Background: The goal of this study is to compare the misfit (>150µm) generated once the restoration, made by different techniques, is retained to a single conical implant. Material and Methods: 15 internal connection implants (MIS C1 4'20x10mm) are embedded each one perpendicularly to an horizontal surface of the 1x1x2cm poliuretan resin model. The 15 samples obtained are divided in 5 groups depending on the framework process (n=3): 1/casting, 2/overcasting, 3/Ti-base, 4/milling and 5/laser sintering. The cobalt-chromium alloy frameworks are screw-retained to their respective implants to a 30-Ncm torque. Once it is retained the framework to the implant, the next step is to section the sample in half with a diamond saw and verify the correct fit with a stereomicroscope, measuring 4 distances in each side (A, B, C and D). Data is submitted to one-way analysis of variance (ANOVA). Results: According to equality of variances, significant differences are found in A and B measures (p=0,000 in left side in both groups and, p=0,007 and p=0,001 in right side). In C and D, there are not statistical differences (p=0,586 and p=0,110 in left side and, p=0,101 and p=0,089 in right side). However, once it has realized ANOVA test, only C retains the hypothesis and accepts independence. Conclusions: More samples are needed to conclude reliable statements. However, what it is observed is that milled group presents the best marginal fit. Overcasted and Ti-Base abutments also have good results above casted ones, and, sintered groups has the lowest result. Although, all systems have gaps below 150 µm, so all of them are good options for prosthetic rehabilitation.
Resumen: El tallado insuficiente de un diente que va a recibir un retenedor en metal-porcelana supone confeccionar una restauración con adecuada morfología pero escaso grosor de porcelana o bien una restauración sobrecontorneada y grosor adecuado de porcelana. En este último caso, la consecución de una correcta oclusión puede obligar a un desgaste clínico intraoral de la porcelana lo que ocasiona una superficie altamente abrasiva que posteriormente requerirá un retoque por pulido mecáni-co o glaseado final. De Cualquier manera este retoque y pulido modifica la superficie de la porcelana y puede influenciar en el efecto cromático final de la restauración. Con esta base diseñamos una investigación para valorar los cambios de color ocasionados por el pulido de la porcelana. Las muestras fueron 95 especímenes de metal-porcelana combinando 2 colores, 6 aleaciones y 3 cerámicas diferentes. Todos se sometieron a un análisis colorimétrico. Los resultados muestran que existen diferencias de color entre aleaciones, cerámicas y tonos antes y después de un pulido de una superficie cerámica glaseada; siendo la aleación Cosmor la que más variación de color tiene y la aleación Wirón la que menos variación tiene. La cerámica que más ve influido su color por el pulido es la Vita VMK.Palabras Clave: Cerámica, Color, Metal,Pulido.Abstract: An insufficient tooth reduction for a subsequent PFM-retainer leads to the fabrication of either a restoration with an adequate morphology, but insufficient porcelain thickness or to an overcontoured restoration with an adequate porcelain thickness. In the last case, in order to achieve a proper occlusion it will be necessary to carry out an intraoral adjustment of the porcelain, producing a highly abrasive surface, which will need to be finished by mechanical polishing or final glazing. In both cases, these final adjustments and polishing steps will modify the porcelain surface and can have an impact on the final chromatic effect of the restoration. Based on this, we have designed a study to evaluate the colour changes associated to the polishing of the porcelain. It was carried out on 95 PFMsamples, combining two shades, six alloys and three ceramics. All were subjected to colorimetric analysis. The results show that there are differences in shade between the different alloys, ceramics and hues before and after the polishing of a glazed ceramic surface. The «Cosmor» -alloy shows the largest colour variation, while the «Wiron»-alloy exhibits the smallest variation. The ceramic whose shade is more influenced by the polishing is «Vita VMK».
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