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Finite automata appear in almost every branch of computer science, for example in model checking, in natural language processing and in database theory. In many applications where finite automata occur, it is highly desirable to deal with automata that are as small as possible, in order to save memory as well as excecution time. Deterministic finite automata (DFAs) can be minimized efficiently, i.e., a DFA can be converted to an equivalent DFA that has a minimal number of states. This is not the case for non-deterministic finite automata (NFAs). To minimize an NFA we need to compute the corresponding DFA using subset construction and minimize the resulting automaton. However, subset construction may lead to an exponential blow-up in the size of the automaton and therefore even if the minimal DFA may be small, it might not be feasible to compute it in practice since we need to perform the expensive subset construction. To aviod subset construction we can reduce the size of an NFA using heuristic methods. This can be done by identifying and collapsing states that are equal with respect to some suitable equivalence relation that preserves the language of the automaton. The choice of an equivalence relation is a trade-off between the desired amount of reduction and the computation time since the coarser a relation is, the more expensive it is to compute. This way we obtain a reduction method for NFAs that is useful in practice. In this thesis we address the problem of reducing the size of non-deterministic automata. We consider two different computation models: finite tree automata and finite automata. Finite automata can be seen as a special case of finite tree automata and all of the previously mentioned results concerning finite automata are applicable to tree automata as well. For non-deterministic bottom-up tree automata, we present a broad spectrum of different relations that can be used to reduce their size. The relations differ in their computational complexity and reduction capabilities. We also provide efficient algorithms to compute the relations where we translate the problem of computing a given relation on a tree automaton to the problem of computing the relation on a finite automaton. For finite automata, we have extended and re-formulated two algorithms for computing bisimulation and simulation on transition systems to operate on finite automata with alphabets. In particular, we consider a model of automata where the labels are encoded symbolically and we provide an algorithm for computing bisimulation on this partial symbolic encoding.

Made available in DSpace on 2014-06-11T19:23:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-07-25Bitstream added on 2014-06-13T18:09:30Z : No. of bitstreams: 1 muraishi_ri_me_jabo.pdf: 172407 bytes, checksum: 09fe9bde72c559512205ec4e2f28c4ee (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A necessidade de se estudar a utilização do resíduo de podas de árvores é de grande importância ambiental para solucionar os problemas de resíduos sólidos gerados nas áreas urbanas junto com os resíduos de lixos domésticos. O estudo deste material foi avaliado com base no desenvolvimento de mudas de ipê-amarelo [Tabebuia Chrysotricha (Mart. ex DC.) standl.] cultivados em diferentes substratos e com 2 tipos de água para irrigação. O experimento foi instalada no setor de plasticultura do Departamento de Engenharia Rural da Faculdade de Ciências Agrárias e Veterinárias – UNESP, Campus de Jaboticabal. Foram realizados 2 experimentos, avaliados conjuntamente com delineamento experimental em blocos casualizados, de 8 substratos, 2 qualidades de águas e 4 repetições, totalizando 64 parcelas. Cada parcela foi composta por 30 plantas (5 linhas de 6 plantas), sendo consideradas como úteis, as 3 linhas de 4 plantas centrais da parcela. Para estudar o desenvolvimento das mudas de ipê amarelo, foram avaliadas a altura da parte aérea das plantas (H), diâmetro do colmo (D), matéria seca (MS) e composição química. As características de desenvolvimentos foram avaliadas aos 21, 42, 63 e 84 dias após a emergência das plantas. Da análise dos resultados concluiu-se que os substratos estudados promoveram diferenças significativas para altura média das plantas, diâmetro médio de colmo, acúmulo de matéria seca e teores de nutriente nas