• The Journal of Health Technology Assessment
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• v.6 no.2
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• pp.100-105
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• 2018

Objectives: The purpose of this research is to investigate regional variations of mastication difficulty rates in the elderly over 65 in 229 primary autonomous districts in Korea and explore relevant characteristics. For the research data, local community health survey conducted in 2015 and data from Ministry of the Interior and Safety, Ministry of Health & Welfare, National Health Insurance Service and Statistics Korea were used. Methods: Frequency analysis was conducted for general characteristics and mastication difficulty rates of each region, and distribution of mastication difficulty rates was displayed for each town, city and province by mapping them. Extremal quotient (EQ), coefficient of variation (CV) values were calculated for regional variations, and logistic regression analysis was performed to reveal the relationship between each independent variable and mastication difficulty rates. Results: The average of standardized mastication difficulty rate was 46.78%, and regional variations were significant with EQ 3.46, CV 0.18. Characteristic factors that have significant effects on mastication difficulty rate included sex ratio, elderly population and the number of dentists per 10000 people. Conclusion: As a result, there were variations among mastication difficulty rates in 229 primary local governments across the country, and the distribution of health care resources by the characteristics of the local environment by region affected mastication difficulty rates. Accordingly, it is required to provide political supports to overcome regional inequality of oral health levels and develop cooperative system between local governments and local dentists.

• Macromolecular Research
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• v.8 no.2
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• pp.73-79
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• 2000

The influence of mastication of natural rubber (NR) on properties of carbon black-filled NR compounds was studied. Variations of viscosities of the masticated NR and the carbon black-filled NR compound by heating were also investigated. The viscosities of the compounds decreased by increasing the mastication time of the raw rubber. The viscosities of the masticated NR and the compounds increased by increasing the heating time. This was explained by the combination reaction between functional groups in the rubber. The viscosity increment of the masticated rubber and the compounds by heating became larger with increased mastication time. Cure rate of the compound became faster by increasing the mastication time. Modulus of the vulcanizate made of the rubber masticated for a long time was higher than that of the vulcanizate made of the rubber masticated for a short time while elongation at break of the former was shorter than that of the latter. This was explained by the content of bound rubber and chain length of the rubber molecules.

• Journal of the Korean Chemical Society
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• v.17 no.4
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• pp.298-305
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• 1973

Following results were obtained for the mechanical degradation of polystyrene (for polystyrene itself and when blended with rubber) by roll mastication. 1) The rate of mechanical degradation for polystyrene itself can be represented by the second-order rate equation proposed by Goto. $-\frac{dP_t}{dt} = k_s(P_t-P_{\infty})^2$ Where Pt is the degree of polymerization of the degraded polymer at t minutes and $P{\infty}$ is the final degree of polymerization. 2) The mechanical degradation of polystyrene component in the polystyrene-rubber (SBR, BR) blend system occurred similarly as that of polystyrene itself. 3) Under the experimental conditions the mechanical degradation rate of the polystyrene component of the polystyrene-rubber, (SBR, BR) blend system followed approximately the same second-order equation as that for polystyrene itself.

• Korean Journal of Adult Nursing
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• v.24 no.2
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• pp.130-138
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• 2012

Purpose: The purpose of this study was to verify the effects of gum chewing temporalis muscle exercise on masticatory discomforts after craniotomy. Methods: Data collection was performed from July 10 to October 24, 2008. Forty participants who were treated with elective craniotomy were enrolled in this study. Twenty participants in the exercise group were given a gum chewing exercise protocol for five days and twenty participants in the control group received usual postoperative care only. All the participants were examined on the first, third and fifth postoperative day regarding the masticatory pain score, mouth opening range, and satisfaction with mastication. Collected data were analyzed using t-test, $x^2$-test and repeated measures ANOVA. Result: Masticatory pain of experimental group was significantly lower than the control group ($p$ <.001). Mouth opening range and satisfaction with mastication of experimental group were significantly improved in experimental group compared with the control group ($p$ <.001). Conclusion: The gum chewing temporalis muscle exercise after craniotomy is a useful intervention to reduce masticatory pain and to improve mouth opening range, recovery rate of mouth opening range and satisfaction with mastication.

