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La pensée politique moderne a admis la dichotomie entre réforme et révolution. Le réformisme en a fait un principe qui domine actuellement les esprits. Mais la politique n’est-elle pas irrémédiablement partagée entre révolution et réforme ? La politique de Kant constitue un paradigme idéal pour poser le problème du rapport entre réforme et révolution. A l’initiative de Burke, l’opposition moderne entre réforme et révolution se forme à cette époque en réaction aux révolutions en Europe. Kant accepte bien l’opposition entre la réforme entreprise par le souverain et la révolution accomplie par le peuple. Mais sa sympathie bien connue pour la Révolution française l’amène à élaborer une politique pragmatique qui prend en compte les conditions historico-politiques de l’application des principes républicains défendus par la Révolution. Animé par un esprit révolutionnaire, le réformisme kantien entend réussir le processus politique de la républicanisation par le moyen de la réforme, tout en rendant justice à la nécessité du processus naturel de la révolution qui réagit à l’oppression de la liberté. Selon le philosophe de la Révolution, la réforme (révolutionnaire) accomplit la révolution. Pour le montrer, il faut réinscrire la politique de Kant dans son temps. La partie I en précise le contexte historique et sémantique : la réfutation kantienne du droit de rébellion est dirigée contre les monarchomaques ; l’articulation kantienne de la réforme à la révolution s’inscrit dans la lignée du consensus entre réforme et révolution mise en place par les Lumières. La partie II retrace la mise en place de la dichotomie « réformiste » entre réforme et révolution par les burkiens allemands : ils opposent à la violence destructrice de la Révolution l’option d’une réforme conservatrice qui se contente d’améliorer ponctuellement les institutions monarchiques. Kant, en revanche, se révèle être le théoricien secret d’une réforme révolutionnaire qui bouleverse le système monarchique de fond en comble : pour le montrer, la partie III décrypte l’esprit révolutionnaire de sa politique. / Modern political thought has admitted the dichotomy between reform and revolution. Reformism has turned it into a principle that currently dominates our minds. But isn't politics irremediably torn between reform and revolution?Kant's politics is an ideal paradigm to pose the problem of the relation between reform and revolution. At Burke's initiative, the modern opposition between reform and revolution is formed at that time as a reaction to the revolutions in Europe. Kant accepts the opposition between reforms adopted by the sovereign and the revolution done by the people. But his well-known sympathy for the French Revolution leads him to elaborate a pragmatic political philosophy that takes into account the historico-political conditions of the implementation of the republican principles defended by the Revolution. Stimulated by a revolutionary spirit, Kantian reformism means to successfully establish the political process of republicanisation thanks to reform, while doing justice to the necessity of the natural process of the revolution which reacts to the oppression of liberty. According to the philosopher of the Revolution, (revolutionary) reform accomplishes the revolution.So as to show it, one must place Kant's politics in his time. Part I makes clear its historical and semantic context: the Kantian refutation of the right to rebel is directed against the Monarchomachists; the Kantian way of articulating reform to revolution is inscribed in the tradition of a consensus between reform and revolution implemented by the Enlightenment. Part II charts the creation of the 'reformist' dichotomy between reform and revolution by German Burkians: rather than the destructive violence of the Revolution, they opted for a conservative reform that managed only to bring about ad hoc improvements to the monarchic institutions. Kant, on the contrary, turns out to be the secret theoretician of a revolutionary reform which totally upsets the monarchic system: to show this, part III deciphers the revolutionary spirit of his political thought.

