The dental COVID-19 paradox: Disparity in behaviors inside and outside dental schools in Canada.

OBJECTIVE: To describe the personal and professional behavior and assess the perceptions of protection and fear of contracting coronavirus disease 2019 (COVID-19) among faculty, staff, and students from all 10 Canadian dental schools during the second year of the pandemic. METHOD: Participants from a Pan-Canadian prospective study answered monthly questionnaires about their activities between April 2021 and March 2022. In May 2022, additional questions were asked about their perception of protection, fear of infection, and instances of COVID-19 testing. RESULTS: Six hundred participants were initially recruited. Over time, the participants spent less time at home and increased their participation in indoor social activities, a trend influenced by the fluctuations in COVID-19 cases (ß = â€’0.02). Over 90% of the participants were fully vaccinated, which decreased their fear of contracting the virus (χ2[4, 241‒243] = 196.07, p < 0.0001). Yet, their attitude toward protective measures did not change, and they followed them within school. CONCLUSIONS: This work shows a paradoxical behavior among dental students, staff, and faculty members in Canadian dental schools. While factors such as the vaccine's limited efficacy and a desire to protect others may contribute to stringent protective behaviors within dental schools, the mandatory nature of these measures was likely the primary motivator for the compliance. Despite potential efforts to minimize exposure to the virus during risk periods and the frequent COVID-19 testing, this paradoxical behavior raises questions about professional responsibilities extending beyond the workplace. Thus, dental schools should incorporate education about the rationale behind following different protocols and the potential consequences of outside school behaviors.

Microstructure and Mechanical Behavior Comparison between Cast and Additive Friction Stir-Deposited High-Entropy Alloy Al0.35CoCrFeNi.

High-entropy alloys (HEAs) are new alloy systems that leverage solid solution strengthening to develop high-strength structural materials. However, HEAs are typically cast alloys, which may suffer from large as-cast grains and entrapped porosity, allowing for opportunities to further refine the microstructure in a non-melting near-net shape solid-state additive manufacturing process, additive friction stir deposition (AFSD). The present research compares the microstructure and mechanical behavior of the as-deposited AFSD Al0.35CoCrFeNi to the cast heat-treated properties to assess its viability for structural applications for the first time. Scanning electron microscopy (SEM) revealed the development of fine particles along the layer interfaces of the deposit. Quasi-static and intermediate-rate compression testing of the deposited material revealed a significant strain-rate sensitivity with a difference in yield strength of ~400 MPa. Overall, the AFSD process greatly reduced the grain size for the Al0.35CoCrFeNi alloy and approximately doubled the strength at both quasi-static and intermediate strain rates.

Investigating the perceptions and experiences of Canadian dentists on dental regulatory bodies' communications and guidelines during the COVID-19 pandemic.

OBJECTIVE: Dental regulatory bodies aim to ensure the health and safety of dentists, dental staff patients and the public. An important responsibility during a pandemic is to communicate risk and guidelines for patient care. Limited data exist on the perceptions and experiences of dentists navigating new guidelines for mitigating risk in dental care during the pandemic. The objective of this study was to use a qualitative approach to explore how dentists in Canada experienced and perceived their regulatory bodies' communication about COVID-19 risks and guidelines during the pandemic. METHODS: Participants were Canadian dentists (N = 644) recruited through the email roster of nine provincial dental associations or regulatory bodies. This qualitative analysis was nested within a prospective longitudinal cohort study in which data were collected using online questionnaires at regular intervals from August 2020 to November 2021. To address the objective reported in this paper, a conventional qualitative content analysis method was applied to responses to three open-ended questions included in the final questionnaire. RESULTS: Participants encountered challenges and frustrations amid the COVID-19 pandemic, grappling with diverse regulations and communications from dental bodies. While some bodies offered helpful guidance, many participants felt the need for improved communication on guidelines. Dentists urged for expedited, clearer and more frequent updates, expressing difficulty in navigating overwhelming information. Negative views emerged on the vague and unclear communication of COVID-19 guidelines, contributing to confusion and frustration among participants. CONCLUSION: As COVID-19 persists and in planning for future pandemics, these experiential findings will help guide regulatory bodies in providing clear, timely and practical guidelines to protect the health and safety of dentists, dental staff, patients and the public.

