Influence of thicknesses of smear layer on the transdentinal cytotoxicity and bond strength of a resin-modified glass-ionomer cement

This study evaluated the transdentinal cytotoxicity (TC) and the bond strength (BS) of a resin-modified glass-ionomer cement (RMGIC) applied to dentin covered with smear layer (SL) of different thicknesses. Forty dentin discs had thick (TSL) or thin (THSL) smear layer created on their occlusal side. In artificial pulp chambers, MDPC-23 cells were seeded on the pulpal side of the dentin discs and divided into five groups: G1TC: no treatment (control); G2TC: TSL + RMGIC; G3TC: THSL + RMGIC; G4TC: TSL removal + RMGIC; G5TC: THSL removal + RMGIC. After 24 h, cell metabolism and morphology were evaluated by the methyltetrazolium (MTT) assay and by scanning electron microscopy (SEM), respectively. For BS, the following groups were determined: G1BS: TSL removal + RMGIC; G2BS: THSL removal + RMGIC; G3BS: TSL + RMGIC; G4BS: THSL + RMGIC. Shear bond strength was tested to failure in a mechanical testing machine MTS (0.5 mm/min). Statistically significant difference was observed only between the control and experimental groups (Kruskal-Wallis, p0.05). RMGIC presented moderate transdentinal cytotoxic effects. Maintenance or removal of smear layer did not affect the bond strength of RMGIC to dentin substrate.._________________________________________________________________________________________ RESUMO: Este estudo avaliou a citotoxicidade transdentinária (CT) e a resistência de união (RU) de um cimento de ionômero de vidro modificado por resina (CIVMR) aplicado sobre dentina coberta com smear layer (SL) de diferentes espessuras. Quarenta discos de dentina tiveram smear layer espessa (TSL) ou delgada (THSL) criadas sobre a superfície oclusal. Após terem sido posicionados em câmaras pulpares artificiais, os discos de dentina receberam células MDPC-23, as quais foram semeadas sobre a supefície pulpar. Assim, os seguintes grupos foram estabelecidos: G1TC: sem tratamento (controle); G2TC: TSL + CIVMR; G3TC: THSL + CIVMR; G4TC: remoção TSL + CIVRM; G5TC: remoção THSL + CIVMR. Após 24 h, o metabolismo e morfologia celular foram avaliados pelo ensaio de metiltetrazolium (MTT) e por microscopia eletrônica de varredura (MEV), respectivamente. Para BS, os seguintes grupos foram determinados: G1BS: remoção TSL + CIVRM; G2BS: remoção THSL + CIVRM; G3BS: TSL + CIVRM; G4BS: THSL + CIVMR. A resistência de união ao cisalhamento foi avaliada em uma máquina de ensaios mecânicos MTS (0,5 mm/min). Diferença estatisticamente significativa foi observada apenas entre os grupos controle e experimentais (Kruskal-Wallis, p0,05). O CIVMR avaliado neste estudo apresentou moderado efeito citotóxico transdentinário. A manutenção ou remoção da smear layer não afetou a resistência de união deste material resinoso ionomérico sobre a dentina

Adhesion strategy and early bond strengths of glass-fiber posts luted into root canals

This study investigated the effect of coinitiator solutions and self-adhesive resin cement on the early retention of glass-fiber posts. Cylindrical glass-fiber posts were luted into 40 incisor roots with different adhesion strategies (n = 10): SB2, Single Bond 2 + conventional resin cement (RelyX ARC); AP, Scotchbond Multipurpose Plus (SBMP) activator + primer + ARC; APC, SBMP activator + primer + catalyst + ARC; and UNI, self-adhesive cement (RelyX Unicem). Pull-out bond strength results at 10 min after cementation showed APC > UNI > SB2 = AP (P < 0.05). The adhesion strategy significantly affected early bonding to root canals

Influence of different power densities during polymerization on the color of composite resins

