Response to the coronavirus disease 2019 pandemic of dental hygienists in South Korea-Part III: COVID-19 vaccination intentions.

OBJECTIVES: This cross-sectional study was to determine the coronavirus disease 2019 (COVID-19) vaccination intention of clinical dental hygienists in South Korea and the factors that influence vaccination intention. METHODS: COVID-19 vaccination intention of the 500 participants was confirmed through a survey including the following options: 'I will vaccinate (VAC)', 'I will not vaccinate (NoVAC)' and 'I do not know if I should get vaccinated (UNK)'. A Chi-square test was performed to determine whether there were differences in COVID-19 vaccination intention according to the general characteristics of the participants, degree of infection control knowledge (Score-K) and practice (Score-P) in response to COVID-19, fears over COVID-19 (Fear-C) and the level of anxiety before (GADBefore ) and after (GADAfter ) the COVID-19 pandemic. Multiple logistic regression was performed to identify factors affecting VAC and NoVAC by setting the base category as UNK. The p-values of <0.05 were considered statistically significant. RESULTS: According to the analysis, 44.8%, 18.8% and 36.4% of participants selected VAC, NoVAC and UNK respectively. There were significant differences in vaccination intention according to age, monthly income, residential area, symptoms related to COVID-19, Score-K, Fear-C and GADBefore . Compared to UNK, < $2000 monthly income, Score-K and Fear-C variables significantly influenced the opinion of VAC. Compared to the answer UNK, monthly incomes of $2000 to $2360 and $2360 to $2730 in residential areas significantly influenced the opinion of NoVAC. CONCLUSIONS: The variables influencing vaccination intention were monthly income, residential area, Score-K and Fear-C.

Effect of the coronavirus disease 2019 pandemic on oral health of Korean adolescents.

OBJECTIVES: To investigate the effect of the coronavirus disease (COVID-19) pandemic on Korean adolescents' oral health and identify the influential factors. METHODS: The raw data from The Korea Youth Risk Behaviour Web-based Survey before (2019) and after (2020) the outbreak of COVID-19 were used in the study. Demographic characteristics and subjective general, mental, and oral health were analysed and compared between the 2 years. Further, the impact of changes in subjective mental health and the duration of indoor activity on oral health were analysed. Data were analysed using IBM SPSS Statistics, and all statistical significance was set at α = 0.05. The analysis was performed using the complex sample analysis module. RESULTS: In 2020, compared with 2019, the proportion of adolescents who rated high on subjective academic performance, smoking, and drinking decreased (p < 0.001). However, there was no difference in the household economic status between 2020 and 2019 (p = 0.917), while subjective mental health improved. In addition, the risk of tooth fracture was 1.321 times higher after the pandemic. After the outbreak of COVID-19, adolescents who were indoors for >24 h for non-learning activities on weekends were 2.97 times more likely to have reported gingival pain and bleeding (p < 0.05). CONCLUSIONS: After the outbreak of COVID-19, smoking and drinking decreased in Korean adolescents, while changes occurred in their learning patterns at home, and their mental health improved. Some oral symptoms increased or showed no change.

Factors affecting the infection control behaviours of Korean dental hygienists in response to the coronavirus disease 2019 pandemic.

OBJECTIVES: This study aimed to identify the factors affecting the prevention of cross-infection with coronavirus disease-19 (COVID-19) among Korean dental hygienists. METHODS: The level of knowledge about COVID-19 (KNWCO ), level of awareness of infection control (AWRIC ), degree of performance for infection control (PRFIC ), and organizational factors for infection control (OFWIC ) of clinical dental hygienists in Korea to prevent COVID-19 transmission were investigated. A self-written online questionnaire was administered to dental hygienists currently working in dental clinics or hospitals, and the survey results of 263 participants were analysed. Pearson's correlation coefficients were calculated for relationships between the KNWCO , AWRIC , PRFIC , and OFWIC . Multiple linear regression analysis was performed to identify the factors affecting the PRFIC . Statistical significance was set at p < 0.05. RESULTS: Knowledge about COVID-19, AWRIC , PRFIC , and OFWIC were significantly correlated with each other. OFWIC (ß = 0.491, p < 0.001), followed by AWRIC (ß = 0.428, p < 0.001) and KNWCO (ß = 0.095, p = 0.013), had the greatest impact on PRFIC with regard to the prevention of COVID-19 transmission. CONCLUSIONS: Organizational factors for infection control and AWRIC should be strengthened to improve PRFIC and prevent COVID-19 transmission during dental care.

