Effect of composite surface treatment and aging on the bond strength between a core build-up composite and a luting agent

Objective The purpose of this study was to assess the influence of conditioning methods and thermocycling on the bond strength between composite core and resin cement. Material and Methods Eighty blocks (8×8×4 mm) were prepared with core build-up composite. The cementation surface was roughened with 120-grit carbide paper and the blocks were thermocycled (5,000 cycles, between 5°C and 55°C, with a 30 s dwell time in each bath). A layer of temporary luting agent was applied. After 24 h, the layer was removed, and the blocks were divided into five groups, according to surface treatment: (NT) No treatment (control); (SP) Grinding with 120-grit carbide paper; (AC) Etching with 37% phosphoric acid; (SC) Sandblasting with 30 mm SiO2 particles, silane application; (AO) Sandblasting with 50 mm Al2O3 particles, silane application. Two composite blocks were cemented to each other (n=8) and sectioned into sticks. Half of the specimens from each block were immediately tested for microtensile bond strength (µTBS), while the other half was subjected to storage for 6 months, thermocycling (12,000 cycles, between 5°C and 55°C, with a dwell time of 30 s in each bath) and µTBS test in a mechanical testing machine. Bond strength data were analyzed by repeated measures two-way ANOVA and Tukey test (α=0.05). Results The µTBS was significantly affected by surface treatment (p=0.007) and thermocycling (p=0.000). Before aging, the SP group presented higher bond strength when compared to NT and AC groups, whereas all the other groups were statistically similar. After aging, all the groups were statistically similar. SP submitted to thermocycling showed lower bond strength than SP without thermocycling. Conclusion Core composites should be roughened with a diamond bur before the luting process. Thermocycling tends to reduce the bond strength between composite and resin cement

Uma aplicação da Geometria Analítica em sistemas de equações lineares de ordem 2 e 3 com solução única

Este artigo propõe uma forma de resolução de sistemas de equações algébricas lineares de ordem 2 e 3 com solução única, baseando-se exclusivamente numa visão geométrica distinta da apresentada em livros de Álgebra Linear. Parte-se do pressuposto que, após algumas operações simples, o produto matricial Ax, com A de ordem nxn e x de ordem nx1, pode ser reescrito como uma combinação linear das colunas de A e desse modo, b, de ordem nx1, é o resultado de uma soma de vetores e portanto, é a diagonal de um paralelogramo, quando A é de ordem 2 e a diagonal de um prisma trapezoidal, quando A é de ordem 3. A partir desse entendimento, desenvolve-se a proposta

Adhesives with different pHs: effect on the MTBS of chemically activated and light-activated composites to human dentin

PURPOSE: To evaluate the bond strength between human dentin and composites, using two light-activated single-bottle total-etch adhesive systems with different pHs combined with chemically activated and light-activated-composites. The tested hypothesis was that the dentin bond strength is not influenced by an adhesive system of low pH, combined with chemically activated or light-activated composites. MATERIAL AND METHOD: Flat dentin surfaces of twenty-eight human third molars were allocated in 4 groups (n=7), depending on the adhesive system: (One Step Plus-OS and Prime & Bond NT-PB) and composite (light-activated Filtek Z-100 [Z100] and chemically activated Bisfil 2B [B2B]). Each adhesive system was applied on acid-etched dentin and then one of the composites was added to form a 5 mm-high resin block. The specimens were stored in tap water (37ºC/24 h) and sectioned into two axes, x and y. This was done with a diamond disk under coolant irrigation to obtain beams with a cross-section area of approximately 0.8 mm². Each specimen was then attached to a custom-made device and submitted to the microtensile test (1 mm.min-1). Data were analyzed using two-way ANOVA and Tukey's tests (

Influence of substrate design for in vitro mechanical testing

The goal of this study was to evaluate the influence of dental substrate simulator material, and the presence of root and periodontal ligament on the stress distribution in an adhesively-cemented monolithic crown. Five (5) 3D models according to the substrate simulator material and shape were modeled with CAD software for conducting non-linear finite element analysis (FEA): Tooth with and without periodontal ligament - subgroup ?pl? (groups Tooth+pl and Tooth-pl), machined tooth in epoxy-resin with and without pulp chamber - subgroup ?pc? (ER+pc and ER-pc) and simplified epoxy-resin substrate without pulp chamber and roots (SiER). Next, adhesively-cemented monolithic crowns in zirconia reinforced lithium silicate were modeled over each substrate. The solids were then imported in STEP format to the analysis software and the contact between teeth and cylinder was considered perfectly bonded; whereas, the contacts involving the resin cement were considered as non-separated. The materials were considered isotropic, linearly elastic, and homogeneous. An axial load (600 N) was applied to the occlusal surface and results of maximum principal stress (MPa) on the restoration were required. FEA revealed that all evaluated subtracts showed the crown intaglio surface as the most stressed region. The average stress and stress peaks were similar for restorations cemented onto Tooth+pl, Tooth-pl and ER+pc substrates, but, 13% higher in comparison to ER-pc and SiER substrates. Simplified substrates can be used to evaluate posterior full crown behavior without periodontal ligaments and roots, since the rigidity of the specimen is taken into account

Caracterização in vitro de um novo sistema de resina composta de laboratório

Aim: this study aimed to determine some of the properties of a laboratory composite indicated for metallic and non-metallic crowns, anterior and posterior bridges, inlays, onlays and laminate veneers. Methology: the properties evaluated were surface roughness, flexural strength, shear bond strength to three metal alloys and the microleakage at the composite/metal interface. All specimens were subjected to cycles of polymerization, according the manufacturer instructions. Ten round specimens (4x3 mm) were prepared for hardness (VHN) and surface roughness tests (Ra). The three-point flexural strength was measured on rectangular shaped specimens (10x5x2 mm), at 1 mm/min speed. The experiments involving dental alloys (bond strength and microleakage) were submitted to statistical analysis (pObjetivo: este estudo caracterizou algumas propriedades de uma resina composta de processamento laboratorial (Resilab, Wilcos do Brasil), indicada para confecção de coroas com e sem metal, pontes anteriores e posteriores, inlays, onlays e facetas laminadas. Metodologia: as propriedades avaliadas foram rugosidade superficial, dureza, resistência à flexão, resistência adesiva a três ligas metálicas (Au, NiCr e CoCr) e microinfiltração da interface resina/metal. Todos os espécimes foram submetidos a dois ciclos de polimerização, conforme instruções do fabricante. Dez espécimes circulares (4x3 mm) foram preparados para os testes de dureza (VHN) e rugosidade superficial (Ra). A resistência flexural em três pontos (MPa) foi medida a partir de espécimes retangulares (10x5x2 mm), sob velocidade de 1 mm/min. Os ensaios que envolveram ligas metálicas (resistência adesiva e microinfiltração) foram submetidos à análise estatística (pResultados: não houve diferenças entre as médias de resistência de união. Quanto à infiltração marginal, o grupo CoCr diferiu dos grupos Au e NiCr em espécimes sem retenção mecânica e submetidos a ciclagem térmica. Conclusão: considerando os resultados deste estudo in vitro e a literatura pesquisada, o sistema Resilab mostrou comportamento satisfatório quanto às propriedades estudadas. A resistência de união não dependeu da liga metálica utilizada

BEYOND ALTRUISTIC PHILOSOPHY: A STUDY ON THE DETERMINANTS OF ORGANIC FOOD CONSUMER INVOLVEMENT

The awareness of ecological preservation and the search for healthy food were widespread ideas in the 1970s. In the late 1980s, new parameters were added to that ideological motivation. This article aimed to understand the involvement of organic product consumers. The literature review developed in this work approaches the involvement construct, its multidimensionality and its measurement, as well as the determinants of high involvement with organic food. The data were collected through an online survey, whose sample consisted of 412 valid respondents. Descriptive and inferential statistics techniques, mainly factorial analysis and logistic regression, were used. In general, it is possible to affirm that the hypotheses were partially confirmed. It is concluded that involvement with organic products occurs in a multifaceted way and the determinants that distinguish highly involved individuals may be associated with selfish circumstances and specific buying situations, such as greater regularity and willingness to pay higher prices

Modulação dos receptores de hormônio tireoidiano, TRα e TRβ, utilizando diferentes doses de triiodotironina (T3) em diferentes tempos

