Effizienz der Revision von Wurzelkanalfüllungen nach Obturation mit fünf verschiedenen Techniken mittels maschineller Wurzelkanalinstrumente

Hintergrund und Ziele Die Revision einer Wurzelkanalfüllung wird notwendig, wenn klinische oder radiologische Befunde einer Parodontitis apicalis an bereits wurzelkanalbehandelten Zähnen auftreten. Ziel der Revisionsbehandlung ist die Wiederherstellung der Integrität periapikaler Verhältnisse und die Beseitigung oder Prävention klinischer Symptome durch die erneute mechanische Aufbereitung und chemische Reinigung des Wurzelkanalsystems sowie den hermetisch dichten Verschluss des Wurzelkanals durch die Wurzelfüllung und die koronale Restauration (Weiger et al. 1994, Hülsmann, Weiger 1994, Stellungnahme der DGZMK und der DGZ: Revision einer Wurzelkanalbehandlung 2004). Im Rahmen der vorliegenden Studie sollte untersucht werden, wie effizient die schrittweise maschinelle Revision verschiedener Kalt- und Warmfülltechniken mit dem maschinell rotierenden D-RaCe-System ist. Dazu wurden die Revisionseffizienz und die Revisionsdauer der unterschiedlichen Wurzelkanalfülltechniken ermittelt und ausgewertet. Methoden Für die Untersuchungen wurden 75 humane, extrahierte, einwurzelige Zähne dekapitiert. Die Proben wurden mit maschinellen Wurzelkanalinstrumenten des BioRaCe-Systems bis zu der Größe .04/#35 aufbereitet. Nach Trennung der Wurzeln in longitudinaler Richtung mittels diamantierter Trennscheibe, wurden die Zahnhälften in speziellen Biresin-Blöcken wieder zueinander fixiert. Es erfolgte eine weitere maschinelle Aufbereitung bis Größe .04/#40 zur Schaffung eines runden Wurzelkanalquerschnitts. Die Proben wurden zu je 15 Zähnen je einer von fünf Gruppen zugeteilt und diese mit der jeweiligen Obturationstechnik gefüllt. Die in dieser Arbeit untersuchten Wurzelkanalfülltechniken waren die laterale Kompaktion, die Non-compaction-Technik und die Single-cone-Technik bei den Kaltfülltechniken, als Vertreter der Warmfülltechniken die Thermafil-Technik und die warme vertikale Kompaktion. Schließlich wurden alle Proben schrittweise revidiert. Der erste Revisionsschritt erfolgte mit D RaCe-Instrumenten der Größen .10/#30 und .04/#25 sowie der BioRaCe-Feile der Größe .04/#40. Im zweiten Revisionsschritt wurden die Wurzelkanäle mit einem „Rondo“ RaCe-Instrument (Spezialanfertigung) der Größen .04/#45 und im letzten Revisionsschritt mit einem BioRaCe-Instrument der Größe .04/#50 erweitert. Nach jedem der drei Revisionsschritte wurden die Proben unter dem Lichtmikroskop (Leica) bei 4-facher und 16-facher Vergrößerung fotografiert und untersucht und mit der Software ImageTool ausgewertet. Die statistische Datenanalyse erfolgte mit dem Auswertungsprogramm SPSS 19.0. Ergebnisse Die Auswertung der schrittweise revidierten Proben zeigte ein eindeutiges Ergebnis. Nach jedem der drei Revisionsschritte wiesen die Kaltfülltechniken weitaus weniger Guttapercha- als Sealerreste auf. Bei den Warmfülltechniken hingegen verblieben weitaus mehr Guttaperchareste im Wurzelkanal, während der Anteil an Sealerresten verhältnismäßig gering war. Insgesamt stellte sich die schrittweise Revision und Erweiterung des Wurzelkanals als äußerst effektiv heraus. In Bezug auf die Revisionszeit erwies sich die Single-cone-Technik als relativ leicht und schnell zu revidierende Wurzelkanalfülltechnik. Im Gegensatz dazu waren die Proben der Thermafil-Technik besonders schwer und mit einem signifikant höheren Zeitaufwand zu revidieren. Praktische Schlussfolgerungen Die Resultate dieser Studie belegen die Effektivität der schrittweisen Aufbereitung und Erweiterung des Wurzelkanals während der Revision. Die Instrumentengröße sollte bei jeder Revision einer Wurzelkanalfüllung zumindest zwei Instrumentengrößen über der ursprünglichen Aufbereitungsgröße liegen, um eine optimale Entfernung von Sealer- und Guttapercharesten von den Wurzelkanalwänden zu gewährleisten. Vor allem bei der Revision einer Thermafil-Wurzelkanalfüllung muss ein höherer Zeitaufwand einkalkuliert werden

