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.

Purpose: To evaluate the correlation between matrix metalloproteinase-9 (MMP-9) point-of-assay and clinical symptoms and signs of dry eye disease. Methods: We performed a retrospective study for patients diagnosed with dry eye. MMP-9 (InflammaDry) was performed on 235 patients. Patients were assessed using Schirmer test, corneal staining score, tear film breakup time (TBUT) and the Ocular Surface Disease Index (OSDI). Results: The score of Schirmer test was lower significantly in MMP-9 positive group than in MMP-9 negative group (for each 4.21 ± 5.80 mm, 5.96 ± 8.14 mm; p = 0.035). TBUT was shorter significantly in MMP-9 positive group than in MMP-9 negative group (for each 5.46 ± 4.06 s, 8.27 ± 4.75 s; p = 0.0008). The ratio of positive corneal stain (for each 83%, 31%) and OSDI even or greater than 13 (for each 80%, 75%) was significantly higher in MMP-9 positive group than in MMP-9 negative group (p = 0.00001, p = 0.0044). The value of MMP-9 point-of-care assay showed showed the negative correlation with Schirmer test (Rs = 0.383, p < 0.001), and TBUT (Rs = 0.310, p < 0.05), and showed the positive correlation with corneal staining score (Rs = 0.527, p < 0.001), OSDI (Rs = 0.510, p < 0.001). Conclusions MMP-9 point-of-assay accords with clinical symptoms and signs of Dry eye disease, and may be helpful in diagnosing Dry eye disease.

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.

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.

OBJECTIVES: We estimated the population prevalence of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), including unreported infections, through a Korea Seroprevalence Study of Monitoring of SARS-CoV-2 Antibody Retention and Transmission (K-SEROSMART) in 258 communities throughout Korea. METHODS: In August 2022, a survey was conducted among 10,000 household members aged 5 years and older, in households selected through two stage probability random sampling. During face-to-face household interviews, participants self-reported their health status, COVID-19 diagnosis and vaccination history, and general characteristics. Subsequently, participants visited a community health center or medical clinic for blood sampling. Blood samples were analyzed for the presence of antibodies to spike proteins (anti-S) and antibodies to nucleocapsid proteins (anti-N) SARS-CoV-2 proteins using an electrochemiluminescence immunoassay. To estimate the population prevalence, the PROC SURVEYMEANS statistical procedure was employed, with weighting to reflect demographic data from July 2022. RESULTS: In total, 9,945 individuals from 5,041 households were surveyed across 258 communities, representing all basic local governments in Korea. The overall population-adjusted prevalence rates of anti-S and anti-N were 97.6% and 57.1%, respectively. Since the Korea Disease Control and Prevention Agency has reported a cumulative incidence of confirmed cases of 37.8% through July 31, 2022, the proportion of unreported infections among all COVID-19 infection was suggested to be 33.9%. CONCLUSIONS The K-SEROSMART represents the first nationwide, community-based seroepidemiologic survey of COVID-19, confirming that most individuals possess antibodies to SARS-CoV-2 and that a significant number of unreported cases existed. Furthermore, this study lays the foundation for a surveillance system to continuously monitor transmission at the community level and the response to COVID-19.

Purpose: We aimed to assess the humoral response to and reactogenicity of coronavirus disease 2019 (COVID-19) vaccination according to the vaccine type and to analyze factors associated with immunogenicity in actively treated solid cancer patients (CPs). Materials and Methods: Prospective cohorts of CPs, undergoing anticancer treatment, and healthcare workers (HCWs) were established. The participants had no history of previous COVID-19 and received either mRNA-based or adenovirus vector–based (AdV) vaccines as the primary series. Blood samples were collected before the first vaccination and after 2 weeks for each dose vaccination. Spike-specific binding antibodies (bAbs) in all participants and neutralizing antibodies (nAbs) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) wild-type, Delta, and Omicron variants in CPs were analyzed and presented as the geometric mean titer. Results: Age-matched 20 HCWs and 118 CPs were included in the analysis. The bAb seroconversion rate and antibody concentrations after the first vaccination were significantly lower in CPs than in HCWs. After the third vaccination, antibody levels in CPs with a primary series of AdV were comparable to those in HCWs, but nAb titers against the Omicron variant did not quantitatively increase in CPs with AdV vaccine as the primary series. The incidence and severity of adverse reactions post-vaccination were similar between CPs and HCWs. Conclusion CPs displayed delayed humoral immune response after SARS-CoV-2 vaccination. The booster dose elicited comparable bAb concentrations between CPs and HCWs, regardless of the primary vaccine type. Neutralization against the Omicron variant was not robustly elicited following the booster dose in some CPs, implying the need for additional interventions to protect them from COVID-19.

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.