Hyun-Duck Kim

The association of metabolic syndrome with periodontal disease is confounded by age and smoking in a Korean population: the Shiwha–Banwol Environmental Health Study

AIM Because metabolic syndrome (MS) is pro-inflammatory and periodontitis is inflammatory, we issued the hypothesis that MS (the explanatory variable) is associated with periodontitis (the outcome variable). This study aimed to examine the link between MS and periodontitis among Koreans. MATERIALS AND METHODS From the Shiwha-Banwol Environmental Health Study, 1046 subjects aged 18 years or older were cross-sectionally surveyed. All participants underwent comprehensive dental and medical health examinations. The community periodontal index was used to assess periodontitis. Age, gender, monthly family income, smoking, drinking, frequency of daily teeth brushing, and physical activity were evaluated as confounders. RESULTS MS was strongly associated with periodontitis [odds ratio (OR): 1.7, 95% confidence interval (CI): 1.22-2.37], and MS with more components had a higher association. The association was higher for elders aged 65 years or more, males, and smokers. MS including both high glucose and hypertension had a higher association with the OR of 2.19 (95% CI: 1.23-3.90) comparing with other types of MS. CONCLUSIONS Our results suggested that MS might be associated with periodontitis and the association was confounded by age, gender, and smoking. MS with high glucose and hypertension showed the higher impact on this link.

Association Between Periodontitis and Hemorrhagic Stroke Among Koreans: A Case‐Control Study

BACKGROUND Several studies suggested that periodontitis is a risk factor for stroke, but the relationship between periodontitis and hemorrhagic stroke has not been widely reported. This study aims to evaluate the association between periodontitis and hemorrhagic stroke and to identify the risk group for this association. METHODS We recruited 165 patients who were diagnosed via computed tomography brain imaging as having had a hemorrhagic stroke and 214 non-stroke control subjects for a case-control study. All participants underwent a clinical periodontal examination using clinical attachment level (CAL) as a marker. Information about sociodemographic factors, behavioral factors, systemic health, and a familial history of systemic health was gathered through an interview using structured questionnaires. The association between periodontitis and hemorrhagic stroke was evaluated using multivariate logistic regression analyses with adjustment for age, gender, income, education, hypertension, diabetes, body mass index, cardiac disease, familial hypertension history, familial diabetes history, familial cardiac disease history, smoking, and alcohol consumption. Subgroup analyses were also performed to investigate potential risk groups. RESULTS After controlling for potential confounders, periodontitis (CAL > or =6 mm) was found to be significantly associated with hemorrhagic stroke (odds ratio: 2.5; 95% confidence interval: 1.1 to 5.6), but this association did not exhibit a dose-dependent response for periodontitis (percentile of sites of periodontal pockets with CAL > or =5 mm among total probed pockets). The association between periodontitis (CAL > or =6 mm) and hemorrhagic stroke was significant for males, patients who had a lower income than control subjects, obese patients, and patients without diabetes. CONCLUSIONS Periodontitis may be an independent risk factor for hemorrhagic stroke. Risk groups include males, patients without diabetes, and obese subjects.

Visceral fat area-defined obesity and periodontitis among Koreans.

AIM Although the association of periodontitis with body mass index (BMI)-defined obesity has been studied, it remains controversial. Hence, this study aims to determine whether the obesity is associated with periodontitis among Koreans and to determine the most significant indicator of the obesity on the link. MATERIALS AND METHODS From the Sihwa-Banwol Environmental Health Cohort, 1046 subjects 15 years of age or older were cross-sectionally surveyed. All participants underwent periodontal and medical health examinations. Age, gender, monthly family income, smoking, drinking, frequency of daily teeth brushing and physical activity were evaluated through interviews. The community periodontal index (CPI) was used to assess periodontitis. BMI, waist circumference (WC), waist hip ratio and visceral fat area (VFA) were used to assess obesity. Multivariate linear and logistic regression analyses were applied. RESULTS BMI, WC and VFA had a dose-effect relationship with the number of sextants with periodontitis. Although subgroup analysis revealed several significant associations between obesity and periodontitis (CPI 3-4), the greatest association between VFA and periodontitis was found in males, age 45-54 (odds ratio=3.30; 95% confidence interval: 1.53-7.09). CONCLUSIONS Obesity was associated with periodontitis. VFA was the most suitable indicator of obesity in relation to periodontitis. Obesity may be a substantial risk factor for periodontitis.