Bandersnatch: an exploratory study about audiovisual media consumption and culture of convergence

O presente artigo é uma análise das interações do público com a narrativa Bandersnatch. A metodologia de abordagem qualitativa tem o viés exploratório, com pesquisa bibliográfica e estudo empírico por meio da observação de postagens na plataforma Facebook. Este artigo tem como objetivo compreender as práticas do público no ambiente digital a partir dos resultados encontrados na etapa exploratória. O referencial teórico concentra-se na cultura da convergência e no consumo midiático como alicerces conceituais. Por fim, os resultados da análise geral são: as tipologias das postagens, os formatos, as temáticas emergentes e os perfis de público.This article is an analysis of audience interactions with Bandersnatch. The methodology of qualitative approach has an exploratory view, with bibliographical research and empirical study through the observation of posts on Facebook. This article aims to understand the practices of the audience in the digital environment from the results found in the exploratory stage. The theoretical framework concentrates on the culture of convergence and media consumption as conceptual foundations. Finally, the results of the general analysis are: postings typologies, formats, emerging themes and audience profiles

Advanced Denoising for X-ray Ptychography

The success of ptychographic imaging experiments strongly depends on achieving high signal-to-noise ratio. This is particularly important in nanoscale imaging experiments when diffraction signals are very weak and the experiments are accompanied by significant parasitic scattering (background), outliers or correlated noise sources. It is also critical when rare events such as cosmic rays, or bad frames caused by electronic glitches or shutter timing malfunction take place. In this paper, we propose a novel iterative algorithm with rigorous analysis that exploits the direct forward model for parasitic noise and sample smoothness to achieve a thorough characterization and removal of structured and random noise. We present a formal description of the proposed algorithm and prove its convergence under mild conditions. Numerical experiments from simulations and real data (both soft and hard X-ray beamlines) demonstrate that the proposed algorithms produce better results when compared to state-of-the-art methods.Comment: 24 pages, 9 figure

Disruption and pseudoautosomal localization of the major histocompatibility complex in monotremes

The characterization and chromosomal mapping of major histocompatibility complex (MHC)-containing BAC clones from platypus and the short-beaked echidna reveals new insights into the evolution of both the mammalian MHC and monotreme sex chromosomes

Influence of gas atmospheres and ceria on the stability of nanoporous gold studied by environmental electron microscopy and <em>In</em> <em>situ</em> ptychography

A novel complementary approach of electron microscopy/environmental TEM and in situ hard X-ray ptychography was used to study the thermally induced coarsening of nanoporous gold under different atmospheres, pressures and after ceria deposition. The temperature applied during ptychographic imaging was determined by IR thermography. While using elevated temperatures (room temperature – 400 °C) and realistic gas atmospheres (1 bar) we achieved for the first time a spatial resolution of about 20 nm during hard X-ray ptychography. The annealing of pure and ceria stabilized nanoporous gold in different atmospheres revealed that the conditions have a tremendous influence on the coarsening. The porous structure of the samples was stable up to approximately 800 °C in vacuum, whereas pronounced changes and coarsening were observed already at approximately 300 °C in oxygen containing atmospheres. A layer of ceria on the nanoporous gold led to an improvement of the stability, but did not alleviate the influence of the gas atmosphere. Different behaviors were observed, such as coarsening and even material loss or migration. The results suggest that additional mechanisms beyond surface diffusion need to be considered and that microscopic studies aimed at more realistic conditions are important to understand the behavior of such materials and catalysts

