Resumo A proantocianidina (PA) é um biomodificador dentinário promissor devido a sua capacidade de estabilizar as fibrilas colágenas contra a degradação por metaloproteinases da matriz (MMPs); no entanto, o protocolo mais eficaz para a incorporação de PA em procedimentos adesivos ainda não está claro. Este estudo avaliou o efeito da biomodificação da dentina com um condicionador ácido contendo PA na atividade de MMPs, morfologia da interface adesiva e resistência à microtração resina-dentina. Molares humanos extraídos foram lixados para exposição da dentina e condicionados com ácido por 15 s de acordo com os grupos: EXP - ácido fosfórico experimental; EXP+PA - ácido fosfórico experimental com 10% PA; TE - sistema total-etch; SE - sistema self-etch. As amostras foram restauradas com resina composta e armazenadas em água destilada (37ºC). A atividade de MMP e morfologia da interface foram analisadas após 24 h por zimografia in situ (n=6) e microscopia eletrônica de varredura (n=3), respectivamente. A resistência à microtração resina-dentina (μTBS) foi avaliada após 24 horas e 6 meses de armazenamento (n=6). Atividade de MMP detectada na dentina condicionada foi significativamente maior em comparação com a dentina não tratada (p <0,05), mas não houve diferenças entre os diferentes ácidos. Tags e microtags de resina, indicativos de uma penetração adequada do sistema adesivo nos túbulos e microtúbulos dentinários, foram observadas ao longo da camada híbrida em todos os grupos. Não houve diferença entre os valores de μTBS de 24 h e 6 meses para EXP+PA; além disso, EXP+PA apresentou maiores valores de μTBS após 6 meses em comparação com TE e EXP (p <0,05). Os resultados sugerem que a biomodificação por 15 s não foi suficiente para reduzir significativamente a atividade de MMP; apesar disso, EXP + PA foi capaz de melhorar a estabilidade da interface resina-dentina em comparação com sistemas total- e self-etch comerciais.

Abstract Proanthocyanidin (PA) is a promising dentin biomodifier due to its ability to stabilize collagen fibrils against degradation by matrix metalloproteinases (MMPs); however, the most effective protocol to incorporate PA into bonding procedures is still unclear. This study evaluated the effect of dentin biomodification with a PA acid etchant on MMP activity, adhesive interface morphology and resin-dentin microtensile bond strength. Sound extracted human molars were flattened to expose dentin and acid-etched for 15 s according to the groups: EXP - experimental phosphoric acid; EXP+PA - experimental phosphoric acid 10% PA; TE - total-etching system; SE - self-etching system. Samples were restored with composite resin and stored in distilled water (37ºC). MMP activity and interface morphology were analyzed after 24 h by in situ zymography (n=6) and scanning electron microscopy (n=3), respectively. The resin-dentin microtensile bond strength (μTBS) was evaluated after 24 h and 6 months storage (n=6). Significantly higher MMP activity was detected in etched dentin compared with untreated dentin (p<0.05), but no difference among acid groups was found. Resin tags and microtags, indicative of proper adhesive system penetration in dentinal tubules and microtubules, were observed along the hybrid layer in all groups. There was no difference in μTBS between 24 h and 6 months for EXP+PA; moreover, it showed higher long-term μTBS compared with TE and EXP (p<0.05). The results suggest that 15 s of biomodification was not sufficient to significantly reduce MMP activity; nonetheless, EXP+PA was still able to improve resin-dentin bond stability compared with total- and self-etching commercial systems.

Abstract: To evaluate the effect of selective or nonselective carious tissue removal and the use of a resin-modified glass ionomer (RMGIC) liner under bulk fill resin composite restoration on the stress at the pulp chamber, the elastic moduli of hard, firm, soft and intact dentin were calculated using nanoindentation. Post-gel shrinkage of the bulk fill resin composite and RMGIC were determined using the strain-gauge method. Six finite element models were created by using digital radiography with the combination of two study factors: a) carious tissue removal: selective removal or nonselective removal of carious tissue, and b) use of RMGIC liner: with or without 1.0 mm of RMGIC liner. The modified von Mises stresses (mvm) (MPa) were extracted on the nodes of the internal wall of the pulp ceiling chamber at 100 N occlusal loading. Data were analyzed descriptively and recorded quantitively. Both study factors influenced the stress distribution. The mvm stress during the restorative procedure was higher for nonselective carious tissue removal without RMGIC (25.9 MPa) and lower for selective carious tissue removal associated with RMGIC (13.5 MPa). The dentin elastic modulus increased from soft carious (3.6 ± 0.3 MPa) to firm carious (5.2 ± 1.0 MPa) to hard carious (10.9 ± 1.2 MPa) to intact dentin (22.7 ± 3.0 MPa). Molars with carious lesions showed high mvm stress at the pulp ceiling (89.6 MPa) and at fragilized coronal structure remaining. Selective carious tissue removal followed by restoration using a Vitrebond liner and Tetric N-Ceram Bulk fill reduced the stress at the pulp chamber ceiling.

