Mechanical and biological properties of polymer materials for oral appliances produced with additive 3D printing and subtractive CAD-CAM techniques compared to conventional methods: a systematic review and meta-analysis.

OBJECTIVES: The aim of this review was to analyze mechanical and biological properties of resin materials used with subtractive or additive techniques for oral appliances fabrication and compare them to those conventionally manufactured. MATERIALS AND METHODS: The protocol was registered online at Open Science Framework (OSF) registries ( https://osf.io/h5es3 ) and the study was based on the preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P). An electronic search was conducted on MEDLINE (via PubMed), Scopus, and Web of Science from 1 February 2022 to 1 May 2022. INCLUSION CRITERIA: in vitro and in vivo studies published in the last 10 years, with CAD-CAM or 3D printed resins for occlusal splints. Data considered homogenous were subjected to meta-analysis (95% confidence interval [CI]; α = 0.05) with Stata17 statistical software. Since all variables were continuous, the Hedge g measure was calculated. A fixed-effects model was used for I2 = 0%, while statistical analysis was conducted using a random-effects model with I2 > 0%. RESULTS: 13 studies were included after full-text reading. The mechanical properties most studied were wear, flexural strength, surface hardness and surface roughness, while only 1 study investigated biological properties, performing the XTT viability assay. For the meta-analysis, only surface roughness, volume loss, and flexural strength were selected. Considering surface roughness, the subtractive specimen had a lower average value compared to traditional ones (Hedge's g with 95% CI = -1.25[ -1.84, - 0.66]). No significant difference was detected in terms of volume loss (P > 0.05) between the groups (Hedge's g with 95% CI = -0.01 [-2.71, - 2.68]). While flexural strength was higher in the control group (Hedge's g with 95% CI = 2.32 [0.10-4.53]). CONCLUSION: 3D printed materials showed properties comparable to conventional resins, while milled splint materials have not shown better mechanical performance compared with conventional heat-cured acrylic resin. Polyetheretherketone (PEEK) have great potential and needs to be further investigated. Biological tests on oral cell populations are needed to confirm the long-term biocompatibility of these materials. CLINICAL RELEVANCE: The use of "mixed splints" combining different materials needs to be improved and evaluated in future research to take full advantage of different characteristics and properties.

Role of blood pressure dysregulation on kidney and mortality outcomes in COVID-19. Kidney, blood pressure and mortality in SARS-CoV-2 infection.

BACKGROUND: In February 2020 the corona virus disease 2019 (COVID-19) infection started spreading throughout Italy, hitting the Lombardy region very hard. Despite the high diffusion, only a subset of patients developed severe COVID-19: around 25% of them developed acute kidney injury (AKI) and one-third of them died. Elderly patients and patients with high comorbidities were identified as being at higher risk of severe COVID-19. METHODS: Our prospective observational cohort study includes 392 consecutive patients hospitalized for COVID-19 in Milan (median age 67 years, 75% male). We evaluated the relationship between blood pressure at presentation, presence of AKI at Emergency Department admission and during hospitalization, and total in-hospital mortality (24%). RESULTS: Although 58% of our study patients reported a history of hypertension (HYP) (86% on treatment), 30% presented with low blood pressure levels. Only 5.5% were diagnosed with AKI on admission; 75% of hypertensive patients discontinued therapy during hospitalization (only 20% were on treatment at discharge). Gender and hypertension were strongly associated with AKI at admission (odds ratio 11). Blood pressure was inversely correlated with increased risk of AKI upon admission, regardless of the severity of respiratory distress. Age over 65, history of hypertension, and severity of respiratory distress were the main predictors of AKI, which developed in 34.7% of cases during hospitalization. AKI was associated with increased in-hospital mortality. Hypertension and low blood pressure at presentation were the main predictors of in-hospital mortality, together with age over 65, baseline pulmonary involvement, and severity of illness. CONCLUSIONS: In patients hospitalized for COVID-19, hypertension and low blood pressure at presentation are important risk factors for AKI and mortality. Early reduction of antihypertensive therapy may improve outcomes in patients with SARS-CoV-2 infection.

