• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.4
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• pp.426-435
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• 2018

The aim of this study was to evaluate the proximal caries detecting ability and identify the optimal cut-off values of two types of laser fluorescence (LF) devices; classic type (DD) and pen type (DDpen). The number of proximal surfaces participated in this study were 164 surfaces in primary dentition and 438 surfaces in permanent dentition. Each tooth surface was sequentially assessed by two types of LF devices, and bitewing radiograph. The radiographs were classified into 3 groups in primary dentition ($pR_0$, $pR_1$, $pR_2$), and 4 groups in permanent dentition ($PR_0$, $PR_1$, $PR_2$, $PR_3$) according to the depth of caries, and used as gold standard. In primary dentition, the area under the curve (AUC) values of DD were 0.851 and 0.890, and those of DDpen were 0.883 and 0.917, respectively in enamel caries and dentin caries. In permanent dentition, the AUC values of DD were 0.762 and 0.886, and those of DDpen were 0.828 and 0.958, respectively in enamel caries and dentin caries. When detecting proximal caries in posterior teeth with LF devices, DDpen is more useful than DD in both primary and permanent dentition. However, in primary dentition, DD can also be useful to detect proximal caries.

• Journal of Korean society of Dental Hygiene
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• v.6 no.4
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• pp.283-294
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• 2006

The purpose of this study was to examine the state of smoking among some college students, the smoking motivation of smoker students, what made them quit smoking and how they got ready for giving up smoking, as smoking had a huge impact on national health and there was a desperate necessity for preventive antismoking education programs to let students keep away from smoking. After a survey was conducted with self-administered questionnaires from October 1 through November 1, 2006, the responses from 400 students were gathered, and 384 answer sheets were analyzed except 16 incomplete ones. The findings of the study were as follows: 1. By gender, 62.4% of the male students and 28.6% of the female students were smokers, and the state of smoking was statistically significantly different according to their gender(p<0.05). 2. The largest number of the male students, which accounted 44.1%, started smoking in their high school days, and 39.5% of the females did that in middle school. As for a daily mean amount of smoking, 41.8% of the male students, the greatest percentage, smoked 10 to 19 cigarettes a day, and one to nine cigarettes were most common among the females, which represented 57.9 %. But the gap between the two was insignificant(p>0.05). As many as 83.6% of the males and 86.8% of the females had ever attempted to quit it. 3. Concerning awareness of antismoking policies, they felt that a raise in cigarette price would lead to less smoking, and that antismoking advertisement or posters through television or newspaper would deliver the same results as well. There was a statistically significant difference among their awareness(p<0.05). 4. Regarding preparation stage for quitting smoking, 31.3% of the male smokers had no intention to give it up, and 23.2% considered it. 36.7%, the largest percentage, got ready to refrain from it. Among the female smokers, 34.2% had no plans to abstain from smoking, and 36.8% took it into consideration. 23.7% got ready to do that. The females who got ready for that were outnumbered the males who did. 5. As to connections between the state of smoking and relevant knowledge, the students didn't have a good knowledge on that, and a statistically significant difference existed between the smokers and nonsmokers in smoking knowledge. 6. As for knowledge about oral diseases, they were highly cognizant of the relationship of smoking to tooth discoloration, nicotine stomatitis and bad breath, but they didn't know well about its relationship to delayed recovery from dental treatment, implant failure and ozena. Their smoking condition made a statistically significant difference to their knowledge(p<0.05). In the future, sustained research efforts should be channeled into determining how much smoking affects health and concerns oral diseases, and antismoking counseling programs should be prepared to bolster people's awareness of oral health.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.4
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• pp.515-522
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• 2021

Successful cases of the implant-assisted removable partial denture and implant overdentures are reported in which a few implants are additionally placed to secure the maintenance, support, and stability of the denture when there are a few residual teeth. When the lateral force applied to the tooth abutment and implant surveyed crown is minimized, the horizontal and rotational movement of the denture is significantly reduced which is an effective method that can improve the address in patients who complain of reduced retention and stability of their dentures. In this case, a small number of implants were placed to fabricate an implant-assisted removable partial denture with implant surveyed crown in the maxilla and implant overdenture with Locator^® attachment in the mandible to improve the retention, stability, and support of the dentures. The patient was satisfied with both functional and aesthetic aspects after the final dentures were delivered.

• Journal of the Korean Institute of Gas
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• v.26 no.3
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• pp.54-59
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• 2022

This paper is a purpose to study and analyze the failure examples for timing belt, camshaft position sensor and ignition coil of LPG automotive engine. The first example, whe the service man install the front case bracket of engine, he excessively tightened up a 12mm bolt for being fixed of brackct. As a results, the bolt was separated from joint part so that it was put in between the crankshaft sprocket. Therefore the belt was broken off because of interference between timing belt and sprocket tooth. The second example, it verified the disharmony phenenomen of engine that the gap of the camshaft position sensor and camshaft senseing point assembled on cylinder head part was small more than iregular value so that the it was generated senseing damage phenomenon by pulse signal misconduct. The third example, it was found the engine disharmony phenomenon that the fire in the ignition coil was leaked by inner damage of Number 2 ignition coil.Therefore, the the manager of a car throughtly have to inspect not in order to arise the failure symptoms.

• Journal of Korean society of Dental Hygiene
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• v.22 no.6
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• pp.485-494
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• 2022

Objectives: The COVID-19 outbreak has resulted in changes in the instructional methods used in kindergartens and daycare centers to prevent viral infections. This study aimed to investigate the changes in oral health care for children before and during COVID-19 and the perceptions of kindergarten and daycare center teachers about oral health care. Methods: The study subjects were 189 teachers of kindergartens and daycare centers in charge of children aged 3 to 5. The data for the analysis were collected through an online survey. Frequency analysis and the chi-squared test were used for statistical analysis. Results: Compared to before COVID-19, the frequency of tooth brushing after lunch, the number of oral health education and regular oral examinations, and the rate of childcare teachers' experiences with oral health education had decreased during COVID-19. In addition, educators in kindergarten and daycare centers responded that an oral health officer at a public health center was the most desirable oral health educator. Conclusions: During the COVID-19 pandemic, the oral health care of children in kindergartens and daycare centers has declined. Efforts are needed to restore it by educating people about oral hygiene care and oral health education, both at home and in kindergartens and daycare centers.

• The korean journal of orthodontics
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• v.29 no.6 s.77
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• pp.673-688
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• 1999

This study was conducted in order to analyze the mechanical characteristics of multiloop edgewise archwire (MEAW). The purposes were 1) to compare load deflection rate (LDR) of MEAW with that of various other arch wires in the individual interbracket span, 2) to compare the wire stiffness in the interbracket span with that in the multi-L-loop region (the span from distal border of the bracket of the lateral incisor to the mesial border of the buccal tube of the second molar), and 3) to verify the experimental results with theoretically derived formula. The single L-loops of five different horizontal lengths and multi-L-loops for the upper and lower arches were made out of .$016\times.022$ permachrome stainless steel wire. Straight segment of plain stainless steel, TMA and NiTi wire of the same dimension were prepared. The LDR was measured using Instron model 4466 with the load cell of 50N capacity at cross head speed of 1.0mm/min, and maximum deflection of 1.0mm. Five specimens were tested under each experimental condition. The wire stiffness number for each interbracket region and multi-L-loop region was calculated from the LDR and the interbracket spans. By dividing the theoretical model of multi-L-loop into 35 linear segments, the energy stored in each segment was obtained. Then the LDR and wire stiffness of single L-loop and multi-L-loop were calculated and compared. The findings were as follows : 1) The average LDR of MEAW in the individual interbracket region was 1/1.53 of that of the NiTi,1/2.47 of TMA and 1/5.16 of the plain stainless steel wire. 2) The wire stiffness of MEAW in the multi-L-loop region was 1.53 times larger than that in the interbracket region, and the LDR was almost twice as large as that of NiTi in that region. 3) According to the theoretically derived equation, the wire stiffness of the single L-loop was lower than that of multi-L-loop. The results of this study suggest that MEAW has the unique mechanical Property which could allow individual tooth movement and transmit elastic force effectively through the entire arch wire.

• Korean Journal of Weed Science
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• v.8 no.3
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• pp.273-282
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• 1988

The seventeen barnyardgrass [Echinochloa crus-galli (L.) Beauv.] accessions, which were collected national-widely in 1986 and selected two times through 1987, were experimented at 1988. To study the degree of ecological variations of the collected accessions of native barngardgrass species as a weed, the experiment was conducted with Wagner pots in size of 1/5000a and under P.E. film house. Among 57 characters, 100 grains weight, rate of tiller increase from transplanting to 30 days, the number of the maximum tillers and rate of dry weight increase from 15 DAS to 22 DAS were become intra-specific variarions as higher coefficient of varation than 30%, the size of the first leaf, fresh weight and dry 22 seedlings, rate of productive tiller, panicle number and tillering divergence made intra-specific variations as more and less C. V. than 25%, while the required days upto heading since seeding at June 6. rate of fresh/dry weight and plant height of 22 days old seedling made intra-specific variations as the coefficient of variation of about 50%. Among the attributes the color in leaf, leaf sheath, mid-ribs, node, spike, grain, and plant type, length of leaf marginal tooth, grain shape, purple bend on leaf were seemed useful to indentify the accessible specific.

• Journal of dental hygiene science
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• v.16 no.1
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• pp.53-61
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• 2016

Eating supports to gain energy and nutrition and improves quality of life. Ageing affects the food intake ability due to loss of natural teeth and the progressive muscle degeneration. Our objective was to investigate how the food intake ability (FIA) and the remaining teeth could influence on oral health related quality of life in the elderly. This study was performed with 503 elderly subjects living in Daejeon, Korea. The questionnaire with the FIA with 30 Korean food and Oral Health Impact Profile 14 (OHIP-14) and oral examination were surveyed. The five groups according to cluster analysis of FIA had the different numbers of remaining teeth and functional posterior teeth with opposing teeth or prosthesis significantly: group 1, $21.78{\pm}8.27$ and $2.80{\pm}2.63$; group 2, $16.75{\pm}7.87$ and $2.16{\pm}2.44$; group 3, $14.68{\pm}9.77$ and $1.73{\pm}2.30$; group 4, $9.93{\pm}8.13$ and $0.78{\pm}1.68$; group 5, $10.18{\pm}8.37$ and $0.51{\pm}1.22$. The more foods the subjects could masticate, the better oral health related quality of life they had. The medium FIA, soft FIA and the number of remaining teeth could explain 46% of OHIP-14, but hard FIA could not in the multiple regression model. We suggested to develop the oral health program for the elderly to be able to eat the food with medium physical property at least be helpful to improve oral health related quality of life.

• Journal of Periodontal and Implant Science
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• v.33 no.3
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• pp.485-497
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• 2003

