• The Journal of Advanced Prosthodontics
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• 제12권1호
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• pp.1-8
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• 2020

PURPOSE. To investigate the influence of crown material (lithium-disilicate, 3Y-TZP zirconia) and abutment type (rigid implant, resin tooth with artificial periodontium) on wear performance of their antagonist teeth and adjacent teeth. MATERIALS AND METHODS. A mandibular left first molar (#36) with adjacent human teeth (mandibular left second premolar: #35, mandibular left second molar: #37) and antagonistic human teeth (maxillary left second premolar: #25, maxillary left first molar: #26, maxillary left second molar: #27) was prepared simulating a section of the jaw. Samples were made with extracted human molars (Reference), crowned implants (Implant), or crowned resin tooth analogues (Tooth). Crowns (tooth #36; n = 16/material) were milled from lithium-disilicate (Li, IPS e.max CAD) or 3Y-TZP zirconia (Zr, IPS e.max ZirCAD, both Ivoclar Vivadent). Thermal cycling and mechanical loading (TCML) in the chewing simulator were applied simulating 15 years of clinical service. Wear traces were analyzed (frequency [n], depth [㎛]) and evaluated using scanning electron pictures. Wear results were compared by one-way-ANOVA and post-hoc-Bonferroni (α = 0.05). RESULTS. After TCML, no visible wear traces were found on Zr. Li showed more wear traces (n = 30-31) than the reference (n = 21). Antagonistic teeth #26 showed more wear traces in contact to both ceramics (n = 27-29) than to the reference (n = 21). Strong wear traces (> 350 ㎛) on antagonists and their adjacent teeth were found only in crowned groups. Abutment type influenced number and depth of wear facets on the antagonistic and adjacent teeth. CONCLUSION. The clinically relevant model with human antagonistic and adjacent teeth allowed for a limited comparison of the wear situation. The total number of wear traces and strong wear on crowns, antagonistic and adjacent teeth were influenced by crown material.

• 보건교육건강증진학회지
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• 제25권4호
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• pp.55-65
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• 2008

Objective: This study aims to investigate the relationship between dental status and oral function by analyzing those in some long-term care elderly patients. Methods: It performed oral examination and 4 oromotor function examinations such as repeated swallowing function, correct pronunciation function, saliva secretion rate and maximum mouth opening to 91 elderly patents aged 65 and older in the municipal geriatric hospital located in Cheonan. Results: Dental status of patients such as the number of dental caries, treated teeth, retained teeth and function teeth were better in mobile elderly patients than in immobile elderly patients. Attachment rate of dental plaque and the number of teeth being extracted were more in mobile patients than in immobile patients. More retained teeth, the number of function teeth and dental caries and the score in pronunciation status test were significantly higher. With more function teeth, the score in pronunciation status test was significantly higher. As saliva secretion rate is higher, repeated swallowing function was significantly better. repeated swallowing function rate is higher pronunciation status was significantly better. Conclusions: With the results of this study, it was found that among long-term care elderly patients, oral function was worse in immobile patients than in mobile patients. Therefore, it may be necessary to plan and perform an oral function improvement program preferentially for elderly patients requiring long-term care.

• Journal of Oral Medicine and Pain
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• 제46권4호
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• pp.131-135
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• 2021

Purpose: Depression is a condition that weakens psychosocial functioning and reduces quality of life. In Korea, the prevalence of depression among the elderly is 29.2% and depression is a considerable public health concern for the elderly. Depression has a statistically significant relationship with oral conditions such as number of teeth and salivary flow rate. Oral health-related quality of life (OHRQoL) is the concept including subjective evaluations of psychological, physical and social aspects of oral health. Tooth loss and hyposalivation can affect mental health and quality of life. Our study was designed to identify the relationship among the number of teeth, salivation, OHRQoL, and depressive symptoms in the elderly in Korea. Methods: We recruited 100 participants, aged over 65 years, and assessed their number of teeth, unstimulated salivary flow rate. All participants filled out oral health impact profile 14 (OHIP-14) and Zung self-rating depression score (SDS) for checking OHRQoL and depressive symptoms. Statistical analysis was done by R program. Results: We found that the positive relationship between OHIP-14 and SDS after Mann-Whitney test (p=0.03). The lower SDS group had an OHIP-14 median score of 4. On the other hand, the higher SDS group had a median value of 7.5. The other factors (number of teeth and salivary flow rate) did not show correlations with OHIP-14 or SDS. Conclusions: OHRQoL and depressive symptoms have significant correlation.

• Journal of Yeungnam Medical Science
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• 제21권1호
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• pp.51-59
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• 2004

Background: The objective of this study is to evaluate the relationship between chewing ability and health status in order to provide basic information for the development of program which may lead to an improvement of a the elderly health status in urban areas. Materials and methods: The subjects of this study were 128 elderly urban female over the age of 65 who reside at house. The data were collected from May 21 to August 20, 2001, through questionnaires about nutrient intake status, direct measurement of anthropometrics, and oral examinations. Results: In terms of remaining teeth, there was significant negative relationship between age and number of remained teeth. The average number of remained teeth our subjects was $13.1{\pm}10.6$. About sixty five percent of the subjects were denture users (partial or full dentures) and there was positive relationship between age and the percentage of denture user. There was a significant negative correlation between age and chewing ability. The group that was able to chew had more remained teeth than the other group. Conclusion: This study suggests that there is strong positive relationship between chewing ability (remaining teeth) and elderly health status in urban areas, and the importance of preserving original teeth to improve the elderly health status in the public health program.