The recent developments in Low Temperature Co-fired Ceramic (LTCC) as a substrate material enable it to be used in the micro and millimetre wave range providing low dissipation factors at high frequencies, good dielectric properties and a high degree of integration for further miniaturised devices. The most common metallisation method used in LTCC technology is screen printing with high cost noble metals such as silver and gold that are compatible with the high sintering temperatures (850°C). However, these techniques require high capital cost and maintenance cost. As the commercial world requires convenient and low cost process technologies for mass production, alternative metallisation methods should be considered. As a result, electroless copper plating of fired LTCC was mainly investigated in this research. The main goals of this project were to carry out electroless plating of fired LTCC with sufficient adhesion and to extend the process to metallise closed LTCC channel structures to manufacture Substrate Integrated Waveguide (SIW) components. The objectives were focused on electroless copper deposition on fired LTCC with improved adhesion. Electroless deposits on the Sn/Pd activated LTCC surface showed poor adhesion without any surface pre-treatments. Hence, chemical etching of fired LTCC was carried out using concentrated NaOH solution. NaOH pre-treatment of LTCC led to the formation of flake like structures on the LTCC surface. A number of surface and chemical analysis techniques and weight measurements were used to investigate the mechanism of the modification of the LTCC surface. The results showed that the flake like structures were dispersed in the LTCC material and a material model for the LTCC structure was proposed. SEM EDX elemental mapping showed that the flake like structure consisted of aluminium, calcium, boron and oxygen. Further experiments showed that both the concentration of NaOH and the immersion time affect the surface morphology and the roughness of fired LTCC. The measured Ra values were 0.6 μm for untreated LTCC and 1.1 μm for the LTCC sample treated with 4M NaOH for 270 minutes. Adhesion tests including peel test and scratch test were carried out to examine the adhesion strength of the deposited copper and both tests indicated that the NaOH pre-treatment led to an improvement, with the best results achieved for samples treated with 4M NaOH. A second aspect of the research focused on the selective metallisation of fired LTCC. Excimer laser machining was used to pattern a resist film laminated on the LTCC surface. This process also roughened the substrate and created channels that were characterised with respect to the laser operating parameters. After patterning the resist layer, samples were activated using Sn/Pd catalyst solution followed by the electroless copper deposition. Electroless copper was selectively deposited only on the patterned LTCC surface. Laser parameters clearly affected the copper plating rate. Even with a similar number of shots per area, the tracks machined with higher repetition rate showed relatively more machining depth as well as good plating conditions with low resistance values. The process was further implemented to realize a complete working circuit on fired LTCC. Passive components including a capacitor and an inductor were also fabricated on LTCC using the mask projection technique of the excimer laser system. This was successful for many designs, but when the separation between conductor lines dropped below 18 μm, electroless copper started to deposit on the areas between them. Finally, a method to deposit copper films on the internal walls of closed channel structures was developed. The method was first demonstrated by flowing electroless copper solutions through silane treated glass capillaries. A thin layer (approx. 60 nm) of electroless copper was deposited only on the internal walls of the glass capillaries. The flow rate of the electroless copper solution had to be maintained at a low level as the copper deposits tended to wash away with higher flow rates. The structures were tested for transmission losses and showed low (<10dB) transmission losses in the terahertz region of the electromagnetic spectrum. The process was further applied to deposit electroless copper on the internal walls of the LTCC closed channel structures to manufacture a LTCC Substrate Integrated Waveguide (SIW).

BEGINNING MIDDLE AND is a project that takes a textile approach to explore repeated pattern and the ongoing. This paper, being a part of this project, is describing and discussing the potentiality of using notions such as softness, folds and ongoingness to widen the views on what a craft practice can be and do. This raises questions about the relevancy of ideas such as finished and the one piece, in a craft context. Based on the properties of a resist dyeing technique, the paper puts the fold in relation to pattern and modularity. It wants to discuss what a fold is and how ideas of folding and unfolding could engage with process based artistic work. Constantly shifting between perspectives and looking for overlaps, the text then touches upon paradoxes and dilemmas found when unfolding the systems and the unruliness that together form the work. Looking at acts of unfinishing, it tries to understand the fascination and the fear that is triggered by incompleteness. The beginning is a wish to enhance the complexity of my craft practice, and to expand the understanding of it. But realizing the difficulties in doing so, the reasoning eventually ends up at the challenging task to break free from your own habits, trying to find a new beginning.