Response to the coronavirus disease 2019 pandemic of dental hygienists in South Korea-Part II: Fear and anxiety.

OBJECTIVES: The purpose of this cross-sectional study was to evaluate the mental fear and anxiety about coronavirus disease 2019 (COVID-19) among Korean clinical dental hygienists and to investigate factors influencing the anxiety felt after the outbreak of COVID-19. METHODS: A questionnaire on mental fear (Fear-C) and anxiety for COVID-19 was conducted among 500 clinical dental hygienists in South Korea. Fear-C was identified with eight questions. The General Anxiety Disorder-7 (GAD-7) questionnaire was scored for the pre-COVID-19 situation (GADBefore ) and the current situation going through the pandemic (GADAfter ). The scores for the responses to the questionnaire were 0 points for strong negative and 3 points for strong positive. Higher scores indicate higher levels of fear and anxiety. All data were analysed using IBM SPSS Statistics, and the statistical significance was set at α = 0.05. RESULTS: The average Fear-C was 16.11 ± 3.89 out of 24.00. There were significant differences in Fear-C when the type of work organization and symptoms related to COVID-19 (Sx-C) differed. Significant differences were confirmed in GADBefore according to age range, systemic diseases, and Sx-C (p < 0.05). There was no difference in GADAfter for all general characteristics, except Sx-C (p > 0.05). In the regression model of GADAfter , Sx-C (ß = 0.526), Fear-C (ß = 0.358), and GADBefore (ß = 0.515) were positively related to GADAfter (p < 0.001), respectively. CONCLUSIONS: Most dental hygienists complained of Fear-C. GADAfter was significantly higher than GADBefore . The factor that had the greatest impact on GADAfter was Sx-C.

A novel mechanism of Korean Red Ginseng-mediated anti-inflammatory action via targeting caspase-11 non-canonical inflammasome in macrophages.

Background: Korean Red Ginseng (KRG) was reported to play an anti-inflammatory role, however, previous studies largely focused on the effects of KRG on priming step, the inflammation-preparing step, and the anti-inflammatory effect of KRG on triggering, the inflammation-activating step has been poorly understood. This study demonstrated anti-inflammatory role of KRG in caspase-11 non-canonical inflammasome activation in macrophages during triggering of inflammatory responses. Methods: Caspase-11 non-canonical inflammasome-activated J774A.1 macrophages were established by priming with Pam3CSK4 and triggering with lipopolysaccharide (LPS). Cell viability and pyroptosis were examined by MTT and lactate dehydrogenase (LDH) assays. Nitric oxide (NO)-inhibitory effect of KRG was assessed using a NO production assay. Expression and proteolytic cleavage of proteins were examined by Western blotting analysis. In vivo anti-inflammatory action of KRG was evaluated with the LPS-injected sepsis model in mice. Results: KRG reduced LPS-stimulated NO production in J774A.1 cells and suppressed pyroptosis and IL-1ß secretion in caspase-11 non-canonical inflammasome-activated J774A.1 cells. Mechanistic studies demonstrated that KRG suppressed the direct interaction between LPS and caspase-11 and inhibited proteolytic processing of both caspase-11 and gasdermin D in caspase-11 non-canonical inflammasome-activated J774A.1 cells. Furthermore, KRG significantly ameliorated LPS-mediated lethal septic shock in mice. Conclusion: The results demonstrate a novel mechanism of KRG-mediated anti-inflammatory action that operates through targeting the caspase-11 non-canonical inflammasome at triggering step of macrophage-mediated inflammatory response.

Response to the coronavirus disease 2019 pandemic of dental hygienists in South Korea-Part â : Knowledge and practice of infection control.

