Erfolgs- und Überlebensraten von vollkeramischem implantatgetragenem Zahnersatz zur Versorgung zahnloser und teilbezahnter Kiefer. Eine systematische Übersichtsarbeit und Meta-analyse

Objective: Aim of this systematic review and meta-analysis was to determine both the survival and the technical complication rates of implant supported fixed dental prostheses made of all-ceramic materials. Materials and methods: Three electronic databases (MEDLINE/Pubmed, Cochrane Library, Embase) were screened for relevant articles. Eligibility criteria included clinical investigations, ≥15 participants, partial and full-arch all-ceramic implant-supported fixed dental prostheses (P-FDP, FA-FDP) and at least one year of follow up. Multiple variables at the implant and prosthetic levels, including materials, location in the mouth and retention mode were reported. Statistical analyses to assess both failure and complication rates were performed. Finally, 5-year survival and complication estimates were calculated. Results: A total of 12 studies were selected out of the 4214 records initially screened. Seven of the included investigations referred to FA-FDPs and five to P-FDPs. All the included studies evaluated solely reconstructions made of veneered zirconia and all the P-FDPs were located in the posterior regions. The overall survival rate of the reconstructions was estimated 98.3% (P-FDP) and 97.7% (FA-FDP) after a follow up of 60 months. Furthermore, the most frequent complication was the chipping of the veneering ceramic, which lead to 5-year complication rates of 22.8% (P-FDPs) and 34.8% (FA-FDPs). Survival rate estimates of the supporting implants resulted in 98.5% for P-FDPs and 99.4% for FA-FDPs after 5 years. None of the evaluated confounding variables had a significant influence on the main outcomes. Conclusions: High survival rates resulted for all-ceramic implant-supported P- and FA-FDPs at both the implant and reconstruction levels. However, technical complications (chipping) were frequent. Further long-term clinical investigations, which also evaluate additional all-ceramic materials, are needed.Ziele: Die Bestimmung der Überlebens- und technischen Komplikationsrate vollkeramischer implantatgetragener Brücken zum partiellen (engl.: „partial all-ceramic implant-supported fixed dental prostheses, P-FDP“) und vollständigen Zahnersatz (engl.: „full arch all-ceramic implant-supported fixed dental prostheses, FA-FDP“). Darüber hinaus wurde die Überlebens- und Komplikationsrate der tragenden Implantate kalkuliert. Materialien und Methoden: Unter Zuhilfenahme dreier Datenbanken (MEDLINE/PubMed, Cochrane Library und Embase) wurde eine elektronische Suche durchgeführt. Es sollten relevante Studien mit einem durchschnittlichen Beobachtungszeitraum von mindestens einem Jahr und ≥15 Patienten identifiziert werden. Dabei wurden Daten zu folgenden Parametern erhoben: Überlebensraten von Implantaten und prothetischen Versorgungen, technische Komplikationen und potentielle Einflussfaktoren (z. B. verarbeitete Werkstoffe, Befestigung des Zahnersatzes oder Implantatposition). Misserfolgs- und Komplikationsraten wurden mit Hilfe von Poisson-Regressionsmodellen analysiert, um 5-Jahres-Überlebens- und Komplikationsraten zu kalkulieren. Ergebnisse: Fünf Studien der P-FDP Gruppe sowie sieben Studien der FA-FDP Gruppe entsprachen den Einschlusskriterien und konnten für eine Metaanalyse herangezogen werden. Insgesamt wurden 540 Versorgungen analysiert. Hierbei wurde in allen Studien Zahnersatz aus verblendetem Zirkoniumdioxid (ZrO2) untersucht. Alle P-FDPs waren im Seitenzahnbereich lokalisiert. Im Rahmen der Metaanalyse konnte eine Überlebensrate der prothetischen Versorgungen von jeweils 98,3 % (P-FDP) und 97,7 % (FA-FDP) errechnet werden. Dennoch führten regelmäßig auftretende Abplatzungen der Verblendkeramik (engl.: „chipping“) zu 5-Jahres-Komplikationsraten von 22,8 % (P-FDP) und 34,8 % (FA-FDP). Die mittlere Überlebensrate der Implantate lag nach 60 Monaten bei 98,5 % (P-FDP) und 99,4 % (FA-FDP). Es wurde von einer Schraubenlockerung sowie elf Dezementierungen der Brücken berichtet. Keine Variable hatte einen signifikanten Einfluss auf die Überlebens- oder Komplikationsraten. 3 Schlussfolgerungen: Vollkeramische implantatgetragene P- und FA-FDPs aus verblendetem Zirkoniumdioxid zeigen hohe Überlebens-, jedoch inakzeptable technische Komplikationsraten des Verblendmaterials. Deshalb gilt es die klinische Eignung sowie den langfristigen Erfolg dieser Versorgungen kritisch zu bewerten

Neighborhood effects in wind farm performance: An econometric approach

The optimization of turbine density in wind farms entails a trade-off between the usage of scarce, expensive land and power losses through turbine wake effects. A quantification and prediction of the wake effect, however, is challenging because of the complex aerodynamic nature of the interdependencies of turbines. In this paper, we propose a parsimonious data driven econometric wake model that can be used to predict production losses of existing and potential wind parks. Motivated by simple engineering wake models, the predicting variables are wind speed, turbine alignment angle, and distance. By utilizing data from two wind parks in Germany, a significantly better prediction of wake effect losses is attained compared to the standard Jensen model. A scenario analysis reveals that a distance between turbines can be reduced up to three times the rotor size without entailing substantial production losses. In contrast, a suboptimal configuration of turbines with respect to the main wind direction can result in production losses that are five times higher

