statistics ver. 18.0. Results: The experimental group, showed an increase in lip strength (from 9.79 to 10.31) and tongue strength (from 41.26 to 43.97) after orofacial myofunctional training. The perception of oral health-relatedquality of life was enhanced (from 2.26 to 2.07). In particular, the frequency of dry cough for food removal while swallowing decresed due to an incresed in the secretion of saliva (p<0.05). Correlation analysis showed that the number of functional teeth was positively related to oral health-related quality of life. Conclusion: Orofacial myofunctional training for improving lip and tongue strength is effective in the elderly. In older societies, oral strength should be maintained to improve oral health-related quality of life. It also suggests the interest of oral health workers and applying orofacial myofunctional training programs.

• The korean journal of orthodontics
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• v.48 no.2
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• pp.81-89
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• 2018

Objective: The aim of this study was to evaluate the stress distribution and displacement of various craniofacial structures after nonsurgical rapid palatal expansion (RPE) with conventional (C-RPE), bone-borne (B-RPE), and miniscrew-assisted (MARPE) expanders for young adults using three-dimensional finite element analysis (3D FEA). Methods: Conventional, bone-borne, and miniscrew-assisted palatal expanders were designed to simulate expansion in a 3D FE model created from a 20-year-old human dry skull. Stress distribution and the displacement pattern for each circumaxillary suture and anchor tooth were calculated. Results: The results showed that C-RPE induced the greatest stress along the frontal process of the maxilla and around the anchor teeth, followed by the suture area, whereas B-RPE generated the greatest stress around the miniscrew, although the area was limited within the suture. Compared with the other appliances, MARPE caused relatively even stress distribution, decreased the stress on the buccal plate of the anchor teeth, and reduced tipping of the anchor teeth. Conclusions: The findings of this study suggest that the incorporation of miniscrews in RPE devices may contribute to force delivery to the sutures and a decrease in excessive stress on the buccal plate. Thus, MARPE may serve as an effective modality for the nonsurgical treatment of transverse maxillary deficiency in young adults.