Do new matrix formulations improve resin composite resistance to degradation processes?

The aim of this study was to determine the degradation resistance of three new formulations-silorane-, Ormocer- and dimer-acid-based materials-and compare them to the traditional dimethacrylate-based materials. One silorane- (Filtek P90, P90), one Ormocer- (Ceram-X, CX), one dimer-acid- (N'Durance, ND) and two dimethacrylate-based (Filtek P60, P60; Tetric Ceram, TC) materials were investigated. Water sorption (Wsp) and solubility (Wsl) were determined after the materials were immersed in water for 28 days. Knoop hardness (KH) was determined before and after 24 h immersion in pure ethanol. The flexural-strength (FS) was determined by the bending test after one-week storage in a dry environment or after one-week immersion in pure ethanol. Data were submitted to analysis of variance (ANOVA) and Tukey's test (95%). The three new formulations showed lower Wsp than the dimethacrylate-based formulation. CX (0.50 ± 0.17%) and ND (0.72 ± 0.19%) exhibited the lowest Wsp, whereas P90 (0.02 ± 0.03%) and P60 (0.04 ± 0.03%) showed the lowest Wsl. All resins showed reduced Knoop hardness number (KHN) after ethanol immersion. P60 presented the lowest decrease in KH value (19 ± 5%). TC (48 ± 3%) and P90 (39 ± 9%) showed the highest KHN decrease after ethanol storage. The FS of CX, ND and TC were affected by ethanol storage. The new formulations did not improve the degradation resistance, as compared with the traditional methacrylate-based materials.41041

Use of information and communications technology in learning by undergraduation dental students

The teaching-learning process has in the novel information and communications technologies (ICTs), in particular the Internet, an important tool. In this context, educational institutions are challenged to develop pedagogical practices integrated into the virtual environment. This approach demands, among other things, knowledge of the profile of the technology used by the students to develop educational content and pedagogical practices aligned with the use of ICTs by the students. Therefore, the aim of this study was to investigate the use of ICTs by undergraduate dental students in the learning process, considering the profile of Internet access and interest in videos of dental materials topics. The study sample was composed by, 597 dental students from the Federal Universities of Pelotas (UFPel), Rio de Janeiro (UFRJ), and Fluminense (UFF). A self-applicable paper questionnaire handed to the student in the classroom was used. The questionnaire contained questions on the use of ICTs in individual and collaborative learnings, the use of apps to study dentistry, and interest in topics of videos related to dental materials. It was found that the students use ICT resources in the process of individual learning as well as communication resources mediated by the Internet in collaborative learning. The access to study is done mainly by mobile devices. The websites most used are Google.com, YouTube, and Passei Direto, whereas the least accessed website amongst those listed was Portal Capes. Communication between students is carried out mainly through instant messaging, especially via WhatsApp app. Regarding the format of content to study dentistry, most students prefer to use content in physical format, such as books and photocopies, instead of digital formats. Less than half of the respondents use apps in learning. As regards the interest for videos related to dental materials topics, most respondents expressed interest in the topics presented and indicated a total of 1248 topics that they have interest in videos. The points identified by the present study can aid in drawing a general profile of the use of ICTs by the respondents, provoke reflection on the adoption and development of digital tools for the teaching-learning process, as well as hybrid teaching methodologies that can be integrated both into the dental materials area and the undergraduate dental education in general.O processo ensino-aprendizagem tem nas novas tecnologias de informação e comunicação (TIC), em especial na Internet, uma importante ferramenta. Nesta perspectiva, as instituições de ensino são desafiadas a desenvolver práticas pedagógicas integradas ao ambiente virtual. Para isto, entre outros aspectos, é preciso conhecer o perfil da tecnologia utilizada pelos alunos para elaborar conteúdos didáticos e práticas pedagógicas alinhadas com o modo de uso das TICs pelos estudantes. Sendo assim, o objetivo deste trabalho foi investigar o uso da TIC por alunos de graduação de Odontologia no processo de aprendizado, considerando o perfil de acesso a Internet e o interesse por temas de vídeos de materiais odontológicos. A amostra do estudo foi composta por um grupo de 597 alunos de Odontologia das Universidades Federais de Pelotas (UFPel), Rio de Janeiro (UFRJ) e Fluminense (UFF). Foi utilizado questionário autoaplicável entregue em papel ao estudante em sala de aula. O questionário continha questões sobre utilização das TICs no aprendizado individual e colaborativo, a utilização de aplicativos para estudar Odontologia e interesse por temas de vídeos relacionados a materiais odontológicos. Constatou-se que os discentes utilizam recursos das TICs no processo de aprendizagem individual bem como recursos de comunicação mediados pela Internet no aprendizado colaborativo. O acesso para estudar é feito principalmente por dispositivos móveis. Os websites mais utilizados são o Google.com, YouTube e Passei Direto, enquanto o website menos acessado dentre os listados foi o Portal Capes. A comunicação entre os estudantes é realizada principalmente por meio de mensagens instantâneas, especialmente via o aplicativo WhatsApp. Quanto ao formato de conteúdos para estudar Odontologia, a maioria prefere usar conteúdos no formato físico, como livros e fotocópias, ao invés de formatos digitais. Quanto ao uso de aplicativos, menos da metade dos entrevistados os utiliza no aprendizado. No que diz respeito ao interesse por vídeos relacionados a temas de materiais odontológicos, a maioria dos entrevistados manifestaram interesse pelos temas apresentados e indicaram um total de 1248 temas que despertam seu interesse em vídeos. Os pontos identificados pelo estudo permitiram traçar um perfil geral da utilização das TICs pelos respondentes, suscitam a reflexão sobre a adoção e desenvolvimento de ferramentas digitais no processo ensino-aprendizagem, bem como de metodologias híbridas de ensino que podem ser integradas tanto à área de materiais odontológicos quanto ao ensino de graduação em Odontologia de forma geral