Diverse migration tactics of fishes within the large tropical Mekong River system

Fish often migrate to feed, reproduce and seek refuge from predators and prevailing environmental conditions. As a result, migration tactics often vary among species based on a diversity of life history needs, although variation within species is increasingly being recognised as important to population resilience. In this study, within- and among-species diversity in life history migratory tactics of six Mekong fish genera was examined using otolith microchemistry to explore diadromous and potamodromous traits. Two species were catadromous and one species was an estuarine resident, while the remaining three species were facultative in their migration strategies, with up to four tactics within a single species. Migrant and resident contingents co-existed within the same species. Management, conservation and mitigation strategies that maintain connectivity in large tropical rivers, such as effective fishway design, should consider a diversity of migration tactics at the individual level for improved outcomes

Towards real-time cardiovascular magnetic resonance guided transarterial CoreValve implantation: in vivo evaluation in swine

<p>Abstract</p> <p>Background</p> <p>Real-time cardiovascular magnetic resonance (rtCMR) is considered attractive for guiding TAVI. Owing to an unlimited scan plane orientation and an unsurpassed soft-tissue contrast with simultaneous device visualization, rtCMR is presumed to allow safe device navigation and to offer optimal orientation for precise axial positioning. We sought to evaluate the preclinical feasibility of rtCMR-guided transarterial aortic valve implatation (TAVI) using the nitinol-based Medtronic CoreValve bioprosthesis.</p> <p>Methods</p> <p>rtCMR-guided transfemoral (n = 2) and transsubclavian (n = 6) TAVI was performed in 8 swine using the original CoreValve prosthesis and a modified, CMR-compatible delivery catheter without ferromagnetic components.</p> <p>Results</p> <p>rtCMR using TrueFISP sequences provided reliable imaging guidance during TAVI, which was successful in 6 swine. One transfemoral attempt failed due to unsuccessful aortic arch passage and one pericardial tamponade with subsequent death occurred as a result of ventricular perforation by the device tip due to an operating error, this complication being detected without delay by rtCMR. rtCMR allowed for a detailed, simultaneous visualization of the delivery system with the mounted stent-valve and the surrounding anatomy, resulting in improved visualization during navigation through the vasculature, passage of the aortic valve, and during placement and deployment of the stent-valve. Post-interventional success could be confirmed using ECG-triggered time-resolved cine-TrueFISP and flow-sensitive phase-contrast sequences. Intended valve position was confirmed by ex-vivo histology.</p> <p>Conclusions</p> <p>Our study shows that rtCMR-guided TAVI using the commercial CoreValve prosthesis in conjunction with a modified delivery system is feasible in swine, allowing improved procedural guidance including immediate detection of complications and direct functional assessment with reduction of radiation and omission of contrast media.</p

Functional identity versus species richness: herbivory resistance in plant communities

The resistance of a plant community against herbivore attack may depend on plant species richness, with monocultures often much more severely affected than mixtures of plant species. Here, we used a plant–herbivore system to study the effects of selective herbivory on consumption resistance and recovery after herbivory in 81 experimental grassland plots. Communities were established from seed in 2002 and contained 1, 2, 4, 8, 16 or 60 plant species of 1, 2, 3 or 4 functional groups. In 2004, pairs of enclosure cages (1 m tall, 0.5 m diameter) were set up on all 81 plots. One randomly selected cage of each pair was stocked with 10 male and 10 female nymphs of the meadow grasshopper, Chorthippus parallelus. The grasshoppers fed for 2 months, and the vegetation was monitored over 1 year. Consumption resistance and recovery of vegetation were calculated as proportional changes in vegetation biomass. Overall, grasshopper herbivory averaged 6.8%. Herbivory resistance and recovery were influenced by plant functional group identity, but independent of plant species richness and number of functional groups. However, herbivory induced shifts in vegetation composition that depended on plant species richness. Grasshopper herbivory led to increases in herb cover at the expense of grasses. Herb cover increased more strongly in species-rich mixtures. We conclude that selective herbivory changes the functional composition of plant communities and that compositional changes due to selective herbivory depend on plant species richness