Background: This study aimed to investigate the erosive potential of powdered vitamin C on the bovine enamel tooth surface. Methods: The experiment included five groups: Lemona, Vitagran, Korea Eundan, Coca-Cola (positive controls), and artificialsaliva (negative controls). The pH and titratable acidity were measured. Bovine enamel specimens were immersed in the experimental solutions for 15 minutes each day for 7 days. The surface microhardness was measured using the Vickers hardness number before immersion and on the 1st, 3rd, 5th, and 7th days. The surfaces of the bovine enamel specimens were observed by scanning electron microscopy (SEM). Results: The pH of the experimental groups was as follows: Lemona (2.04±0.04) had the lowest pH, followed by Vitagran(2.56±0.01), the positive control group Coca-Cola (2.60±0.03), Korea Eundan (3.14±0.02), and the negative control group artificial saliva (7.06±0.05). Surface microhardness decreased significantly during the immersion period (p＜0.001). The largest surface microhardness reduction value was shown in Lemona (–201.22±20.60), followed by Vitagran (–190.02±14.73), Korea Eundan (–189.27±27.14), Coca-Cola (–99.28±17.21), artificial saliva (–10.99±9.94). According to the SEM findings, the experimental and positive control groups exhibited rough surfaces with micropores, whereas the negative control group exhibited smooth surfaces before specimen immersion. Conclusion Consuming powdered vitamin C at a low pH may degrade the enamel surface. To reduce the erosive effect, it isrecommended to rinse the mouth with water and brush the teeth after an hour.

Purpose: Few studies have assessed the prevalence of temporomandibular disorders (TMD) in the Korean population. Methods: We used cohort data from the Korean National Health Insurance Service between 2012 and 2020. The data consisted of main diagnoses related to TMD (International Classification of Diseases 10th Revision [ICD-10] code: K07.6 and K07.6x). The age-standardized prevalence of TMD was calculated using the estimated Korean population in 2020 as a reference. Results: The age-standardized prevalence of TMD increased from 604 persons per 100,000 persons in 2012 to 869 persons in 2020. In 2020, the overall age-standardized prevalence was 1,355 persons in the 10 to 19 years age group, 1,809 persons in the 20 to 29 years age group, and 979 persons in the 30 to 39 years age group. The age-standardized prevalence was approximately 1.5 times higher in females than in males (698 persons in males vs. 1,040 persons in females). Among the specific TMD subtypes, the age-standardized prevalence of internal derangement of the temporomandibular joint and pain in the temporomandibular joint, not classified elsewhere, was higher than that of other specific TMDs. Conclusion The overall age-standardized prevalence of TMD was higher in the 10s, 20s, and 30s age groups and in females between 2012 and 2020. The age-standardized prevalence of internal derangement of temporomandibular joint was the highest among specific TMD subtypes.

Purpose: This study aimed to assess the survival rate (SR) and death risk for associated pulmonary arterial hypertension (aPAH; 10th revision of the International Statistical Classification of Diseases [ICD-10], I27.2) in Koreans. Methods: The data were collected from the Korean National Health Insurance Service from 2006 through 2017 (n= 15,448). We analyzed the SR using the Kaplan-Meier method and carried out Cox proportional hazards analyses. Results: Patients’ mean age upon aPAH diagnosis was 60.1±24.0 years, and 60.7% of the patients were female. The 10-year SR of aPAH was 46.3% (95% confidence interval, 45.0 to 47.6). The factors associated with an increase in the adjusted death risk included age of 0 to 9 years, advancing age, male sex, lower income level, and comorbidities including diabetes mellitus, myocardial infarction, heart failure, hemorrhagic stroke, chronic kidney disease, malignant neoplasm, hereditary hemorrhagic telangiectasia, and systemic lupus erythematosus. Conclusion The 10-year SR of aPAH was over 46%. The risk of death from aPAH was significantly higher with advancing age, sex, lower income level, and comorbidities.

Background: This study aimed to investigate the erosive potential of powdered vitamin C on the bovine enamel tooth surface. Methods: The experiment included five groups: Lemona, Vitagran, Korea Eundan, Coca-Cola (positive controls), and artificialsaliva (negative controls). The pH and titratable acidity were measured. Bovine enamel specimens were immersed in the experimental solutions for 15 minutes each day for 7 days. The surface microhardness was measured using the Vickers hardness number before immersion and on the 1st, 3rd, 5th, and 7th days. The surfaces of the bovine enamel specimens were observed by scanning electron microscopy (SEM). Results: The pH of the experimental groups was as follows: Lemona (2.04±0.04) had the lowest pH, followed by Vitagran(2.56±0.01), the positive control group Coca-Cola (2.60±0.03), Korea Eundan (3.14±0.02), and the negative control group artificial saliva (7.06±0.05). Surface microhardness decreased significantly during the immersion period (p＜0.001). The largest surface microhardness reduction value was shown in Lemona (–201.22±20.60), followed by Vitagran (–190.02±14.73), Korea Eundan (–189.27±27.14), Coca-Cola (–99.28±17.21), artificial saliva (–10.99±9.94). According to the SEM findings, the experimental and positive control groups exhibited rough surfaces with micropores, whereas the negative control group exhibited smooth surfaces before specimen immersion. Conclusion Consuming powdered vitamin C at a low pH may degrade the enamel surface. To reduce the erosive effect, it isrecommended to rinse the mouth with water and brush the teeth after an hour.

Background: This study aimed to investigate the erosive potential of powdered vitamin C on the bovine enamel tooth surface. Methods: The experiment included five groups: Lemona, Vitagran, Korea Eundan, Coca-Cola (positive controls), and artificialsaliva (negative controls). The pH and titratable acidity were measured. Bovine enamel specimens were immersed in the experimental solutions for 15 minutes each day for 7 days. The surface microhardness was measured using the Vickers hardness number before immersion and on the 1st, 3rd, 5th, and 7th days. The surfaces of the bovine enamel specimens were observed by scanning electron microscopy (SEM). Results: The pH of the experimental groups was as follows: Lemona (2.04±0.04) had the lowest pH, followed by Vitagran(2.56±0.01), the positive control group Coca-Cola (2.60±0.03), Korea Eundan (3.14±0.02), and the negative control group artificial saliva (7.06±0.05). Surface microhardness decreased significantly during the immersion period (p＜0.001). The largest surface microhardness reduction value was shown in Lemona (–201.22±20.60), followed by Vitagran (–190.02±14.73), Korea Eundan (–189.27±27.14), Coca-Cola (–99.28±17.21), artificial saliva (–10.99±9.94). According to the SEM findings, the experimental and positive control groups exhibited rough surfaces with micropores, whereas the negative control group exhibited smooth surfaces before specimen immersion. Conclusion Consuming powdered vitamin C at a low pH may degrade the enamel surface. To reduce the erosive effect, it isrecommended to rinse the mouth with water and brush the teeth after an hour.

Objective: To evaluate the association between atopic dermatitis (AD) and suicidal behaviors in adolescent defectors among residents who escaped from North Korean (adolescent defectors, n=423) and adolescents with South Korean parents (Korean adolescents, n=540,265). Methods: The study used data from the Korea Youth Risk Behavior Survey conducted from 2011 to 2019. Differences in general characteristics, health behaviors, suicidal ideation, suicide plans, suicide attempts, and AD between adolescent defectors and Korean adolescents were examined. Multiple logistic regression analysis was used to determine the association between AD and suicidal behaviors. Results: The adolescent defectors group had lower AD (16.3% vs. 24.2%), poorer subjective health (10% vs. 6%), smoked more (47% vs. 18%), drank more (60% vs. 43%), lived with family less frequently (56% vs. 96%), and were more than twice as likely to have depression (42% vs. 27%), suicidal ideation (30% vs. 14%), a suicide plan (23% vs. 5%), or have made a prior suicide attempt (19% vs. 3%) compared with the Korean adolescent group (p<0.001). The adjusted odds ratio for the adolescent defectors group compared to the Korean adolescent group was 1.66 for suicidal ideation, 3.59 for suicide plans, and 4.34 for suicide attempts (p<0.001). AD was found to be associated with suicide plans and attempts in adolescent defectors and associated with suicidal ideation in Korean adolescents. Conclusion AD was significantly associated with suicide plans and suicidal attempts among adolescent defectors and suicidal ideation in Korean adolescents, based on a random sample of middle- and high-school students.

Objective: To investigate the effect of low frequency cerebellar repetitive transcranial magnetic stimulation (rTMS) on balance impairment in patients with cerebral infarction. Methods: Thirty-two patients were randomly divided into two groups: rTMS group (n=16) and control (n=16). In the rTMS group, treatment was performed five times per week for 2 weeks (10 sessions), and in the control group, a sham coil was used with the sound and sensation of scalp similar to the rTMS coil. Patients in both groups underwent a conventional rehabilitation program. Berg Balance Scale (BBS) was used as the primary outcome measurement. Timed Up and Go test (TUG), 10-m walk test (10mWT), and Activity-specific Balance Confidence scale (ABC) were used as the secondary outcome measurement. All scales were measured at baseline (T0), after 10 sessions of rTMS (T1), and at 4 weeks after treatment completion (T2) by therapists with over 5 years of clinical experience. Results: There were significant improvements between T0 and T1, and between T0 and T2, for all assessed items in the rTMS group. Whereas there were significant improvements between T0 and T1, and between T0 and T2, for the BBS and 10mWT in the control group. TUG (-4.87±5.05 vs. -0.50±2.97 seconds) and ABC score (8.10±8.33 vs. 0.16±0.97) were observed significant differences in comparison of the changes from T0 to T1 between the two group. BBS score (4.40±3.66 vs. 1.88±3.14), TUG (-4.87±4.56 vs. -0.62±2.96 seconds) and ABC score (8.22±7.70 vs. -0.09±0.86) differed significantly from T0 to T2 between the two groups. Conclusion Our findings suggest that low-frequency cerebellar rTMS is helpful for improving balance in patients with cerebral infarction, and maybe a beneficial treatment for these patients.

Background: Although respiratory tract infection is one of the most important factors triggering acute exacerbation of chronic obstructive pulmonary disease (AE-COPD), limited data are available to suggest an epidemiologic pattern of microbiology in South Korea. Methods: A multicenter observational study was conducted between January 2015 and December 2018 across 28 hospitals in South Korea. Adult patients with moderate-to-severe acute exacerbations of COPD were eligible to participate in the present study. The participants underwent all conventional tests to identify etiology of microbial pathogenesis. The primary outcome was the percentage of different microbiological pathogens causing AE-COPD. A comparative microbiological analysis of the patients with overlapping asthma–COPD (ACO) and pure COPD was performed. Results: We included 1,186 patients with AE-COPD. Patients with pure COPD constituted 87.9% and those with ACO accounted for 12.1%. Nearly half of the patients used an inhaled corticosteroid-containing regimen and one-fifth used systemic corticosteroids. Respiratory pathogens were found in 55.3% of all such patients. Bacteria and viruses were detected in 33% and 33.2%, respectively. Bacterial and viral coinfections were found in 10.9%. The most frequently detected bacteria were Pseudomonas aeruginosa (9.8%), and the most frequently detected virus was influenza A (10.4%). Multiple bacterial infections were more likely to appear in ACO than in pure COPD (8.3% vs. 3.6%, p=0.016). Conclusion Distinct microbiological patterns were identified in patients with moderate-to-severe AE-COPD in South Korea. These findings may improve evidence-based management of patients with AE-COPD and represent the basis for further studies investigating infectious pathogens in patients with COPD.

In this study, surface characteristics of plasma electrolytic oxidized Ti-mesh for dental use were studied using various experimental instruments. The titanium mesh was used as a substrate for PEO. Using a pulsed DC power supply, PEO treatment was carried out at 280 V for 3 min in the electrolytic solution containing Ca, Mg, and P ions. And the electrolyte used for PEO was prepared by mixing with Ca(CH 3COO)2·H 2O, C 3H 7CaO 6P, and (CH 3COO) 2Mg·4H 2O. The PEO-treated surface was observed by using X-ray diffraction, field-emission scanning electron microscope, energy dispersive X-ray spectroscopy, atomic force microscopy (AFM), and nanoindentation tester.PEO-treated Ti-mesh in solution containing Ca, Mg, and P ions (CaMgP) sample showed the active spark discharge reaction compared to in solution containing Ca and P ions (CaP) sample. In CaP and CaMgP samples, the PEO surface of Ti-mesh showed mainly circular, irregular, and oval shapes of pores. In the case of CaMgP, the defects and precipitates such as MgO were formed on the surface. On the sample surface, the distribution of the desired element was detected homogeneously.The PEO-treated CaP and CaMgP specimens were mainly composed of anatase, Mg, and hydroxyapatite. From the AFM result, the average roughness was 0.247 µm for CaP and 0.226 µm for CaMgP, respectively. The hardness of CaMgP containing Mg ions was increased compared to CaP containing without Mg ions, also, the elastic modulus of CaMgP sample was higher than that of CaP sample.

Objective: To investigate changes in blood glucose level after steroid injection in patients with type 2 diabetes mellitus (DM) and factors affecting those changes. Methods: We retrospectively studied 51 patients with type 2 DM who underwent steroid injection for shoulder and back pain. Mean fasting blood sugar (FBS) levels for 7 days before steroid injection was used as the baseline blood glucose level, which was compared with FBS levels for 14 days after steroid injection. We compared the differences in blood glucose changes between HbA1c >7% and HbA1c ≤7% groups and those between insulin and non-insulin treated groups. Demographic data, injection site, and steroid dose were analyzed. Results: Compared to baseline, blood glucose significantly (p=0.012) elevated 1 day after steroid injection but not 2 days after injection. In the HbA1c >7% and insulin groups, blood glucose was significantly increased 1 day after injection compared to that in the HbA1c ≤7% (p=0.011) and non-insulin (p=0.024) groups, respectively. Higher HbA1c level before injection was significantly (p=0.003) associated with the degree of blood glucose increase 1 day after injection. No significant differences were noted in the degree of blood glucose increase according to injection site or steroid dose. Conclusion Higher HbA1c level was associated with greater elevation in blood glucose 1 day after steroid injection. Careful monitoring of blood glucose is required on the first day after steroid injection in patients with poorly controlled DM.