OBJECTIVES: To evaluate infection control knowledge and its practice of clinical dental hygienists in response to Coronavirus Disease 2019 (COVID-19) in South Korea. METHODS: Nine questions (Q9-K) on the degree of knowledge acquisition of dental hygienists in response to COVID-19, and another 9 questions (Q9-P) on the practices for COVID-19 infection and spread prevention were prepared. From 500 clinical dental hygienists in South Korea, answers about their general characteristics, Q9-K, and Q9-P were collected. 1 point was given to each question based on the 'yes' answers from Q9-K and Q9-P, and Score-K and Score-P were calculated, respectively. To identify factors affecting Score-P, a multiple linear regression analysis was performed. In all analyses, p-values lower than 0.05 were considered statistically significant. RESULTS: Average scores of Score-K and Score-P were 7.36 ± 1.35 and 6.26 ± 2.07, respectively. The regression model of Score-P was significant (F = 20.788, p < 0.001). Concerning Score-P, Score-K (ß = 0.385), age (ß = 0.275), dental hospital (ß = 0.158), monthly income of $2,360~$2,730 (ß = 0.104) had a significantly positive correlation, and the total years of career (ß = -0.293) are found to have a significantly negative correlation. CONCLUSIONS: Infection control knowledge and practice of clinical dental hygienists in South Korea was found to be vulnerable in the group of hygienists who are younger than 27 years old, working in dental clinics, and whose monthly income is less than under $2,000. Also, the factor that influences infection control practice the most was the degree of knowledge. Therefore, continuous infection control education and supplement targeting these vulnerable groups are necessary.

Optical detection of the potential for tooth discoloration from children's beverages by quantitative light-induced fluorescence technology.

BACKGROUND: Some beverages are known to cause extrinsic staining on the tooth. This study investigated the degree of pigmentation caused by children's acidic beverages, and to confirm the possibility of the quantitative light-induced fluorescence (QLF) technology in assessing staining of the tooth. METHODS: Bovine tooth specimens were subjected to an 8-day pH-cycling model, using six children's beverages (experimental groups) and a cola (control group), and a remineralizing solution. Before and after the pH-cycling, white-light and fluorescence images of the enamel surface were photographed with a QLF to evaluate color change (ΔEafter) and fluorescence loss (ΔFafter), respectively. Paired t-test was used to compare the tooth colors obtained before and after the pH-cycling. Spearman correlation analysis was performed to examine the correlation between the ΔEafter and ΔFafter values. RESULTS: Median ΔEafter values of all the beverages ranged from 1.33 to 20.42, showing the greatest value in Koal-Koal Koala™ (KKK, p < 0.001). The ΔEafter was correlated with ΔFafter value negatively (ρ=-0.611, p < 0.001). The median ΔFafter varied by beverages (-38.86-0.00) and KKK caused the greatest value. CONCLUSIONS: The cola and 6 children's beverages showed the possibility for discoloration on the tooth. The QLF technology may enable monitoring the discoloration induced on the tooth surface by acidic beverage.

Effect of Using an 8-Figure Shoulder Brace on Posture and Muscle Activities during the Performance of Dental Hygiene Procedures.

The incidence of work-related musculoskeletal disorders (MSDs) among dental workers has been increasing. Many ergonomic devices and accessories have been introduced. The aim of this study was to investigate the effects of an 8-figure shoulder brace on posture-related muscle activities in dental hygiene practitioners during scaling procedures. In this study, 33 participants (age: 21.9 ± 2.1 years, height: 162.0 ± 6.0 cm, weight: 55.8 ± 9.0 kg, body mass index: 21.2 ± 2.4 kg/m2) performed the scaling procedure with and without the 8-figure shoulder brace in a randomized order. The normalized electromyography activity in the amplitude probability distribution function and joint angles (cervical, thoracic, lumbar, and shoulder joints) were simultaneously recorded during scaling. A paired t test was used to compare the differences in muscle kinematics, with the alpha level set at 0.05. The dental hygienists who wore the 8-figure shoulder brace during scaling showed thoracic and lumbar extension, improved sitting postures, and reduced shoulder joint abduction. However, we also observed an unintended increase in internal rotation. Use of the 8-figure shoulder brace could prevent work-related MSDs in lumbar and thoracic regions by reducing the effort exerted by the upper trapezius and deltoid muscles, despite the increased muscular effort of the cervical erector spinae.

Assessment of Cellular Uptake Efficiency According to Multiple Inhibitors of Fe3O4-Au Core-Shell Nanoparticles: Possibility to Control Specific Endocytosis in Colorectal Cancer Cells.