OBJECTIVE: To examine the effect of different doses of triiodothyronine (T3) on mRNA levels of thyroid hormone receptors, TRα and TRβ, at different times. MATERIALS AND METHODS: 3T3-L1 adipocytes were incubated with T3 (physiological dose: F; supraphysiological doses: SI or SII), or without T3 (control, C) for 0.5, 1, 6, or 24h. TRα and TRβ mRNA was detected using real-time polymerase chain reaction. RESULTS: F increased TRβ mRNA levels at 0.5h. After 1h, TRα levels increased with F and SI and TRβ levels decreased with SII compared with C, F, and SI. After 6h, both genes were suppressed at all concentrations. In 24h, TRα and TRβ levels were similar to those of C group. CONCLUSIONS: T3 action with F began at 1h for TRα and at 0.5h for TRβ. These results suggest the importance of knowing the times and doses that activate T3 receptors in adipocytes.OBJETIVO: Examinar o efeito de diferentes doses de triiodotironina (T3) sobre a expressão gênica dos receptores TRα e TRβ em diferentes tempos. MATERIAIS E MÉTODOS: Adipócitos, 3T3-L1, foram incubados com T3 nas doses fisiológica (F, 10nM) e suprafisiológicas (SI, 100nM ou SII, 1000nM) ou veículo (controle, C) durante 0,5, 1, 6 ou 24h. mRNA dos TRs foram detectados utilizando PCR em tempo real. RESULTADOS: Níveis de TRβ aumentaram em F em 0,5h. Após 1h, níveis de TRα aumentaram em F e SI comparado ao C, enquanto TRβ diminuiu no SII comparado com C, F, e SI. Após 6h, ambos os genes foram suprimidos em todas concentrações. Em 24h, níveis de TRα e TRβ retornaram aos do C. CONCLUSÕES: Ação do T3 em F iniciou-se em 1h para TRα e 0,5h para TRβ. Esses resultados são importantes para determinar tempo inicial e dose de T3 em que os receptores de HT são ativados em adipócitos.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Unesp Botucatu Medicine School Department of Internal ClinicUniversidade Federal de São Paulo (UNIFESP) Department of PhysiologyUnesp Biosciences Institute Department of BiostatisticsUNIFESP, Department of PhysiologySciEL

Distribuição dos casos de cardiopatias congênitas em um hospital do Oeste Paulista

O objetivo deste trabalho foi analisar a distribuição espaço-temporal dos pacientes com cardiopatias congênitas atendidos no Ambulatório de Cardiologia Pediátrica do Hospital de referência do Oeste Paulista. Realizamos um estudo retrospectivo com análise de dados de base eletrônica e prontuários dos pacientes diagnosticados com cardiopatiacongênita entre os períodos de julho de 2013 a julho de 2018. Foram selecionados 298 prontuários para análise das variáveis de CID-10, gênero, distribuição espacial e série temporal. Foi possível observar que os defeitos septais foram as cardiopatias mais prevalentes, não houve diferença entre os gêneros. Notou-se aumento do diagnóstico a partir de 2014, com implementação do teste do coraçãozinho e 51% dos casos eram da cidade de Presidente Prudente,com maior concentração de casos na região do parque industrial. Há uma relação na incidência das malformações cardíacas com o meio ambiente desfavorável. Os resultados encontrados podem guiar políticas de saúde pública, visando reduzir a exposição da população mais vulnerável, na busca da melhora nos índices de saúde.The aim of this research was to conduct a comprehensive spatial-temporal analysis of the population affected by congenital heart anomalies assisted at the Pediatric Cardiology Outpatient Department at the distinguished Western Paulista reference hospital. We conducted a retrospective study involving the analysis of electronic databaserecords and patient medical charts for individuals diagnosed with congenital heart disease during the period from July 2013 to July 2018. A total of 298 medical records were selected for the analysis of variables encompassing the ICD-10 codes, gender, spatial distribution, and temporal trends. It was possible to observe that septal defects were the most prevalent congenital heart abnormalities, and there was no gender-based difference. An increase in diagnoses was noted from 2014, coinciding with the implementation of the “heart test,” and 51% of the cases were from Presidente Prudente, with a higher concentration of cases in the industrial park area. There is an association between cardiac congenital malformations and an adverse environmental context. The findings can inform public health policies aimed at reducing the exposure of the most vulnerable population in pursuit of improvinghealth indicators

A model for evaluating sustainability applied to two urban cycleways in brasilia

Este artigo propôs um modelo quantitativo usando Dimensões, Características e Indicadores de Sustentabilidade para avaliar a sustentabilidade das ciclovias. O modelo foi aplicado como um estudo de caso a duas ciclovias reais na capital brasileira, Brasília. O processo de seleção de indicadores de sustentabilidade empregou o método Delphi com 9 especialistas seniores da área de transporte e, originalmente, foram identificados 650 indicadores. Estes foram convertidos para fornecer 28 indicadores consolidados. Utilizou-se o método Função Multiatributo Aditiva (Multiattribute Utility Theory) para estabelecer uma hierarquia de dimensões, características e indicadores. Outros nove especialistas definiram níveis de importância e atribuíram pesos a Dimensões, Características e Indicadores. No total, 40 pesos foram atribuídos aos três níveis hierárquicos e o peso final de cada nível foi considerado a média aritmética dos pesos indicados pelos 9 especialistas. Os pesos dos indicadores foram multiplicados pelos pesos de suas respectivas Características e Dimensões, resultando em uma equação para o Índice de Sustentabilidade na forma de uma combinação linear dos pesos com os indicadores. Os usuários das ciclovias analisadas foram entrevistados e atribuíram pontuações a cada um dos indicadores. A partir dessas pontuações, foi possível calcular o indicador de sustentabilidade de cada ciclovia. A ciclovia 2 obteve uma melhor avaliação em relação a ciclovia 1 em todos os cenários de ponderação analisados.This paper proposed a quantitative model using Sustainability Dimensions, Characteristics and Indicators for evaluating the sustainability of cycleways. The model was applied as a case study to two actual cycleways in the Brazilian capital, Brasília. The sustainability indicator selection process employed the Delphi method with 9 senior experts from the field of transportation and originally 650 indicators were identified. These were converted to provide 28 consolidated indicators. Multi-attribute Utility Theory method was used to establish a hierarchy of the Dimensions, Characteristics and Indicators. Nine other experts defined levels of importance and attributed weights to Dimensions, Characteristics and Indicators. 40 weights altogether were attributed to the three hierarchic levels and the final weight for each level was taken to be the arithmetical average of the weights indicated by the 9 experts. The weights of the indicators were multiplied by the weights of their respective Characteristics and Dimensions, resulting in an equation for the Sustainability Index in the form of a linear combination of the weights with the indicators. The users of the analyzed cycleways were interviewed and assigned scores to each of the indicators. From these scores, it was possible to calculate the sustainability indicator of each bicycle path. The cicloway 2 had a better rating compared to cicloway 1 in all weighting scenarios analyzed

The impact of restorative material and ceramic thickness on CAD\CAM endocrowns

Endocrown restorations as a conservative approach to restore endodontically treated teeth still need in vitro investigation under fatigue and made in different materials. This study evaluated the effect of restorative material and restoration thickness on the maximum fracture load of endocrowns subjected to cyclic loading. Sixty (60) third molar teeth received an endocrown preparation with three different heights of remaining dental tissue (1.5, 3.0 or 4.5 mm). A leucite-based ceramic (LEU) and a lithium disilicate (LD) based ceramic were selected to manufacture the CAD/CAM endocrown restorations, totaling 6 groups (n=10). The specimens were subjected to fatigue loading (200N, 2 x 106 cycles, water) and then to the single load to failure test (1 mm/min crosshead speed). Data were analyzed by using two-way ANOVA and Tukey tests (p< 0.05). All endocrowns survived the fatigue test. The thickness did not influence the restoration?s fracture load (p=0.548) instead the restorative material (p=0.003). LD showed higher mean values (1714.43 N)A than LEU (1313.47 N)B. Endocrowns manufactured with CAD/CAM lithium disilicate blocks showed superior fracture load than the leucite-based blocks after mechanical fatigue. Nevertheless, both materials presented acceptable survival and fracture load as long as the material?s minimum thickness and the enamel adhesion are respected