Keun-Bae Song

Expression patterns of bone-related proteins during osteoblastic differentiation in MC3T3-E1 cells.

Bone formation involves several tightly regulated gene expression patterns of bone‐related proteins. To determine the expression patterns of bone‐related proteins during the MC3T3‐E1 osteoblast‐like cell differentiation, we used Northern blotting, enzymatic assay, and histochemistry. We found that the expression patterns of bone‐related proteins were regulated in a temporal manner during the successive developmental stages including proliferation (days 4–10), bone matrix formation/maturation (days 10–16), and mineralization stages (days 16 –30). During the proliferation period (days 4–10), the expression of cell‐cycle related genes such as histone H3 and H4, and ribosomal protein S6 was high. During the bone matrix formation/maturation period (days 10–16), type I collagen expression and biosynthesis, fibronectin, TGF‐β1 and osteonectin expressions were high and maximal around day 16. During this maturation period, we found that the expression patterns of bone matrix proteins were two types: one is the expression pattern of type I collagen and TGF‐β1, which was higher in the maturation period than that in both the proliferation and mineralization periods. The other is the expression pattern of fibronectin and osteonectin, which was higher in the maturation and mineralization periods than in the proliferation period. Alkaline phosphatase activity was high during the early matrix formation/maturation period (day 10) and was followed by a decrease to a level still significantly above the baseline level seen at day 4. During the mineralization period (days 16–30), the number of nodules and the expression of osteocalcin were high. Osteocalcin gene expression was increased up to 28 days. Our results show that the expression patterns of bone‐related proteins are temporally regulated during the MC3T3‐E1 cell differentiation and their regulations are unique compared with other systems. Thus, this cell line provides a useful in vitro system to study the developmental regulation of bone‐related proteins in relation to the different stages during the osteoblast differentiation.

The relationship between metabolic conditions and prevalence of periodontal disease in rural Korean elderly

The aim of this study was to investigate the relationship between the duration and number of components of metabolic syndrome and periodontal disease among rural elderly in Korea over 60 years old. This longitudinal study consisted of 399 participants who underwent regular health examinations at Seongju-gun Public Health Center from 2000 to 2007. The components of metabolic syndrome (diabetes mellitus, hypertension, obesity, and hypercholesterolemia) were evaluated from clinical records of Seongju-gun Public Health Center, which were recorded from 2000 to 2007, and periodontal examination by Community Periodontal Index, recorded from 2006 to 2007. Participants suffering from longer durations of diabetes mellitus, hypertension, and obesity were more likely to have periodontal disease. Individuals with a greater number of metabolic syndrome components were more likely to have periodontal disease. Older rural Koreans with components of metabolic syndrome have unmet periodontal treatment needs. Medical and dental professionals need to coordinated systemic and oral care for these people.

Dental composite fillings and bisphenol A among children: a survey in South Korea

AIMS Bisphenol A (BPA)-based dental composites have commonly been used to fill dental cavities or seal pits and fissures on teeth. However, epidemiological evidence with regard to the BPA exposure from dental composites among children has rarely been reported. This study investigated whether there is a relationship between the BPA concentration in urine and the presence of composite restorations and sealants among South Korean children. METHODS Oral examinations and urine sample analyses were conducted on a total of 495 children aged 8-9 years. We classified the participants into four groups by the number of resin composites and sealant surfaces (0, 1-5, 6-10 and 11+). RESULTS BPA concentrations in urine were higher in children with 11 or more surfaces restored with sealants and resin composites than in those with zero restored surfaces, although no difference was seen in the group with 1-10 surfaces. After adjusting for gender and age, the urinary BPA concentration in children with 11 or more resin composite surfaces was 2.67 μg/g creatinine, which was higher than the concentration found in those with no filling surfaces (P < 0.01). CONCLUSIONS Having many dental composite filling surfaces on teeth may increase the urinary BPA concentration in children.

More missing teeth are associated with poorer general health in the rural Korean elderly

The aim was to investigate the association between missing teeth and general health conditions in elderly Korean people. This cross-sectional study was conducted as a part of a health-screening program supported by the National Health Insurance Corporation of Korea in a local region of Sungju-gun, Gyeongsangbuk-do from 2000 to 2006. The participants were 3611 in number (1494 males and 2117 females) aged 60 years and over. The outcome variable was the number of missing teeth in the mouth determined by dental examination; general medical examination included blood pressure, body height and weight to compute body mass index (BMI). Laboratory investigations included aspartate transaminase (AST), hemoglobin (HB), fasting plasma glucose (FPG), and total cholesterol (CHOL). Demographic factors and smoking status were obtained from questionnaires by an interviewer. Multiple regression models were used as a statistical analysis. The subjects were classified into three groups according to the number of missing teeth (<8, 8-18, and >18). In unadjusted analyses individuals with more missing teeth, had poorer general health status (higher blood pressure, higher levels of AST, FPG, and CHOL, and higher BMI in females). In multiple regression models with the number of missing teeth as an outcome, systolic blood pressure, CHOL, FPG, and HB in males were statistically significant after adjusting for age and smoking. In females, systolic blood pressure, CHOL, FPG, and BMI were positively associated with the number of missing teeth. The number of missing teeth was positively related to poorer general health status such as blood pressure, FPG, CHOL, after adjusting for age and smoking in the rural elderly in Korea.