Teledentistry for improving access to, and quality of oral health care: A protocol for an overview of systematic reviews and meta-analyses.

Digital technologies are becoming essential to address and optimize the suboptimal performance of healthcare systems. Teledentistry involves the use of information and communication technology to improve access to oral health care and the quality of oral health care delivery. Several systematic reviews (SRs) have been conducted to synthesize evidence on the effectiveness of teledentistry but with conflicting results. The aim of this review is to comprehensively summarize available SRs and provide evidence on the impact of teledentistry on access to oral care, patients' and oral healthcare providers' outcomes, quality of oral health care and costs. This protocol has been registered with the International Prospective Register of Systematic Reviews (PROSPERO CRD42022373964). Six electronic databases including MEDLINE (Ovid), Embase (Embase.com), CINAHL (EBSCO), Web of Science, Cochrane Library and Epistemonikos will be searched for SRs of quantitative, qualitative, and mixed reviews evaluating teledentistry modalities involving both patients and/or oral health care providers (OHCPs). We will include studies published in English or French. The outcomes will include patients' outcomes (e.g., access to oral health care, patient-reported outcomes, and patient-reported experiences); patient indicators (e.g., clinical outcomes, adherence to treatment, adverse outcomes and costs); and OHCP indicators (e.g., diagnostic accuracy, barriers and enablers costs and equity). Two independent reviewers will perform data screening, data extraction and will assess the quality of included studies using AMSTAR 2 and ROBIS tools. Data will be synthesized narratively and presented by tables and graphs. We will report any overlap of primary studies in the SRs. A statement on the strength of evidence for each outcome will be provided if possible. This review will inform decision-makers, patients, OHCPs, and researchers on the potential effectiveness, benefits, and challenges of teledentistry and support them in making recommendations for its use. Results will be disseminated through peer-reviewed publications, presentations at conferences, and on social media.

Personal protective equipment during COVID-19: A natural history of dental and dental hygiene regulatory guidance in Canada.

BACKGROUND: Due to the evolving nature of COVID-19, there is evidence that COVID-19-specific infection prevention and control guideline (IPCG) documents formulated for oral health care settings are also changing rapidly. To better inform future policies, a comprehensive review of all IPCG documents across different phases of restrictions for oral health care practitioners is required. TYPES OF STUDIES REVIEWED: A search was performed for documents shared from March 2020 through January 2022 on websites of oral health regulatory authorities in Canada's 10 provinces and 3 territories. The authors performed a narrative review of the identified IPCG documents for dentists (n = 78) and dental hygienists (n = 57). RESULTS: Overall findings from more than 100 IPCG documents distributed during a period of 23 months revealed that the frequency of these updates differed among jurisdictions and between the 2 oral health care practitioners (ie, dentists and dental hygienists) within the same jurisdiction. The most notable observation was the different face-covering recommendations for dentists and dental hygienists within the same jurisdiction during the same timeframe. A common document was sometimes observed for dentists and dental hygienists, however, most jurisdictions had separate IPCG documents. CONCLUSIONS AND PRACTICAL IMPLICATIONS: The different approaches could have been justified on the basis of prevalence of COVID-19 and availability of personal protective equipment; however, there was a risk of creating confusion about IPCG best practices. The findings of this review will support decision makers when planning future development and dissemination of regulations for all oral health care practitioners.

Validity and reliability of the COVID-19 Anxiety Syndrome Scale in Canadian dentists.

BACKGROUND: The COVID-19 pandemic has resulted in a high level of mental health problems for the population worldwide including healthcare workers. Several studies have assessed these using measurements for anxiety for general populations. The COVID-19 Anxiety Syndrome Scale (C-19ASS) is a self-report measure developed to assess maladaptive forms of coping with COVID-19 (avoidance, threat monitoring and worry) among a general adult population in the United States. We used it in a prospective cohort study of COVID-19 incidence rates in practising Canadian dentists. We therefore need to ensure that it is valid for dentists in French and English languages. This study aimed to evaluate the validity of the C-19ASS in that population. METHODS: Cross-sectional data from the January 2021 monthly follow-up in our prospective cohort study were used. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were performed. RESULTS: The results of EFA revealed a 2-factor structure solution that explained 47% of the total variance. The CFA showed a good model fit on the data in both English and French languages. The Cronbach's alpha indicated acceptable levels of reliability. Furthermore, the C-19ASS showed excellent divergent validity from the Generalized Anxiety Disorder-7 (GAD-7) scale. CONCLUSIONS: The C-19ASS is valid and reliable instrument to measure COVID-19-related anxiety in English and French among Canadian dentists. PRACTICAL IMPLICATIONS: This validated measure will contribute to understanding of the mental health impact of the pandemic on dentists in Canada and enable the dental regulatory authorities and organizations to intervene to help dentists.

