Preparation of Non-Isocyanate Polyurethanes from Mixed Cyclic-Carbonated Compounds: Soybean Oil and CO2-Based Poly(ether carbonate).

This study presents the synthesis and characterization of non-isocyanate polyurethanes (NIPU) derived from the copolymerization of cyclic-carbonated soybean oil (CSBO) and cyclic carbonate (CC)-terminated poly(ether carbonate) (RCC). Using a double-metal cyanide catalyst, poly(ether carbonate) polyol was first synthesized through the copolymerization of carbon dioxide and propylene oxide. The terminal hydroxyl group was then subjected to a substitution reaction with a five-membered CC group using glycerol-1,2-carbonate and oxalyl chloride, yielding RCC. Attempts to prepare NIPU solely using RCC and diamine were unsuccessful, possibly due to the low CC functionality and the aminolysis of RCC's linear carbonate repeating units. However, when combined with CSBO, solid NIPUs were successfully obtained, exhibiting good thermal stability along with enhanced mechanical properties compared to conventional CSBO-based NIPU formulations. Overall, this study underscores the potential of leveraging renewable resources and carbon capture technologies to develop sustainable NIPUs with tailored properties, thereby expanding their range of applications.

Association between diet quality and untreated dental caries: results from the Korea National Health and Nutrition Examination Survey.

BACKGROUND/OBJECTIVES: Few studies have provided evidence of the association between diet quality and dental caries. This study aimed to examine the association between diet quality and untreated dental caries in a Korean representative population. SUBJECTS/METHODS: The study population included a sample of 13,815 participants, aged ≥ 19 from the Korea National Health and Nutrition Examination Survey during 2013-2015. The explanatory variable was diet quality and the outcome variable was untreated dental caries. Untreated dental caries were defined by the number of decayed teeth recorded according to the criteria established by the World Health Organization. Diet quality was defined by using the Korean Healthy Eating Index (KHEI) through the 24-h recall methods. We assessed the association between diet quality and untreated dental caries while adjusting for age, sex, education, income, smoking status, dental visits, toothbrushing frequencies, obesity, and diabetes mellitus. RESULTS: The mean overall KHEI scores in the untreated dental caries group were significantly lower than those in the group without untreated dental caries. Significant differences were observed in the untreated dental caries group based on the KHEI quartiles (P < 0.001). After adjusting for potential confounders, the quartiles of KHEI scores showed an association with untreated dental caries, demonstrating a dose-effect trend (odds ratio [OR], 1.57; 95% confidence interval [CI], 1.35-1.84 for 1st quartile; OR, 1.38; 95% CI, 1.19-1.59 for 2nd quartile; OR, 1.32; 95% CI, 1.14-1.53 for 3rd quartile; reference quartile highest]). CONCLUSIONS: The findings indicated an inverse association between diet quality and untreated dental caries in Korean adults. Healthcare providers should take into account the significant role of diet quality in preventing and managing oral health.

The co-occurrence of the two main oral diseases: periodontitis and dental caries.

OBJECTIVES: Limited studies are available testing through multiple regression models the association between the two main oral diseases: dental caries and periodontitis. The aim of this cross-sectional population-based study was to verify whether dental caries and periodontitis co-occur in a representative sample of the South Korea population. MATERIALS AND METHODS: A total of 23,405 subjects representative of 36.2 million of adults (KNHANES) were examined. Univariate and multiple regression analyses using 7 different models were applied, controlling for age, gender, smoking status, frequency of toothbrushing, use of interproximal toothbrushes and flossing, educational level, income, gum diseases treatment and tooth filling in the previous year, BMI, Vitamin D serum levels, alcoholism, diabetes status, stress and carbohydrates dietary intake. RESULTS: In the fully adjusted model, participants with periodontitis had, respectively, a mean of 0.82 (95% CI: 0.41-1.23) and of 0.36 (95% CI: 0.22-0.50) more untreated decayed surfaces and teeth than participants without periodontitis, with an OR to have at least one untreated decayed surface of 1.96 (95% CI: 1.66-2.32). However, cumulative caries experience (DF scores) and periodontitis were not associated. CONCLUSIONS: In this large nationally representative population, periodontitis and untreated dental caries co-occur. However, when considering cumulative caries experience (DF scores), the two diseases do not appear related. CLINICAL RELEVANCE: In light of their possible co-occurrence, clinicians should implement integrative diagnostic, preventive and treatment strategies for both diseases.