Abstract The Astronomy Nucleus of the Federal University of Pará is a science center located in the Brazilian Amazonia, dedicated to spread knowledge on Astronomy to the general public. Over the last ten years, this science center has promoted several activities, including astronomical observations, demonstrations with industrially manufactured and low cost material equipment, seminars, workshops, among others. We describe and discuss the role of the Astronomy Nucleus and other science centers dedicated to Astronomy communication and popularization in the Brazilian Amazonia.

Este estudio tuvo como objetivo desarrollar dos PCR multiplex (mPCR) para la detección de los genes de enterotoxinas estafilococicas (EE) A (sea), B (seb), C (sec) y D (sed) en Staphylococcus aureus aislados de alimentos de origen animal, y relacionar la presencia de los genes con el origen del microorganismo. Las mPCR fueron estandarizadas utilizando cepas toxigénicas de S. aureus, cuya capacidad fue previamente confirmada por ELISA indirecto, con la utilización de toxinas y sueros de referencia. En seis (12%) de los 50 S. aureus aislados fue posible detectar uno o mas genes de EE, siendo que un aislado albergaba sea y seb, tres aislados albergavam seb y dos albergavam sed. Los dos conjuntos de mPCR desarrollados son eficaces en la detección de los genes sea, seb, sec y sed, y, teniendo en cuenta la asociación entre S. aureus enterotoxigénicos con genes sea y seb y humanos, y los genes sec y sed con otros animales, el origen más probable de la mayoría de los aislados son los manipuladores de alimentos.

The object of this work was to develop two multiplex PCR (mPCR) for the detection of genes of staphylococcal enterotoxins (EE) A (sea), B (seb), C (sec) and D (sed) of Staphylococcus aureus isolated from food of animal origin and to relate the presence of the genes with the origin of the microorganism. The two mPCR were standardized using strains of S. aureus whose toxigenic capacity was previously confirmed through indirect ELISA, with the use of reference toxins and serum antitoxins. In six (12%) out of 50 isolates of S. aureus it was possible to detect one or more genes of EE; one isolate harbored sea and seb genes, three isolates harbored seb and two harbored sed. The two sets of mPCR developed are efficient for the detection of the sea, seb, sec and sed, and, considering the existing association of enterotoxigenic S. aureus genes sea and seb with human beings and genes sec and sed with other animals, the most likely origin of the majority of the isolates are the food handlers.

Este trabalho teve como objetivo desenvolver duas PCR multiplex (PCRm) para a detecção dos genes das enterotoxinas estafilocócicas (EE) A (sea), B (seb), C (sec) e D (sed) em Staphylococcus aureus isolados de alimentos de origem animal, bem como relacionar a presença desses genes com a origem do microrganismo. As duas PCRm foram padronizadas utilizando-se cepas de S. aureus cuja capacidade toxigênica foi previamente confirmada através de ELISA indireto, com o uso de toxinas e soros antitoxinas de referência. Em seis (12%) dos 50 isolados de S. aureus foi possível detectar um ou mais genes de EE, sendo que um isolado albergava os genes sea e seb, três isolados albergavam seb e dois albergavam sed. As duas PCRm desenvolvidas são eficientes para a detecção dos genes sea, seb, sec e sed e, considerando-se a associação existente entre S. aureus enterotoxigênicos portadores dos genes sea e seb e humanos, e genes sec e sed com outros animais, a origem mais provável da maioria dos isolados foram os manipuladores de alimentos.

O objetivo do trabalho foi a determinação da retentividade, por ensaio de tração, entre uma liga de níquel-cromo e cimentos resinosos (Comspan, Panavia Ex e All-Bond C & B), com quatro tratamentos superficiais (liso, microjateado, ataque eletrolítico e silicoater) e armazenagem por 3 e 30 dias em solução de NaCl a 0,9%, a 37° C e termociclagem intercalada na segunda (a 5 e 55° C, por 1 minuto em cada banho, perfazendo 600 ciclos). Os corpos de prova eram discos, providos de alça fixadora entre si dois a dois. Os resultados permitiram concluir que: superfícies lisas conduzem a baixíssimas retentividades e tratadas com silicoater a altíssimos valores, com qualquer cimento e condição de armazenagem; Panavia Ex com superfícies microjateadas também conduz a altas retentividades; a maior retentividade foi obtida pela combinação silicoater/All-Bond C&B.

The purpose of the investigation was to test tensile strength between Ni-Cr alloy and adhesive cements. Variables were: three cements (Comspan, Panavia Ex and All-Bond C&B); four surface treatments (smooth, sandblasted, electrolytic etching and silicoater); two types of storage (3 and 30 days in NaCl 0.9% solution at 37° C, performing in the latter 600 thermocycles at 5 and 55° C). Specimens were discs obtained through conventional casting procedures and cemented together two by two. Opposite sides of cementing discs were provided with a loop for fixing to the testing equipment. Conclusions were that: smooth surfaces presented very low retentivity and those with silicoater a very high one; Panavia Ex with sandblasting also led to very high retention; highest retention was obtained with the combination silicoater/All-Bond C&B.