Identifying potentially undiagnosed nontuberculous mycobacterial lung disease among patients with chronic obstructive pulmonary disease: Development of a predictive algorithm using claims data.

BACKGROUND: Nontuberculous mycobacterial lung disease (NTMLD) is a debilitating disease. Chronic obstructive pulmonary disease (COPD) is the leading comorbidity associated with NTMLD in the United States. Their similarities in symptoms and overlapping radiological findings may delay NTMLD diagnosis in patients with COPD. OBJECTIVE: To develop a predictive model that identifies potentially undiagnosed NTMLD among patients with COPD. METHODS: This retrospective cohort study developed a predictive model of NTMLD using US Medicare beneficiary claims data (2006 - 2017). Patients with COPD with NTMLD were matched 1:3 to patients with COPD without NTMLD by age, sex, and year of COPD diagnosis. The predictive model was developed using logistic regression modeling risk factors such as pulmonary symptoms, comorbidities, and health care resource utilization. The final model was based on model fit statistics and clinical inputs. Model performance was evaluated for both discrimination and generalizability with c-statistics and receiver operating characteristic curves. RESULTS: There were 3,756 patients with COPD with NTMLD identified and matched to 11,268 patients with COPD without NTMLD. A higher proportion of patients with COPD with NTMLD, compared with those with COPD without NTMLD, had claims for pulmonary symptoms and conditions, including hemoptysis (12.6% vs 1.4%), cough (63.4% vs 24.7%), dyspnea (72.5% vs 38.2%), pneumonia (59.2% vs 13.4%), chronic bronchitis (40.5% vs 16.3%), emphysema, (36.7% vs 11.1%), and lung cancer (15.7% vs 3.5%). A higher proportion of patients with COPD with NTMLD had pulmonologist and infectious disease (ID) specialist visits than patients with COPD without NTMLD (≥ 1 pulmonologist visit: 81.3% vs 23.6%, respectively; ≥ 1 ID visit: 28.3% vs 4.1%, respectively, P < 0.0001). The final model consists of 10 risk factors (≥ 2 ID specialist visits; ≥ 4 pulmonologist visits; the presence of hemoptysis, cough, emphysema, pneumonia, tuberculosis, lung cancer, or idiopathic interstitial lung disease; and being underweight during a 1-year pre-NTMLD period) predicting NTMLD with high sensitivity and specificity (c-statistic, 0.9). The validation of the model on new testing data demonstrated similar discrimination and showed the model was able to predict NTMLD earlier than the receipt of the first diagnostic claim for NTMLD. CONCLUSIONS: This predictive algorithm uses a set of criteria comprising patterns of health care use, respiratory symptoms, and comorbidities to identify patients with COPD and possibly undiagnosed NTMLD with high sensitivity and specificity. It has potential application in raising timely clinical suspicion of patients with possibly undiagnosed NTMLD, thereby reducing the period of undiagnosed NTMLD. DISCLOSURES: Dr Wang and Dr Hassan are employees of Insmed, Inc. Dr Chatterjee was an employee of Insmed, Inc, at the time of this study. Dr Marras is participating in multicenter clinical trials sponsored by Insmed, Inc, has consulted for RedHill Biopharma, and has received a speaker's honorarium from AstraZeneca. Dr Allison is an employee of Statistical Horizons, LLC. This study was funded by Insmed Inc.

Indicators of integrating oral health care within universal health coverage and general health care in low-, middle-, and high-income countries: a scoping review.