Dual role of enhancer of zeste homolog 2 in the regulation of ultraviolet radiation-induced matrix metalloproteinase-1 and type I procollagen expression in human dermal fibroblasts.

Abnormalities in the extracellular matrix (ECM) caused by ultraviolet (UV) radiation are mediated by epigenetic mechanisms. Enhancer of zeste homolog 2 (EZH2) is a histone methyltransferase that is implicated in inflammation, immune regulation, and senescence. However, its role in controlling UV-induced ECM alterations in the skin remains elusive. Here, we investigated the role of EZH2 in UV-induced expression of matrix metalloproteinase (MMP)-1 and type I procollagen. We found that UV induced EZH2 expression in human skin in vivo and in human dermal fibroblasts (HDFs). EZH2 knockdown reduced the expression and promoter activity of MMP-1 and increased those of type I procollagen, whereas EZH2 overexpression had the opposite effects. Mechanistically, EZH2 increased NF-κB activity, and p65 and p50 expression and promoter activity. Intriguingly, chromatin immunoprecipitation assays revealed that the EZH2/p65/p50 complex was recruited and bound to the MMP-1 promoter after UV irradiation, independent of its histone methyltransferase activity. In contrast, EZH2-induced DNA methyltransferase 1 (DNMT1) formed a complex with EZH2 and enhanced the enrichment of H3K27me3 on the COL1A2 promoter following UV irradiation. These findings indicate that EZH2 plays a dual role in regulating MMP-1 and type I procollagen expression and improve our understanding of how this epigenetic mechanism contributes to UV-induced skin responses and photoaging. This study shows that inhibiting EZH2 is a potential anti-aging strategy for preventing UV-induced skin aging by reducing MMP-1 expression and inducing type I procollagen expression.

Air Pollution as a Risk Indicator for Periodontitis.

BACKGROUND: Air pollutants can influence local and systemic inflammation, oxidative stress and microbiome composition. Therefore, air pollution may potentially represent an unexplored modifiable risk indicator for periodontitis. The aim of the current cross-sectional study was to investigate the epidemiological association between outdoor air pollution and periodontitis in a representative sample of the South Korean population. METHODS: A total of 42,020 individuals, which were representative of 35.2 million South Koreans, were examined. The mean annual levels of particulate matter of 10 µm (PM10), ozone, sulfur dioxide (SO2), nitrogen dioxide (NO2) and humidity, were studied. Periodontitis was defined according to the Community Periodontal Index (CPI ≥ 3). Simple and multiple regression analyses using four different models were applied. RESULTS: Every 5-µg/m3 increase in PM10 (OR = 1.17; 95% confidence interval-CI: 1.11-1.24) and of 0.005 ppm in ozone levels (OR = 1.4; 95% CI: 1.00-1.30) were positively associated with periodontitis prevalence. Conversely, every 5% increase in humidity (OR = 0.94; 95% CI: 0.90-0.99) and 0.003 ppm increase in NO2 levels (OR = 0.93; 95% CI: 0.89-0.96) were inversely associated with periodontitis occurrence. CONCLUSIONS: In this nationally representative population several air pollutants were found to be associated with periodontitis occurrence. Hence, the present results suggest that air pollution may be a new modifiable risk indicator for periodontitis.

Periodontal disease could be a potential risk factor for non-alcoholic fatty liver disease: An 11-year retrospective follow-up study.

