Mechanical properties of different stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramics after veneering with ceramic

Orientação: Prof. Dr. Maximiliano Piero NeisserCoorientação: Prof. Dr. Carlos Nelson EliasTese (doutorado) - Universidade de Taubaté, Programa de Pós-graduação em Odontologia,Taubaté, 2009.Made available in DSpace on 2019-08-20T18:31:13Z (GMT). No. of bitstreams: 1 Marcelo Garbossa Francisco.pdf: 2892525 bytes, checksum: 60fa58c1488473c5e7f0adf533bb12bf (MD5) Previous issue date: 2009Resumo: Objetivo: Quantificar e comparar propriedades mecânicas, tais como resistência ao cisalhamento da interface de aderência zircônia/cerâmica, microdureza e resistência à flexão de corpos-de-prova confeccionados com diferentes cerâmicas de zircônia tetragonal policristalina contendo ítrio (Y-TZP) e cerâmica de revestimento aplicada. Método: Foram comparados, por meio de ensaios mecânicos, corpos-de-prova contendo zircônia nanopartículada ProtMat (Guaratinguetá, Brasil) e corpos-de-prova contendo zircônia microparticuladas ProtMat (Guaratinguetá, Brasil), Vita 2000 YZ CUBES (Zahnfabrik, Bad Säckingen Alemanha) e IPS e.maxZircad Ivoclar (Schaan/Liechtenstein). Foram confeccionados 84 corpos-de-prova (CP) em forma de blocos ou barras, estas últimas para o ensaio de flexão, sendo 21 de cada marca de zircônia. Todos os CPs foram sinterizados e uma zircônia de cada grupo foi caracterizada por difração de raios-X. Posteriormente foi realizada a aplicação de cerâmica CZR-Cerabien Zr (Noritake shinmachi, Nishi-ku, Nagoya, Japão) sobre os outros oitenta CPs, dos quais cinco CPs de cada grupo receberam a cerâmica em forma quadrangular e nos outros cinco CPs e em todas as barras foi aplicada à cerâmica de revestimento em toda a face. Foi realizado o ensaio de cisalhamento na interface de aderência zircônia/cerâmica dos CPs a partir de uma máquina de ensaio universal e avaliada a microdureza Vickers da interface dos CPs e o ensaio de flexão em quatro pontos das barras. Os CPs foram ainda avaliados sob microscópio óptico para verificação da interface zircônia/cerâmica e análise do tipo de fratura apresentada. Resultados: Os valores de dureza Vickers, tenacidade à fratura, resistência à flexão e resistência ao cisalhamento apresentados pelos corpos-de-prova preparados com partículas micrométricas foram de 1300HV, 9MPam-½, 850MPa e 60kgf, respectivamente. Só houve diferença estatística nos ensaios de flexão e tenacidade à fratura, tendo a ProtMat nanoparticulada apresentado valores superiores quando comparada às demais. Conclusões: Os CPs apresentaram dureza, tenacidade à fratura, resistência à flexão e ao cisalhamento adequados para a utilização em odontologia, tendo os mesmos apresentado comportamentos semelhantes, apesar da resistência dos CPs em zircônia nanoparticulada ter sido superior à resistência da zircônia microparticulada.Abstract: Aim: The aim of this study was to quantify and compare mechanical and physical properties, such as Vickers hardness, fracture toughness, flexural strength and shear resistance of blanks of different Y-TZP zirconia ceramics used in the manufacture of dental prostheses after veneering with Noritake. Method: Commercially nano and microcrystalline zirconia blocks, pre-sintered bars and stabilized with yttria produced in Brazil (ProtMat) and imported (VITA 2000 YZ CUBES and IPS e.maxZircad Ivoclar). Eighty-four commercially samples were sintered from 1350ºC to 1530ºC as recommended procedure by the manufactures. The results of X-ray diffraction showed that the blocks presented just the tetragonal phase. The blocks were veneered with CZR-Cerabien Zr ceramic (Noritake shinmachi, Nishi-ku, Nagoya, Japão) and afterwards submitted to mechanical tests. Vickers indentation tests were performed to determine hardness and toughness. The shear loading test was performed by using an universal machine and then evaluate the Vickers hardness of the blocks. The flexural resistance was done in four different points in the bars. The samples were observed by SEM to analyze fractures characteristics. Results: Zirconium showed similar physical and mechanical properties with no statistically significant differences on the hardness and resistance to fracture. Nanocrystalline zirconium showed higher toughness and flexural resistance results when compared with microcrystalline ones. Conclusions: Although the samples of nanocrystaline zirconium showed high values, the materials showed similar Vickers hardness, fracture toughness, flexural strength and shear resistance and all of them can be indicated to be used in dentistry

Concurrence between Interpupillary Line and Tangent to the Incisal Edge of the Upper Central Incisor Teeth

Made available in DSpace on 2019-09-12T16:56:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2009Objective: Dento-facial harmony is essential to obtain adequate esthetics and a successful treatment. Therefore, the aim of the present study was to analyze the existence of polar symmetry, obtained by two parallel lines, one along the pupils and another along the incisal edge of the upper central incisor teeth of 102 dental students distributed across five Brazilian dental schools. Materials and Methods: One hundred and two students with no missing teeth, who had never been subjected to any kind of dental treatment, not even orthodontic treatment, were selected and photographed using a dental eye II camera (Yashica-Kyocera Optics Inc., Somerset, NJ, USA) with a macro-objective lens of 100 mm and using a scale of 1:10 of the natural size. All the individuals were positioned parallel to the plane of Frankfurt and to the ground, and were photographed smiling in order to expose the central incisors. The pictures were transformed into digital images (1,840 x 1,252 pixels) and analyzed later using Microsoft Office Power Point 2007 software. Two lines (along the pupils and another along the maxillary incisive teeth) were drawn, and the inclination obtained was generated by the program itself. Symmetrical cases were classified as "yes" (Y), and the remainder as "no" (N). Cases were also divided according to gender. Results were statistically assessed by analysis of variance and Student's t-test (alpha = 0.05). Results: There was a statistically significant correlation between the line parallel with the pupils and the tangent of the incisal edge of the incisors, irrespective of gender. Conclusion: Regardless of gender, there is a correlation between the pupils and the tangent with the incisal edge of the maxillary central incisors. CLINICAL SIGNIFICANCE Despite diversity in individuals, facial and anatomic measurements may aid in the execution and planning of rehabilitation treatments.[Malafaia, Fabiano Martins; Garbossa, Marcelo Francisco; Claro Neves, Ana Christina; Da Silva-Concilio, Lais Regiane; Neisser, Maximiliano Piero] Universidade de Taubaté (Unitau), Dept Den