• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.20 no.4
• /
• pp.279-283
• /
• 1998

The osteoporosis is a disease that represents a reduction in the volume of bony tissue relative to whole bone volume. And mandible also may be affected. Such porotic mandible may influence the result of the surgery like dental implant surgery relating mandible. So, the author examed the panoramic view of 89 persons for finding the possibility of useful diagnostic parameters of osteoporosis. To know the correlationship between the condition of vertebra and mandible, bone marrow density of lumbar spine from 2nd to 4th, and the number of residual tooth, panoramic mandibular index (PMI), angular cortical bone thickness (ACT) and ramus cortical bone thickness (RCT) were compared. The result is that PMI and ACT have similar relative weak linear correlationship, RCT have very weak linear correlationship, the number of residual tooth have not linear correlationship.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.9
• /
• pp.48-53
• /
• 1999

In this paper, a practical method for design and machining of cycloid gear was investigated. Based on the proposed method, a systematic program was developed for automatically designing the tooth profiles of epicycloid and hypocycloid gears for the case fo one difference between the number of teeth of cycloid gear and the number coordinates of tooth profiles and pressure angles. The error analysis between cycloid curve and Biarc curve was performed to show the effective method of equidistant partitioning of cycloid curve so that efficient method of Biarc curve fitting was also proposed for the partitioned curve.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.36 no.1
• /
• pp.38-45
• /
• 2009

The aim of this study was to examine efficacy of the commercially available 10% CPP-ACP cream (Tooth mousse, GC Co., Japan) and/or 0.05% NaF solution on the remineralization of artifical caries-like lesion in the bovine teeth enamel. Sixty bovine teeth were embedded in orthodontic resin and flattened. The enamel surface in 3 mm diameter was exposed with nail varnish. Specimens were stored in demineralizing solution and divided 5 groups; Group 1 (No treatment), 2 (0.05% NaF solution 1 min), 3 (Tooth mousse 3 min), 4 (After 0.05% NaF solution, Tooth mousse treatment), and 5 (After Tooth mousse treatment, soaking in 0.05% NaF solution during 1 min). After treatment by groups, all specimens was stored in artificial saliva for 30 min. After the process described as above was performed during 10 days without pH cycling, surface hardness (Vickers Hardness Number, VHN) was tested and analyzed by paired t-test and one-way ANOVA test with SPSS 14.0. In intragroup comparison between surface hardness of pre and post-treatment, group 3, 4, 5 showed statistically significant increase (P < 0.05). In intergroup comparison among surface hardness increase of all groups, difference of group 5 between pre and post-treatment ($15.80{\pm}12.21$) was the highest, and followed by group 4 ($14.27{\pm}11.73$), 3 ($4.05{\pm}5.18$), 2 ($1.15{\pm}6.83$), 1 ($0.78{\pm}6.21$). Tooth mousse can be a good alternative agent for the fluoride, and the combination use with fluoride might have the additional anticariogenic effect.

• Journal of dental hygiene science
• /
• v.17 no.5
• /
• pp.423-432
• /
• 2017

This study aimed to investigate the effect of repeated oral health education on the oral health of preschool children. This study classified the control group of children of 5~6 years of age where the oral health education was conducted one time, and the experiment group where the oral health education was conducted 4 times. The oral health conditions of each group and their risk of developing dental caries were also assessed. No significant difference was observed in the participants in terms of general characteristics, oral health conditions, risk of developing dental caries, and oral health behavior after oral health education. The two groups did not show a significant difference (p<0.001) in dental plaque index before and after oral health education, and showed a significant difference (p<0.001) according to the number of education sessions. Before oral health education, the participants in both groups were brushing their teeth incorrectly. However, after the third session, 56.7% of the participants in the experimental group and 9.4% in the control group used the correct method of tooth brushing. A significant difference was observed between the two groups (p<0.05). In addition, when the tooth-brushing time was compared, the two groups showed a significant difference (p<0.001), and a significant difference was observed in terms of the number of education sessions (p<0.05). In summary, repeated oral health education had significant influences on the dental plaque index, tooth-brushing method, brushing occlusal surfaces, and tooth-brushing time. Therefore, when oral health education is carried out, repeated oral health education in children is more effective than one-time oral health education as reflected in the changes in dental plaque index and oral health behavior. Moreover, oral health education is considered effective in changing the oral health behavior of children when conducted at least 3 times.