Cavitand-functionalized porous silicon as an active surface for organophosphorus vapor detection.

This paper reports on the preparation of a porous silicon-based material covalently functionalized with cavitand receptors suited for the detection of organophosphorus vapors. Two different isomeric cavitands, both containing one acid group at the upper rim, specifically designed for covalent anchoring on silicon, were grafted on H-terminated porous silicon (PSi) by thermal hydrosilylation. The covalently functionalized surfaces and their complexation properties were characterized by combining different analytical techniques, namely X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and mass spectroscopy analysis coupled with thermal desorption experiments. Complexation experiments were performed by exposing both active surfaces and a control surface consisting of PSi functionalized with a structurally similar but inactive methylene-bridged cavitand (MeCav) to dimethyl methylphosphonate (DMMP) vapors. Comparison between active and inactive surfaces demonstrated the recognition properties of the new surfaces. Finally, the nature of the involved interactions, the energetic differences between active and inactive surfaces toward DMMP complexation, and the comparison with a true nerve gas agent (sarin) were studied by DFT modeling. The results revealed the successful grafting reaction, the specific host-guest interactions of the PSi-bonded receptors, and the reversibility of the guest complexation.

Molecular recognition of halogen-tagged aromatic VOCs at the air-silicon interface.

Selective and reversible complexation of halogen-tagged aromatic VOCs by a quinoxaline cavitand-decorated Si surface is demonstrated. The specific host-guest interactions of the Si-bonded receptors are proved to be responsible of the surface recognition properties, while extracavity non specific adsorptions are totally suppressed compared to the bulk material.

The role of triphenylamine in the stabilization of highly efficient polyfluorene-based OLEDs: a model oligomers study.

In order to understand the factors responsible for the improved efficiency and stability of organic light-emitting diodes (OLEDs) based on poly(9,9-dioctylfluorene) (PFO) when triphenylamine (TPA) is introduced as lateral fluorene substituent, we synthetize mono-disperse fluorene-thiophene oligomers as model compounds. Their blends with different concentrations of the fluorenone containing oligomer are studied in order to verify if only a reduction of ketonic defect sites or also an impeded energy transfer (ET) towards such sites are responsible for the suppression of the green emission band. We show that the introduction of TPA groups leads specifically both to an antioxidant action and a reduced ET towards residual defect sites, thanks to the environmental micro-encapsulation role played by TPA units surrounding the polymer backbone. As a result, the performances and colour stability of a device fabricated with TPA-substituted PFO (PFTPA) are strongly improved with respect to standard PFO device prepared in the same conditions.

Innovative cavitand-based sol-gel coatings for the environmental monitoring of benzene and chlorobenzenes via solid-phase microextraction.

An innovative and very selective solid-phase microextraction coating synthesized by sol-gel technology was developed for the determination of environmental pollutants such as aromatic hydrocarbons at trace levels in air, water, and soil samples. The obtained fibers, composed of quinoxaline-bridged cavitand units, were characterized in terms of film thickness, morphology, thermal stability, and pH resistance. Fibers, characterized by an average thickness of 56 +/- 6 mum, exhibited an excellent thermal stability until 400 degrees C and a very good fiber-to-fiber and batch-to-batch repeatability with RSD lower than 6%. Finally, the capabilities of the developed coating for the selective sampling of aromatic hydrocarbons were proved, obtaining LOD values in the subnanogram per liter range. Extraction efficiency at least 2-fold higher than that obtained using commercial devices was proved for chlorobenzenes sampling in river water, obtaining extraction recoveries ranging from 87.4 +/- 2.6% to 94.7 +/- 1.9%. The selective desorption of benzene in the presence of high amounts of other airborne pollutants was also demonstrated.

A supramolecular approach to sub-ppb aromatic VOC detection in air.

Micromachining technology is coupled to a selective pre-concentration material for the development of a portable sub-ppb level monitoring system for aromatic volatile organic compounds (VOC); the high sensitivity of Metal Oxide (MOX) gas sensors is combined with a supramolecular concentration unit to increase selectivity and reduce the detection limits.