Effect of changes in sintering parameters on physical properties of monolithic translucent zirconia

The aim of this study was to determine the effect of changing the sintering temperature (1,460°, 1,530°, and 1,600°C) and the sintering holding time (1, 2 and 4 hours) on the color reproduction, translucency, surface roughness, microstructure, biaxial flexural strength, and surface hardness of monolithic translucent zirconia

Microbiological assessment of COVID-19 associated acute invasive fungal rhinosinusitis: A tertiary hospital based study

Background:  Acute invasive fungal rhinosinusitis (AIFRS) is an emerging disease on top of SARS CoV-2 virus infection and associated with severe and fatal prognosis especially in the presence of other immunosuppressive conditions. Aim of study: Identification of the causative agents of AIFRS in COVID-19 patients and its impact on the survival outcome. Methods: This retrospective study was carried out on 70 clinically and radiologically diagnosed AIFRS patients either in concomitant with COVID-19 infection or following recovery. Exudates from the lesions were collected during surgical debridement. Both microbiological and pathological examinations were done to identify the type of the causative fungi followed by assessment of the relation between different type of fungi and the outcome in the affected patients. Results: Positive fungal cultures were detected in 54 cases out of 70 where Mucor species were the most common isolates (42 patients) and only 12 cases were proven to be Aspergillus species. All patients were diabetic and under steroid therapy. Mortality rate was 42.9% and 25% in mucormycosis and aspergillosis respectively. High dose of steroid together with Mucor species infection were the most important risk factors in determining the prognosis and the outcome of the infection. Conclusion: Microbiological diagnosis together with other methods plays an important role in accurate and rapid diagnosis of AIFRS in association with COVID-19 for proper management and improving the outcome

Geoeconomic variations in epidemiology, ventilation management, and outcomes in invasively ventilated intensive care unit patients without acute respiratory distress syndrome: a pooled analysis of four observational studies

Background: Geoeconomic variations in epidemiology, the practice of ventilation, and outcome in invasively ventilated intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) remain unexplored. In this analysis we aim to address these gaps using individual patient data of four large observational studies. Methods: In this pooled analysis we harmonised individual patient data from the ERICC, LUNG SAFE, PRoVENT, and PRoVENT-iMiC prospective observational studies, which were conducted from June, 2011, to December, 2018, in 534 ICUs in 54 countries. We used the 2016 World Bank classification to define two geoeconomic regions: middle-income countries (MICs) and high-income countries (HICs). ARDS was defined according to the Berlin criteria. Descriptive statistics were used to compare patients in MICs versus HICs. The primary outcome was the use of low tidal volume ventilation (LTVV) for the first 3 days of mechanical ventilation. Secondary outcomes were key ventilation parameters (tidal volume size, positive end-expiratory pressure, fraction of inspired oxygen, peak pressure, plateau pressure, driving pressure, and respiratory rate), patient characteristics, the risk for and actual development of acute respiratory distress syndrome after the first day of ventilation, duration of ventilation, ICU length of stay, and ICU mortality. Findings: Of the 7608 patients included in the original studies, this analysis included 3852 patients without ARDS, of whom 2345 were from MICs and 1507 were from HICs. Patients in MICs were younger, shorter and with a slightly lower body-mass index, more often had diabetes and active cancer, but less often chronic obstructive pulmonary disease and heart failure than patients from HICs. Sequential organ failure assessment scores were similar in MICs and HICs. Use of LTVV in MICs and HICs was comparable (42\ub74% vs 44\ub72%; absolute difference \u20131\ub769 [\u20139\ub758 to 6\ub711] p=0\ub767; data available in 3174 [82%] of 3852 patients). The median applied positive end expiratory pressure was lower in MICs than in HICs (5 [IQR 5\u20138] vs 6 [5\u20138] cm H2O; p=0\ub70011). ICU mortality was higher in MICs than in HICs (30\ub75% vs 19\ub79%; p=0\ub70004; adjusted effect 16\ub741% [95% CI 9\ub752\u201323\ub752]; p<0\ub70001) and was inversely associated with gross domestic product (adjusted odds ratio for a US$10 000 increase per capita 0\ub780 [95% CI 0\ub775\u20130\ub786]; p<0\ub70001). Interpretation: Despite similar disease severity and ventilation management, ICU mortality in patients without ARDS is higher in MICs than in HICs, with a strong association with country-level economic status. Funding: No funding

THE INFLUENCE OF BITING FORCE ON THE STRAIN INDUCED WITHIN POSTERIOR ZIRCONIA THREE-UNIT FPD FABRICATED WITH TWO DIFFERENT VENEERING TECHNIQUES

Purpose: This study investigated the influence of biting force on the strain induced within posterior zirconia three-unit FPD fabricated with two different veneering techniques. Materials and Methods: Twenty 3-unit all ceramic zirconia bridges replacing missing upper second premolar were constructed and divided according to their veneering technique into two groups (n = 10/group). Group 1: Translucent Zirconia fabricated by fully anatomical technique (n=10), Group 2: Zirconia framework veneered by condensing and sintering VM9 low-fusing veneering porcelain by layering technique (n=10). The restorations were cemented on epoxy resin dies using dual cure adhesive resin Cement. Four KYOWA strain gauges (KYOWA, Tokyo, Japan) of 1 mm length were bonded, (1) at the cervical third (mesial margin) of the mesial wall of the 1st premolar retainer, (2) gingival surface of the Pontic, (3) buccal wall of the Pontic (below buccal cusp tip) and (4) at the cervical third of the distal surface of the 1st molar retainer using strain gauge cement (KYOWA, Tokyo, Japan). The samples were subjected to vertical loading (800 N) using universal testing machine

EFFECT OF LOW THERMAL DEGRADATION AND VENEERING TECHNIQUES ON COLOR AND TRANSLUCENCY OF ZIRCONIA RESTORATIONS

Purpose: This study evaluated the effect of veneering techniques and aging on the color reproduction, stability and translucency of zirconia (Y-TZP) all-ceramic restorations. Materials and Methods: Thirty all ceramic crowns were constructed and divided according to their veneering technique into three groups (n = 10/group).Group 1: Translucent Zirconia milled by (fully anatomical technique), Group 2: Zirconia coping was veneered by condensing and sintering VM9 low-fusing veneering porcelain (layering technique), Group 3: Zirconia coping was veneered by heat-pressing IPS e.max ZirPress fluorapatite glass-ceramic ingots (press-on technique). Low thermal degradation (LTD) using autoclaving for 8 hours was performed. Color parameters (L*, a*, b*) of zirconia crowns were measured with Vita Easyshade Compact (VITA, Zahnfabrich H. Rauter GmbH and Co. KG). Color reproduction, color stability, contrast ratio and translucency parameter were calculated before and after aging. Two-way analysis of variance (ANOVA), followed by Tukey’s post hoc test at a significance level of p≤0.05 was performed

Effect of changes in sintering parameters on monolithic translucent zirconia

Objectives. Aim of this study was to evaluate the effect of different sintering parameters on color reproduction, translucency and biaxial flexural strength of monolithic zirconia. Methods. Translucent zirconia discs having 15 mm diameter, 1 mm thickness, and shade A3 were milled and divided according to the sintering temperatures (1460C) into three groups (n = 30). Each group was later divided into three subgroups (n = 10) according to the sintering holding time (1, 2, and 4 h). Easyshade spectrophotometer (Vita, Bad Säckingen, Germany) was used to obtain the E between the specimens and the shade A3. Mean E values below 3.0 were considered “clinically imperceptible”, E values between 3.0 and 5.0 were considered “clinically acceptable” and E values above 5.0 were considered “clinically unacceptable”. Contrast ratio (CR) was obtained after comparing the reflectance of light through the specimens over black and white background. Biaxial flexural strength was tested using the piston-on-three balls technique in a universal testing machine. Results. Mean E results ranged from 4.4 to 2.2. Statistically significant decrease in the Delta E was observed as the sintering time and temperature increased. CR decreased from 0.75 to 0.68 as the sintering time and temperature increased. No significant change in the biaxial flexural strength was observed.Significance. Sintering zirconia using long cycles and high temperatures will result in reduc- tion of E and CR. Biaxial flexural strength is not affected by changes in the evaluated sintering parameters

Multisource Smart Computer-Aided System for Mining COVID-19 Infection Data

In this paper, we approach the problem of detecting and diagnosing COVID-19 infections using multisource scan images including CT and X-ray scans to assist the healthcare system during the COVID-19 pandemic. Here, a computer-aided diagnosis (CAD) system is proposed that utilizes analysis of the CT or X-ray to diagnose the impact of damage in the respiratory system per infected case. The CAD was utilized and optimized by hyper-parameters for shallow learning, e.g., SVM and deep learning. For the deep learning, mini-batch stochastic gradient descent was used to overcome fitting problems during transfer learning. The optimal parameter list values were found using the naïve Bayes technique. Our contributions are (i) a comparison among the detection rates of pre-trained CNN models, (ii) a suggested hybrid deep learning with shallow machine learning, (iii) an extensive analysis of the results of COVID-19 transition and informative conclusions through developing various transfer techniques, and (iv) a comparison of the accuracy of the previous models with the systems of the present study. The effectiveness of the proposed CAD is demonstrated using three datasets, either using an intense learning model as a fully end-to-end solution or using a hybrid deep learning model. Six experiments were designed to illustrate the superior performance of our suggested CAD when compared to other similar approaches. Our system achieves 99.94, 99.6, 100, 97.41, 99.23, and 98.94 accuracy for binary and three-class labels for the CT and two CXR datasets