Attachments for the orthodontic aligner treatment—State of the art—A comprehensive systematic review

Background: In recent years the burden of aligner treatment has been growing. However, the sole use of aligners is characterized by limitations; thus attachments are bonded to the teeth to improve aligner retention and tooth movement. Nevertheless, it is often still a challenge to clinically achieve the planned movement. Thus, the aim of this study is to discuss the evidence of the shape, placement and bonding of composite attachments. Methods: A query was carried out in six databases on 10 December 2022 using the search string (“orthodontics” OR “malocclusion” OR “Tooth movement techniques AND (“aligner*” OR “thermoformed splints” OR “invisible splint*” AND (“attachment*” OR “accessor*” OR “auxill*” AND “position*”). Results: There were 209 potential articles identified. Finally, twenty-six articles were included. Four referred to attachment bonding, and twenty-two comprised the influence of composite attachment on movement efficacy. Quality assessment tools were used according to the study type. Conclusions: The use of attachments significantly improves the expression of orthodontic movement and aligner retention. It is possible to indicate sites on the teeth where attachments have a better effect on tooth movement and to assess which attachments facilitate movement. The research received no external funding. The PROSPERO database number is CRD42022383276

Study of applied nanostructured and conventional dental materials

Composite resins are the most modern, widespread, aesthetic and conservative materials in the field of direct restorative dentistry. During the last years, the manufacturers of dental materials have launched onto the market composite resins with inorganic nanofillers with diameter less than 100 nm. These materials are considered nowadays the state of the art in terms of filler formulation. Nanofilled and nanohybrid composite resins have been introduced fairly recently in the clinical practice, so that there is less information about their properties and clinical effectiveness in comparison to traditional materials. The present work of thesis examined in both the laboratory and clinical setting the performance of several composite resins with nanofillers. The following items were analysed in five different phases: 1) roughness and microhardness of nanohybrid composites; 2) sealing ability of a nanohybrid flowable composite; 3) influence of finish line on the marginal seal of nanohybrid composite crowns after periodontal scaling; 4) two-year in vitro and in vivo evaluation of surface roughness of a flowable nanohybrid composite; 5) clinical effectiveness of nanofilled and nanohybrid composite resins: a systematic review

Fracture resistance of restorations with fiber-reinforced composites: systematic analysis

Aims: This study aimed to evaluate and compare the fracture resistance values of composed/complex fiber-reinforced composite restorations, in posterior teeth, with those of healthy teeth, or of non-fiber-reinforced composites restorations or, of unrestored cavity preparations by means of an in vitro outputs systematic quantitative and qualitative analysis. Methodology: Methodic search was performed using PubMed, Web of Science and Google Scholar from 15th may to 12th June 2023. Only in vitro studies published as articles in English idiom in the last 10 years, and that evaluate/compared the fracture resistance values of human posterior teeth with extensive fiber-reinforced composite restorations, with those of healthy teeth, or of non-fiber-reinforced composites restorations or, of unrestored cavity preparations were included. This study was registered (425509) in PROSPERO database and followed the PRISMA guidelines. The risk of bias assessed by The QUIN tool. The fracture resistance median values, in Newton (N), were calculated for all, experimental and control groups with a 95% confidence interval. For pairwise comparation nonparametric tests (<0.05) were applied. Results: From 932 articles obtained, only 24 publications met the inclusion criteria; 23 had moderate and one high risk of bias. Overall fracture resistance of experimental group median value was of 976.0 N and differ from all control groups. Pairwise comparison revealed that experimental group showed lower values of fracture when compared with healthy teeth (1459.9; p=0.048) but higher than those of two control groups, composite non-fiber-reinforced restoration (771.0 N; p=0.008) and cavity preparation without restoration (386.6 N; p<0.001). Conclusion: In vitro systematic outputs evidenced that glass and/or polyethylene fibers can improve composite restorations fracture resistance values.Objetivos: Este estudo pretendeu avaliar e comparar os valores de resistência à fratura de dentes posteriores com restaurações compostas/complexas com compósitos reforçados por fibras em comparação com dentes hígidos, ou restaurações com compósitos não reforçados por fibras ou com preparos cavitários não restaurados, através uma análise sistemática quantitativa e qualitativa de resultados de estudos in vitro. Metodologia: Uma pesquisa foi realizada na PubMed, Web of Science e Google Scholar entre 15 de maio a 12 de junho de 2023. Foram incluídos estudos in vitro publicados em língua inglesa, nos últimos 10 anos, que avaliaram/compararam os valores de resistência à fratura de dentes posteriores humanos com restaurações extensas com compósitos reforçados com fibras, com valores obtidos em dentes, hígidos, com restaurações com compósitos não reforçados por fibras ou, com preparos cavitários não restaurados. Este estudo foi registado (425509) na base de dados PROSPERO e seguiu as diretrizes PRISMA. Para análise do risco de viés dos estudos recorreu-se ao The QUIN. Os valores medianos da resistência à fratura, em Newton (N), foram calculados para todos os grupos, experimental e controlos com um intervalo de confiança de 95%. Para comparação de resultados foram aplicados testes não paramétricos (<0,05). Resultados: De 932 possíveis artigos obtidos, apenas 24 publicações cumpriram os critérios de inclusão, dos quais 23 revelaram risco de viés moderado e um alto. O valor mediano da resistência à fratura global do grupo experimental foi de 976.0 N e diferiu dos obtidos nos grupos controlo. A comparação entre os grupos revelou que o grupo experimental apresentou valores mais baixos de resistência à fratura quando comparado com os obtidos em dentes hígidos (1459.9, p=0.048), mas mais elevados do que os dos restantes dois grupos de controlo, restauração de compósito não reforçada com fibra (771.0 N, p=0.008) e preparação cavitaria sem restauração (386.6 N, p<0.001). Conclusão: Os resultados sistemáticos de estudos in vitro evidenciaram que fibras de vidro e/ou polietileno podem melhorar os valores de resistência à fratura de dentes posteriores com restaurações com compósitos

