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.

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.

Time-restricted feeding (TRF), devoid of calorie restriction, is acknowledged for promoting metabolic health and mitigating various chronic metabolic diseases. While TRF exhibits widespread benefits across multiple tissues, there is limited exploration into its impact on kidney function. In this study, our aim was to investigate the potential ameliorative effects of TRF on kidney damage in a mouse model of cisplatin-induced acute kidney injury (AKI). Methods: Cisplatin-induced AKI was induced through intraperitoneal injection of cisplatin into C57BL/6 male mice. Mice undergoing TRF were provided unrestricted access to standard chow daily but were confined to an 8-hour feeding window during the dark cycle for 2 weeks before cisplatin injection. The mice were categorized into four groups: control, TRF, cisplatin, and TRF + cisplatin. Results: The tubular damage score and serum creatinine levels were significantly lower in the TRF + cisplatin group compared to the cisplatin group. The TRF + cisplatin group exhibited reduced expression of phosphorylated nuclear factor kappa B, inflammatory cytokines, and F4/80-positive macrophages compared to the cisplatin group. Furthermore, oxidative stress markers for DNA, protein, and lipid were markedly decreased in the TRF + cisplatin group compared to the cisplatin group. TUNEL-positive tubular cells, cleaved caspase-3 expression, and the Bax/Bcl-2 ratio in the TRF + cisplatin group were lower than those in the cisplatin group. Conclusion: TRF, without calorie restriction, effectively mitigated kidney damage by suppressing inflammatory reactions, oxidative stress, and tubular apoptosis in a mouse model of cisplatin-induced AKI. TRF holds promise as a novel dietary intervention for preventing cisplatin-induced AKI.

Background: Occupational allergic contact dermatitis accounts for about half of all occupational skin diseases. Patch testing is essential for establishing a diagnosis of occupational allergic contact dermatitis. To date, allergic contact dermatitis caused by seawater has rarely been reported. Objective: The aim of this study was to investigate the patch test results of seawater in foreign maritime workers. Methods: We retrospectively reviewed the clinical photos and medical records of patients who underwent the patch test with the Korean standard series and sea-water at Uijeongbu St. Mary’s Hospital and St. Vincent’s Hospital from January 2017 to August 2020. Results: A total of 26 patients were enrolled in the study. All patients were men with a median age of 26.5 years.Twenty-five patients were Sri Lankan, and 25 patients (96.2%) showed a positive reaction to seawater. Patients showed positive reactions with multiple allergens (average: 4), and the positive rates were higher than those reported in previous studies. Atypical reactions, such as pricking patterns or erosive patches, have been observed. A marked erosive reaction was observed even at the site without allergen attachment in a patient who showed a negative reaction to seawater. Conclusion These results suggest the possibility of artificially inducing positive reactions to seawater in maritime workers. Therefore, it is necessary to identify atypical reactions and confirm the relationship between positive reactions and medical history when judging contact dermatitis with unknown substances such as seawater. This study emphasizes education on the standardization of the reading of results.

Objective: This study aims to investigate the prevalence and psychological impact of social isolation and loneliness in South Korea. Loneliness and social isolation have been regarded as a risk to both physical and mental health. However, most studies have focused on the elderly; hence, there are limited studies on the characteristics of socially isolated or lonely people considering age. Methods: A sample of 1,700 participants was selected from three major cities in South Korea. In-person interviews were conducted to evaluate loneliness, social isolation and mental health status. Results: Among the participants, the prevalence of social isolation and loneliness was 17.8% and 4.1%, respectively. Males decreased the odds of loneliness (AOR 0.49, 95% CI=0.28–0.87), while increasing the odds of social isolation (AOR 1.44, 95% CI=1.12–1.86) after adjusting for age and sex. Greater depressive and social phobic symptoms were associated with increased odds of loneliness and social isolation. Conclusion Social isolation and loneliness are prevalent among Koreans and associated with depression, social phobic symptoms, and suicidality. This study provides a foundation for further research to investigate nationwide prevalence and a more in-depth analysis of loneliness and social isolation.