• 치위생과학회지
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• 제12권4호
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• pp.329-334
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• 2012

이 연구는 경상북도 지역의 제조업 근로자를 대상으로 상실치아실태와 관련요인을 분석하고자 실시하였다. 1. 일반적 특성에 따른 상실치아 개수와의 관련성 분석에서는 연령, 교육수준, 월평균소득, 근무분야가 유의한 관련성이 있는 것으로 나타났다(p<.01). 2. 구강건강상태와 상실치아 개수와의 관련성 분석에서는 점심식사 후 잇솔질 여부(p<.05), 구강검진경험(p<.01)이 유의한 관련성이 있었다. 3. 상실치아개수를 종속변수로 한 다중회귀분석에서는 연령, 교육수준, 결혼여부와 주관적 구강건강수준이 유의한 변수였다(p<.01). 이 결과로 볼 때, 나이가 많고 교육수준이 낮은 생산직 근로자들을 대상으로 잇솔질에 대한 교육을 실시하고, 정기적인 스케일링을 권장하며, 구강검진과 스케일링을 할 수 있는 여건조성을 위한 정책을 만들어 구강건강을 유지할 수 있도록 할 필요가 있다.

• 한국수산과학회지
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• 제22권4호
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• pp.214-218
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• 1989

SEM observation revealed that the gastric mill of Nyctiphanes australis consists of paired cluster spines and paired lateral teeth, while the filter-press is absent. The morphology of the gastric mill was extremely constant; the numbers of both setiform processes of cluster spines and serrated spines of lateral teeth increased with increasing body length. The cluster spines of N. australis consisted of a single row of stout setiform processes but the lateral teeth comprised a large projection with small serrated spines. The cluster spines are symmetrical in setiform process distribution, however, the lateral teeth are asymmetrical in number of serrated spines.

• 치과방사선
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• 제15권1호
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• pp.41-49
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• 1985

The purpose of this study was to evaluate the initial and postoperative radiographic features of the endodontic treated teeth. The author examined the radiographs which comprise 114 teeth with 155 canals of 64 persons. The following factors were considered; Age, sex, tooth location, number of root canals, postoperative periods, initial diagnosis, and radiographic findings, postoperative radiographic findings. The apical levels of the root fillings were 76.8% to apex, 19.0% underfilling, 3.9% overfilling. The following results were obtained. 1. Of the 93 teeth which revealed initial periapical rarefaction, 66 teeth (71.0%) had showed complete bone healing, 19 teeth (20.4%) decreased rarefaction, 6 teeth (6.5%) no change, 2 teeth (2.2%) increased rarefaction after 20.0 months mean healing time. 2. 21 teeth which had no initial periapical rarefaction showed no occurrence of new periapical rarefaction. 3. Of the 66 teeth completely healed, 53 teeth (80.3%) had showed reappearance of lamina dura, 64 teeth (97.0%) reappearance of periodontal ligament space after 23.4 months mean healing time.

• 한국정밀공학회지
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• 제11권4호
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• pp.26-37
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• 1994

A kinematically admissible velocity field for the numerical analysis of closed-die forging process of spur gear is proposed. The velocity field is divided into three regions of deformation. In the analysis, the involute curve is approximated to be straight line and the upper-bound method is used to calculate energy dissipation rate. A constant frictional frictional factor has been assumed on the contacting surfaces. The effects of root diameter, number of teeth, and friction factor are determined on the relative forging pressure. The frictionless relative pressure is independent of root diameter for the same number of teeth, but increases with the number of teeth on a given root diameter. In the presence of friction, the relative forging presure increasing root diameter at the start of forging, but decreases with increasing root diameter in the processing of forging.

• Journal of Biosystems Engineering
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• 제12권3호
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• pp.42-49
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• 1987

The threshing action of the head-fed type threshing unit occurs mainly by the impact between threshing tooth and grains. It may be therefore the most fundamental step to calculate the time and order of the occurrance of impact by the tooth for predicting the performance of threshing unit. The threshing teeth arrangement was defined by length and diameter of threshing dram, number of spiral arrays, number of threshing teeth by kind per one spiral array, number of windings of spiral array around the threshing drum, delay angle of impact line. The linear equations for locus of left and right margin of paddy bundle, spiral array, impact line on the development figure of the threshing drum were expressed by fastors of the threshing teeth arrangement. In the computer program, the teeth which inflict impact were searched successively along the impact line. Searching range and impact condition were defined by the relation between four linear equations. If the impacting tooth was found, time and the kind of threshing tooth was derived from the coordinate of the threshing tooth. At this time the unit torque curve was accumulated on the array of computer memory. At last the completed torque curve of threshing drum shaft was described on the computer screen. Remarkably the peack valae and fluctuation of torque curve was decreased by adopting the delay angle of impact line.

• Restorative Dentistry and Endodontics
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• 제7권1호
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• pp.117-124
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• 1981

In order to observe the frequency of visits and the distribution of endodontically treated patients according to age, sex, diagnosis, type of teeth, the author had surveyed the 17,250 outpatients of the Infirmary of the College Dentistry, Yonsei University from January 1976 to December 1978. 773 cases, 660 patients among 728 endodontically treated patients were studied. The obtained results were as follow; 1. The average frequency of visits were 5.95 in uppers and 5.88 in lowers. 2. The average frequency of visits were 5.79 in males and 6.02 in females. 3. At the age of under 14, the average frequency of visits were 7.42 in uppers and 6.76 in lowers. 4. According to diagnoses, the average frequency of visits in periapical granuloma or cyst were 2.80 in uppers and 3.16 in lowers. 5. The number of endodontically treated teeth had revealed as follow; upper incisors 27.94%, lower molars 25.87%, and upper molars 15.13% 6. The number of endodontically treated teeth by diagnoses were as follow; periapical abscess 45.27%, pulpit is 37.51%, tooth fracture 8.40%. 7. The number of endodontically treated teeth were 51.99% in the age of from 20 to 34.