COVID-19 Guidelines to Protect Healthcare Workers at Hospitals and Dental Professionals at Dental Office

BACKGROUND፡ Coronavirus disease 2019 is an infectious disease caused by severe acute respiratory syndrome coronavirus 2. This study aimed to address the preventive procedures to protect healthcare workers at hospital to avoid COVID-19, and infection control procedures to protect dental professionals in dental office.METHODS: We conducted a search of published articles from PubMed, google scholar databases using key words such as COVID-19, healthcare worker, infection control, and dental practice. Relevant articles were identified and reviewed. Most published papers were clinical reports and case studies. We have selected some of the current published papers written in English in 2020.RESULTS: Infection control procedures to protect health workers at hospitals, and dental professionals at dental office were summurised and presented. Infection control procedures for healthcare workers at hospitals include Personal protective equipment, Korea filter (KF)94 respirator, goggles, face protector,disposable waterproof long-arm gown, and gloves, and others. Extra-protection procedures should be taken with old and vulnerable healthcare workers. Dental professionals should evaluate patients in advance before starting dental treatment. Aerosols generating procedures should be avoided and personal protective equipment should be used. Dental treatment should be restricted to emergency cases only.CONCLUSION: Old medical staff should be in safer distance to avoid infection, but young physicians and nurses should work at frontline as their immunity is better than their colleagues at old age. Screening patients and measurement of the body temperature are essential measures before dental treatment

The effect of radiotherapy on survival of dental implants in head and neck cancer patients

Objectives: To explore the current literature of the survival of dental implants in irradiated head and neck cancer patients considering the role of implant location, bone augmentation, dose of radiation and timing of implant placement. Study Design: Pubmed search was conducted to identify articles published between January 2000 and December 2014 and presenting data of dental implant survival with radiotherapy in head and neck cancer patients. Studies on animal subjects and craniofacial implants were excluded. Results: 18 articles out of 27 were eligible for inclusion in this systematic review. 12 out of 18 studies reported favorable outcome of dental implants and radiotherapy with survival rates between 74.4% and 97%. Seven out of ten studies comparing the survival rates according to site of implant placement reported that implants were found to osseointegrate with greater success in the irradiated mandible than irradiated maxilla. 5 studies which compared implant survival in irradiated native bone versus irradiated grafted bone reported that irradiated grafted bone showed a significantly reduced dental implant survival rate in comparison to irradiated native bone. 6 out of 18studies in which radiation doses exceeded 70 Gy reported lower survival rates of dental implants in comparison to the studies in which radiation doses were ≤70Gy. Higher survival rates were reported in 2 studies in which implants placement was before radiotherapy in comparison to the remaining 16 studies in which implants placement was after radiotherapy. Conclusions: Dental implants may be affected by radiotherapy especially when they are placed in maxilla, in grafted bone, or after radiation, however, they remain a functional option for rehabilitation of head and cancer patients. More prospective cohort studies and randomized controlled trails are still needed to draw more evidence based conclusion

Lip and oral lesions in children with Down syndrome: a controlled study

Background: Down syndrome (DS) is the most common chromosomal abnormality affecting numerous organs, including the orofacial region. The objective of the present study was to assess the prevalence of lip and oral soft tissue lesions, with particular emphasize on the incidence of fissured tongue, lip fissures and angular cheilitis, among individuals with DS in Yemen. Material and Methods: This controlled cross-sectional study included 50 children with DS (6-18 years), and 50 age- and gender-matched healthy controls. The prevalence of orofacial soft tissue lesions was evaluated in both groups. Data were analyzed by Chi-square and Fisher tests, and p <0.05 was considered to be statistically significant. Results: Ten orolabial lesions were identified among the subjects. The most frequently seen lesions were: Fissured tongue (78.0%), lip fissures (64.0%), angular cheilitis (38.0%) and Cheilitis (14.0%). The frequencies of these lesions were significantly higher in children with DS than healthy controls ( P < 0.001). Most of lip fissures were in the lower lip, and 80% of the fissures were in the midline. Conclusions: The prevalence of lip and oral lesions among individuals with DS is remarkably high. Hence, oral physicians should be more aware of the orofacial findings seen more frequently in this genetic disorder

Challenges of providing healthcare worker education and training in protracted conflict: a focus on non-government controlled areas in north west Syria

Without healthcare workers (HCWs), health and humanitarian provision in Syria cannot be sustained either now or in the post-conflict phase. The protracted conflict has led to the exodus of more than 70% of the healthcare workforce. Those remaining work in dangerous conditions with insufficient resources and a healthcare system that has been decimated by protracted conflict. For many HCWs, particularly those in non-government-controlled areas (NGCAs) of Syria, undergraduate education and postgraduate training has been interrupted with few opportunities to continue. In this manuscript, we explore initiatives present in north west Syria at both undergraduate and postgraduate level for physician and non-physician HCWs. Conclusion: Challenges to HCW education in north west Syria can be broadly divided into 1. Organisational (local healthcare leadership and governance, coordination and collaboration between stakeholders, competition between stakeholders and insufficient funding.) 2. Programmatic (lack of accreditation or recognition of qualifications, insufficient physical space for teaching, exodus of faculty affecting teaching and training, prioritisation of physicians over non-physicians, informally trained healthcare workers.) 3. Healthcare system related (politicisation of healthcare system, changing healthcare needs of the population, ongoing attacks on healthcare.) Locally implementable strategies including dedicated funding are key to supporting retention of HCWs and return during post-conflict reconstruction