The strength of age effect on tooth loss and periodontal condition in Korean elderly

Aging is a well-known risk factor associated with oral diseases. The aim of this cross-sectional study was to compare tooth loss and periodontal health between the relatively young elderly (65-74 years) and the old elderly (≥ 75 years) and to investigate the strength of the age effect on oral health status in the Korean elderly. Study population 65 years of age or older were selected from the participants of the Korean National Oral Health Survey (2006) (n = 1193). Oral examination was conducted by eight dentists trained in the World Health Organization (WHO) recommended examination procedure. The chi-square test, multiple regression analyses and multinomial logistic regression analyses were performed using SAS 9.1.3. The oral health status including decayed, missing, and filled teeth (DMFT), missing teeth, and residual teeth significantly differed between the young elderly and the old elderly (p < 0.01). Moreover, the regression coefficients of tooth loss linearly increased across different age groups (5-year intervals, starting at age 65 years) (p < 0.05). However, the odds ratios of periodontal health did not significantly differ across 5-year interval age groups. The findings that age and the number of missing teeth are significantly and linearly related could contribute to the development of oral health care and promotion programs for the elderly tailored to their own age.

Metabolic Syndrome Parameters in adolescents may be determinants for the future periodontal diseases

AIM The prevalence of metabolic syndrome (MetS) increases even in adolescents. The evidence that MetS is associated with the periodontal diseases in adolescents has been understudied. Therefore, our aim was to assess the association between MetS parameters and gingivitis in adolescents. MATERIAL AND METHODS A total of 941 participants (590 boys, 351 girls), aged 12-18 years was selected from the Fourth Korea National Health and Nutrition Examination Survey, a cross-sectional and nationally representative survey, which had had information on waist circumference, blood pressure, serum triglyceride, high-density lipoprotein (HDL) cholesterol, and the fasting blood sugar and community periodontal Index (CPI). RESULTS The number of positive parameters of MetS showed significant positive correlation with gingivitis; adjusted and crude ORs with one positive parameters of MetS were 1.92 (95% CI: 1.21-3.04) and 1.88(95% CI: 1.28-2.76), respectively. And adjusted OR with three or more positive parameters of MetS was 3.29 (95% CI: 1.24-8.71). Among five parameters of MetS, Low HDL-cholesterol showed significant association with gingivitis (crude OR 2.12, 95% CI 1.20-3.73; adjusted OR 1.96, 95% CI 1.24-3.12). CONCLUSIONS Having more positive parameters of MetS and low HDL-cholesterol parameter had an independent relationship with the prevalence of gingivitis, which may be determinants for the future periodontal diseases even in adolescents.

Current status of the types of dental filling and preventive materials among children in mixed dentition

Abstract The purpose of this study was to examine current status of the types of dental filling materials and preventive materials among Korean children in mixed dentition. Seven elementary schools were randomly selected from four metropolitan regions in South Korea. The total of 711 children aged 9-10 years old were examined with their parents’ informed consents. Oral examination was conducted by one trained dentist. The mean number of dfs was 7.9±8.0 (ds=1.3±2.5, fs=6.6±7.6) and DMFS was 1.4±2.2 (DS=0.2±0.8, FS=1.1±2.1). The average of filled surfaces using amalgam, composites, sealants, and others were 2.8±3.9, 1.6±2.8, 2.9±3.2, and 4.5±7.0, respectively. The use of dental filling material according to region, the amalgam was the highest in Daegu and the resin was the highest in Pusan. In permanent teeth, about 70% of total filling surfaces had sealant and about 20% was resin fillings, and the proportion of amalgam filling surfaces was less than 10%. Key Words : children, dental filling materials, sealants

Polycan suppresses osteoclast differentiation and titanium particle-induced osteolysis in mice

Particle-induced osteolysis is a major issue, and it is most likely the result of enhanced osteoclast activation in the pathogenesis of various skeletal diseases. This study investigated whether the inhibitory effect that Polycan has on osteoclast differentiation can be used to treat osteolysis induced by titanium (Ti) particles. To this end, the effects of Polycan were examined in terms of the cytotoxicity, osteoclast differentiation, cytokine expression, and Ti-induced calvarial osteolysis. Polycan had no significant cytotoxic effects on bone marrow macrophages (BMMs) but instead increased BMM proliferation. High levels of interleukin (IL)-6, IL-12, and macrophage colony-stimulating factor (M-CSF) were expressed in BMM cells in the presence of Polycan, suggesting that Polycan drives the differentiation of BMMs into M1 macrophages. Polycan significantly inhibited osteoclast differentiation induced by M-CSF and the receptor activator of nuclear factor kappa-B ligand (RANKL). The expression levels of the osteoclast marker genes significantly decreased, and Polycan induced and maintained the expression of IL-12, which suppressed osteoclast differentiation. In contrast, the RANKL signaling pathway was not inhibited by Polycan. An in vivo calvarial osteolysis model revealed that Polycan significantly decreased the osteoclast numbers and suppressed osteolysis. Our results suggest that the natural compound Polycan is a good candidate for therapeutic intervention against enhanced osteoclast differentiation and Ti particle-induced osteolysis.

Can the number of functional teeth potentially affect cognitive function

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Relationship between the activities of daily living, oral health-related quality of life and dementia: ADL and OHRQoL and dementia

The aim of the present study was to investigate the association between the activities of daily living and the oral health‐related quality of life and dementia in older adults.