OBJECTIVE: This study aimed to evaluate the association of periodontal disease with non-alcoholic fatty liver disease (NAFLD). MATERIALS AND METHODS: A retrospective follow-up study using the National Health Insurance Service-National Sample Cohort was performed from 2002 to 2015 in the Korean population. A total of 165,032 subjects were followed up for incident NAFLD during 11 years. Periodontal disease and NAFLD were defined by a diagnosis using the International Statistical Classification of Diseases and Related Health Problems, 10th revision (ICD-10) codes. Periodontal status was used as the severity of periodontal status and the number of dental visit due to PD. RESULTS: Periodontitis was associated with a 4% increase in risk for NAFLD after adjusting for socio-demographic factor, health behaviors, and systemic diseases (adjusted hazard ratio [aHR] = 1.04, 95% CI = 1.01 to 1.07). Between the number of dental visit due to PD and the risk for NAFLD was observed a dose-effect association (aHR = 1.02, 95% CI = 0.99 to 1.05 for once; aHR = 1.10, 95% CI = 1.06 to 1.15 for two times; aHR = 1.14, 95% CI = 1.06 to 1.24 for three times). CONCLUSIONS: Our data confirmed that periodontitis showed an association with a higher incidence of NAFLD. CLINICAL RELEVANCE: Prevention and management of periodontal disease could be beneficial for reducing the risk of NAFLD.

Socioeconomic status, food security, and chewing discomfort of Korean elders: results from the Korea National Health and Nutrition Examination Survey.

BACKGROUND/OBJECTIVES: The purpose of this study was to investigate the association between socioeconomic status and chewing discomfort and identify the role of food insecurity in the association's causal pathway in a representative sample of Korean elders. MATERIALS/METHODS: We conducted cross-sectional analyses of the Korea National Health and Nutrition Examination Survey (2013-2015) data for elders aged ≥ 65 years. Socioeconomic status indicators used included household income and education level. Chewing discomfort was assessed according to the self-reported presence of chewing problems. Food security was surveyed using a questionnaire based on the US Household Food Security Survey Module. RESULTS: The odds ratios of chewing discomfort in the 1st and 2nd income quartiles were 1.55 (95% confidence interval [CI], 1.15-2.10) and 1.40 (95% CI, 1.03-1.90), respectively, compared to participants in the highest income quartile. Participants with the lowest education level were 1.89 (95% CI, 1.30-2.75) times more likely to have chewing discomfort than those without chewing discomfort. After including food security in the final model, the logistic coefficients were attenuated in the income and education quartiles. CONCLUSIONS: Low socioeconomic status was associated with chewing discomfort. In addition, the results confirm that food insecurity can mediate the association between socioeconomic inequalities and chewing discomfort among the elderly.

Determination of Residual Triflumezopyrim Insecticide in Agricultural Products through a Modified QuEChERS Method.

A rapid and simple analytical method for triflumezopyrim, a new class of mesoionic insecticides and commercialized molecules from DuPont, was developed with a modified QuEChERS method. The pH adjustment was used to improve the extraction efficiency of acetonitrile solvent, and dispersive solid-phase extraction was employed for the clean-up process. The five selected food commodities were used to verify the present optimized method, which displayed good linearity with an excellent correlation coefficient (R2 = 0.9992-0.9998) in the 0.003-0.30 mg/kg calibration range. The method limits of detection (LOD) and quantification (LOQ) were determined to be a value of 0.003 and 0.01 mg/kg, respectively. The mean recovery for the triflumezopyrim was in the 89.7-104.3% range. The relative standard deviations were ≤9.8% for intra- (n = 5) and inter-day (n = 15) precisions at concentrations of 0.01, 0.1, and 0.5 mg/kg in the five representative samples. The matrix effect has been calculated to confirm the effect during ionization of the analyte in the UPLC-MS/MS. The matrix effects of the instrumental analysis showed that triflumezopyrim was less susceptible to matrices. The proposed analytical method in this study has effectively improved the accuracy, selectivity, and sensitivity for the determination of triflumezopyrim in agricultural commodities; therefore, it can serve as a reference method for the establishment of maximum residue limits (MRLs).