BACKGROUND: The World Health Organization (WHO) has recently devoted special attention to oral health and oral health care recommending the latter becoming part of universal health coverage (UHC) so as to reduce oral health inequalities across the globe. In this context, as countries consider acting on this recommendation, it is essential to develop a monitoring framework to measure the progress of integrating oral health/health care into UHC. This study aimed to identify existing measures in the literature that could be used to indicate oral health/health care integration within UHC across a range of low-, middle- and high-income countries. METHODS: A scoping review was conducted by searching MEDLINE via Ovid, CINAHL, and Ovid Global Health databases. There were no quality or publication date restrictions in the search strategy. An initial search by an academic librarian was followed by the independent reviewing of all identified articles by two authors for inclusion or exclusion based on the relevance of the work in the articles to the review topic. The included articles were all published in English. Articles concerning which the reviewers disagreed on inclusion or exclusion were reviewed by a third author, and subsequent discussion resulted in agreement on which articles were to be included and excluded. The included articles were reviewed to identify relevant indicators and the results were descriptively mapped using a simple frequency count of the indicators. RESULTS: The 83 included articles included work from a wide range of 32 countries and were published between 1995 and 2021. The review identified 54 indicators divided into 15 categories. The most frequently reported indicators were in the following categories: dental service utilization, oral health status, cost/service/population coverage, finances, health facility access, and workforce and human resources. This study was limited by the databases searched and the use of English-language publications only. CONCLUSIONS: This scoping review identified 54 indicators in a wide range of 15 categories of indicators that have the potential to be used to evaluate the integration of oral health/health care into UHC across a wide range of countries.

Virtual Oral Health across Canada: A Critical Comparative Analysis of Clinical Practice Guidances during the COVID-19 Pandemic.

During the COVID-19 pandemic, teledentistry was suggested as a cost-effective and promising approach to improve access to oral health care. In response, Canadian provincial and territorial dental regulatory authorities (DRAs) published teledentistry-related clinical practice guidances (TCPGs). However, an in-depth comparison between them is needed to understand their gaps and commonalities so as to inform research, practice, and policy. This review aimed to provide a comprehensive analysis of TCPGs published by Canadian DRAs during the pandemic. A critical comparative analysis of these TCPGs published between March 2020 and September 2022 was conducted. Two members of the review team screened the official websites of dental regulatory authorities (DRAs) to identify TCPGs and performed data extraction. Among Canada's 13 provinces and territories, only four TCPGs were published during the relevant time period. There were some similarities and differences in these TCPGs, and we identified gaps pertaining to communication tools and platforms, and measures to safeguard patients' privacy and confidentiality. The insights from this critical comparative analysis and the unified workflow on teledentistry can aid DRAs in their development of new or an improvement to existing TCPGs or the development of nationwide TCP guidelines on teledentistry.

Canadian dental hygienists' experiences and perceptions of regulatory guidelines during the COVID-19 pandemic: a qualitative descriptive analysis.

BACKGROUND: In Spring of 2020, due to the COVID-19 pandemic, Canadian provincial dental hygiene regulatory bodies implemented new practice guidelines. Reports of stress, anxiety and conflict experienced by dental hygienists have been linked to miscommunication between oral health regulators at this time. Limited data exists on the perceptions and experiences of dental hygienists navigating new guidelines for dental hygiene care during the pandemic. Therefore, the objective of our study was to explore via descriptive thematic analysis how dental hygienists experienced and perceived: i) dental hygiene practice during the COVID-19 pandemic, and ii) their regulatory body's COVID-19 guidelines. METHODS: Participants were identified through provincial dental hygiene licensing bodies. Online bi-monthly questionnaires were administered to participants (n = 876) from December 2021 to January 2022. Two open-ended questions were asked in the questionnaire. A qualitative descriptive thematic analysis was applied to these two questions. RESULTS: Major themes at baseline relayed challenges related to workplace compliance, patient treatment and communication of practice protocols. Across responses, hygienists confirmed conflicting messaging from regulators and guideline interpretations as stressors impacting their professional practice and satisfaction within the profession. Participant responses at endpoint cited increased satisfaction with regulatory guidelines as the pandemic evolved, yet inconsistencies in regulators' messaging was noted as a prevailing issue. CONCLUSION: Inconsistent guideline messaging reflects an increased need for collaboration amongst oral health care regulators to streamline protocols for practice and reduce interprofessional conflict in pandemic circumstances. A national unified approach is warranted in establishing guidelines for dental hygiene practice in Canada.

COVID-19 incidence and vaccination rates among Canadian dental hygienists.