Purpose: This cross-sectional study aimed to identify factors affecting coronavirus disease 2019 (COVID-19) vaccination intention. Methods: For an anonymous online survey, recruitment notices were posted on an anonymous community by each university, and an online survey was conducted through online form from June to July 2021. COVID-19 knowledge and health-protective behavior were measured using a questionnaire based on previous literature and reflecting the Korea Centers for Disease Control and Prevention’s COVID-19 Response Guidelines. The psychological antecedents of vaccination were measured by 5C scale. Results: Two-hundred and ninety-four college students (women 67.3%) answered the survey; 179 (60.9%) reported that they would accept a COVID-19 vaccine. The mean scores for COVID-19 knowledge and health-protective behavior were 22.97 ± 5.33 (out of 35) and 9.92 ± 2.22 (out of 12), respectively. For the psychological antecedents of vaccination, the mean scores for confidence, collective responsibility, calculation, complacency, and constraints were 4.45 ( ± 1.24), 5.61 ( ± 1.09), 5.09 ( ± 1.18), 2.42 ( ± 1.11), and 2.37 ( ± 1.19) out of 5 points, respectively. The confidence, calculation, and collective responsibility were associated with vaccination intention. Additionally, the top reason for those who were less prone to accept vaccination against COVID-19 was concern about vaccine safety. Conclusion The higher the confidence in the vaccine and the higher the collective responsibility, the higher the vaccination intention. As it is a factor related to an individual’s perception of COVID-19 information, it is necessary to increase confidence in the vaccines through obtaining accurate information on the safety, effectiveness, and side effects of the COVID-19 vaccines and vaccination.

Background: Occupational allergic contact dermatitis accounts for about half of all occupational skin diseases. Patch testing is essential for establishing a diagnosis of occupational allergic contact dermatitis. To date, allergic contact dermatitis caused by seawater has rarely been reported. Objective: The aim of this study was to investigate the patch test results of seawater in foreign maritime workers. Methods: We retrospectively reviewed the clinical photos and medical records of patients who underwent the patch test with the Korean standard series and sea-water at Uijeongbu St. Mary’s Hospital and St. Vincent’s Hospital from January 2017 to August 2020. Results: A total of 26 patients were enrolled in the study. All patients were men with a median age of 26.5 years.Twenty-five patients were Sri Lankan, and 25 patients (96.2%) showed a positive reaction to seawater. Patients showed positive reactions with multiple allergens (average: 4), and the positive rates were higher than those reported in previous studies. Atypical reactions, such as pricking patterns or erosive patches, have been observed. A marked erosive reaction was observed even at the site without allergen attachment in a patient who showed a negative reaction to seawater. Conclusion These results suggest the possibility of artificially inducing positive reactions to seawater in maritime workers. Therefore, it is necessary to identify atypical reactions and confirm the relationship between positive reactions and medical history when judging contact dermatitis with unknown substances such as seawater. This study emphasizes education on the standardization of the reading of results.

Objective: This study aims to investigate the prevalence and psychological impact of social isolation and loneliness in South Korea. Loneliness and social isolation have been regarded as a risk to both physical and mental health. However, most studies have focused on the elderly; hence, there are limited studies on the characteristics of socially isolated or lonely people considering age. Methods: A sample of 1,700 participants was selected from three major cities in South Korea. In-person interviews were conducted to evaluate loneliness, social isolation and mental health status. Results: Among the participants, the prevalence of social isolation and loneliness was 17.8% and 4.1%, respectively. Males decreased the odds of loneliness (AOR 0.49, 95% CI=0.28–0.87), while increasing the odds of social isolation (AOR 1.44, 95% CI=1.12–1.86) after adjusting for age and sex. Greater depressive and social phobic symptoms were associated with increased odds of loneliness and social isolation. Conclusion Social isolation and loneliness are prevalent among Koreans and associated with depression, social phobic symptoms, and suicidality. This study provides a foundation for further research to investigate nationwide prevalence and a more in-depth analysis of loneliness and social isolation.

As an alternative to the conventional fixed appliance that uses orthodontic brackets, a simple round tube without a bonding base can be bonded to the tooth surface by covering the tube with flowable resin. In this technique, bent wires cannot be inserted into the simple tubes; therefore, repositioning of the simple tubes is often required for adjustments. To reduce repositioning of simple tubes, a dome-shaped resin covering of the simple tube can be designed with a customized in-and-out compensation, using three-dimensional computer-aided design software based on digital simulation of orthodontic tooth movement. In the present case, the use of simple tubes bonded with customized resin coverings in a Class I nonextraction case is described in a 17-year-old male, in whom moderate crowding of the anterior teeth was treated over an 8-month period. This case shows that simple tubes can be used as an alternative to brackets in some Class I nonextraction cases, with the potential benefit of reducing decalcification.