Si\u3csub\u3e3\u3c/sub\u3eN\u3csub\u3e4\u3c/sub\u3e/AlGaN/GaN-Metal-Insulator-Semiconductor Heterostructure Field-Effect Transistors

We report on a metal–insulator–semiconductor heterostructurefield-effect transistor (MISHFET) using Si3N4 film simultaneously for channel passivation and as a gate insulator. This design results in increased radio-frequency (rf) powers by reduction of the current collapse and it reduces the gate leakage currents by four orders of magnitude. A MISHFET room temperature gate current of about 90 pA/mm increases to only 1000 pA/mm at ambient temperature as high as 300 °C. Pulsed measurements show that unlike metal–oxide–semiconductor HFETs and regular HFETs, in a Si3N4 MISHFET, the gate voltage amplitude required for current collapse is much higher than the threshold voltage. Therefore, it exhibits significantly reduced rf current collapse

AlGaN/GaN Metal-Oxide-Semiconductor Heterostructure Field-Effect Transistors on SiC Substrates

We report on AlGaN/GaN metal–oxide–semiconductor heterostructurefield-effect transistors (MOS-HFETs) grown over insulating 4H–SiC substrates. We demonstrate that the dc and microwave performance of the MOS-HFETs is superior to that of conventional AlGaN/GaN HFETs, which points to the high quality of SiO2/AlGaNheterointerface. The MOS-HFETs could operate at positive gate biases as high as +10 V that doubles the channel current as compared to conventional AlGaN/GaN HFETs of a similar design. The gate leakage current was more than six orders of magnitude smaller than that for the conventional AlGaN/GaN HFETs. The MOS-HFETs exhibited stable operation at elevated temperatures up to 300 °Cwith excellent pinch-off characteristics. These results clearly establish the potential of using AlGaN/GaN MOS-HFET approach for high power microwave and switching devices

Maximum Current in Nitride-Based Heterostructure Field-Effect Transistors

We present experimental and modeling results on the gate-length dependence of the maximum current that can be achieved in GaN-based heterostructurefield-effect transistors(HFETs) and metal–oxide–semiconductor HFETs (MOSHFETs). Our results show that the factor limiting the maximum current in the HFETs is the forward gate leakage current. In the MOSHFETs, the gate leakage current is suppressed and the overflow of the two dimensional electron gas into the AlGaN barrier region becomes the most important factor limiting the maximum current. Therefore, the maximum current is substantially higher in MOSHFETs than in HFETs. The measured maximum current increases with a decrease in the gate length, in qualitative agreement with the model that accounts for the velocity saturation in the channel and for the effect of the source series resistance. The maximum current as high as 2.6 A/mm can be achieved in MOSHFETs with a submicron gate

Highly Doped Thin-Channel GaN-Metal-Semiconductor Field-Effect Transistors

We report on the influence of the channel doping on dc, high frequency, and noise performance of GaN metal–semiconductor field-effect transistors (MESFETs) grown on sapphire substrates. The devices with the channel thicknesses from 50 to 70 nm and doping levels up to 1.5×1018 cm−3 were investigated. An increase in the channel doping results in the improved dc characteristics, higher cutoff, and maximum oscillation frequencies, and reduced low frequency and microwave noise. The obtained results demonstrate that the dc and microwave performance characteristics of short-channel GaN MESFETs may be comparable to those for conventional AlGaN/GaN heterostructure FETs

Induced Strain Mechanism of Current Collapse in AlGaN/GaN Heterostructure Field-Effect Transistors

Gated transmission line model pattern measurements of the transient current–voltage characteristics of AlGaN/GaN heterostructurefield-effect transistors(HFETs) and metal–oxide–semiconductor HFETs were made to develop a phenomenological model for current collapse. Our measurements show that, under pulsed gate bias, the current collapse results from increased source–gate and gate–drain resistances but not from the channel resistance under the gate. We propose a model linking this increase in series resistances (and, therefore, the current collapse) to a decrease in piezoelectriccharge resulting from the gate bias-induced nonuniform strain in the AlGaN barrier layer

Cost-Effectiveness Analyses of an Absorbable Antibacterial Envelope for Use in Patients at Increased Risk of Cardiac Implantable Electronic Device Infection in Germany, Italy, and England

Objectives: To model the cost-effectiveness of the TYRX Absorbable Antibacterial Envelope when used in patients at increased risk of cardiac implantable electronic device (CIED) infection in the context of 3 European healthcare systems: Germany, Italy, and England. Methods: A decision tree model with a lifetime horizon was populated using data from the Worldwide Randomized Antibiotic Envelope Infection Prevention Trial, a large multicenter randomized controlled trial. Use of the antibacterial envelope adjunctive to standard of care was compared to standard of care infection prevention alone. Patients in the model were divided into subgroups based on presence of factors known to increase infection risk. Results: The antibacterial envelope had the most favorable cost-effectiveness profile when patients had previously experienced CIED infection, had a history of immunosuppressive therapy, or had a Prevention of Arrhythmia Device Infection Trial (PADIT) score indicating high risk of infection (scores ≥6) at cost-effectiveness thresholds of €50 000 in Germany (assumed in the absence of an official threshold), €40 000 in Italy, and £30 000 in England. Probabilistic sensitivity analysis indicated that the antibacterial envelope was likely to be cost-effective in patients with other risk factors (including replacement of high power CIEDs, generator replacement with lead modification, and PADIT scores indicating intermediate risk of infection) when used with some device types and in some countries. Conclusions: The absorbable antibacterial envelope was associated with cost-effectiveness ratios below European benchmarks in selected patients at increased risk of infection, suggesting the envelope provides value for European healthcare systems by reducing CIED infections