Substance P Sensitizes P2X3 in Nociceptive Trigeminal Neurons

Peripheral inflammation produces pain hypersensitivity by sensitizing nociceptors. Potentiation of P2X3 receptor activity in nociceptors may play an important role in this peripheral sensitization. However, we do not fully understand how P2X3 activity is elevated in inflammation. Thus, we investigated whether P2X3 activity in trigeminal nociceptive neurons is regulated by the neurokinin-1 (NK-1) receptor that is activated by an inflammatory mediator, substance P. Single-cell RT-PCR and immunohistochemistry revealed that NK-1 in nociceptive neurons was mainly co-expressed with P2X3. Ca2+ imaging and whole-cell patch-clamp recordings indicated that both substance P and Sar-substance P, a selective NK-1 agonist, significantly potentiated α,β-meATP-induced currents and [Ca2+]i responses in nociceptive neurons. These potentiating effects were completely blocked by GR82334, a specific NK-1 antagonist. Our results demonstrate that substance P sensitizes P2X3 receptor through the activation of NK-1, thus warranting these receptors as possible targets for pain therapy in the orofacial region. Abbreviations: α,β-methylene adenosine 5′-triphosphate (ATP), α,β-meATP; neurokinin-1, NK-1; single-cell reverse-transcription polymerase chain-reaction, single-cell RT-PCR; [Sar9,Met(O2)11]-substance P, Sar-substance P.

A comparison of implant stability quotients measured using magnetic resonance frequency analysis from two directions: a prospective clinical study during the initial healing period.

OBJECTIVES Given that the orientation of the transducer (mesiodistal or buccolingual) affects the data obtained from a piezoelectric resonance frequency analysis (RFA), this study evaluated whether it is necessary to use measurements taken in two different directions (mesiodistal and buccolingual) when using magnetic RFA to assess changes in the stiffness of dental implants. MATERIALS AND METHODS A prospective clinical trial was completed, in a total of 53 patients, on 71 non-submerged dental implants that were inserted to replace the unilateral loss of mandibular molars. All of the implants were of the same diameter (4.1 mm), length (10 mm), and collar height (2.8 mm). The implant stability quotient (ISQ) was measured during the surgical procedure, and at 4 and 10 weeks after surgery. Measurements were taken twice in each direction: in the buccolingual direction from the buccal side and in the mesiodistal direction from the mesial side. The average of two measurements in each direction was regarded as the representative ISQ of that direction. The higher and lower values of the two ISQs (buccolingual and mesiodistal) were also classified separately. In addition, the variation in ISQ was quantified by subtracting the lower value from the higher value, and the implants were classified into two groups according to this variation: one with ISQ variation of 3 or more and the other with a variation of <3. RESULTS There were no differences between the two ISQs when measured from different directions, but there were significant differences between the higher and lower values of the ISQs at each measurement point. A significant difference was also observed between the two ISQ variation groups in the pattern of change of the lower value for the period from immediately after surgery to 10 weeks after surgery. CONCLUSION Acquisition of two directional measurements and classification of the higher and lower values of the two directional ISQs may allow clinicians to detect patterns of change in ISQ that would not be identified if only one directional measurement were made.

Effectiveness of slow freezing and vitrification for long-term preservation of mouse ovarian tissue.

This study was conducted to evaluate the interaction between cryo-damage and ART outcome after cryopreservation of mouse ovarian tissues with different methods. Either a vitrification or a slow freezing was employed for the cryopreservation of B6CBAF1 mouse ovaries and follicle growth and the preimplantation development of intrafollicular oocytes following parthenogenesis or IVF were monitored. Both cryopreservation protocols caused significant damage to follicle components, including vacuole formation and mitochondrial deformities. Regardless of the cryopreservation protocols employed, a sharp (P < 0.0001) decrease in follicle viability and post-thaw growth was detected. When IVF program was employed, significant (P < 0.05) decrease in cleavage and blastocyst formation was notable in both modes of cryopreservation. However, such retardation was not found when oocytes were parthenogenetically activated. In the IVF oocytes, slow freezing led to better development than vitrification. In conclusion, a close relationship between cryopreservation and ART methods should be considered for the selection of cryopreservation program.

Group of serum inflammatory markers and periodontitis-metabolic syndrome coexistence in Koreans.