Made available in DSpace on 2015-04-14T13:58:35Z (GMT). No. of bitstreams: 1 422849.pdf: 6410464 bytes, checksum: ccd93368032fc92429c59317d9dbf9fe (MD5) Previous issue date: 2010-03-30 / Este estudo prop?e a caracteriza??o estrutural, por meio de ensaios mec?nicos, de postes de eucalipto em servi?o usados na rede el?trica. Os testes de flex?o est?tica foram realizados em uma ?rea de teste em campo constru?da de acordo com a NBR 6231 (ABNT, 1980) e ASTM D 1036-americanos (1990), enquanto os testes de compress?o paralela as fibras foram feitos de acordo com a NBR 7190 (ABNT1997). As propriedades mec?nicas, densidade e umidade ao longo de tr?s postes novos, de diferentes esp?cies de eucalipto, tamb?m foram avaliadas, levando em conta a quantidade de cerne e alburno presentes nas amostras. Correla??es entre os ensaios de compress?o e flex?o foram obtidos considerando-se a as diferentes faixas de densidade da madeira. Os resultados indicaram que a quantidade de cerne e alburno nas amostras afeta as propriedades mec?nicas, especialmente se o corpo de prova for composto de apenas um desses componentes. Foi poss?vel encontrar, dentre as esp?cies, a mais adequada para a fabrica??o poste. Al?m disso, ensaios de compress?o realizados tanto em postes em servi?o como novos, flexionados ou n?o, indicaram propriedades mec?nicas semelhantes quando classificados na mesma faixa de densidades. As correla??es estabelecidas s?o ?teis para obter uma estimativa das propriedades mec?nicas dos postes com a vantagem de ser um teste semi destrutivo, ao contr?rio dos testes de flex?o.

Submitted by Caroline Xavier (caroline.xavier@pucrs.br) on 2017-06-30T13:59:55Z No. of bitstreams: 1 DIS_GICELDA_JULIA_DAL_BO_COMPLETO.pdf: 3328714 bytes, checksum: c1dae6f11752d09fdfaddc8e2f46a7ce (MD5) / Made available in DSpace on 2017-06-30T13:59:55Z (GMT). No. of bitstreams: 1 DIS_GICELDA_JULIA_DAL_BO_COMPLETO.pdf: 3328714 bytes, checksum: c1dae6f11752d09fdfaddc8e2f46a7ce (MD5) Previous issue date: 2017-03-09 / This dissertation explores structures of power from the point of view of empowerment and resistance in a shared economy model, having Uber (since its arrival in the country) as object of study. To this end, it relies on a qualitative method of interpretativist approach through a single case study. By identifying the agents' discourses of the urban mobility socio-technical system, in the voice of media vehicles and specialized websites, this research proposes to analyze how power structures are organized. The study lists three perspectives, an ?economic model?, a ?business model? and ?sustainable development?, built to group the ?two sides of the same coin?, empowerment and resistance, proposing a ?conversation? between them. It presents a view of the relationship with the collectivity through two mechanisms, also of opposing forces: ?quest for legitimacy? and ?reinforcement to the status quo?. In a complementary way, it proposes a discussion section about uberism and its variations. Among the aspects listed in this section, issues of regulation and characteristics of the so-called Uber economy stand out. It brings, as theoretical basis, concepts of the Transition Theory for Sustainable Development, the Multiple Level Perspective (MLP) and an applied study that links sharing economy to the notion of socio-technical systems. With this, it seeks to demonstrate the ?game? of forces between empowerment and resistance in the Brazilian context of the socio-technical system of urban mobility. A combination of technological trajectories that have been destabilizing and pressuring the existing socio-technical structures pointed out for the existence of transitions to sustainable development. / Esta disserta??o explora estruturas de poder sob o ponto de vista de empoderamento e de resist?ncia em um modelo de economia compartilhada, tendo a Uber (desde sua chegada ao pa?s) como objeto de estudo. Para tal, apoia-se em um m?todo qualitativo de abordagem interpretativista por meio de um estudo de caso ?nico. Prop?e-se a analisar como est?o organizadas as estruturas de poder identificando os discursos de agentes do sistema sociotecnico de mobilidade urbana na voz dos ve?culos de m?dia e de sites especializados. O estudo elenca tr?s perspectivas, modelo econ?mico, modelo de neg?cio e desenvolvimento sustent?vel, constru?das de forma a agrupar os ?dois lados da mesma moeda?, empoderamento e resist?ncia, propondo uma ?conversa? entre eles. Apresenta um olhar da rela??o com a coletividade atrav?s de dois mecanismos, tamb?m de for?as contr?rias: ?busca por legitimidade? e ?refor?o ao status quo?. De forma complementar, prop?e uma se??o de discuss?o acerca de uberismo e suas varia??es. Dentre os aspectos elencados nesta se??o, destacam-se quest?es de regula??o e caracter?sticas da chamada Uber economia. Como suporte te?rico apresenta conceitos da Teoria das Transi??es para o Desenvolvimento Sustent?vel, da Perspectiva de M?ltiplos N?veis (MLP) e de um estudo aplicado que vincula economia compartilhada ? no??o de sistema sociot?cnico. Com isso, busca demonstrar o ?jogo? de for?as entre empoderamento e resist?ncia no contexto brasileiro do sistema sociot?cnico de mobilidade urbana. Os resultados apontaram em dire??o a exist?ncia de transi??es para o desenvolvimento sustent?vel, permeadas por uma combina??o de trajet?rias que tem desestabilizado e pressionado as estruturas sociot?cnicas vigentes.