Adaptiver Suchansatz zur multidisziplinären Optimierung von Leichtbaustrukturen unter Verwendung hybrider Metaheuristik

Within the last few years environmental regulations, safety requirements and market competitions forced the automotive industry to open up a wide range of new technologies. Lightweight design is considered as one of the most innovative concepts to fulfil environmental, safety and many other objectives at competitive prices. Choosing the best design and production process in the development period is the most significant link in the automobile production chain. A wide range of design and process parameters needs to be evaluated to achieve numerous goals of production. These goals often stand in conflict with each other. In addition to the variation of the concepts and following the objectives, some limitations such as manufacturing restrictions, financial limits, and deadlines influence the choice of the best combination of variables. This study introduces a structural optimization tool for assemblies made of sheet metal, e.g. the automobile body, based on parametrization and evaluation of concepts in CAD and CAE. This methodology focuses on those concepts, which leads to the use of the right amount of light and strong material in the right place, instead of substituting the whole structure with the new material. An adaptive hybrid metaheuristic algorithm is designed to eliminate all factors that would lead to a local minimum instead of global optimum. Finding the global optimum is granted by using some explorative and exploitative search heuristics, which are intelligently organized by a central controller. Reliability, accuracy and the speed of the proposed algorithm are validated via a comparative study with similar algorithms for an academic optimization problem, which shows valuable results. Since structures might be subject to a wide range of load cases, e.g. static, cyclic, dynamic, temperature-dependent etc., these requirements need to be addressed by a multidisciplinary optimization algorithm. To handle the nonlinear response of objectives and to tackle the time-consuming FEM analyses in crash situations, a surrogate model is implemented in the optimization tool. The ability of such tool to present the optimum results in multi-objective problems is improved by using some user-selected fitness functions. Finally, an exemplary sub-assembly made of sheet metal parts from a car body is optimized to enhance both, static load case and crashworthiness.Die Automobilindustrie hat in den letzten Jahren unter dem Druck von Umweltvorschriften, Sicherheitsanforderungen und wettbewerbsfähigem Markt neue Wege auf dem Gebiet der Technologien eröffnet. Leichtbau gilt als eine der innovativsten und offenkundigsten Lösungen, um Umwelt- und Sicherheitsziele zu wettbewerbsfähigen Preisen zu erreichen. Die Wahl des besten Designs und Verfahrens für Produktionen in der Entwicklungsphase ist der wichtigste Ring der Automobilproduktionskette. Um unzählige Produktionsziele zu erreichen, müssen zahlreiche Design- und Prozessparameter bewertet werden. Die Anzahl und Variation der Lösungen und Ziele sowie einige Einschränkungen wie Fertigungsbeschränkungen, finanzielle Grenzen und Fristen beeinflussen die Auswahl einer guten Kombination von Variablen. In dieser Studie werden strukturelle Optimierungswerkzeuge für aus Blech gefertigte Baugruppen, z. Karosserie, basierend auf Parametrisierung und Bewertung von Lösungen in CAD bzw. CAE. Diese Methodik konzentriert sich auf die Lösungen, die dazu führen, dass die richtige Menge an leichtem / festem Material an der richtigen Stelle der Struktur verwendet wird, anstatt vollständig ersetzt zu werden. Eine adaptive Hybrid-Metaheuristik soll verhindern, dass alle Faktoren, die Bedrohungsoptimierungstools in einem lokalen Minimum konvergieren, anstelle eines globalen Optimums. Das Auffinden des globalen Optimums wird durch einige explorative und ausbeuterische Such Heuristiken gewährleistet. Die Zuverlässigkeit, Genauigkeit und Geschwindigkeit des vorgeschlagenen Algorithmus wird mit ähnlichen Algorithmen in akademischen Optimierungsproblemen validiert und führt zu respektablen Ergebnissen. Da Strukturen möglicherweise einem weiten Bereich von Lastfällen unterliegen, z. statische, zyklische, dynamische, Temperatur usw. Möglichkeit der multidisziplinären Optimierung wurde in Optimierungswerkzeugen bereitgestellt. Um die nichtlineare Reaktion von Zielen zu überwinden und um den hohen Zeitverbrauch von FEM-Analysen in Absturzereignissen zu bewältigen, könnte ein Ersatzmodell vom Benutzer verwendet werden. Die Fähigkeit von Optimierungswerkzeugen, optimale Ergebnisse bei Problemen mit mehreren Zielsetzungen zu präsentieren, wird durch die Verwendung einiger vom Benutzer ausgewählten Fitnessfunktionen verbessert. Eine Unterbaugruppe aus Blechteilen, die zur Automobilkarosserie gehören, ist optimiert, um beide zu verbessern; statischer Lastfall und Crashsicherheit