BACKGROUND Recent epidemiologic studies have shown that individuals with periodontitis have a significantly increased risk of metabolic syndrome (MetS). Chronic infection and subsequent production of systemic inflammatory markers may be associated with this increased risk. The aim of present study is to determine whether the presence of periodontitis and MetS is associated with a group or an individual of C-reactive protein (CRP), interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor-α (TNF-α), and homocysteine (HCY) in the serum of a Korean population. METHODS Medical and periodontal parameters, including CRP, IL-1β, IL-6, IL-8, TNF-α, and HCY, were evaluated in 118 individuals (73 healthy; 20 with periodontitis only; 13 with MetS only; and 12 with both). The community periodontal index was used to assess periodontitis. Age, sex, monthly household income, smoking, and drinking were evaluated as confounders. Analysis of covariance, linear regression analysis, and factor analysis were applied. RESULTS The group of serologic cytokines was synergistically associated with the periodontitis-MetS coexistence. TNF-α and IL-6 were two representing serologic cytokines in the group. CONCLUSIONS Our results suggest that a group of systemic biologic markers represented by TNF-α and IL-6 might mediate the association between MetS and periodontitis adjusted for various confounders. Additional evidence is needed to generalize our results more widely.

Putative association of transforming growth factor-α polymorphisms with clearance of hepatitis B virus and occurrence of hepatocellular carcinoma in patients with chronic hepatitis B virus infection.

Summary.  Previous studies showed that several genetic polymorphisms might influence the clinical outcome of chronic hepatitis B virus (HBV) infection, including HBV clearance or development of hepatocellular carcinoma (HCC). The aim of this study was to determine whether polymorphisms of the transforming growth factor‐α (TGF‐α) gene are associated with clinical outcome of HBV infection. A total of 1096 Korean subjects having either present or past evidence of HBV infection were prospectively enrolled between January 2001 and August 2003. Among 16 genetic variants in TGFA gene, nine variants were genotyped using TaqMan assay and the genetic association with HBV clearance and HCC occurrence was analysed. Statistical analyses revealed that TGFA+103461T>C, TGFA+106151C>G and TGFA‐ht2 were marginally associated with clearance of HBV infection. However, only TGFA‐ht2 retained significance after multiple correction (OR = 0.39, Pcorr = 0.007 in recessive model). Although no variants were significant after multiple correction, TGFA+88344G>A and TGFA+103461T>C were weakly associated in recessive model in the analysis of HCC occurrence. In addition, Cox relative hazards model also revealed that TGFA+88344G>A was associated with onset age of HCC occurrence in subjects (RH = 1.46, Pcorr = 0.04). TGF‐α polymorphisms might be an important factor in immunity, progression of inflammatory process and carcinogenesis, which explains the variable outcome of HBV infection at least in part. Further biological evidence is warranted in the future to support these suggestive associations.

The association of hypertension with periodontitis is highlighted in female adults: results from the Fourth Korea National Health and Nutrition Examination Survey

AIM To evaluate the association of hypertension and high systolic and diastolic blood pressure (SBP and DBP) with periodontitis in a nationally representative Korean adult population. MATERIALS AND METHODS Total of 14,625 participants of Fourth Korea National Health and Nutrition Examination Survey (KNHANES IV) aged over 19 years were cross-sectionally surveyed. Periodontitis was defined as CPI score of 3 or 4. Hypertension was categorized as: normotensive (SBP < 120 mmHg and DBP < 80 mmHg), pre-hypertensive (120 < SBP < 140 mmHg or 80 < DBP < 90 mmHg) and hypertensive (SBP ≥ 140 mmHg or DBP ≥ 90 mmHg or taking antihypertensive medication). Multivariate Poisson regression analyses were performed controlling for age, sex, household income, drinking, smoking, physical activity, obesity, hypercholesterolaemia and diabetes mellitus. Stratified analyses were performed to identify specific risk groups. RESULTS Hypertension showed a significant positive association with periodontitis in the fully adjusted model in female adults with a dose-response relationship. This association was highlighted in females aged 30-59 years (prevalence ratio = 1.25; 95% confidence interval: 1.11-1.40). The strength of the association was highest in females aged 30-39 years and decreased with increasing age. Among females aged 30-59 years, high-risk groups of this link were lower middle income quartile, never drinker and non-diabetes groups for both pre-hypertension and hypertension. CONCLUSION Our data showed that hypertension was associated with periodontitis in Korean female adults independent of known confounders.

Periodontitis Is Associated with Cognitive Impairment in Elderly Koreans: Results from the Yangpyeong Cohort Study

To investigate the association between periodontitis and cognitive impairment in elderly Koreans.