3-D Printed Protective Equipment during COVID-19 Pandemic

While the number of coronavirus cases from 2019 continues to grow, hospitals are reporting shortages of personal protective equipment (PPE) for frontline healthcare workers. Furthermore, PPE for the eyes and mouth, such as face shields, allow for additional protection when working with aerosols. 3-D printing enables the easy and rapid production of lightweight plastic frameworks based on open-source data. The practicality and clinical suitability of four face shields printed using a fused deposition modeling printer were examined. The weight, printing time, and required tools for assembly were evaluated. To assess the clinical suitability, each face shield was worn for one hour by 10 clinicians and rated using a visual analogue scale. The filament weight (21-42 g) and printing time (1:40-3:17 h) differed significantly between the four frames. Likewise, the fit, wearing comfort, space for additional PPE, and protection varied between the designs. For clinical suitability, a chosen design should allow sufficient space for goggles and N95 respirators as well as maximum coverage of the facial area. Consequently, two datasets are recommended. For the final selection of the ideal dataset to be used for printing, scalability and economic efficiency need to be carefully balanced with an acceptable degree of protection

Fracture Resistance of Zirconia Oral Implants In Vitro: A Systematic Review and Meta-Analysis

Various protocols are available to preclinically assess the fracture resistance of zirconia oral implants. The objective of the present review was to determine the impact of different treatments (dynamic loading, hydrothermal aging) and implant features (e.g., material, design or manufacturing) on the fracture resistance of zirconia implants. An electronic screening of two databases (MEDLINE/Pubmed, Embase) was performed. Investigations including > 5 screw-shaped implants providing information to calculate the bending moment at the time point of static loading to fracture were considered. Data was extracted and meta-analyses were conducted using multilevel mixed-effects generalized linear models (GLMs). The Šidák method was used to correct for multiple testing. The initial search resulted in 1864 articles, and finally 19 investigations loading 731 zirconia implants to fracture were analyzed. In general, fracture resistance was affected by the implant design (1-piece > 2-piece, p = 0.004), material (alumina-toughened zirconia/ATZ > yttria-stabilized tetragonal zirconia polycrystal/Y-TZP, p = 0.002) and abutment preparation (untouched > modified/grinded, p < 0.001). In case of 2-piece implants, the amount of dynamic loading cycles prior to static loading (p < 0.001) or anatomical crown supply (p < 0.001) negatively affected the outcome. No impact was found for hydrothermal aging. Heterogeneous findings of the present review highlight the importance of thoroughly and individually evaluating the fracture resistance of every zirconia implant system prior to market release

Chapter Poesia del Gulag o della zona? Problemi e prospettive di analisi per una descrizione del corpus poetico dei prigionieri politici in URSS

The present survey aims at creating the basis for an extensive study on poetry written by victims of political repressions in the whole area of Segregation in the Soviet Union: prisons, forced labour camps, Gulags and confinement. The research relies on evidence drawn from published and archive materials, concerning the 1918-1956 period. We propose a systematization of the corpus, based on a new methodology: the key-concept of ‘poetry of Zone’ as a literary track of testimony of political repression, which was synchronical to the imprisonment experience in the USSR

L’epiteto οἰκουμενικός nelle firme nominali di ratifica dei patriarchi di Costantinopoli

The article deals with the nominal signature by which the patriarchs of Constantinople used to ratify documents granting favours in the Middle Ages. Particular attention has been paid to the adoption of the epithet οἰκουμενικός, which appears in the signature of ratification only during the late Comnenian period, as clearly evidenced by the surviving originals. The opinion, accepted so far by scholars of Byzantine diplomatics, that the adoption of this epithet goes back to the years of Nicene exile is critically discussed and refuted. This opinion is based on an article of Vitalien Laurent, which has been reconsidered in the light of the advancement of the studies on diplomatics in the last decades. We publish here for the first time the pictures of the most ancient granting documents of the Comnenian period, now in the Archives of the Monastery of Saint John the Theologian on Patmos, which are not yet critically edited

Il pensiero estetico di Nikolaj Evreinov dalla teatralità alla 'poetica della rivelazione'

This research offers an integral analysis of the aesthetic thought of the director, playwright and art theorist Nikolaj Nikolaevic Evreinov. The work focuses on the analysis of the treaty The revelation of art, written in Paris in the 1930s, which represents the greatest testimony of the author's research in the aesthetic field. Henceforth, a connection is offered between the known aspects of Evreinov's theatrical thought, relating to the period of the avant-garde in Russia, and others, of a broader nature, which have long been precluded from being known. Through insights on the Russian theatrical history of the early 20th century, reflections touching textual criticism, the history of aesthetic thought and Russian criticism, the complex figure of an artist emerges against the background of the culture expressed by post-revolutionary Russian emigration. An artist who, as an intellectual, begins a dialogue with the Western European cultural tradition. This book thus intends to restore the visibility, as well as an exegetical and historiographic completeness, of Evreinov’s rich legacy as a writer, a philosopher and a critic