folhas em todos os períodos de avaliação. Houve interação positiva entre substrato e água de irrigação, para altura média das plantas e diâmetro médio de colmo aos 42, 63 e 84 dias após emergência e em todos nutrientes foliar. Os substratos 3 (5% composto lixo + 95% composto de poda, 4 (10% composto de lixo +90% composto de poda) e 5 (20% de composto de lixo + 80% composto de poda) e a água residuária apresentaram os melhores resultados no desenvolvimento das mudas de ipê amarelo. / The need to study the use of waste pruning of trees is of great importance to solve the environmental problems of solid waste in the urban areas along with the waste of household waste. The study of these materials was evaluated with the development of seedlings of yellow-ipe [Tabebuia chrysotricha (Mart. ex DC.) Sandl.] in mixtures of different substrates and types of water for irrigation. The experiment was installed at the Department of Rural Engineering of de São Paulo University State, Campus of Jaboticabal. Two experiments were conducted, evaluated together with experimental design in randomized blocks of 8 substrates, 2 qualities of water and 4 repetitions, totaling 64 parcels. Each parcel was composed of 30 plants (5 rows of 6 plants) and is regarded as useful, the 3 lines of 4 plants of the central plot. Eight substrates were tested, resulting from the combination of commercial substrate, composed of household waste and composed of pruning of trees with 2 types of irrigation water (clean water and residuary) and 4 repetitions. To observe the development of seedlings of yellow-ipe, were evaluated the height of the shoots of plants, diameter of the stem, dry material and leaf analysis. The characteristics were evaluated at 21, 42, 63 and 84 days after the emergency. The analysis of results allowed to conclude that the substrates studied promoted significant differences in average height of the plants, stem diameter, dry material and leaf analysis in all periods of assessment. The interaction between substrate and water for irrigation were to average height and diameter of the plant stem at 42, 63 and 84 days after emergency and in all of leaf analysis nutrients. The substrates 3, 4 and 5 with residuary water showed the best results in the development of seedlings of yellow-ipe.

Orientador: João Antonio Galbiatti / Banca: Jairo Augusto Campos de Araújo / Banca: Emerson Fachini / Resumo: A necessidade de se estudar a utilização do resíduo de podas de árvores é de grande importância ambiental para solucionar os problemas de resíduos sólidos gerados nas áreas urbanas junto com os resíduos de lixos domésticos. O estudo deste material foi avaliado com base no desenvolvimento de mudas de ipê-amarelo [Tabebuia Chrysotricha (Mart. ex DC.) standl.] cultivados em diferentes substratos e com 2 tipos de água para irrigação. O experimento foi instalada no setor de plasticultura do Departamento de Engenharia Rural da Faculdade de Ciências Agrárias e Veterinárias - UNESP, Campus de Jaboticabal. Foram realizados 2 experimentos, avaliados conjuntamente com delineamento experimental em blocos casualizados, de 8 substratos, 2 qualidades de águas e 4 repetições, totalizando 64 parcelas. Cada parcela foi composta por 30 plantas (5 linhas de 6 plantas), sendo consideradas como úteis, as 3 linhas de 4 plantas centrais da parcela. Para estudar o desenvolvimento das mudas de ipê amarelo, foram avaliadas a altura da parte aérea das plantas (H), diâmetro do colmo (D), matéria seca (MS) e composição química. As características de desenvolvimentos foram avaliadas aos 21, 42, 63 e 84 dias após a emergência das plantas. Da análise dos resultados concluiu-se que os substratos estudados promoveram diferenças significativas para altura média das plantas, diâmetro médio de colmo, acúmulo de matéria seca e teores de nutriente nas folhas em todos os períodos de avaliação. Houve interação positiva entre substrato e água de irrigação, para altura média das plantas e diâmetro médio de colmo aos 42, 63 e 84 dias após emergência e em todos nutrientes foliar. Os substratos 3 (5% composto lixo + 95% composto de poda, 4 (10% composto de lixo +90% composto de poda) e 5 (20% de composto de lixo + 80% composto de poda) e a água residuária apresentaram os melhores resultados no desenvolvimento das mudas de ipê amarelo. / Abstract: The need to study the use of waste pruning