Submitted by PPG Odontologia (odontologia-pg@pucrs.br) on 2018-05-28T13:41:25Z No. of bitstreams: 1 RAQUEL_DE_OLIVEIRA_LOPES_TES.pdf: 2230148 bytes, checksum: a749d045cae0f8098669b38fe6b648b6 (MD5) / Approved for entry into archive by Caroline Xavier (caroline.xavier@pucrs.br) on 2018-06-11T18:19:23Z (GMT) No. of bitstreams: 1 RAQUEL_DE_OLIVEIRA_LOPES_TES.pdf: 2230148 bytes, checksum: a749d045cae0f8098669b38fe6b648b6 (MD5) / Made available in DSpace on 2018-06-11T18:25:33Z (GMT). No. of bitstreams: 1 RAQUEL_DE_OLIVEIRA_LOPES_TES.pdf: 2230148 bytes, checksum: a749d045cae0f8098669b38fe6b648b6 (MD5) Previous issue date: 2018-01-17 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / (Artigo Os adesivos universais s?o t?o eficientes quanto um primer para a ades?o ? zirc?nia?) O objetivo do trabalho foi comparar a resist?ncia de uni?o ? cer?mica de zirc?nia de quatro adesivos universais e um primer para zirc?nia. Setenta e cinco amostras de zirc?nia foram confeccionadas e inclu?das em resina acr?lica. A superf?cie das amostras foi polida com lixas de carbeto de sil?cio nas granula??es 600, 800 e 1.200 e jateadas com ?xido de alum?nio 50 ?m por 5 s. As amostras foram divididas aleatoriamente em cinco grupos (n=15): G1 ? Single Bond Universal (SBU); G2 ? All Bond Universal (ABU); G3 ? Peak Universal Bond (PUB); G4 ? Ambar Universal (AU) e G5 ? Z-Prime Plus (ZP). Um cone de resina composta foi constru?do, atrav?s de uma matriz, sobre o material adesivo aplicado na superf?cie das amostras. Os corpos de prova foram armazenados em ?gua destilada a 37?C por 24 h, sendo submetidos ao teste de resist?ncia de uni?o ? tra??o em m?quina de ensaio universal EMIC com velocidade de 0,5 mm/min. Os tipos de falhas foram classificados em adesiva, coesiva ou mista. Os valores de resist?ncia de uni?o foram submetidos ? an?lise de vari?ncia (ANOVA), seguido do teste de Tukey (?=0,05). M?dias de resist?ncia de uni?o (MPa) seguidas de letras distintas diferem estatisticamente entre si: G5=21,12a, G1=20,55a, G4=19,12ab, G2=14,22b, G3=8,45c. As falhas foram predominantemente mistas no G1, G4 e G5, e predominantemente adesivas no G2 e G3. Os adesivos SBU e AU obtiveram resist?ncia de uni?o compar?vel ao ZP. / (Artigo Bond to zirconia ceramic: evaluation of different primers and a universal adhesive) The aim of the study was to evaluate the effect of a universal adhesive and different primers on the bond strength to zirconia ceramic. Seventy-five zirconia ceramic samples were obtained and divided into five groups (n=15): G1 ? Scothbond Universal (SBU); G2 ? silane + SBU; G3 - Signum Zirconia Bond; G4 - Z-Prime Plus; G5 - MZ Primer. A cone of composite resin was built. The specimens were stored in 100% relative humidity with distilled water at 37?C for 48 h, and then submitted to a tensile bond strength test in a universal testing machine at a crosshead speed of 0.5 mm/min. The type of failure that occurred during the debonding procedure was analyzed. The mean results of the bond strength test (MPa) followed by the same letter represent no statistical difference by ANOVA and Tukey?s post-hoc test (p<0.05): G2=27.55a (?6.99), G4=23.71a (?5.65), G1=22.64a (?5.67), G5=13.64b (?5.49), G3=7.54c (?4.75). G2 and G4 exhibited predominantly cohesive failure in the resin composite cone. G1 and G5 had predominantly mixed failures, and G3 exhibited only adhesive failures. The SBU and Z-Prime Plus provided higher bond strength to zirconia ceramic. / (Artigo Os adesivos universais s?o t?o eficientes quanto um primer para a ades?o ? zirc?nia?) The aim of the study was to compare four universal adhesives and a primer on the bond strength to zirconia ceramic. Seventy-five zirconia ceramic samples were obtained and embedded in acrylic resin. The surface of the samples was polished with 600-, 800- and 1200-grit silicon carbide abrasive papers, and sandblasted with 50 ?m aluminum oxide particles for 5 s. The samples were divided into five groups (n=15): Single Bond Universal (SBU); G2 ? All Bond Universal (ABU); G3 ? Peak Universal Bond (PUB); G4 ? Ambar Universal (AU) e G5 ? Z-Prime Plus (ZP). A cone of composite resin was built on the adhesives and primer applied. The specimens were stored in distilled water at 37oC for 24 h, and then submitted to a tensile bond strength test in a universal testing machine at a crosshead speed of 0.5 mm/min. The type of failure that occurred during the debonding procedure was classified as adhesive, cohesive or mixed. The values of bond strength were analyzed by analysis of variance (ANOVA) followed by Tukey?s test (?=0.05). Means of bond strength (MPa) followed by the distinct letters represent statistical difference: G5=21,12a, G1=20,55a, G4=19,12ab, G2=14,22b, G3=8,45c. The failures were predominantly mixed in G1, G4 and G5, and predominantly adhesive in G2 and G3. SBU and AU adhesives obtained bond strength comparable to ZP.

Submitted by PPG Odontologia (odontologia-pg@pucrs.br) on 2018-06-04T18:19:16Z No. of bitstreams: 1 BIANCA_SOARES_ZAMBIASI_DIS.pdf: 758503 bytes, checksum: 8be0192f396b8b0f4c6df98b83a9d972 (MD5) / Rejected by Sheila Dias (sheila.dias@pucrs.br), reason: Devolvido devido ? falta de capa institucional no arquivo em PDF. on 2018-06-14T17:04:02Z (GMT) / Submitted by PPG Odontologia (odontologia-pg@pucrs.br) on 2018-06-26T12:16:19Z No. of bitstreams: 1 BIANCA_SOARES_ZAMBIASI_DIS.pdf: 578649 bytes, checksum: c63b0e7591fc3dce9a38312f414e4e43 (MD5) / Approved for entry into archive by Sheila Dias (sheila.dias@pucrs.br) on 2018-07-02T16:48:43Z (GMT) No. of bitstreams: 1 BIANCA_SOARES_ZAMBIASI_DIS.pdf: 578649 bytes, checksum: c63b0e7591fc3dce9a38312f414e4e43 (MD5) / Made available in DSpace on 2018-07-02T16:57:34Z (GMT). No. of bitstreams: 1 BIANCA_SOARES_ZAMBIASI_DIS.pdf: 578649 bytes, checksum: c63b0e7591fc3dce9a38312f414e4e43 (MD5) Previous issue date: 2018-01-26 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Aims: To evaluate, in vitro, the fracture resistance and the pattern of failure of endodontically treated molars restored with different direct restorative techniques. Materials and methods: 70 third healthy molars extracted were divided into 7 groups (n = 10): (all groups except H received root canal treatment) H-sound; Z250PT ? horizontally transfixed fiberglass post + Z250 composite resin; Z250FO ? Z250 + occlusal fiberglass tape; Z250FP ? Z250 + fiberglass tape along the floor of the pulp chamber; PREP-only cavity preparation; COL ? Restored with Coltosol. After the restorative procedures, the samples were subjected to 250,000 cycles of mechanical testing fatigue under 200N. Right after, the samples were submitted to the fracture resistance