Background: Oral health care settings potentially carry a high risk of cross-infection due to close contact and aerosol-generating procedures. There is limited evidence of the impact of COVID-19 among dental hygienists. This longitudinal study aimed to 1) estimate COVID-19 incidence rates among Canadian dental hygienists over a 1-year period; and 2) estimate vaccination rates among Canadian dental hygienists. Methods: A prospective cohort study design was used to collect self-reported COVID-19 status from 876 registered dental hygienists across Canada via an online baseline survey and then 6 follow-up questionnaires delivered between December 2020 and January 2022. Bayesian Poisson and binomial models were used to estimate the incidence rate and cumulative incidence of self-reported COVID-19. Results: The estimated cumulative incidence of COVID-19 in dental hygienists in Canada from December 2020 to January 2022 was 2.39% (95% CrI, 1.49%-3.50%), while the estimated cumulative incidence of COVID-19 in corresponding Canadian provinces was 5.12% (95% CrI, 5.12%-5.13%) during the same period. At last follow-up, 89.4% of participants self-reported that they had received at least 1 dose of a COVID-19 vaccine. Conclusion: The low infection rate observed among Canadian dental hygienists between December 2020 and January 2022 is reassuring to the dental hygiene and general community.

Contexte: Les milieux de soins buccodentaires présentent potentiellement un risque élevé d'infections croisées en raison des contacts étroits et des procédures qui produisent des aérosols. Il y a peu de preuves de l'effet de la COVID-19 chez les hygiénistes dentaires. La présente étude longitudinale visait à 1) estimer les taux d'incidence de la COVID-19 chez les hygiénistes dentaires canadiens sur une période d'un an; et 2) estimer les taux de vaccination chez les hygiénistes dentaires canadiens. Méthodologie: Une méthodologie prospective des cohortes a été utilisée pour recueillir le statut de COVID-19 autodéclaré de 876 hygiénistes dentaires autorisés au Canada par l'intermédiaire d'une enquête initiale en ligne, puis de 6 questionnaires de suivi, distribués entre décembre 2020 et janvier 2022. Des modèles bayésiens de Poisson et binomiaux ont été utilisés pour estimer le taux d'incidence et l'incidence cumulative de la COVID-19 autodéclarée. Résultats: L'incidence cumulative estimée de la COVID-19 chez les hygiénistes dentaires au Canada entre décembre 2020 et janvier 2022 était de 2,39 % (intervalle de crédibilité à 95 %, 1,49 % ­ 3,50 %), alors que l'incidence cumulative estimée de la COVID-19 dans les provinces canadiennes correspondantes était de 5,12 % (intervalle de crédibilité à 95 %, 5,12 % ­ 5,13 %) au cours de la même période. Lors du dernier suivi, 89,4 % des participants ont déclaré avoir reçu au moins une dose du vaccin contre la COVID-19. Conclusion: Le faible taux d'infection constaté chez les hygiénistes dentaires canadiens entre décembre 2020 et janvier 2022 est rassurant pour la communauté d'hygiène dentaire et la communauté générale.

Required sample size to detect mediation in 3-level implementation studies.

BACKGROUND: Statistical tests of mediation are important for advancing implementation science; however, little research has examined the sample sizes needed to detect mediation in 3-level designs (e.g., organization, provider, patient) that are common in implementation research. Using a generalizable Monte Carlo simulation method, this paper examines the sample sizes required to detect mediation in 3-level designs under a range of conditions plausible for implementation studies. METHOD: Statistical power was estimated for 17,496 3-level mediation designs in which the independent variable (X) resided at the highest cluster level (e.g., organization), the mediator (M) resided at the intermediate nested level (e.g., provider), and the outcome (Y) resided at the lowest nested level (e.g., patient). Designs varied by sample size per level, intraclass correlation coefficients of M and Y, effect sizes of the two paths constituting the indirect (mediation) effect (i.e., X→M and M→Y), and size of the direct effect. Power estimates were generated for all designs using two statistical models-conventional linear multilevel modeling of manifest variables (MVM) and multilevel structural equation modeling (MSEM)-for both 1- and 2-sided hypothesis tests. RESULTS: For 2-sided tests, statistical power to detect mediation was sufficient (≥0.8) in only 463 designs (2.6%) estimated using MVM and 228 designs (1.3%) estimated using MSEM; the minimum number of highest-level units needed to achieve adequate power was 40; the minimum total sample size was 900 observations. For 1-sided tests, 808 designs (4.6%) estimated using MVM and 369 designs (2.1%) estimated using MSEM had adequate power; the minimum number of highest-level units was 20; the minimum total sample was 600. At least one large effect size for either the X→M or M→Y path was necessary to achieve adequate power across all conditions. CONCLUSIONS: While our analysis has important limitations, results suggest many of the 3-level mediation designs that can realistically be conducted in implementation research lack statistical power to detect mediation of highest-level independent variables unless effect sizes are large and 40 or more highest-level units are enrolled. We suggest strategies to increase statistical power for multilevel mediation designs and innovations to improve the feasibility of mediation tests in implementation research.