Do new matrix formulations improve resin composite resistance to degradation processes?

The aim of this study was to determine the degradation resistance of three new formulations-silorane-, Ormocer- and dimer-acid-based materials-and compare them to the traditional dimethacrylate-based materials. One silorane- (Filtek P90, P90), one Ormocer- (Ceram-X, CX), one dimer-acid- (N'Durance, ND) and two dimethacrylate-based (Filtek P60, P60; Tetric Ceram, TC) materials were investigated. Water sorption (Wsp) and solubility (Wsl) were determined after the materials were immersed in water for 28 days. Knoop hardness (KH) was determined before and after 24 h immersion in pure ethanol. The flexural-strength (FS) was determined by the bending test after one-week storage in a dry environment or after one-week immersion in pure ethanol. Data were submitted to analysis of variance (ANOVA) and Tukey's test (95%). The three new formulations showed lower Wsp than the dimethacrylate-based formulation. CX (0.50 ± 0.17%) and ND (0.72 ± 0.19%) exhibited the lowest Wsp, whereas P90 (0.02 ± 0.03%) and P60 (0.04 ± 0.03%) showed the lowest Wsl. All resins showed reduced Knoop hardness number (KHN) after ethanol immersion. P60 presented the lowest decrease in KH value (19 ± 5%). TC (48 ± 3%) and P90 (39 ± 9%) showed the highest KHN decrease after ethanol storage. The FS of CX, ND and TC were affected by ethanol storage. The new formulations did not improve the degradation resistance, as compared with the traditional methacrylate-based materials

Neotropical freshwater fisheries : A dataset of occurrence and abundance of freshwater fishes in the Neotropics

The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's most diverse regions for freshwater fishes. Our NEOTROPICAL FRESHWATER FISHES data set is the first to produce a large-scale Neotropical freshwater fish inventory, covering the entire Neotropical region from Mexico and the Caribbean in the north to the southern limits in Argentina, Paraguay, Chile, and Uruguay. We compiled 185,787 distribution records, with unique georeferenced coordinates, for the 4225 species, represented by occurrence and abundance data. The number of species for the most numerous orders are as follows: Characiformes (1289), Siluriformes (1384), Cichliformes (354), Cyprinodontiformes (245), and Gymnotiformes (135). The most recorded species was the characid Astyanax fasciatus (4696 records). We registered 116,802 distribution records for native species, compared to 1802 distribution records for nonnative species. The main aim of the NEOTROPICAL FRESHWATER FISHES data set was to make these occurrence and abundance data accessible for international researchers to develop ecological and macroecological studies, from local to regional scales, with focal fish species, families, or orders. We anticipate that the NEOTROPICAL FRESHWATER FISHES data set will be valuable for studies on a wide range of ecological processes, such as trophic cascades, fishery pressure, the effects of habitat loss and fragmentation, and the impacts of species invasion and climate change. There are no copyright restrictions on the data, and please cite this data paper when using the data in publications

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved