Análise da adaptação marginal e alteração dimensional de supraestruturas próteticas fundidas em diferentes ligas de Co-Cr

Abstract

The purpose of this study was to evaluate the influence of Co-Cr dental casting alloys presenting distinct melting ranges for compound casting technique, with lower and higher melting temperature, on the marginal adaptation of prefabricated cast-to implant cylinders for implant support prosthesis. Two cobalt-chromium base metal alloys were cast to prefabricated Co-Cr cast-to implant cylinders. The cylinders were placed in the abutments and mounted in epoxy resin. Three groups were formed according with base alloy. Group 1: Cylinder as manufactured (Control); Group 2: lower melting temperature alloy; Group 3: higher melting temperature alloy. The specimens were ground to their central portion longitudinally by a surface grinding machine, polished and evaluated by optical and scanning electron microscopy. The images were analyzed and the misfit areas between the cylinders and abutments were, if present, measured. For statistical evaluation of misfit areas ANOVA multivariate analysis and Tukey tests were used. Pre-fabricated cast-to cylinders which received higher melting temperature alloy showed significant differences in terms of marginal misfit. No significant differences were observed comparing the control and the lower melting temperature alloy group. Co-Cr casting alloy with a higher melting temperature cast on prefabricated Co-Cr implant cylinders might induce greater marginal misfit areas. The selected alloy for compound casting must not exceed the melting temperature of prefabricated implant cylinder base as recommended by manufactures.