of trees is of great importance to solve the environmental problems of solid waste in the urban areas along with the waste of household waste. The study of these materials was evaluated with the development of seedlings of yellow-ipe [Tabebuia chrysotricha (Mart. ex DC.) Sandl.] in mixtures of different substrates and types of water for irrigation. The experiment was installed at the Department of Rural Engineering of de São Paulo University State, Campus of Jaboticabal. Two experiments were conducted, evaluated together with experimental design in randomized blocks of 8 substrates, 2 qualities of water and 4 repetitions, totaling 64 parcels. Each parcel was composed of 30 plants (5 rows of 6 plants) and is regarded as useful, the 3 lines of 4 plants of the central plot. Eight substrates were tested, resulting from the combination of commercial substrate, composed of household waste and composed of pruning of trees with 2 types of irrigation water (clean water and residuary) and 4 repetitions. To observe the development of seedlings of yellow-ipe, were evaluated the height of the shoots of plants, diameter of the stem, dry material and leaf analysis. The characteristics were evaluated at 21, 42, 63 and 84 days after the emergency. The analysis of results allowed to conclude that the substrates studied promoted significant differences in average height of the plants, stem diameter, dry material and leaf analysis in all periods of assessment. The interaction between substrate and water for irrigation were to average height and diameter of the plant stem at 42, 63 and 84 days after emergency and in all of leaf analysis nutrients. The substrates 3, 4 and 5 with residuary water showed the best results in the development of seedlings of yellow-ipe. / Mestre

Orientador: Lourenço Correr Sobrinho / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-12T22:17:02Z (GMT). No. of bitstreams: 1 Moraes_RafaelRattode_D.pdf: 3063279 bytes, checksum: c97e74bafe910eaf9a62355e1364e95d (MD5) Previous issue date: 2009 / Resumo: Neste estudo foi avaliado o efeito da adição de nanopartículas poliméricas reticuladas (nanogéis) em resinas e compósitos odontológicos baseados em dimetacrilatos na contração volumétrica de polimerização. As partículas poliméricas foram sintetizadas utilizando mistura dos monômeros uretano dimetacrilato e isobornil metacrilato (razão 30:70 mol%) dissolvidos em tolueno, utilizando 2-mercaptoetanol como agente de transferência de cadeia (ATC). Metade dos nanogéis foi utilizada como sintetizada (partículas não-reativas), enquanto para a outra metade (nanogéis reativos) foi realizado processo de fixação de grupamentos metacrilato nas moléculas utilizando as hidroxilas do ATC. Trietileno glicol dimetacrilato (TEGDMA) foi utilizado como monômero base, sendo a ele adicionado nanogéis nas seguintes concentrações: 5, 10, 20, 30 ou 40% em peso. Além das resinas modificadas, compósitos foram obtidos pela incorporação de 70% em peso de partículas de vidro de bário às resinas. TEGDMA não-modificado foi utilizado como controle. O tamanho e distribuição das partículas poliméricas foram avaliados por análise de espalhamento dinâmico de luz. A contração volumétrica foi mensurada utilizando linômetro (resinas) e dilatômetro de mercúrio (compósitos). A cinética de conversão foi avaliada por espectroscopia de infravermelho próximo. A viscosidade das resinas foi mensurada em viscosímetro, enquanto a consistência dos compósitos avaliada utilizando máquina de ensaios mecânicos. As propriedades mecânicas dos materiais (resistência à flexão, módulo de elasticidade e trabalho de fratura) foram avaliadas em teste de flexão de três pontos. O índice de refração dos monômeros e a translucidez dos polímeros foram também avaliados. Análises de Variância de 1 fator (compósitos) ou 2 fatores (resinas) foram realizadas, seguidas do teste post-hoc de Student-Newman-Keuls (P < 0,05). O tamanho das partículas variou entre 20 e 210 nm. Redução linear da contração foi observada com aumento da fração de nanogel, com reduções de até 43% em volume para resinas e até 26% para compósitos. Não foram verificadas diferenças significativas na cinética de conversão. A adição de nanogéis aumentou gradualmente a viscosidade das resinas e a consistência dos compósitos. Entretanto, foi possível incorporar altas quantidades de partículas inorgânicas (> 75% em peso) mesmo nas resinas contendo 40% de nanogel. A incorporação de altas quantidades de nanogéis não-reativos reduziu a resistência à flexão e o trabalho de fratura das resinas, enquanto o uso de partículas reativas não afetou as propriedades de flexão. Índices de refração das resinas e opacidade dos compósitos aumentaram com a adição de nanogéis. Em conclusão, a incorporação de nanopartículas poliméricas reticuladas reativas como aditivos em resinas e compósitos odontológicos experimentais reduziu a contração volumétrica gradualmente na medida em que a fração de nanogel incorporada foi aumentada sem afetar negativamente as propriedades dos materiais. / Abstract: In this study the effect of adding polymeric crosslinked nanoparticles (nanogels) to dimethacrylate-based dental resins and composites on the volumetric polymerization shrinkage was evaluated. The polymeric particles were synthesized using a mixture of the monomers urethane dimethacrylate and isobornyl methacrylate (30:70 mol% ratio) dissolved in toluene, using 2- mercaptoethanol as chain transfer agent (CTA). Half of the nanogels was used as synthesized (non-reactive particles), while for the other half (reactive nanogels) a process for fixing methacrylate groups to the molecules was carried out using the hydroxyls of the CTA. Triethylene glycol dimethacrylate (TEGDMA) was used as base monomer and loaded with nanogel at the following concentration: 5, 10, 20, 30 or 40 wt%. In addition to the modified resins, composites were obtained by incorporating 70 wt% of barium glass fillers to the resins. Unmodified TEGDMA was used as control. The size and distribution of the polymeric particles was evaluated by dynamic light scattering analysis. Volumetric shrinkage was measured using a linometer (resins) and mercury dilatometer (composites). Conversion kinetics was evaluated by near infrared spectroscopy. Viscosity of the resins was measured using a viscometer, while the consistency of the composites evaluated using a mechanical testing machine. Mechanical properties of the materials (flexural strength, flexural modulus and work of fracture) were measured in the three-point bending mode. Refractive indices of the resins and translucency of the polymers were also evaluated. One-way (composites) or Twoway (resins) Analyses of Variance were carried out, followed by Student- Newman-Keuls' post-hoc test (P < 0.05). The size of the particles ranged between 20 and 210 nm. A linear decrease in shrinkage was observed with increased nanogel fraction, with reductions up to 43 vol% for resins and up to 26 vol% for composites. No substantial differences in conversion kinetics were observed. The addition of nanogels gradually increased the viscosity of the resins and consistency of the composites. However, it was possible to incorporate high amounts of inorganic filler (> 75 wt%) even for resins containing 40 wt% of nanogel. Incorporation of high amounts of non-reactive nanogels decreased flexural strength and work of fracture of the resins, while the use of reactive particles did not affect the flexural properties. Refractive indices of the resins and opacity of the polymers were increased with addition of nanogels. In conclusion, the incorporation of reactive polymeric crosslinked nanoparticles as additives in experimental dental resins and composites reduced volumetric shrinkage associated with increasing nanogel fraction without negatively affecting the properties of the materials. / Doutorado / Doutor em Materiais Dentários

The construction of road works in the world has always been a challenge for engineering, especially in areas where the conditions and types of soil are not adequate for the execution of this type of projects. The present investigation has as main objective to determine the influence that has the rice husk ash (RHA) to stabilize the subgrade layer of a pavement, composed of a low resistance clayey soil. RHA is a waste and pollutant material for the environment; therefore that its use can be considered as an economic and ecological alternative. Thus, several tests were carried out where it proved the value of CBR increased from 4.30% to 20.70%, by adding a 20% RHA dosage, achieving its optimum value to be considered a very good subgrade. In this way, it is possible to affirm that the addition of RHA improves the geotechnical properties of the soil.

We propose a framework for managing changes in Long term Composed Services (LCSs). The key components of the proposed framework include a Web Service Change Management Language (SCML), change enactment, and change optimization. The SCML is a formal language to specify top-down changes. It is built upon a formal model which consists of a Web service ontology and a LCS schema. The Web service ontology gives a semantic description on the important features of a service, including functionality, quality, and context. The LCS schema gives a high-level overview of a LCS's key features. A top-down change is specified as the modification of a LCS schema in the first place. Change enactment is the process of reacting to a top-down change. It consists of two subcomponents, including change reaction and change verification. The change reaction component implements the proposed change operators by modifying a LCS schema and the membership of Web services. The change verification component ensures that the correctness of a LCS is maintained during the process of change reaction. We propose a set of algorithms for the processes of change reaction and verification. The change optimization component selects the Web services that participate in a LCS to ensure that the change has been reacted to in the best way. We propose a two-phase optimization process to select services using both service reputation and service quality. We present a change management system that implements the proposed approaches. We also conduct a set of simulations to assess the performance. / Ph. D.

This study explores how respondents perceive human-composed music and AI-computer-composed music. The aim was to find out if there is a negative bias against AI-computer-composed music. The research questions are 1. How is AI-computer-composed music perceived compared to human-composed music? 2. Are there prejudices towards AI-computer-composed music? If yes, what are the prejudices? Four participants took part in a qualitative experiment and a semi-structured interview. Two music pieces were used as artifacts, one was human-composed, and the AI-computer AIVA composed the other. The results showed that although the researchers have not revealed to the participants if they had chosen the AI-computer-composed song or the human-composed song as their favorite, all the participants strongly believed that their favorite song was human-composed. Thus, indicating a bias towards human-composed music The results also showed that the two music pieces were not perceived to have the same characteristics or evoke the same emotions; furthermore, there was some skepticism, whether an AI-computer-composed song could recall the same emotions as a human-composed song. However, none of the respondents explicitly expressed negativity towards AI-computer-composed music.

The objective of this study was to evaluate the resistance the microabrasion of composed resins, amalgam, human and bovine dental enamel. A microabrasion apparel was used (Calowear Tester) whose main characteristic is to evaluate the wear of the surface of the materials. Being the abrasive wear a process of multiple risks, the resistance to the wear can be intimately related to the resistance to the risk. Like this, of ownership of the resistances the microabrasion was possible compare them the resistances to the wear of the standard minerals of the scale of hardness Mohs. Seven universal resins were used (Charisma, Esthet X, Filtek Supreme, Filtek Z250, Herculite XRV, Tetric Ceram and Z100), two universal resins compacted (Filtek P60 and Surefil) and two laboratory resins (ArtGlass and Cristobal); an amalgam with high copper tenor (GS80); third ten human molars and ten incisive bovine. After the preparation of the samples, they were submitted to the microabrasion test with application of load of 0,16 N tends aqueous dispersion of alumina as abrasive for 1 minute. This process generated impressions that were measured being used an image analyzer. Of ownership of these measured the Analysis of Variance was applied for p <0,05 and test of Tukey. The results showed different resistance levels the microabrasion for the rehearsed materials what allowed classify them orderly in agreement with his/her resistance the microabrasion. The human enamel obtained the smallest wear. Among the restoring materials the amalgam and Filtek Supreme presented larger resistance to the wear. In relation to hardness Mohs the dental enamels and the amalgam presented