Magnetite (Fe3O4)-gold (Au) core-shell nanoparticles (NPs) have unique magnetic and optical properties. When combined with biological moieties, these NPs can offer new strategies for biomedical applications, such as drug delivery and cancer targeting. Here, we present an effective method for the controllable cellular uptake of magnetic core-shell NP systems combined with biological moieties. Vimentin, which is the structural protein, has been biochemically confirmed to affect phagocytosis potently. In addition, vimentin affects exogenic materials internalization into cells even though under multiple inhibitions of biological moieties. In this study, we demonstrate the cellular internalization performance of Fe3O4-Au core-shell NPs with surface modification using a combination of biological moieties. The photofluorescence of vimentin-tagged NPs remained unaffected under multiple inhibition tests, indicating that the NPs were minimally influenced by nystatin, dynasore, cytochalasin D, and even the Muc1 antibody (Ab). Consequently, this result indicates that the Muc1 Ab can target specific molecules and can control specific endocytosis. Besides, we show the possibility of controlling specific endocytosis in colorectal cancer cells.

The effects of discrete and gradient mid-shell structures on the photoluminescence of single InP quantum dots.

We investigated the dependence of the spectral diffusion and blinking behaviors of indium phosphide (InP) based core/shell/shell quantum dots (QDs) on their mid-shell compositions. We synthesized two types of core/shell/shell QDs having different mid-shell structures by controlling the shell thickness, the total sizes, and the selenium to sulfur ratios. The QDs with a discrete mid-shell (DS-QDs) exhibited a higher photoluminescence (PL) quantum yield (QY) and a narrower PL linewidth than the QDs with a gradient mid-shell (GS-QDs). By analyzing X-ray diffraction (XRD) patterns, and Raman spectra, we found that GS-QDs showed a larger lattice mismatch between the core and the shell than DS-QDs. Also, the spectral diffusion, PL blinking, Auger ionization efficiencies, and the lifetime blinking behavior on single QDs revealed that DS-QDs were nearly unaffected by the defect traps.

Validity and Reliability of an Inertial Measurement Unit-based 3-Dimensional Angular Measurement of Cervical Range of Motion.

OBJECTIVE: This study aimed to assess the reliability and validity of an inertial measurement unit (IMU)-based 3-dimensional (3D) angular measurement system for evaluating cervical range of motion. METHODS: Thirty-three healthy participants (21.9 ± 2.1 years; 162.0 ± 6.0 cm; 55.8 ± 9.0 kg; 21.2 ± 2.4 kg/m2) were evaluated. Kinematic data of the cervical joints were simultaneously obtained using the IMU 3D angular, goniometer, and photographic measurements during cervical flexion (0°, 30°, and 50°), extension (30°, 50°), side-bending (0°, 20°, 40°), and rotation (45°). Test-retest reliability was investigated in each measurement method. Concurrent validity was assessed with the direct comparison between the IMU 3D angular measurement and other methods. RESULTS: The IMU 3D angular measurement showed mostly good to high test-retest reliability with relatively small standard error of measurement and the minimal detectable change values. The concurrent validity of IMU 3D angular measurements in the cervical range of motion was mostly reasonable. However, the measurement bias between the 2 methods tended to be larger at the end range of each plane. CONCLUSION: Using the IMU 3D angular measurement in cervical spine is recommended because of its mostly good to high reliability and reasonable validity. However, using the IMU 3D angular measurement at the end range of each plane should be carefully considered owing to the poorer validity.

Evaluation of resin infiltration using quantitative light-induced fluorescence technology.

