RESUMO
Durante los últimos 40 años las cerámicas dentales han presentado significativos avances tecnológicos, desde la porcelana feldespática a las cerámicas basadas en zirconio, mejorando sus propiedades mecánicas aumentando aproximadamente en casi 10 veces la resistencia a la flexión y a la fractura. Característica importante, común a todos los sistemas cerámicos es la proporción de la fase vítrea y cristalina y el grado de porosidad dado que ambas afectan las propiedades ópticas y mecánicas de la restauración. Para la mejor comprensión de la diversidad de cerámicas desarrolladas durante los últimos años se proponen dos clasificaciones, una basada en su composición, que permite relacionar el material con sus propiedades físicas y otra basada en el método de fabricación que define las opciones de manejo y que adicionalmente, permite conocer con mayor facilidad las ventajas y limitaciones de las cerámicas dentales además de ayudar a definir la selección del material más indicado para cada requerimiento clínico.
During the last 40 years, dental ceramics had showed significant technological advances, from feldsphatics porcelain to ceramics based on zirconio, improving mechanicals properties, reaching close to 10 foils of flexural and fracture strength. Important characteristics, common to all ceramic systems, are glass phase and crystalline phase proportion, and the amount of porosity, because both affect the mechanicals and optical properties of the final restorations. For better understanding of the wide ceramics options, we propose two ceramics classifications based on composition, which associate the material with their physical properties and the fabrication method, which define the laboratory options and give information related to ceramics advantages and limitations, those information help to make the ceramic selection for each especial clinical requirement.
Assuntos
Humanos , Masculino , Feminino , Cerâmica/classificação , Materiais Dentários , Estética Dentária , Restauração Dentária PermanenteRESUMO
AIM: Aim of the study was to evaluate the biaxial flexural strength of ceramics processed using the Cerec inLab system. The hypothesis was that the flexural strength would be influenced by the type of ceramic. METHODS: Ten samples (ISO 6872) of each ceramic (N.=50/n.=10) were made using Cerec inLab (software Cerec 3D) (Ø:15 mm, thickness: 1.2 mm). Three silica-based ceramics (Vita Mark II [VM], ProCad [PC] and e-max CAD ECAD]) and two yttria-stabilized tetragonal-zirconia-polycrystalline ceramics (Y-TZP) (e-max ZirCad [ZrCAD] and Vita In-Ceram 2000 YZ Cubes [VYZ]) were tested. The samples were finished with wet silicone carbide papers up to 1 200-grit and polished in a polishing machine with diamond paste (3 µm). The samples were then submitted to biaxial flexural strength testing in a universal testing machine (EMIC), 1 mm/min. The data (MPa) were analyzed using the Kruskal-Wallis and Dunn (5%) tests. Scanning electronic microscopy (SEM) was performed on a representative sample from each group. RESULTS: The values (median, mean±sd) obtained for the experimental groups were: VM (101.7, 102.1±13.65 MPa), PC (165.2, 160±34.7 MPa), ECAD (437.2, 416.1±50.1 MPa), ZrCAD (804.2, 800.8±64.47 MPa) and VYZ (792.7, 807±100.7 MPa). The type of ceramic influenced the flexural strength values (P=0.0001). The ceramics ECADa, e-max ZrCADa and VYZa presented similar flexural strength values which were significantly higher than the other groups (PCb and VM IIb), which were similar statistically between them (Dunn's test). The hypothesis was accepted. CONCLUSION: The polycrystalline ceramics (Y-TZP) should be material chosen for make FPDs because of their higher flexural strength values.