Histone Deacetylase 1 Reduces Lipogenesis by Suppressing SREBP1 Transcription in Human Sebocyte Cell Line SZ95.

Proper regulation of sebum production is important for maintaining skin homeostasis in humans. However, little is known about the role of epigenetic regulation in sebocyte lipogenesis. We investigated histone acetylation changes and their role in key lipogenic gene regulation during sebocyte lipogenesis using the human sebaceous gland cell line SZ95. Sebocyte lipogenesis is associated with a significant increase in histone acetylation. Treatment with anacardic acid (AA), a p300 histone acetyltransferase inhibitor, significantly decreased the lipid droplet number and the expression of key lipogenic genes, including sterol regulatory-binding protein 1 (SREBP1), fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC). In contrast, treatment with trichostatin A (TSA), a histone deacetylase (HDAC) inhibitor, increased the expression of these genes. Global HDAC enzyme activity was decreased, and HDAC1 and HDAC2 expression was downregulated during sebaceous lipogenesis. Interestingly, HDAC1 knockdown increased lipogenesis through SREBP1 induction, whereas HDAC1 overexpression decreased lipogenesis and significantly suppressed SREBP1 promoter activity. HDAC1 and SREBP1 levels were inversely correlated in human skin sebaceous glands as demonstrated in immunofluorescence images. In conclusion, HDAC1 plays a critical role in reducing SREBP1 transcription, leading to decreased sebaceous lipogenesis. Therefore, HDAC1 activation could be an effective therapeutic strategy for skin diseases related to excessive sebum production.

Increased Histone Acetylation and Decreased Expression of Specific Histone Deacetylases in Ultraviolet-Irradiated and Intrinsically Aged Human Skin In Vivo.

Histone deacetylases (HDACs) are conserved enzymes that remove acetyl groups from lysine side chains in histones and other proteins and play a crucial role in epigenetic regulation. Previously, we showed that histone acetylation is implicated in ultraviolet (UV)-induced inflammation and matrix impairment. To elucidate the histone acetylation status and specific HDACs involved in skin aging, we examined the changes in histone acetylation, global HDAC activity, and the expression of HDACs and sirtuins (SIRTs) in intrinsically aged and photoaged human skin as well as in UV-irradiated human skin in vivo. Following acute UV irradiation, the acetylated histone H3 (AcH3) level was increased, but HDAC activity and the expression levels of HDAC4, HDAC11, and SIRT4 were significantly decreased. In intrinsically aged skin, AcH3 levels were increased, but HDAC activity and the expression levels of HDAC4, HDAC5, HDAC10, HDAC11, SIRT6, and SIRT7 were significantly decreased. However, histone acetylation and HDAC expression in photoaged skin were not significantly different from those in intrinsically aged skin. Collectively, HDAC4 and HDAC11 were decreased in both UV-irradiated and intrinsically aged skin, suggesting that they may play a universal role in increased histone acetylation associated with skin aging.

Ultraviolet irradiation-induced inhibition of histone deacetylase 4 increases the expression of matrix metalloproteinase-1 but decreases that of type I procollagen via activating JNK in human dermal fibroblasts.

BACKGROUND: Ultraviolet (UV) irradiation is the main contributing factor for skin aging. UV irradiation induces epigenetic changes in skin. It increases the activity of histone acetylases (HATs) but decreases that of histone deacetylases (HDACs). OBJECTIVE: We aimed to investigate alterations in all classes of HDACs and sirtuins (SIRTs) in response to UV irradiation, and determine the HDACs regulating the expressions of matrix metalloproteinase 1 (MMP-1) and type I procollagen. METHODS: Primary human dermal fibroblasts were UV irradiated. HDAC4 was knocked-down or overexpressed to investigate its effect on the expression of MMP-1 and type I procollagen. The mRNA and protein levels were analyzed by quantitative real-time polymerase chain reaction and western blotting. RESULTS: Among 11 HDACs and 7 SIRTs, we found that the expression of HDAC4, HDAC5, HDAC6, HDAC7, HDAC8, HDAC11, SIRT2, and SIRT3 were significantly and consistently reduced by UV at both mRNA and protein levels. Among these, the reduction of HDAC4 was responsible for the basal and UV-induced increase in the expression of MMP-1 and decrease in that of type I procollagen. Furthermore, the reduced HDAC4 could activate c-Jun N-terminal kinase (JNK), resulting in an increase in MMP-1 and decrease in type I procollagen. CONCLUSIONS: UV treatment decreases the expression of HDACs and SIRTs in dermal fibroblasts; in particular, the UV-induced reduction in the expression of HDAC4 might play an important role in regulating the expression of MMP-1 and type I procollagen.