Infection Prevention Strategies Concordance in Canadian Dental Schools During the COVID-19 Pandemic.

OBJECTIVE: The aim of this research was to identify variation in specific infection prevention and control (IPC) strategies across all dental schools in Canada and to evaluate the concordance concerning COVID-19 pandemic-related IPC strategies reported by clinic directors or IPC officers (CDs/IPCOs) and those reported by students, staff, and faculty in the schools. METHOD: A cross-sectional analysis within a prospective cohort study. Participants in the cohort study reported IPC strategies used in their schools during April or May 2021. Independently, CDs/IPCOs reported IPC strategies in school protocols in July 2021. RESULTS: Of the 600 participants recruited, 332 participants who were involved in the provision of in-person dental care were further analysed. Of the 16 IPC strategies investigated, only 3 were reported by CDs/IPCOs to be used at all schools, and another 8 strategies were used by 8 or 9 of 10 or by 1 of 10 schools, indicating that concordance across schools was good for 11 of 16 strategies. Agreement between study participants and the CDs/IPCOs varied considerably by strategy (ranging between 50% and 100%) and by school (ranging between 42.9% and 97.2%). The strategies with the highest mean agreement percentage across schools were "screening or interviewing patients before appointment for COVID-19-related symptoms" (92.7%) and "checking the temperature of the staff members at least once a day using a thermometer" (91.5%). CONCLUSIONS: The level of agreement in the use of strategies between participants working in clinics and CDs/IPCOs varied considerably by strategy and by school. Given the low COVID-19 infection rates in dental schools and the reported differences in IPC protocols, key strategies should be identified. During the pandemic, IPC protocols in Canadian dental schools evolved rapidly. Comparing different strategies might help develop a unified standard IPC protocol.

The incidence of COVID-19 among dentists practicing in the community in Canada: A prospective cohort study over a 6-month period.

BACKGROUND: Oral health care settings carry a potentially high risk of causing cross-infection between dentists and patients and among dental staff members due to close contact and use of aerosol-generating procedures. The authors aimed to estimate COVID-19 incidence rates among Canadian dentists over a 6-month period. METHODS: The authors conducted a prospective cohort study of 644 licensed dentists across Canada from July 29, 2020, through February 12, 2021. An online questionnaire, adapted from the World Health Organization's Unity Studies protocols for assessment of COVID-19 risk among health care workers, was used to collect data on self-reported severe acute respiratory syndrome coronavirus 2 infections every 4 weeks. A bayesian Poisson model was used to estimate the incidence rate and corresponding 95% credible intervals (CIs). RESULTS: Median age of participants was 47 years; most participants were women (56.4%) and general practitioners (90.8%). Median follow-up time was 188 days. Six participants reported COVID-19 infections during the study period, giving an incidence rate of 5.10 per 100,000 person-days (95% CI, 1.86 to 9.91 per 100,000 person-days). The incidence proportion was estimated to be 1,084 per 100,000 dentists (95% CI, 438 to 2,011 per 100,000 dentists) and 1,864 per 100,000 people (95% CI, 1,859 to 1,868 per 100,000 people) in the Canadian population during the same period. CONCLUSIONS: The low infection rate observed among Canadian dentists from July 29, 2020, through February 12, 2021, should be reassuring to the dental and general community. PRACTICAL IMPLICATIONS: Although the infection rates were low among Canadian dentists, it is important to continue to collect disease surveillance data.

Effect of Carbon Nanofiber Clustering on the Micromechanical Properties of a Cement Paste.