• Korean journal of food and cookery science
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• v.33 no.2
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• pp.181-189
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• 2017

Purpose: This study was conducted to examine the effects of the starch concentration of filled hydrogel and the addition of ${\alpha}-amylase$ and simulated mastication processing in an oral phase on lipid digestion and ${\beta}-carotene$ bioaccessibility of filled hydrogels. Methods: Lipid digestion and ${\beta}-carotene$ bioaccessibility of the filled hydrogels were measured after the samples were passed through an in vitro gastrointestinal tract model consisting of oral, gastric, and small intestinal phases. Results: The initial rate and final extent of lipid digestion were higher in the filled hydrogels than in the emulsion when the filled hydrogels were treated in an oral phase without simulated mastication processing and addition of ${\alpha}-amylase$, regardless of starch concentration. However, when the filled hydrogels were minced using mortar and pestle for 2 min and were exposed to ${\alpha}-amylase$, the filled hydrogel fabricated with 5% starch showed the lowest lipid digestion rate and extent compared to the emulsion and other filled hydrogels. Bioaccessibility of ${\beta}-carotene$ was higher in the filled hydrogels than in the emulsion, regardless of the digestion method performed in an oral phase and starch concentration. However, there were appreciable differences in bioaccessibility of the filled hydrogels depending on whether or not simulated mastication and addition of ${\alpha}-amylase$ were employed. Conclusion: These results suggested that the rheological properties of initial filled hydrogels and simulated mastication processing in an oral phase plays an important role in determining the lipid digestion and ${\beta}-carotene$ bioacccessibility entrapped within filled hydrogels.

• Journal of the Korean Chemical Society
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• v.19 no.5
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• pp.386-393
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• 1975

Polystyrene and polystyrene blended with SBR were subjected to the mechanical degradation by roll mastication. The results obtained are as follows. 1. For the polystyrene which is blended with SBR, the overall shape of the molecular weight distribution curve moves from the higher molecular weight portion to the lower molecular weight portion, becomes narrower in breadth, and its peak becomes higher as the degradation proceeds. The final molecular weight distribution exhibits a relative uniformity. This is due to the fact that only the polymer molecules with the high molecular weight consisted in original polystyrene are degraded mechanically and produced the polymer molecules with the low molecular weight. 2. The scission number of polystyrene chains increases with mastication time, and the number of degraded polymer chains produced when the polymer is masticated for 100 minutes at 140, 150 and $160^{\circ}C$ are $2.36{\times}10^{20},\;1.76{\times}10^{20}\;and\;1.52{\times}10^{20}$, respectively. 3. The rate of the degradation of polystyrene decreases with the mastication temperature. The activation energy is found to have the negative value, -8.7 kcal/mole. Therefore it is indicated that the mechanical degradation is a chemical process of which the activation energy is supplied mechanically.

• Journal of Korean society of Dental Hygiene
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• v.16 no.3
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• pp.463-469
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• 2016

Objectives: The purpose of the study is to investigate the effect of chewing gum containing Prunus mume extract(PME) on the change of saliva ingredients. On the basis of the biological background of molecules and diagnostic indices in the use of saliva, the mastication effect of chewing gum containing PME was demonstrated in terms of secretory IgA concentration and total protein concentration in stimulated saliva. Methods: This study is an experimental research on the use of a research design before and after applying a randomized control group. Participants were distributed randomly to the experimental group and the control group, respectively. The experiment group was instructed to masticate the chewing gum containing PME for 10 minutes for one month after each meal within 30 minutes. Salivary secretion was collected by the participants between 8 and 10 a.m in the morning in the research office. For the measurement of secretory IgA and total protein concentrations in the saliva, indirect enzyme-linked immunosorbent assay(ELISA) was used. Results: The salivation stimulation rate was significantly increased after four weeks of masticating chewing gum containing PME after each meal(p<0.001). Mastication of chewing gum containing PME for four weeks decreased the concentration of secretory IgA much more significantly than that after mastication for one week(p=0.003). The concentration of total protein in the saliva was decreased after four weeks in the experimental and control groups. Conclusions: Mastication of chewing gum containing PME stimulated salivary secretion and led to oral disease prevention in patients with xerostomia. Furthermore, it seems to be urgent to seek measures that can be utilized in intervention for patients with xerostomia.

• Journal of Korean society of Dental Hygiene
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• v.19 no.6
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• pp.941-950
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• 2019

Objectives: The aim of this study was to evaluate the relationship between depressive symptoms and oral health status in Korean middle-aged women. Methods: We analyzed data from the sixth Korea National Health and Nutrition Examination Survey (KNHANES VI). The final sample consisted of 2,691 adults aged 40-64 years. The Chi-squared test was used to assess the rate of depressive symptoms, oral health status, and relationship between oral health status and depressive symptoms. Moreover, logistic regression analysis was used to examine the association between depressive symptoms and oral health status. Data were analyzed using SPSS 20.0 program. Results: Overall, 15.1% of subjects experienced depressive symptoms. The rate of depressive symptoms in self-aware oral health, toothache, and mastication problem groups were 19.6%, 19.9%, and 25.3%, respectively. Compared to other groups, the likelihood (odds ratio) of having depressive symptoms was 1.47 (95% confidence interval [CI] : 1.16-1.88), 1.58 (95% CI: 1.22-2.04), and 1.73 (95% CI: 1.32-2.28) higher in self-aware bad oral health, toothache, and mastication problem groups, respectively. Conclusions: We found an association between depressive symptoms and oral health status. Thus, oral health status should be evaluated as a potential risk factor for depressive symptoms.

• Journal of The Korean Society of Integrative Medicine
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• v.10 no.4
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• pp.35-47
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• 2022

Purpose : As the number of patients with systemic diseases is increasing in the old, the relevance of oral health is gaining particular research interest. To provide fundamental resources for dental services, this study examined the relationship between doctors' diagnoses of circulatory diseases and patients' awareness of oral health and oral care behaviors. Methods : SPSS 26.0 was used to assess various variables, including doctor's diagnosis of circulatory diseases, gender, age, household income quintile, participation in economic activity, marital status, subjective level of oral health awareness, mastication discomfort, speaking and chewing discomfort, dental inspection, use of oral care goods, teeth brushing during the previous day, and untreated oral conditions. Results : The circulatory diseases suffered by the subjects were as follows: 56 % high blood pressure, 36 % dyslipidemia, 6 % stroke, and 8 % myocardial infarction or angina. A higher age meant a higher diagnosis rate of high blood pressure (p<.001) and stroke (p<.001). Those with dyslipidemia showed a higher rate of receiving oral inspection (p=.040), and an untreated oral condition was more frequently observed among those not diagnosed with the disease (p=.035). The subjects who were not diagnosed with stroke showed a higher rate of oral inspection (p<.001), while those who had a prior experience of stroke suffered a higher rate of mastication discomfort (p=.020). People who had high blood pressure showed a lower rate of using oral care goods (p<.001), and those diagnosed with stroke showed a lower rate of brushing teeth the previous day. Conclusion : This study found a correlation between the diagnosis of circulatory diseases and the awareness of oral health and oral care behavior. Consequently, oral health education should be included in mental health-related education, and customized training to teach teeth brushing and the use of oral care goods should be provided to patients with circulatory diseases during dentist visits.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.2
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• pp.69-77
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• 2001

'Chalok 1/Cooktail 51' corns, supersweet corn gene controlled by either brittle-l (bt l) or shrunken-2(sh2) gene introduced into waxy corn, showed agronomic characteristics between supersweet corn and waxy corn. The ears were harvested at different development stages from 15 to 35 days after silking (DAS). Ear diameter of Cocktail 51 and 'Cocktail 51'/Chalok 1 increased from 15 DAS to 30 DAS and little increased thereafter, but that of Chalok 1/Cocktail 51 and 'Chalok l' increased until 35 DAS. Diameter of ear extension increased more in Cocktail 51 and Chalok 1/Cocktail 51 corn than Chalok 1. Ear fresh weight of Cocktail 51 decreased later 30 DAS but those of the other hybrids were vice versa. Rate of super-sweet kernels per ear of Chalok 1/Cocktail 51 corns was about 38 %. Development, and elongation of kernel were much more prominent in supersweet kernel than in waxy kernel, but fresh weight increased higher in waxy kernel than supersweet kernel. Moisture content in kernel decreased from 15 DAS to 35 DAS. Total sugar content of the kernel increased until 25 DAS, and that of Cocktail 51 kernel showed the highest among of them. After cooked by steam, flavor and mastication feeling rate cooked by steam of Cocktail 51 and Chalok 1/Cocktail 51 were increased from 15 DAS to 25 DAS and markedly decreased thereafter. But those of Chalok l/Cocktail 51 and, Chalok 1 were decreased after 30 DAS. These results suggested that the optimum harvest date for fresh supersweet corn (Cocktail 51), Cocktail 51/Chalok 1 seems to be about 20 DAS and Chalok 1/Cocktail 51 and waxy com (Chalok 1) was about 25 DAS.