testing and the analysis of the type of fracture which were classified as follows: Pulp chamber floor (non-repairable) or cusps (repairable). Results: (means (N) followed by the same letter do not present statistical difference to ANOVA and Tukey (p > 0.05): H 3832A; Z250PT 2726B; Z250FO 1647C; Z250FP 1548C; Z250 1622C; PREP 514D; COL 450D. Conclusion: The restorative technique that presents higher resistance to the fracture as well as higher percentage of repairable failures is horizontal transfixing with fiberglass post, Z250PT group. The insertion of fiberglass tape into the composite resin did not present improvement in the resistance, nor in the fracture pattern, when compared to the use of traditional composite resin. / Objetivo: Avaliar, in vitro, a resist?ncia ? fratura e o padr?o de falha de dentes tratados endodonticamente restaurados com diferentes t?cnicas restauradoras diretas. Materiais e M?todos: Setenta terceiros molares h?gidos extra?dos foram divididos em 7 grupos (n=10) assim distribu?dos: (todos os grupos exceto H receberam endodontia) H- h?gidos; Z250PT ? pino de fibra de vidro transfixado horizontalmente + resina composta Z250; Z250FO ? Z250+fita de fibra de vidro oclusal; Z250FP ? Z250 + fita de fibra de vidro junto ao assoalho da c?mara pulpar; PREP ? apenas preparo cavit?rio; COL ? restaurado com material provis?rio Coltosol. Ap?s o t?rmino das restaura??es as amostras foram submetidas a 250 mil ciclos de fadiga mec?nica sob 200N. Em seguida, foi realizado o ensaio de resist?ncia ? fratura e a an?lise do tipo de fratura p?sensaio as quais foram classificadas em: assoalho da c?mara pulpar (irrepar?vel) ou c?spides (repar?vel). Resultados: (m?dias (N) seguidas de mesma letra n?o apresentam diferen?a estat?stica para ANOVA e Tukey (p>0,05): H 3832A; Z250PT 2726B; Z250FO 1647C; Z250FP 1548C; Z250 1622C; PREP 514D; COL 450D. Conclus?o: A t?cnica restauradora que apresenta maior resist?ncia ? fratura. bem como maior percentual de falhas repar?veis ? a transfixa??o horizontal com pino de fibra de vidro, grupo Z250PT. A inser??o de fita de fibra de vidro na resina composta n?o apresentou melhora na resist?ncia, nem no padr?o de fratura, quando comparado a utiliza??o de resina composta tradicional.

Submitted by PPG Odontologia (odontologia-pg@pucrs.br) on 2018-06-27T13:42:26Z No. of bitstreams: 1 DEBORAH_STONA_TES.pdf: 479572 bytes, checksum: 09946538cb3d70a32dd07508ec13bcce (MD5) / Rejected by Sheila Dias (sheila.dias@pucrs.br), reason: Trabalho devolvido devido constar no sum?rio o t?pico "Hip?teses", mas no corpo do trabalho n?o aparece, do t?pico "Objetivos" passa para "Materiais e m?todos" no arquivo PDF. on 2018-07-04T12:49:48Z (GMT) / Submitted by PPG Odontologia (odontologia-pg@pucrs.br) on 2018-07-19T10:52:46Z No. of bitstreams: 1 DEBORAH_STONA_TES.pdf: 842939 bytes, checksum: 8b8eda0f9181f560f275f85833a4faec (MD5) / Approved for entry into archive by Sheila Dias (sheila.dias@pucrs.br) on 2018-07-24T12:53:45Z (GMT) No. of bitstreams: 1 DEBORAH_STONA_TES.pdf: 842939 bytes, checksum: 8b8eda0f9181f560f275f85833a4faec (MD5) / Made available in DSpace on 2018-07-24T13:02:33Z (GMT). No. of bitstreams: 1 DEBORAH_STONA_TES.pdf: 842939 bytes, checksum: 8b8eda0f9181f560f275f85833a4faec (MD5) Previous issue date: 2018-03-26 / Conselho Nacional de Pesquisa e Desenvolvimento