Fabrication, Modeling and Characterization of Multi-Crosslinked Methacrylate Copolymeric Nanoparticles for Oral Drug Delivery

Nanotechnology remains the field to explore in the quest to enhance therapeutic efficacies of existing drugs. Fabrication of a methacrylate copolymer-lipid nanoparticulate (MCN) system was explored in this study for oral drug delivery of levodopa. The nanoparticles were fabricated employing multicrosslinking technology and characterized for particle size, zeta potential, morphology, structural modification, drug entrapment efficiency and in vitro drug release. Chemometric Computational (CC) modeling was conducted to deduce the mechanism of nanoparticle synthesis as well as to corroborate the experimental findings. The CC modeling deduced that the nanoparticles synthesis may have followed the mixed triangular formations or the mixed patterns. They were found to be hollow nanocapsules with a size ranging from 152 nm (methacrylate copolymer) to 321 nm (methacrylate copolymer blend) and a zeta potential range of 15.8–43.3 mV. The nanoparticles were directly compressible and it was found that the desired rate of drug release could be achieved by formulating the nanoparticles as a nanosuspension, and then directly compressing them into tablet matrices or incorporating the nanoparticles directly into polymer tablet matrices. However, sustained release of MCNs was achieved only when it was incorporated into a polymer matrix. The experimental results were well corroborated by the CC modeling. The developed technology may be potentially useful for the fabrication of multi-crosslinked polymer blend nanoparticles for oral drug delivery

National Educators' Workshop: Update 1993. Standard Experiments in Engineering Materials Science and Technology

This document contains a collection of experiments presented and demonstrated at the National Educators' Workshop: Update 93 held at the NASA Langley Research Center in Hampton, Virginia, on November 3-5, 1993. The experiments related to the nature and properties of engineering materials and provided information to assist in teaching about materials in the education community

System Design for Digital Experimentation and Explanation Generation

Experimentation increasingly drives everyday decisions in modern life, as it is considered by some to be the gold standard for determining cause and effect within any system. Digital experiments have expanded the scope and frequency of experiments, which can range in complexity from classic A/B tests to contextual bandits experiments, which share features with reinforcement learning. Although there exists a large body of prior work on estimating treatment effects using experiments, this prior work did not anticipate the new challenges and opportu- nities introduced by digital experimentation. Novel errors and threats to validity arise at the intersection of software and experimentation, especially when experimentation is in service of understanding humans behavior or autonomous black-box agents. We present several novel tools for automating aspects of the experimentation- analysis pipeline. We propose new methods for evaluating online field experimentation, automatically generating corresponding analyses of treatment effects. We then draw the connection between software testing and experimental design and argue that applying software testing techniques to a kind of autonomous agent—a deep reinforcement learning agent—to demonstrate the need for novel testing paradigms when a software stack uses learned components that may have emergent behavior. We show how our system may be used to evaluate claims made about the behavior of autonomous agents and find that some claims do not hold up under test. Finally, we show how to produce explanations of the behavior of black-box software-defined agents interacting with white-box environments via automated experimentation. We show how an automated system can be used for exploratory data analysis, with a human in the loop, to investigate a large space of possible counterfactual explanations