Health Behavior, Emotional Intelligence, and Stress of Elementary School Students in Korea.

BACKGROUND: We aimed to provide the baseline data of nursing intervention for promoting the health promotion and promotion of growth and development for elementary students. METHODS: By subjecting the 887 elementary students from 20 elementary schools located in the northern area of Gyeonggi-do Province, South Korea, data were gathered from April 10-May 30, 2017. The SPSS was used for analysis of data. RESULTS: Some elements of emotional intelligence were found to differ depending on the gender and family type of lower-grade children, and depending on gender, sleep time, family type, and physical activity experience of higher-grade children. Some factors of stress were found to have differences according to sleeping time of the lower grades, and according to gender, sleeping time, family type, and whether they have experience in physical activity of higher-graders. CONCLUSION: It is possible to improve emotional intelligence and solve the stress of elementary students. This study will be the baseline data on developing the Health Promotion Education Arbitration Program for elementary students.

Rare-earth-platinum alloy nanoparticles in mesoporous zeolite for catalysis.

Platinum is a much used catalyst that, in petrochemical processes, is often alloyed with other metals to improve catalytic activity, selectivity and longevity1-5. Such catalysts are usually prepared in the form of metallic nanoparticles supported on porous solids, and their production involves reducing metal precursor compounds under a H2 flow at high temperatures6. The method works well when using easily reducible late transition metals, but Pt alloy formation with rare-earth elements through the H2 reduction route is almost impossible owing to the low chemical potential of rare-earth element oxides6. Here we use as support a mesoporous zeolite that has pore walls with surface framework defects (called 'silanol nests') and show that the zeolite enables alloy formation between Pt and rare-earth elements. We find that the silanol nests enable the rare-earth elements to exist as single atomic species with a substantially higher chemical potential compared with that of the bulk oxide, making it possible for them to diffuse onto Pt. High-resolution transmission electron microscopy and hydrogen chemisorption measurements indicate that the resultant bimetallic nanoparticles supported on the mesoporous zeolite are intermetallic compounds, which we find to be stable, highly active and selective catalysts for the propane dehydrogenation reaction. When used with late transition metals, the same preparation strategy produces Pt alloy catalysts that incorporate an unusually large amount of the second metal and, in the case of the PtCo alloy, show high catalytic activity and selectivity in the preferential oxidation of carbon monoxide in H2.

The number of teeth is associated with diet quality in Korean adult population.

OBJECTIVE: The objective of this study was to investigate the association between the number of teeth and diet quality for Korean adult population. METHODS: Eligible participants in the Korea National Health and Nutrition Examination Survey during 2013-2015 were included (N = 11,461). Participants were grouped into three groups depending on the total number of teeth: 28 teeth, 20-27 teeth, and 0-19 teeth. Diet quality was defined using the Korean Healthy Eating Index (KHEI) by 24 -h recall methods. Univariate and multivariate regression analyses were applied controlling for age, income, education, smoking, diabetes mellitus, obesity, and hypertension. RESULTS: In fully adjusted models, each tooth showed an increased KHEI score by 0.133 score and 0.150 score in males and females, respectively (p < 0.001 for all). The KHEI scores of participants with 0-19 and 20-27 teeth were 2.357 and 0.810 lower in males than those with 28 teeth (p = 0.001). The KHEI scores for females with 0-19 and 20-27 teeth were 3.008 and 1.223 lower than those with all teeth (p < 0.001). Considering KHEI 14 components, there was a clear association between the components and the number of teeth in females and males. CONCLUSIONS: The results found a positively significant association between the number of teeth and diet quality in a nationally representative sample of the Korean adult population.