OBJECTIVES: To determine whether quantitative light-induced fluorescence (QLF) technology can be used to classify the colour of teeth specimens before and after resin infiltration (RI) treatment, and calculate the correlation between the ΔF value and colour difference (ΔE) in fluorescence images of the specimens obtained using a QLF-digital (QLF-D) device. METHODS: Sixty sound bovine permanent teeth specimens were immersed in demineralized solution. Two exposed windows were formed in each specimen, and RI treatment was applied to one of them. The ΔE values were obtained for the differences between a sound tooth surface (SS), an early dental caries surface (ECS) and an ECS treated with RI (RS) in white-light and fluorescence images obtained using QLF-D, respectively. The ΔF value was obtained from fluorescence images using dedicated software for QLF-D. The mean differences between the ΔE values obtained from the white-light and fluorescence images were analyzed by paired t-test. Pearson correlation analysis and Bland-Altman plots were applied to the differences between the ΔF value for ECS (ΔFSS-ECS) and the ΔE value between SS and ECS (ΔESS-ECS), and between the ΔF value for RS (ΔFSS-RS) and the ΔE value between SS and RS (ΔESS-RS) in fluorescence images. RESULTS: The ΔE values obtained from fluorescence images were three times higher than the ΔE values obtained from white-light images (p<0.001). Significant correlations were confirmed between ΔESS-ECS and ΔFSS-ECS (r=-0.492, p<0.001) and between ΔESS-RS and ΔFSS-RS (r=-0.661, p<0.001). CONCLUSION: QLF technology can be used to confirm the presence of RI in teeth.

Resveratrol inhibits collagen-induced platelet stimulation through suppressing NADPH oxidase and oxidative inactivation of SH2 domain-containing protein tyrosine phosphatase-2.

Reactive oxygen species (ROS) produced upon collagen stimulation are implicated in propagating various platelet-activating pathways. Among ROS-producing enzymes, NADPH oxidase (NOX) is largely responsible for collagen receptor-dependent ROS production. Therefore, NOX has been proposed as a novel target for the development of antiplatelet agent. We here investigate whether resveratrol inhibits collagen-induced NOX activation and further examine the effects of resveratrol on ROS-dependent signaling pathways in collagen-stimulated platelets. Collagen-induced superoxide anion production in platelets was inhibited by resveratrol. Resveratrol suppressed collagen-induced phosphorylation of p47(phox), a major regulatory subunit of NOX. Correlated with the inhibitory effects on NOX, resveratrol protected SH2 domain-containing protein tyrosine phosphatase-2 (SHP-2) from ROS-mediated inactivation and subsequently attenuated the specific tyrosine phosphorylation of key components (spleen tyrosine kinase, Vav1, Bruton's tyrosine kinase, and phospholipase Cγ2) for collagen receptor signaling cascades. Resveratrol also inhibited downstream responses such as cytosolic calcium elevation, P-selectin surface exposure, and integrin-αIIbß3 activation. Furthermore, resveratrol inhibited platelet aggregation and adhesion in response to collagen. The antiplatelet effects of resveratrol through the inhibition of NOX-derived ROS production and subsequent oxidative inactivation of SHP-2 suggest that resveratrol is a potential compound for prevention and treatment of thrombovascular diseases.

Peroxiredoxin II is an antioxidant enzyme that negatively regulates collagen-stimulated platelet function.

Collagen-induced platelet signaling is mediated by binding to the primary receptor glycoprotein VI (GPVI). Reactive oxygen species produced in response to collagen have been found to be responsible for the propagation of GPVI signaling pathways in platelets. Therefore, it has been suggested that antioxidant enzymes could down-regulate GPVI-stimulated platelet activation. Although the antioxidant enzyme peroxiredoxin II (PrxII) has emerged as having a role in negatively regulating signaling through various receptors by eliminating H2O2 generated upon receptor stimulation, the function of PrxII in collagen-stimulated platelets is not known. We tested the hypothesis that PrxII negatively regulates collagen-stimulated platelet activation. We analyzed PrxII-deficient murine platelets. PrxII deficiency enhanced GPVI-mediated platelet activation through the defective elimination of H2O2 and the impaired protection of SH2 domain-containing tyrosine phosphatase 2 (SHP-2) against oxidative inactivation, which resulted in increased tyrosine phosphorylation of key components for the GPVI signaling cascade, including Syk, Btk, and phospholipase Cγ2. Interestingly, PrxII-mediated antioxidative protection of SHP-2 appeared to occur in the lipid rafts. PrxII-deficient platelets exhibited increased adhesion and aggregation upon collagen stimulation. Furthermore, in vivo experiments demonstrated that PrxII deficiency facilitated platelet-dependent thrombus formation in injured carotid arteries. This study reveals that PrxII functions as a protective antioxidant enzyme against collagen-stimulated platelet activation and platelet-dependent thrombosis.