This study evaluated the influence of different levels of power density on resin polymerization in the staining of composite resins. Thirty-six specimens were made with composite resin (Z350 3M ESPE) with cylindrical Teflon matrix (8 mm X 1 mm). The light curing was performed with different degrees of power density for each group (n=12): 300mW/cm², 700mW/cm² e 1000mW/cm². Afterwards, the specimens had their color checked, with the help of a spectrophotometer and immersed in coffee solution during 7 days. After, a new measuring was done (CIEL*a*b* color system). Results showed, for Δa, only G1000 group obtained a significantly lower value, and the same result was found in the evaluation of Δb. For ∆E and ∆L, no significant differences were found between groups. It is concluded that, low and medium power density entails more reddish and bluish composite resin, while the specimens submitted to high power density and then immersed in coffee did not present color change in a short term.Keywords: Composite resin. Staining. Light curing.

Genomic epidemiology unveils the dynamics and spatial corridor behind the Yellow Fever virus outbreak in Southern Brazil

Despite the considerable morbidity and mortality of yellow fever virus (YFV) infections in Brazil, our understanding of disease outbreaks is hampered by limited viral genomic data. Here, through a combination of phylogenetic and epidemiological models, we reconstructed the recent transmission history of YFV within different epidemic seasons in Brazil. A suitability index based on the highly domesticated Aedes aegypti was able to capture the seasonality of reported human infections. Spatial modeling revealed spatial hotspots with both past reporting and low vaccination coverage, which coincided with many of the largest urban centers in the Southeast. Phylodynamic analysis unraveled the circulation of three distinct lineages and provided proof of the directionality of a known spatial corridor that connects the endemic North with the extra-Amazonian basin. This study illustrates that genomics linked with eco-epidemiology can provide new insights into the landscape of YFV transmission, augmenting traditional approaches to infectious disease surveillance and control

Cianoacrilato na colagem de Bráquetes ortodônticos em resina acrílica: há maior adesão?

Pacientes em tratamento ortodôntico apresentam restaurações provisórias com frequência. No entanto, poucos estudos avaliam a influência dos adesivos na resistência ao cisalhamento dos bráquetes nessas superfícies. A resina acrílica é comumente indicada para colagem de bráquetes, porém o uso do cianoacrilato como adesivo ortodôntico é uma opção analisada. O objetivo do presente trabalho foi avaliar o desempenho do cianoacrilato associado aos materiais comumente utilizados para a fixação de bráquetes metálicos em restaurações provisórias de resina acrílica. Quarenta amostras em resina acrílica foram preparadas e as superfícies homogeinizadas com lixas de carboneto de silício (320 e 600). Em seguida, as amostras foram divididas aleatoriamente em quatro grupos (n=10) com base no tratamento de superfície e agente de união: G1 - bráquetes colados com resina acrílica; G2 - bráquetes colados com resina acrílica e aplicação de cianoacrilato; G3 - bráquetes colados com Transbond(tm) XT; G4 - bráquetes colados com Transbond(tm) XT e aplicação de cianoacrilato. Foram utilizados bráquetes ortodônticos de aço inoxidável, prescrição Roth, Kirium (3M/Abzil) para incisivos centrais superiores direitos, slot 022. Após colagem, as amostras foram submetidas ao teste de cisalhamento a uma velocidade de 0,5mm/min em uma máquina de ensaios universal (EMIC DL-1000). Os dados foram coletados e submetidos à análise estatística pelo teste ANOVA com nível de significância de 5%. A associação de resina acrílica ao cianoacrilato (G2) resultou na maior resistência ao cisalhamento (13,76 MPa), mas não significativa em comparação aos valores obtidos para a resina acrílica (G1= 7,76 MPa). O mesmo pôde ser observado para a associação Transbond(tm) XT e cianoacrilato (G4= 4,03 MPa) em relação a utilização da Transbond(tm) XT de forma isolada (G3= 3,87 MPa) e resina acrílica. O tratamento de superfície tem efeito significativo na resistência da união dos bráquetes colados aos materiais provisórios. A associação de cianoacrilato ao monômero de metilmetacrilato apresentou maior resistência ao cisalhamento, sendo mais indicada clinicamente

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio