• The Journal of Korean Academy of Prosthodontics
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• v.40 no.6
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• pp.577-589
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• 2002

There are several variations in normal mastication. In them, unilateral mastication is chewing, predominantly on a preferred side of the dentition and hardly on e non-preferred side. Continual unilateral mastication may alter the coordination of masticatory muscles. Although they studied about these EMG of masticatory muscles, there were no information about characteristics of masticatory muscle activity in unilateral mastication. Therefore, In this study, we investigated the activity of the masseter and anterior temporal muscles during rest, clenching in maximum intercuspation and gum chewing in habitually unilateral mastication group compared with normal group and tried to know effects of continual unilateral mastication on activity of masticatory muscles. The results of this study were as follows 1. In electromyographic activity during rest, in bilateral mastication group pattern of muscle activity of right and left side was symmetrical. But, in unilateral mastication group, records of anterior part of temporal muscle was higher than that of bilateral mastication group (p<.01) and patterns of muscle activity of right and left side in both muscle were asymmetrical.(p<.05) 2. In electromyographic activity during clenching in maximum intercuspation, records of superficial part of masseter muscle were higher than anterior part of temporal muscle in both group. Muscle activity of temporal muscle in unilateral mastication group was a little higher han bilateral mastication group and asymmetry of activity pattern in temporal and masseter muscle was shown but these differences were not statistically significant. (p<.05) 3. In electromyographic activity during gum chewing, temporal muscle was activated earlier than masseter muscle and maximum bite force is derived from masseter muscle in both group. In unilateral mastication group, electromyographic activity of masseter and temporal muscle of preferred chewing side, regardless of right or left side chewing, was higher than that of bilateral mastication group and especially, difference in masseter muscle was statistically significant. (p<.01) Based on the above results, our study suggested that recording of masticatory muscle activity will be helpful in the effective diagnosis and treatment of some types of the parafunctional habits.

• Journal of Korean society of Dental Hygiene
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• v.14 no.3
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• pp.293-302
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• 2014

Objectives : The objective of this study was to investigate the relationship between the status and necessity of dental prosthesis and mastication function in the Korean elderly. Methods : This study investigated 4,557 elderly people aged over 65 in the 5th Korea National Health and Nutrition Examination Survey(2010-2012). Frequency analysis, ${\chi}^2$ test, and logistic regression analysis were used. Results : Those aged over 75 complained of greater discomfort in mastication function than those from 65 to 74, and it was statistically significant(p<0.001). Mastication discomfort was not so significant in those with higher education and higher income(p<0.001). Those who did not use prosthesis tended to have better mastication function(p<0.001). Denture users complained of mastication discomfort when they used it(p<0.001). Conclusions : This study verified the relationship between the discomfort in mastication and related factors, and will provide the basic data for the access to dental clinic services.

• 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.

• 대한약리학회:학술대회논문집
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• 2006.10a
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• pp.122.1-122.1
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• 2006

• Journal of Convergence for Information Technology
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• v.10 no.7
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• pp.215-222
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• 2020

The purpose of this study was to investigate the relationship between mastication problems and quality of life among middle-aged Koreans. The study used data from the 6^th Korea National Health and Nutrition Examination Survey(KNHANES VI). Data on 7,125 respondents aged 40 to 64 were analyzed to evaluate quality of life as measured by the Euro Quality of Life-5D(EQ-5D) index and mastication problems. Quality of life was classified as either low or high based on 0.96. The data were analyzed using SPSS 20.0. The prevalence of low quality of life was significantly higher in the group with mastication problems, at 41.9%, than in the group with no mastication problems(24.4%). After adjusting the general characteristics and oral health status, the odds of a lower quality of life were higher in the those with mastication problems, at 1.77 (95% CI: 1.53-2.06), than in those with no mastication problems. Mastication problem was significantly related to the quality of life. The studies are needed to reflect the oral factors in diverse age groups.

• 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.

• Elastomers and Composites
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• v.27 no.4
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• pp.262-266
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• 1992

A number of tin-containing elastomers are produced commercially by Korea Kumho Petrochemical Co., Ltd. (KKPC) under the Kosyn Sol tradename. The effect of mastication of commercial and laboratory polymerized S-SBR has, been investigated using chemical mixer(ML-500), NMR, GPC and Mooney viscometer. Mastication of polymers containings coupling bonds is affected by the amount of stearic acid, the temperature of mixing and the time length of mixing.

• The Journal of Korean Academy of Prosthodontics
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• v.33 no.3
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• pp.440-452
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• 1995

A success of complete denture prosthesis can be determined by the satisfaction degree of the dentist and the patient. There are many factors influencing on the satisfaction of the complete denture patients. The purpose of this study is to analyze the correlation between the masticatory satisfaction and clinical evaluation, and the speech satisfaction and clinical evaluation in complete denture patients. 79 patients(total 119 complete dentures) were examined in this study who were treated in Seoul National University Dental Hospital. Through clinical evaluation, 2 examiners evaluated sex, age, edentulous period, the years of having used present complete denture, the number of the previous dentures, the state of the opposite arch, retention, stability, support, occlusion, vertical dimension of the complete denture and the condition of the residual alveolar ridge. Through questionnaires concerned with mastication and speech, examiners evaluate the satisfaction degree of the patients. This study led to the conclusion that : 1. The satisfaction degree of the mastication was lower in older patients(p<0.001) and in patients whose present complete denture period was shorter(p<0.05). The satisfaction degree of the mastication in male was higher than in female patients(p<0.01). 2. The satisfaction degree of the mastication was high when the retention of the complete denture was good(p<0.05), and when the condition of the residual alveolar ridge was good(p<0.05). 3. The satisfacion degree of the speech was high when the retention of the complete denture was good(p<0.01). 4. The satisfaction degree of the mastication was higher in patients with upper and lower complete denture than in patients with single complete denture whose oppsite arch was unilateral partial denture(p<0.05).

• 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.