• Korean Journal of Health Education and Promotion
• /
• v.16 no.2
• /
• pp.93-104
• /
• 1999

For studying on the actual condition of the oral health control of the old there were invastigations on the Questions with the college of the old in Chonbuk as the central figure from June 1 to June 30, 1998 and the analyses about the frequency and the mutual relation through χ²-test. The results are as follow: 1. According to the result of the investigation into the actual condition about the oral health of the old, two times a day in the frequency of tooth brush per day was the highest at the rate of 50.35％, the use of dentifrice was 45.4％, and the exchanging time of tooth-brush after six months was the highest at the rate of 19.7％. And 96.1％ didn't use dental floss and 73.6％ didn't do scaling. It is thought that since 50％ used tooth sticks and match sticks we have to inform the old of the necessity of dental plague and period oral examination. 2. In oral health situation, it showed that the number of people who were very week was the highest at the rate of 37％ and there was the mutual relation between the use of tooth sticks and match sticks and present situation of oral health. And 54.93％ visited the dental clinic wethin a year, and 22.3％ among them made full denture. There was the mutual relation between the visit of dental clinic within a year and the consultation content and the number of people who teld that the consultation expense was very expensive was the higest at the rate of 27.8％ and 87％ didn't experience the oral education. So it is thought that we have to make an systematic education about the oral to the old and inform them of the necessity of oral health control. 3. We think it needs the establishment and plane of the systematic basis material and the oral education which is necessary in oral public industry for the dental preventive suitable to the characteristic of the old.

• Journal of Preventive Medicine and Public Health
• /
• v.52 no.5
• /
• pp.333-343
• /
• 2019

Objectives: This study aimed to evaluate the association between dental implants and cognitive function in community-dwelling older adults. Methods: Data were collected from the baseline survey (2016-2017) of the Korean Frailty and Aging Cohort Study. The study sample comprised 1115 community-dwelling people aged 70 years to 84 years who had 0-19 natural teeth. Dental implants and natural teeth were identified by panoramic radiography, while the cognitive function was assessed by the Korean version of the Mini-Mental State Examination (MMSE-KC). The association between dental implants and cognitive function was analyzed by multiple linear regression. Sensitivity analysis was performed to test for potential bias. Results: The mean number of natural teeth in the study population was 9.50 (standard deviation [SD], 6.42), and the mean MMSE-KC score was 24.93 (SD, 3.55). In the simple univariate analysis, tooth replacement, age, sex, smoking status, alcohol consumption, body mass index, osteoporosis, number of natural teeth, periodontitis, chewing discomfort, tooth-brushing frequency, education level, monthly household income, participation in economic activity, living alone, and marital status had a significant impact on the association. After adjusting for confounders, the association between dental implants and cognitive function remained significant (B, 0.85; standard error, 0.40; p<0.05). Age, body mass index, periodontitis, tooth-brushing frequency, and education level were also significantly associated with cognitive function. The results of the sensitivity analyses were consistent with those of the primary analysis. Conclusions: Dental implants were associated with cognitive function in older adults living in the community. Dental implants as tooth replacements may play a role in preserving cognitive function.

