• The Journal of Advanced Prosthodontics
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• v.12 no.1
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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.

• Nutrition Research and Practice
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• v.18 no.3
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• pp.387-399
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• 2024

BACKGROUND/OBJECTIVES: Poor oral health has been predicted the development of frailty and sarcopenia as well as the subsequent need for long-term care. This cross-sectional study examined the relationships among tooth loss, prefrailty, and dietary patterns in community-dwelling older Japanese females. SUBJECTS/METHODS: Information on the number of teeth, food consumption, and lifestyle factors was collected from 271 participants aged ≥ 65 yrs using a questionnaire. The number of teeth was self-reported and classified into 2 groups: natural teeth ≥ 20 and natural teeth < 20. Prefrailty was assessed using the Japanese version of the Cardiovascular Health Study. Three dietary patterns ("vegetables and dairy products" [VD], "rice and fish and shellfish" [RF], and "bread and beverages") were adopted from a cluster analysis of the intakes of 20 foods evaluated using the Food Frequency Questionnaire. The odds ratios (ORs) for prefrailty and dietary patterns were calculated using a binary logistic regression analysis. RESULTS: A total of 267 participants were analyzed, excluding those with frailty (n = 4). The rates of natural teeth < 20 and prefrailty were 57.3 and 37.4%, respectively. Natural teeth < 20 was positively correlated with prefrailty (OR, 4.66; 95% confidence interval [CI], 2.54-8.52) and inversely correlated with VD pattern (OR, 0.43; 95% CI, 0.27-0.69). Furthermore, both VD (OR, 0.38; 95% CI, 0.16-0.91) and RF (OR, 0.26; 95% CI, 0.11-0.62) patterns were inversely correlated with prefrailty. CONCLUSIONS: Maintaining the number of natural teeth ≥ 20 into old age plays an important role in preventing a prefrailty. The promotion of VD and RF dietary patterns has potential as an effective nutritional strategy for preventing tooth loss and prefrailty.

• Korean Journal of Health Education and Promotion
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• v.25 no.4
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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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• v.46 no.4
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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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• v.21 no.1
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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.

• Journal of dental hygiene science
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• v.12 no.4
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• pp.329-334
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• 2012

This study was conducted to investigate the health behavior and the oral health status of workers engaged in a manufacturing business, and to analyze the related factors that affect their number if teeth loss. References for the study involved the materials of 526 individuals whose occupational categories are of a manufacturing business, amongst the survey participants in seven city or gun (county) area including Gyeongsan-si, Gyeongju-si, Mungyeong-si, Chilgok-gun, Yecheon-gun and Sangju-gun for the Community Health Survey (CHS) conducted in 2008. The CHS 2008 was conducted for three months from September to November 2008, and the survey details utilized in the study included the number of loss of teeth and teeth-brushing frequency, which was a part of CHS questionnaires and also additionally included for the study. The analysis with respect to the number of teeth loss on sociodemographic factors, was found to be significantly related to the age, educational status, average monthly income and occupation (p<.01). In the $x^2$-test in terms of the oral health status and the number of teeth loss, it was found that the teeth-brushing after lunch (p<.05) and an experience in an oral examination were statistically significant factors (p<.01). According to the multiple-regression analysis with the number of teeth loss being a dependent variable, the age, educational status, marital status and subjective oral health status were the statistically significant (p<.01). In conclusion, it is important to provide education on the teeth-brushing subjected to workers engaged in a manufacturing business with many dental caries and low educational status, and to recommend a regular scaling as well as to establish policy for creating conditions upon an oral health check-up and a tooth scaling and thus allow the maintenance of an oral health.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.4
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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.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.15 no.1
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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.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.4
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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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• v.12 no.3
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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.