Cient?fico e Tecnol?gico - CNPq / Aims: 1) to evaluate the fracture resistance of posterior full-contour crowns of lithium dissilicate, lithium silicate reinforced by zirconia or translucent zirconia cemented on solid abutments; 2) to evaluate if the presence of a zirconia coping can increase the fracture resistance of lithium dissilicate crowns compared to monolithic ceramics made in lithium dissilicate, lithium silicate reinforced by zirconia or translucent zirconia. Materials and methods: Forty RN (regular-neck, Straumann) implant analogs and 4.0 mm solid abutments (Straumann) were embedded in acrylic resin and divided into 5 groups (n = 8): 1) e.max CAD; 2) Celtra Duo; 3) Incoris zirconia TZI; 4) 0.6 mm zirconia coping + e.max CAD; 5) 0.3 mm zirconia coping + e.max CAD. After preparation of the specimens, they were subjected to mechanical fatigue testing with 200N and 500,000 cycles. Following, the samples were submitted to the fracture resistance testing. Results: the means in Newtons (N) were as follows: e.max CAD 210.6Na ? 1447; Celtra Duo 2026Nb ? 355.8; zirconia TZI 2850Nc ? 287.6; 0.6 mm coping + e.max CAD 851Nd ? 108.1; 0.3 mm coping + e.max CAD 980Nd ? 133. Conclusion: monolithic translucent zirconia crowns cemented on solid abutments showed the higher fracture resistance in comparison to lithium dissilicate (e.max CAD) and lithium silicate reinforced by zirconia (Celtra Duo). The use of a zirconia coping associated with lithium dissilicate does not promote superior fracture resistance than monolithic crowns regardless of the thickness of coping and veneering ceramics. / Objetivos: 1) Avaliar a resist?ncia ? fratura de coroas cer?micas de dissilicato de l?tio, silicato de l?tio refor?ada por zirc?nia e zirc?nia transl?cida cimentadas sobre pilares s?lidos; 2) Avaliar se a presen?a de um coping em zirc?nia pode aumentar a resist?ncia ? fratura de coroas de dissilicato de l?tio quando comparadas ?s cer?micas monol?ticas confeccionadas em dissilicato de l?tio, zirc?nia transl?cida ou silicato de l?tio refor?ada por zirc?nia cimentadas sobre pilares s?lidos. Materiais e m?todos: Quarenta an?logos de implantes RN (regular neck, Straumann) e pilares s?lidos 4.0mm (Straumann) foram inclu?dos em resina acr?lica e divididos em 5 grupos (n=8) os quais receberam as seguintes coroas prot?ticas cimentadas: 1) e.max CAD; 2) Celtra Duo; 3) zirc?nia Incoris TZI; 4) coping zirc?nia 0,6mm + e.max CAD; 5) coping zirc?nia 0,3mm + e.max CAD. Ap?s confec??o dos corpos de prova os mesmos foram submetidos ? fadiga mec?nica com carga de 200N e 500.000 ciclos. Na sequ?ncia foram submetidos ao ensaio de carga m?xima de carregamento. Resultados: as m?dias de resist?ncia ? fratura obtidas foram: e.max CAD 1447Na ? 210,6; Celtra Duo 2026Nb ? 355,8; zirc?nia TZI 2850Nc ? 287,6; coping 0,6mm + e.max CAD 851Nd ? 108,1; coping 0,3mm + e.max CAD 980Nd ? 133. Conclus?o: Coroas monol?ticas realizadas em zirc?nia transl?cida cimentadas sobre pilares s?lidos apresentaram a maior resist?ncia ? fratura quando comparadas ao dissilicato de l?tio (e.max CAD) e silicato de l?tio refor?ado por zirc?nia (Celtra Duo). O uso de um coping de zirc?nia associado ao dissilicato de l?tio n?o promove resist?ncia ? fratura superior as coroas monol?ticas independentemente das espessuras do coping e da cer?mica de cobertura.