Grapefruit seed extract has been reported to have antimicrobial effect. The purpose of this study was to evaluate the antimicrobial and anti-gingivitis effect of chewing gum containing grapefruit seed extract and xylitol. 40 healthy subjects with gingivitis or early periodontitis were divided into two groups. Subjects in the experimental group chewed gum containing grapefruit seed extract and xylitol while subjects in the control group chewed gum containing only xylitol. All subjects received scaling and tooth brushing instruction. 1 week after scaling was set as baseline. Gingival index and plaque index were scored at baseline, 1 week, 2 week, 3 week and 4 week. Bleeding index, probing pocket depth and clinical attachment level were scored at baseline, 2 week and 4 week. The number of total bacteria and Streptococcus mutans in unstimulated saliva of experimental group were counted at 1 week, 2 week, 3 week and 4 week. Gingival indices of experimental group and control group at baseline, 1 week, 2 week, 3 week and 4 week were 0.850${\pm}$0.298, 0.575${\pm}$0.345, 0.533${\pm}$0.332, 0.459${\pm}$0.311, 0.408${\pm}$0.224 and 0.758${\pm}$0.379, 0.592${\pm}$0.276, 0.563${\pm}$0.281, 0.454${\pm}$0.194, 0.413${\pm}$0.199 (mean${\pm}$SD), respectively. Plaque indices of experimental group and control group at baseline, 1 week. 2 week, 3 week and 4 week were 0.497${\pm}$0.500, 0.375${\pm}$0.484, 0.332${\pm}$0.471, 0,286${\pm}$0.452, 0.210${\pm}$0.407 and 0.411${\pm}$0.492, 0.375${\pm}$0.484, 0.354${\pm}$0.479, 0.313${\pm}$0.463, 0.193${\pm}$0.395, respectively. Bleeding indices of experimental group and control group at baseline, 2 week and 4 week were 0.377${\pm}$0.177, 0.298${\pm}$0.152, 0.192${\pm}$0.108 and 0.383${\pm}$0.124, 0.318${\pm}$0.153, 0.225${\pm}$0.126, respectively. Probing pocket depth of experimental group and control group at baseline, 2 week and 4 week were 2.56${\pm}$1.00, 2.40${\pm}$0.65, 2.23${\pm}$0.64 and 2.45${\pm}$0.682.37${\pm}$0.57, 2.19${\pm}$0.57, respectively. Clinical attachment level of experimental group and control group at baseline, 2 week and 4 week were 2.58${\pm}$1.01, 2.43${\pm}$0.67, 2.26${\pm}$0.65 and 2.49${\pm}$0.70, 2.40${\pm}$0.59, 2.22${\pm}$0.62, respectively. The % of reduction of total bacteria in saliva of experimental group at 2 week, 3 week and 4 week were 46 ${\pm}$ 53%, 53 ${\pm}$ 5% and 69 ${\pm}$ 33%. The % of reduction of Streptococcus mutans count in saliva of experimental group at 2 week, 3 week and 4 week were 52${\pm}$69%, 88${\pm}$30% and 89${\pm}$17%. From these findings, it can be concluded that regular use of grapefruit seed extract /xylitol chewing gum may be effective to control and prevent gingivitis and may have caries-preventive effect.

• The korean journal of orthodontics
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• v.31 no.5 s.88
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• pp.517-523
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• 2001

Titanium miniscrews we being used increasingly as an anchorage for tooth movement, because they ate easy to place and to remove, increase the number of sites available, give minimum strain to patients regarding surgical procedures, and offer uneventful healing alter removal. The use of titanium miniscrews as an orthodontic anchorage has been reported in clinical case reports, but clinicians have experienced screw loosening when using such screws.' To our knowledge, there are no published reports evaluating the stability of miniscrews. Information about the length of miniscrews used in relation to the location is of some importance, as stability will vary depending on bone duality The purpose of this study was to evaluate a variety of Lengths of miniscrews (dimeter: 2mm) which were inserted in maxilla or mandible and to demonstrate in a dog model which miniscrew provides fundamental stability in the jaws. 10 mm long miniscrews in the maxilla and 8mm long: miniscrews in the mandible showed no clinical mobility and retained their position throughout an 8 weeks force (200g) application. The mucosal condition around the screws was healthy in cases in which miniserews were inserted in the alveolar bone between the roots and the head of the screws emerged into the attached gingiva. When the force application was terminated, radiographic analysis revealed neither rent resorption not periodontal pathology around the miniscrews that remained stable during the entire treatment period. This study suggests that if titanium miniscrews with adequate length are properly used depending on the location, they provide sufficient stability for orthodontic anchorage.