PURPOSE: The aim of this study was to compare the marginal adaptation of metal-ceramic crowns made with 3 different metal substructures. MATERIALS AND METHODS: Seventy-five gypsum dies were fabricated from a master steel die. They were randomly divided into 3 groups of 25 dies each. A metal coping was prepared on each die using a different technique for each group: composite alloy, electroforming, and cast high-noble alloy. Ceramic was baked on all of the samples following the same protocol and simulating the shape and size of a maxillary central incisor. All specimens were evaluated under a stereomicroscope at 200x magnification. The marginal gap was measured at 8 different points on each specimen before and after ceramic application and also on the master steel die. A total of 3,600 measurements was evaluated. The results were statistically elaborated by means of a t test and one-way analysis of variance (ANOVA). RESULTS: The ANOVA revealed a significant difference in mean marginal gap before and after ceramic application within each group. Electroforming (mean 32 microns) and high-noble alloy (mean 31 microns) showed better marginal fit after ceramic application and on the master steel die compared to composite alloy (mean 68 microns; P < 0.0001). CONCLUSION: Marginal gaps are influenced by the application of ceramic and by the alloy used for the substructure, and the values obtained were within the limits of clinical acceptability (70 microns).

Comparison of marginal fit of 3 different metal-ceramic systems: an in vitro study.

SCHIERANO, Gianmario;BASSI, Francesco;CAROSSA, Stefano
2000-01-01

Abstract

PURPOSE: The aim of this study was to compare the marginal adaptation of metal-ceramic crowns made with 3 different metal substructures. MATERIALS AND METHODS: Seventy-five gypsum dies were fabricated from a master steel die. They were randomly divided into 3 groups of 25 dies each. A metal coping was prepared on each die using a different technique for each group: composite alloy, electroforming, and cast high-noble alloy. Ceramic was baked on all of the samples following the same protocol and simulating the shape and size of a maxillary central incisor. All specimens were evaluated under a stereomicroscope at 200x magnification. The marginal gap was measured at 8 different points on each specimen before and after ceramic application and also on the master steel die. A total of 3,600 measurements was evaluated. The results were statistically elaborated by means of a t test and one-way analysis of variance (ANOVA). RESULTS: The ANOVA revealed a significant difference in mean marginal gap before and after ceramic application within each group. Electroforming (mean 32 microns) and high-noble alloy (mean 31 microns) showed better marginal fit after ceramic application and on the master steel die compared to composite alloy (mean 68 microns; P < 0.0001). CONCLUSION: Marginal gaps are influenced by the application of ceramic and by the alloy used for the substructure, and the values obtained were within the limits of clinical acceptability (70 microns).
2000
13
405
408
http://www.ncbi.nlm.nih.gov/pubmed/11203662
Metal-ceramic crowns; marginal gap
PETTENO D; SCHIERANO G; F. BASSI; BRESCIANO; CAROSSA S.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/37193
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