• Smart Structures and Systems
• /
• v.23 no.1
• /
• pp.81-90
• /
• 2019

The shear behavior of soil-concrete interface is mainly affected by the surface roughness of the two contact surfaces. The present research emphasizes on investigating the effect of roughness of soil-concrete interface on the interface shear behavior in two-layered laboratory testing samples. In these specially prepared samples, clay silt layer with density of $2027kg/m^3$ was selected to be in contact a concrete layer for simplifying the laboratory testing. The particle size testing and direct shear tests are performed to determine the appropriate particles sizes and their shear strength properties such as cohesion and friction angle. Then, the surface undulations in form of teeth are provided on the surfaces of both concrete and soil layers in different testing carried out on these mixed specimens. The soil-concrete samples are prepared in form of cubes of 10*10*30 cm. in dimension. The undulations (inter-surface roughness) are provided in form of one tooth or two teeth having angles $15^{\circ}$ and $30^{\circ}$, respectively. Several direct shear tests were carried out under four different normal loads of 80, 150, 300 and 500 KPa with a constant displacement rate of 0.02 mm/min. These testing results show that the shear failure mechanism is affected by the tooth number, the roughness angle and the applied normal stress on the sample. The teeth are sheared from the base under low normal load while the oblique cracks may lead to a failure under a higher normal load. As the number of teeth increase the shear strength of the sample also increases. When the tooth roughness angle increases a wider portion of the tooth base will be failed which means the shear strength of the sample is increased.

• Korean Journal of Cleft Lip And Palate
• /
• v.10 no.2
• /
• pp.81-88
• /
• 2007

Cleft lip and palate (CLP) is one of the most prevalent congenital craniofacial anomalies. It has a significantly greater incidence of dental abnormalities in number, size, shape, and eruption of the teeth. Knout-out mouse model can identify several genes which play an important role in tooth agenesis. Since disruption of these genes has been confirmed to result in tooth agenesis in humans, CLP associated with hypodontia may be the best models for isolated tooth agenesis. According to the studies of dental abnormalities in CLP, the severity of dental defect is known to be influenced by the CLP phenotype. The cumulative data obtained from mouse and human genetic studies indicated that MSX1, PAX9 and AXIN2 are considered as candidate genes in non-syndromic hypodontia, while Shh, Pitx2, Irf6, p63 and EDA pathway genes are involved in syndromic one. We expect that genetic approach of CLP can offer the basis for tooth regeneration and be a new target in hypodontia therapy.

• Korean Journal of Computational Design and Engineering
• /
• v.7 no.1
• /
• pp.27-33
• /
• 2002

MDO(Multidisciplinary Design Optimization) methodology is a new technology to solve a complicate design problem with a large number of design variables and constraints. The design of a dental implant system is a typical complicate problem, and so it requires the MDO methodology. Actually, several analyses such as rigid body dynamic analysis and structural stress analysis etc. should be carried out in the MDO methodology application to the design of a dental implant system. In this paper, as a first step of MDO methodology application to the design of a dental implant system, the impact force which is applied on the tooth in masticating is calculated through the rigid body dynamic analysis of upper and lower jaw-bones. This analysis is done using ADAMS. The impact force calculated through the rigid body dynamic analysis can be used for the structural stress analysis of a dental implant system which is needed for the design of a dental implant system. In addition, the rigid body dynamic analysis results also show that the impact time decreases as the impact force increases, the largest impact force occurs on the front tooth, and the impact force is almost normal to the tooth surface with a slight tangential force.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.11 no.2
• /
• pp.296-303
• /
• 1987

The composite gear which is composed of involute curve and circular arc has been studied. In the vicinity of pitch point, its profile is an involute curve, and in the dedenum, a circular arc. The curve in the dedendum is generated by the circular arc of the mating gear. Though the available range between minimum and maximum radius of circular arc can be given by existing tooth profile equation, there was no formulation which relates design parameters to the desired radius. It is attempted to get the formula for the radius of circular arc as a function of design parameters, such as unwounded angle, number of teeth, module, and pressure angle. The radius of circular arc, the chordal tooth thickness at working root circle, nominal bending stress, Hertz stress and contact ratio obtained from derived formula are compared with those of the existing design criteria. And these are compared with those of involute gear.