Kaempferol suppresses collagen-induced platelet activation by inhibiting NADPH oxidase and protecting SHP-2 from oxidative inactivation.

Reactive oxygen species (ROS) generated upon collagen stimulation act as second messengers to propagate various platelet-activating events. Among the ROS-generating enzymes, NADPH oxidase (NOX) plays a prominent role in platelet activation. Thus, NOX has been suggested as a novel target for anti-platelet drug development. Although kaempferol has been identified as a NOX inhibitor, the influence of kaempferol on the activation of platelets and the underlying mechanism have never been investigated. Here, we studied the effects of kaempferol on NOX activation, ROS-dependent signaling pathways, and functional responses in collagen-stimulated platelets. Superoxide anion generation stimulated by collagen was significantly inhibited by kaempferol in a concentration-dependent manner. More importantly, kaempferol directly bound p47(phox), a major regulatory subunit of NOX, and significantly inhibited collagen-induced phosphorylation of p47(phox) and NOX activation. In accordance with the inhibition of NOX, ROS-dependent inactivation of SH2 domain-containing protein tyrosine phosphatase-2 (SHP-2) was potently protected by kaempferol. Subsequently, the specific tyrosine phosphorylation of key components (Syk, Vav1, Btk, and PLCγ2) of collagen receptor signaling pathways was suppressed by kaempferol. Kaempferol also attenuated downstream responses, including cytosolic calcium elevation, P-selectin surface exposure, and integrin-αIIbß3 activation. Ultimately, kaempferol inhibited platelet aggregation and adhesion in response to collagen in vitro and prolonged in vivo thrombotic response in carotid arteries of mice. This study shows that kaempferol impairs collagen-induced platelet activation through inhibition of NOX-derived ROS production and subsequent oxidative inactivation of SHP-2. This effect suggests that kaempferol has therapeutic potential for the prevention and treatment of thrombovascular diseases.

The toxicity and distribution of iron oxide-zinc oxide core-shell nanoparticles in C57BL/6 mice after repeated subcutaneous administration.

Therapeutic cancer vaccines promote immune responses by delivering tumour-specific antigens. Recently, we developed iron oxide (Fe3 O4 )-zinc oxide (ZnO) core-shell nanoparticles (CSNPs) as carriers for antigen delivery into dendritic cells (DCs), and the CSNPs were injected subcutaneously into C57BL/6 mice to examine the systemic toxicity, tissue distribution and excretion of the CSNPs. The doses injected were 0, 4, 20 and 200 mg kg(-1) weekly for 4 weeks. No significant changes were observed after the CSNPs administration with respect to mortality, clinical observations, body weight, food intake, water consumption, urinalysis, haematology, serum biochemistry,and organ weights. A dose-dependent increase in granulomatous inflammation was observed at the injection site of the CSNP-treated animals, but no other histopathological lesions in other organs could be attributed to the CSNPs. The Zn concentration, which is an indicator for CSNPs, was not significantly higher in the sampled tissues, urine, or faeces after the CSNP injection. In contrast, the Zn concentration at the subcutaneous skin of the site injected with the CSNPs increased in a dose-dependent manner, along with a macroscopic deposition of the CSNPs. The CSNP residue at the injection site resulted in a foreign body response with the appearance of macrophage infiltration, but otherwise did not show any systemic distribution or toxicity at up to 200 mg kg(-1) during this study. In conclusion, CSNPs could be used as good antigen carriers for DC-based immunotherapy, although further study is needed to completely clear the residue of the CSNPs at the injection site.

Prevention of dental erosion of a sports drink by nano-sized hydroxyapatite in situ study.