hardness Mohs 5 (Apatite) while the resins composed hardness Mohs 4 (Fluorite). The results showed that the evaluation of the resistance the microabrasion of the materials compared the resistance to the wear of the standard minerals of the scale of hardness Mohs, it can contribute to an effective classification of those materials being used of measured no subjective. / O objetivo deste estudo foi avaliar a resistência a microabrasão de resinas compostas, amálgama, esmalte dentário humano e bovino. Foi utilizado um microabrasômetro (Calowear Tester) cuja principal característica é avaliar o desgaste superficial dos materiais. Sendo o desgaste abrasivo um processo de riscamento múltiplo, a resistência ao desgaste pode estar intimamente relacionada à resistência ao risco. Assim, de posse das resistências a microabrasão foi possível compara-las as resistências ao desgaste dos minerais padrões da escala de dureza Mohs. Foram utilizadas sete resinas compostas universais (Charisma, Esthet X, Filtek Supreme, Filtek Z250, Herculite XRV, Tetric Ceram e Z100), duas resinas universais compactáveis (Filtek P60 e Surefil) e duas resinas laboratoriais (ArtGlass e Cristobal); um amálgama com alto teor de cobre (GS80); dez terceiros molares humanos e dez incisivos bovinos. Após o preparo das amostras, elas foram submetidas ao teste de microabrasão com aplicação de carga de 0,16 N tendo dispersão aquosa de alumina como abrasivo durante 1 minuto. Este processo gerou impressões que foram medidas utilizando-se um analisador de imagem acoplado a um banco metalográfico. De posse destas medidas foi aplicada a Análise de Variância para p< 0,05 e teste de Tukey. Os resultados mostraram diferentes níveis de resistência a microabrasão para os materiais ensaiados o que permitiu classificalos ordenadamente de acordo com sua resistência a microabrasão. O esmalte humano obteve o menor desgaste. Dentre os materiais restauradores o amálgama e Filtek Supreme apresentaram maior resistência ao desgaste. Em relação a dureza Mohs os esmaltes dentários e o amálgama apresentaram dureza Mohs 5 (Apatita) enquanto as resinas compostas dureza Mohs 4 (Fluorita). Os resultados mostraram que a avaliação da resistência a microabrasão dos materiais comparada a resistência ao desgaste dos minerais padrões da escala de dureza Mohs, poderá contribuir para uma efetiva classificação desses materiais utilizando-se de medidas não subjetivas. / Mestre em Odontologia

Normalmente, a restauração de dentes tratados endodonticamente e com extensa destruição corono-radicular é um desafio para o clínico. Devido à facilidade de manipulação, resinas compostas fotoativadas têm se apresentado como boa opção para o reforço intrarradicular destes dentes, antes da fixação de pinos. O objetivo desta pesquisa foi avaliar ex vivo a possível interferência de materiais obturadores no reforço interno de raízes fragilizadas restauradas com pinos de fibra e resina composta, por meio do teste de push-out e posterior análise da interface dentina/resina/cimento/pino em microscopia eletrônica de varredura (MEV). Cinquenta caninos superiores tiveram suas coroas removidas e o remanescente dental padronizado em 17 mm de comprimento. Após o preparo mecânico-químico, os espécimes foram distribuídos em um grupo controle (n=10) (preparo normal para pino e sem obturação prévia do canal) e um grupo experimental (n=40). Os espécimes do grupo experimental tiveram suas raízes fragilizadas com brocas diamantadas, de forma a apresentar folga circunferencial de aproximadamente 1,0 mm entre o pino e a estrutura dentinária circundante. Em seguida, os espécimes fragilizados foram redistribuídos em quatro subgrupos (n=10) de acordo com o tipo de material obturador: (G1) Endofill + guta-percha; (G2) AH Plus + guta-percha; (G3) Epiphany + guta-percha; (G4): Epiphany + Resilon. Após 24 h, todos os canais foram preparados em 12 mm. A dentina intrarradicular foi então condicionada com ácido fosfórico a 32% (15s), lavada com água deionizada (30s) e secada com pontas de papel absorvente. A seguir, fina camada de um sistema adesivo de 3 passos (All Bond 2) foi aplicada à dentina com pontas microbrush. Para o reforço das raízes, cada canal foi preenchido com uma resina dual Bis-Core e um pino de fibra (DT Light Post) inserido em toda a extensão do preparo. A fotopolimerização foi feita através do pino por 20 s, com a ponta do fotopolimerizador disposta perpendicularmente a ele. Decorridas 24 h, os espécimes foram seccionados transversalmente em fatias de 1 mm de espessura. A resistência de união foi avaliada por meio do teste de push-out e as falhas observadas em estereomicroscópio. Os espécimes foram avaliados quali-quantitativamente em MEV quanto à interface adesiva, presença de camada híbrida e densidade dos tags. A análise estatística da resistência de união dos materiais, em MPa, após o teste de push-out, revelou diferença entre o grupo controle (15,4 ± 6,91) e os grupos experimentais (GI - 11,41 ± 4,66; GII - 9,97 ± 3,41; GIII - 10,12 ± 4,18; e GIV - 9,0 ± 4,17) (ANOVA, post-hoc Tukey test, p<0,05). Contudo, não houve diferença entre os terços as regiões analisadas dentro de cada grupo (p>0,05). Houve maior ocorrência de falhas adesivas tanto no grupo controle quanto nos experimentais. Em MEV, a análise quantitativa mostrou formação de camada híbrida, tags de resina e ramificações laterais em todas as regiões analisadas. Dentro das limitações do presente estudo, concluiu-se que a obturação prévia do canal radicular reduziu a resistência de união do material de reforço intrarradicular, sem diferença estatística entre os tipos de cimentos testados. / The restoration of endodontically treated teeth commonly presents a challenge in cases of extensive crown-root destruction. Due to their ease of handling, lightactivated composite resins present a better option for intracanal reinforcement before the use of a fiber posts. The aim of this ex vivo study was to evaluate the influence of filling materials in the root reinforcement of weakened experimentally roots restored with composed resin and quartz fiber post by means of push-out bond strength evaluation and scanning electronic microscopy (SEM) analysis of the dentin/resin/cement/post interface. The crowns of 50 upper maxillary canines were removed and the length of roots standardized in 17 mm. After root canal preparation, the specimens were randomly divide into one control (n=10) (normal post preparation with no previous filling) and one experimental groups (n=40). All specimens in the experimental group had their canals enlarged in such a way as to produce a circumferential space of approximately 1.0 mm between the fiber post and the circumjacent dentine walls, using diamond tips. Then, the specimens of the experimental group were subdivided into four subgroups (n=10), according to the filling materials: (G1) Endofill + gutta-percha; (G2) AH Plus + gutta-percha; (G3) Epiphany + gutta-percha; (G4): Epiphany + Resilon. After 24 h of the root canal filling, the canals of all specimens were prepared into 12 mm. The intracanal dentine was etched with 32% phosphoric acid (15s), rinsed with deionised water (30s) and gently dried with absorbent paper points. A 3-step etch-and-rinse adhesive system (All Bond 2) was applied to the slightly moist dentine with disposable microbrush tips. For root reinforcement, each canal was bulk filled with a translucent composite resin (Bis-Core) and a fiber post (DT Light Post) was centrally inserted into the resin mass along the whole post space extension. Light-curing was performed with a conventional device by placing the tip perpendicularly through the post for 20s. After 24 h of the post cementation, the specimens were sectioned perpendicularly to its long axis in 3 slices, with 1 mm of thickness. The bond strength was performed by the push-out test and, after dislodgments, the failures were observed in the stereomicroscope. The specimens were processed for SEM analysis to observe bonding interface formation, hybrid layer quality and resin tag density using a fourstep scale method. The statistical analysis of the bond strength, in MPa, after the push-out test, indicated difference between control (15,4 ± 6,91) and experimental groups (GI - 11.41 ± 4.66; GII - 9.97 ± 3.41; GIII - 10.12 ± 4.18; e GIV - 9.0 ± 4.17) (ANOVA, post-hoc Tukey test, p<0,05), but not between the evaluated regions (p>0.05). The adhesive failures were frequent in the weakened groups as either in the control group. In SEM, the qualitative analysis showed formation of hybrid layer, resin tags and lateral branches in all the analyzed regions, independently of the group. The quantitative analysis (Kruskal-Wallis test, &alpha;=0.05) indicated that previous root canal filling did not influence in the hybrid layer and resin tags formation. Within the limitations of this study, it may be concluded that previous root canal filling have reduced the bond strength in the weakened group, but the type of sealer did not influence in the results.