Three‐electrode plasma jet system consisting of a perforated dielectric tube with two outer and one floating inner electrodes was developed and employed for tooth bleaching. Lowered gas breakdown voltage and increased discharge current were achieved by using the floating inner electrode. Optical emission spectra analysis showed that the rotational temperature of the second positive nitrogen bands was ≈290 K and vibrational temperature was ≈2 500 K, which means this plasma is in highly non‐quilibrium state and nonthermal. The presence of excited He, N2, N 2+ and O in the plasma plume was revealed. The plasma jet was used in combination with hydrogen peroxide (H2O2) to remove stains from extracted teeth stained by either coffee or red wine. Combining the plasma jet and H2O2 improved the bleaching efficacy by a factor of 3.1 (coffee) and 3.7 (red wine) compared with using H2O2 alone.

Light-activated tooth bleaching with a high hydrogen peroxide (HP; H2O2) concentration has risks and the actual role of the light source is doubtful. The use of conventional light might result in an increase in the temperature and cause thermal damage to the health of the tooth tissue.Objective:This study investigated the efficacy of tooth bleaching using non-thermal atmospheric pressure plasma (NAPP) with 15% carbamide peroxide (CP; CH6N2O3) including 5.4% HP, as compared with conventional light sources. Material and Methods:Forty human teeth were randomly divided into four groups: Group I (CP+NAPP), Group II (CP+plasma arc lamp; PAC), Group III (CP+diode laser), and Group IV (CP alone). Color changes (ΔE ) of the tooth and tooth surface temperatures were measured. Data were evaluated by one-way analysis of variance (ANOVA) and post-hoc Tukey's tests. Results:Group I showed the highest bleaching efficacy, with a ΔE value of 1.92-, 2.61 and 2.97-fold greater than those of Groups II, III and IV, respectively (P<0.05). The tooth surface temperature was maintained around 37ºC in Group I, but it reached 43ºC in Groups II and III. Conclusions:The NAPP has a greater capability for effective tooth bleaching than conventional light sources with a low concentration of HP without causing thermal damage. Tooth bleaching using NAPP can become a major technique for in-office bleaching in the near future.

The application of nonthermal atmospheric pressure plasma to intracoronal bleaching could be a novel and efficient therapy in the bleaching of haemorrhagically stained teeth.

The conventional light source used for tooth bleaching has the potential to cause thermal damage, and the actual role of the light source is doubtful. In this study, we evaluated bleaching efficacy, temperature, and morphological safety after tooth bleaching with nonthermal atmospheric pressure plasma. Tooth bleaching combined with plasma had improved efficacy in providing a higher level of brightness. The temperature of the pulp chamber was maintained around 37°C, indicating that the plasma does not cause any thermal damage. The morphological results of tooth bleaching with plasma did not affect mineral composition under scanning electron microscopy (SEM) observations. On the basis of these results, the application of plasma and low concentration of 15% carbamide peroxide (CP) has a high capability for effective tooth bleaching. It can be documented that plasma is a safe energe source, which has no deleterious effects on the tooth surface.

10–20% of COVID (Corona Virus Disease)-19 cases proceed to a severe stage, and age and the presence of comorbidity increased the risk of death from COVID-19. The identification of risk factors on progression to the severity stages is essential in providing more efficient and suitable management to COVID-19 patients. However, there is insufficient study on risk factors for severity stages of COVID-19 patients. In this study, 2959 confirmed COVID-19 patients were analyzed while using national data, COVID-19 patients Clinical Epidemiological Information provided from the Korea Disease Control and Prevention Agency. The epidemiological variable, hospital room, periods from confirmation to release, initial symptom and vital signs, underlying comorbidities, and initial blood variables were used to verify the relation with progression to severity stages of COVID-19 and severe COVID-19. The chi-square test, welch test, multiple regression and logistic regression analysis were performed. The ICU (Intensive Care Unit) admission rate of patients having characteristics, such as older age, male, abnormal BMI (Body Mass Index), high heart rate, high body temperature, fever, cough, sputum, sore throat, rhinorrhea, fatigue, dyspnea, change of consciousness, diabetes mellitus, hypertension, chronic artery disease, chronic kidney disease, cancer, dementia, abnormal hemoglobin, abnormal hematocrit, abnormal lymphocyte, abnormal platelets, and abnormal white blood cell were high. The risk factors for severe COVID-19 were older age, shorter hospitalization, abnormal lymphocyte, abnormal platelets, dyspnea, change of consciousness, and dementia. Whereas, significant predictors for progression to severity stages of COVID-19 were older age, longer period from confirmation to release, higher BMI, higher body temperature, abnormal lymphocyte, abnormal platelets, fever, no sore throat, dyspnea, no headache, COPD (Chronic Obstructive Pulmonary Disease), and dementia. Therefore, classifying patients with a high risk of severe stage of COVID-19 and managing patients by considering the risk factors could be helpful in the efficient management of COVID-19 patients.

It is well known that periodontal disease is highly related to dietary habits. As coffee is a typical beverage consumed worldwide, the relationship between coffee and periodontal disease was analyzed in this study using the data from the Korean National Health and Nutrition Survey (KNHANES) 2013–2015. Complex-samples chi square tests were performed for the comparison of the demographic characteristics of the 6528 study subjects and coffee components. Poisson linear regression analysis was performed for the analysis of the periodontal condition and coffee component effects, while complex-samples logistic regression analysis was performed to determine the demographic characteristics and coffee component effects. Over the years, the proportion of people drinking coffee with syrup or drinking a coffee mix containing both syrup and cream has decreased significantly. The results of the analysis, conducted by integrating the study subjects’ demographic characteristics and the coffee components, showed that the prevalence of periodontal disease was 0.83-times lower when drinking coffee with cream than when drinking black coffee. Coffee is the world’s second largest trade commodity following oil, and about 70%–80% of the world’s population drinks coffee. Drinking coffee with milk or cream can have a beneficial impact on periodontal disease.

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Background: Weissella cibaria CMU (oraCMU) has been commercially available in the market for several years as oral care probiotics. The present study aimed to evaluate the effects of oraCMU-containing tablets on periodontal health and oral microbiota. Methods: A randomised, double-blind, placebo-controlled trial was conducted in 92 adults without periodontitis (20-39 years of age). All subjects received dental scaling and root planing, and were randomly assigned to either probiotic or placebo groups. The tablets were administered once daily for 8 weeks. Periodontal clinical parameters included bleeding on probing (BOP), probing depth (PD), gingival index (GI), and plaque index (PI). In addition, microbiota in the gingival sulcus were analysed. Results: BOP improved more in the probiotic group over 8 weeks. There were statistically significant differences in BOP of the maxilla buccal and lingual sites between the groups during the intervention (P < 0.05). No significant inter-group differences in PD, GI, and PI were observed during the intervention. Oral bacteria were observed to be fewer in the probiotic group. There was a significant change in levels of Fusobacterium nucleatum at four and 8 weeks between the two groups. Besides, there were significant differences at 8 weeks in levels of Staphylococcus aureus. Conclusions: We reported an improvement in BOP and microbial environment and demonstrated the antimicrobial activity of oraCMU against F. nucleatum. Thus, its supplementation may contribute to overall oral health. Trial registration: Ethical issues approved by the Kangwon National University Institutional Review Board with a number of KWNUIRB-2018-05-003-005 and CRIS code Number of KCT0005078 were retrospectively registered on 06/02/2020. This study was conducted in the period of July to November 2018.