AIM: To evaluate the inhibitory effects of the sports drink containing nano-sized hydroxyapatite (nano-HA) on dental erosion in situ. DESIGN: The study had a single-blind, two-treatment crossover design. The two treatment groups were a control group (CG; Powerade only) and an experimental group (EG; 0.25% wt/vol nano-HA was added to Powerade). Ten subjects wore removable palatal appliances containing bovine enamel specimens. The appliances were immersed in each drink for 10 mins, 4 times a day for 10 days. The tooth surface microhardness (SMH) was tested, and the erosion depth and the morphology of the tooth surface were observed. The data were analysed by repeated measures anova and t-test. RESULTS: Between the baseline and the 10th day, SMH was decreased by 80% in the specimens of the CG (P < 0.001), whereas there was only a 6% decrease in the SMH of the specimens in the EG. An erosion depth of 12.70 ± 4.66 µm and an irregular tooth surface were observed on the 10th day in the specimens of the CG. No dental erosions, however, was observed in the specimens of the EG. CONCLUSIONS: The sports drink containing 0.25% nano-HA was effective in preventing dental erosion in situ.

Modification of surface pretreatment of white spot lesions to improve the safety and efficacy of resin infiltration.

OBJECTIVE: A low-viscosity resin (infiltrant) was used to inhibit the progression of white spot lesions (WSLs) and resolve associated esthetic issues. An alternative pretreatment was explored to increase the pore volume of the surface layer of the WSLs. Also, the penetration effects of the infiltrant were evaluated for various pretreatments. METHODS: Sixty two artificial lesions were fabricated on bovine teeth. As a positive control, 15% HCl gel was applied for 120 seconds. Further, 37% H3PO4 gel was applied for 30 seconds using three methods. The samples were divided as follows: H3PO4 only group, H3PO4 sponge group, and H3PO4 brush group. The acid was gently rubbed with the applicators (i.e., a sponge or brush) throughout the application time. To compare the effects of resin infiltration, twenty paired halves of specimens were treated with an infiltrant (ICON®). RESULTS: Thicknesses of the removed surface layers and infiltrated areas were evaluated by confocal laser scanning microscope. The positive control and the 37% H3PO4 brush group failed to show significant differences in the removed thickness (p > 0.05); however, the mean percentage of the infiltrated area was higher in the 37% H3PO4 brush group (84.13 ± 7.58%) than the positive control (63.51 ± 7.62%, p < 0.001). Scanning electron microscope observations indicate higher pore volumes for the 37% H3PO4 brush group than for the positive control. CONCLUSIONS: Application of 37% H3PO4 with a brush for 30 seconds increased the pore volume of WSL surface layers and the percentage of infiltrated areas in comparison to the use of 15% HCl for 120 seconds.

Isolation of DNA using magnetic nanoparticles coated with dimercaptosuccinic acid.

Lately, the isolation of DNA using magnetic nanoparticles has received increased attention owing to their facile manipulation and low costs. Although methods involving their magnetic separation have been extensively studied, there is currently a need for an efficient technique to isolate DNA for highly sensitive diagnostic applications. We describe herein a method to isolate and purify DNA using biofunctionalized superparamagnetic nanoparticles synthesized by a modified polyol method to obtain the desired monodispersity, followed by surface modification with meso-2,3-dimercaptosuccinic acid (DMSA) containing carboxyl groups for DNA absorption. The DMSA-coated magnetic nanoparticles (DMSA-MNPs) were used for the isolation of DNA, with a maximum yield of 86.16%. In particular, we found that the isolation of DNA using small quantities of DMSA-MNPs was much more efficient than that using commercial microbeads (NucliSENS-easyMAG, BioMérieux). Moreover, the DMSA-MNPs were successfully employed in the isolation of genomic DNA from human blood. In addition, the resulting DNA-nanoparticle complex was directly subjected to PCR amplification without prior elution, which could eventually lead to simple, rapid, sensitive and integrated diagnostic systems.

Magnetic nanodiscs fabricated from multilayered nanowires.

We report a simple, high throughput synthesis method of producing magnetic nanodiscs, in which the diameter and thickness are easily controlled. This method consists of two steps: (1) Electrodeposition for growing multilayered nanowires and (2) Selective etching of sacrificial layers. The electrodeposition step results in a bundle of multilayered nanowires. The nanowires consist of alternating layers of magnetic (e.g., Co) and sacrificial materials (e.g., Cu) inside the nanometer-sized pores of an anodized aluminum oxide (AAO) template. The diameter of each layer is determined by pore size, while the thickness is controlled by electrodeposition time. The selective wet etching step removes sacrificial layers, leaving the magnetic nanodiscs. Through this process, the magnetic nanodiscs are fabricated with aspect ratios ranging from 0.25 to 2.0.