The use of carbon nanofibers (CNFs) in cement systems has received significant interest over the last decade due to their nanoscale reinforcing potential. However, despite many reports on the formation of localized CNF clusters, their effect on the cement paste micromechanical properties and relation to the mechanical response at the macroscopic scale are still not fully understood. In this study, grid nanoindentation coupled with scanning electron microscopy and energy dispersive spectroscopy was used to determine the local elastic indentation modulus and hardness of a portland cement paste containing 0.2% CNFs with sub-micro and microscale CNF clusters. The presence of low stiffness and porous assemblage of phases (modulus of 15-25 GPa) was identified in the cement paste with CNFs and was attributed primarily to the interfacial zone surrounding the CNF clusters. The CNFs favored the formation of higher modulus C-S-H phases (>30 GPa) in the bulk paste at the expense of the lower stiffness C-S-H. Nanoindentation results combined with a microscale-macroscale upscaling homogenization method further revealed an elastic modulus of the CNF clusters in the range from 18 to 21 GPa, indicating that the CNF clusters acted as compliant inclusions relative to the cement paste.

Microstructural and Mechanical Characterization of Additive Friction Stir-Deposition of Aluminum Alloy 5083 Effect of Lubrication on Material Anisotropy.

Additive Friction Stir-Deposition (AFS-D) is a transformative, metallic additive manufacturing (AM) process capable of producing near-net shape components with a wide variety of material systems. The solid-state nature of the process permits many of these materials to be successfully deposited without the deleterious phase and thermally activated defects commonly observed in other metallic AM technologies. This work is the first to investigate the as-deposited microstructure and mechanical performance of a free-standing AA5083 deposition. An initial process parameterization was conducted to down-select optimal parameters for a large deposition to examine build direction properties. Microscopy revealed that constitutive particles were dispersed evenly throughout the matrix when compared to the rolled feedstock. Electron backscatter diffraction revealed a significant grain refinement from the inherent dynamic recrystallization from the AFS-D process. Tensile experiments determined a drop in yield strength, but an improvement in tensile strength in the longitudinal direction. However, a substantial reduction in tensile strength was observed in the build direction of the structure. Subsequent fractographic analysis revealed that the recommended lubrication applied to the feedstock rods, necessary for successful depositions via AFS-D, was ineffectively dispersed into the structure. As a result, lubrication contamination became entrapped at layer boundaries, preventing adequate bonding between layers.

Dentists' Experiences and Dental Care in the COVID-19 Pandemic: Insights from Nova Scotia, Canada.

BACKGROUND: This study aimed to describe dental care provision and the perceptions of dentists in Nova Scotia, Canada, during 1 week of the COVID-19 pandemic, shortly after the closing down of non-emergency, in-person care. METHODS: A survey was distributed to all 542 registered dentists in Nova Scotia, asking about dental care provision during 19-25 April 2020. Most answers were categorical, and descriptive analyses of these were performed. Data from the 1 open-ended question were analyzed using an inductive approach to identify themes. RESULTS: The response rate was 43% (n = 235). Most dentists (181) provided care but only 13 provided in-person care. From the open-ended question, 4 concerns emerged: communication from the regulatory authority; respondents' health and that of their staff; the health of and access to care for patients; and the future of their business. CONCLUSION: Most respondents remained engaged in non-in-person dental care using various modes. They expressed concerns about their health and that of their staff and patients as well as about the future of their practice. PRACTICAL IMPLICATIONS: Dentists and dental regulatory authorities should engage in discussions to promote the health of dental staff and patients and quality of care during the chronic phase of the pandemic.

Aortic root repair in a patient with acquired hemophilia A: case report.

BACKGROUND: Patients with acquired hemophilia A (AHA) who require open heart surgery have a life-threatening risk of hemorrhage. Limited data exist to guide perioperative management of these patients. CASE PRESENTATION: A 53-year-old female with rheumatoid arthritis, concomitant aortic valve endocarditis, and severe aortic regurgitation presented to our hospital. Bleeding and abnormal coagulation tests were noted during the initial workup, and she was diagnosed with AHA. The perioperative management plan included the use of pharmaceuticals, porcine recombinant factor VIII, and blood products. Extensive preoperative coagulation data were obtained, and factor VIII levels were continuously monitored to mitigate bleeding complications. The aortic valve replacement and root repair were uneventful. CONCLUSION: Cardiac surgery in patients with AHA is possible as long as complex perioperative hemostatic and hematology management is used.