Hormone-related events and periodontitis in women.

AIM: While the short-term effects of hormonal events on gingival inflammation have been well described, long-term effects on the periodontium have received less attention. The aim of this cross-sectional population-based study was to evaluate the association between hormone-related events and periodontitis in a representative sample of the postmenopausal women of South Korea. MATERIALS AND METHODS: A total of 10,273 postmenopausal women representative of 6.1 million of Koreans were examined. Periodontitis and severe periodontitis were defined according to the Community Periodontal Index (CPI â‰§ 3 and CPI = 4, respectively). Univariate and multivariate regression analyses using 3 different models were applied controlling for age, smoking, marital status, educational level, income, BMI, hypertension, stress and frequency of toothbrushing. RESULTS: Severe periodontitis was directly associated with a longer reproductive life (p-trend = .027) and with a longer duration of breastfeeding (48-72 vs. 1-17 months: OR = 1.49; 95% CI: 1.01-2.21). Conversely, early menopausal age (<46 vs. 49-50 years: OR = 0.74; 95% CI: 0.56-0.97), history of artificial menopause (OR = 0.72; 95% CI: 0.53-0.97), having had more than 6 pregnancies (vs. 4: OR = 0.73; 95% CI: 0.55-0.97), having had more than three abortions (vs. 0: OR = 0.51; 95% CI: 0.28-0.93) and having had the first birth age >26 years (vs. <21 years: OR = 0.71; 95% CI: 0.52-0.97) were inversely associated with severe periodontitis. CONCLUSIONS: In this large nationally representative population, severe periodontitis was related to menopausal age, reproductive life length, number of pregnancies/abortions, first birth age and breastfeeding duration, while it was not to oral contraceptive and hormone replacement therapy usages.

Association between periodontal status and non-alcoholic fatty liver disease in a Korean adult population: A nationwide cross-sectional study.

BACKGROUND: The objective of this study was to investigate the association between periodontal status and non-alcoholic fatty liver disease (NAFLD) indicators in a representative Korean population. METHODS: A cross-sectional study was conducted on 4061 participants >19 years of age using the 2010 Korea National Health and Nutrition Examination Survey data. Periodontal status was assessed by trained dentists using the community periodontal index. To identify the presence of NAFLD, biochemical data were defined using two validated indicators: the fatty liver index (FLI) and the hepatic steatosis index (HSI). The associations of the presence of periodontal pockets with FLI and HSI were evaluated by multivariable logistic regression analysis after adjusting for age, income, education level, smoking status, alcohol consumption, physical activity, diabetes mellitus, obesity, hypertension, and hypercholesterolemia. RESULTS: The adjusted means in the FLI indicator increased in the presence of periodontal pockets, whereas there was no significant difference in the HSI (P = 0.005 for FLI; P = 0.142 for HSI). Periodontal pockets were consistently associated with the two NAFLD indicators in the sequential logistic models for women throughout the adjustment process. (OR = 1.77, 95% CI = 1.05 to 2.98 for FLI, OR = 1.64, 95% CI = 1.08 to 2.51 for HSI). CONCLUSIONS: Our findings showed that the presence of periodontal pockets may be independently associated with NAFLD indicators. Further study will be clarified by well-designed longitudinal studies.

Quantitative analysis of radiation dosage and image quality between digital breast tomosynthesis (DBT) with two-dimensional synthetic mammography and full-field digital mammography (FFDM).

PURPOSE: Currently in diagnostic setting for breast cancer, FFDM and DBT are performed conjunctively. However, performing two imaging modalities may increase radiation exposure by double. Two-dimensional reconstructed images created from DBT with 2DSM, has a potential to replace conventional FFDM in concerning both radiation dosage and image quality. With increasing concerns for individual radiation exposure, studies analyzing radiation dosage in breast imaging modalities are needed. This study compared radiation dosage and image quality between DBT + 2DSM versus FFDM. METHODS AND MATERIALS: 374 patients (mean age 52 years) who underwent both DBT and FFDM were retrospectively reviewed. Radiation dosage data were obtained by radiation dosage scoring and monitoring program Radimetrics (Bayer HealthCare, Whippany, NJ). Entrance dose and mean glandular doses in each breast were obtained for both modalities. To compare image quality of DBT + 2DSM and FFDM, a 5-point scoring system for lesion clarity was assessed. The parameters of radiation dosage (entrance dose, mean glandular dose) and image quality (lesion clarity scoring) were compared. RESULTS: For entrance dose, DBT had lower mean dosage (14.8 mGy) compared with FFDM (21.8 mGy, p-value < 0.0001). Mean glandular doses for both breasts were lower in DBT (Left 1.74, Right 2.1) compared with FFDM (Left 2.85, Right 2.74, p-value < 0.0001). Lesion clarity score was higher in DBT with 2DSM (mean score 4.03) compared with FFDM (3.82, p-value < 0.0001). CONCLUSION: DBT showed lower radiation entrance dose and mean glandular doses to both breasts compared with FFDM. DBT + 2DSM had better image quality than FFDM, suggesting that DBT with 2DSM has potential as an alternative to FFDM.

Handgrip strength and the number of teeth among Korean population.

BACKGROUND: Handgrip strength is easily assessed by muscle strength and is an important factor for health and physical performance. Empirical evidence for the association between the number of teeth and handgrip strength remains controversial. The objective of this study was to investigate the association between the number of teeth and handgrip strength. METHODS: Data from the Korea National Health and Nutrition Examination Survey (KNHANES) 2014 to 2015 were used (N = 7,741). The number of teeth was categorized into three groups: 0 to 9 teeth, 10 to 19 teeth, and 20 to 28 teeth. Handgrip strength of the participants was measured using a digital hand dynamometer. Multivariate linear regression and logistic regression models were fitted to assess the association between the number of teeth and hand grip strength after adjusting for sociodemographic factors, general health behaviors, and oral and general health factors. RESULTS: Reduced handgrip strength was much more frequent in male and female participants with a lower number of teeth. Each tooth increased handgrip strength by 0.12 kg and 0.07 kg in males and females, respectively (P < 0.001 for both males and females). The association between the number of teeth and handgrip strength disappeared in females in the fully adjusted models, but the odds ratio of participants with 0 to 9 teeth was 1.73 (95% confidence interval: 1.02 to 2.95), which was higher than the reference group in males. CONCLUSION: Our results showed a significant association between the number of teeth and handgrip strength in Korean adults.

Social gradients in oral health status in Korea population.

OBJECTIVES: The aim of the present study was to investigate whether clinical (severe tooth loss) and subjective (chewing difficulties) indicators of oral health outcomes are associated with socioeconomic position and to explore the age-sex differences in the magnitude of the social gradient in Korea using data from the representative national data. METHODS: Data were acquired from 10,939 men and women, ≥30 years of age who participated in the Korea National Health and Nutrition Examination Surveys conducted from 2012 to 2014. Education and income were used as socioeconomic position. Self-rated chewing difficulties and severe tooth loss were assessed by dentists and trained interviewers. Confounding variables were demographic factors, general health behaviors, and systemic health status. RESULTS: Significant differences in oral health outcomes were observed according to the quartiles of income and education. In particular, the quartiles of education were significantly associated with oral health outcomes in the fully adjusted model with a dose-response trend. In participants aged 40-49 (OR = 2.30, 95% CI = 1.37-3.88) and 50-59 years (OR = 2.16, 95% CI = 1.49-3.14), the associations between the lowest quartiles of income and chewing difficulties were stronger than in the total population. CONCLUSIONS: Our findings demonstrate a clear and distinct social gradient in clinical and subjective oral health indicators based on socioeconomic position.