E Camposilvan1, R Leone2, L Gremillard3, R Sorrentino2, F Zarone2, M Ferrari4, J Chevalier5. 1. Université de Lyon, INSA de Lyon, MATEIS CNRS UMR5510, 7 Av. Jean Capelle, 69621 Villeurbanne, France; Department of Materials Science and Metallurgical Engineering, Universitat Politècnica de Catalunya, C/Eduard Maristany, 10-14, 08930 Barcelona, Spain. 2. Department of Neurosciences, Reproductive and Odontostomatological Sciences, Prosthodontic Area, University "Federico II", Napoli Italy. 3. Université de Lyon, INSA de Lyon, MATEIS CNRS UMR5510, 7 Av. Jean Capelle, 69621 Villeurbanne, France. 4. Department of Prosthodontics and Dental Materials, University of Siena, V.le Bracci 1, 57100, Italy. 5. Université de Lyon, INSA de Lyon, MATEIS CNRS UMR5510, 7 Av. Jean Capelle, 69621 Villeurbanne, France. Electronic address: jerome.chevalier@insa-lyon.fr.
Abstract
OBJECTIVES: The dental market moves towards high-translucency monolithic zirconia dental crowns, which are usually placed either with - or without - a thin glaze layer. The microstructural features and the mechanical performances of these materials are still controversial, as well as their susceptibility to aging. This paper aims at studying these aspects in the current generation of zirconia dental crowns showing different degrees of translucency. METHODS: Four different commercial zirconia materials were investigated, including one standard 'full-strength' 3Y-TZP and three grades with improved translucency. The microstructural features (phase composition and assemblage, grain size) were carefully studied, as well as mechanical properties (biaxial bending strength and indentation toughness), translucency and aging behavior (in autoclave at 134°C). Aging was conducted on crowns with and without glaze to better represent clinical uses. RESULTS: Important differences are found in terms of microstructures among the materials in terms of cubic phase content and yttria in the tetragonal phase, leading to different optical, mechanical and aging resistance properties. We show that higher cubic phase content leads to better translucency and stability in water steam, but at the expense of strength and toughness. A compromise is always inevitable between translucency and aging resistance on one side and mechanical properties on the other side.
OBJECTIVES: The dental market moves towards high-translucency monolithic zirconia dental crowns, which are usually placed either with - or without - a thin glaze layer. The microstructural features and the mechanical performances of these materials are still controversial, as well as their susceptibility to aging. This paper aims at studying these aspects in the current generation of zirconia dental crowns showing different degrees of translucency. METHODS: Four different commercial zirconia materials were investigated, including one standard 'full-strength' 3Y-TZP and three grades with improved translucency. The microstructural features (phase composition and assemblage, grain size) were carefully studied, as well as mechanical properties (biaxial bending strength and indentation toughness), translucency and aging behavior (in autoclave at 134°C). Aging was conducted on crowns with and without glaze to better represent clinical uses. RESULTS: Important differences are found in terms of microstructures among the materials in terms of cubic phase content and yttria in the tetragonal phase, leading to different optical, mechanical and aging resistance properties. We show that higher cubic phase content leads to better translucency and stability in water steam, but at the expense of strength and toughness. A compromise is always inevitable between translucency and aging resistance on one side and mechanical properties on the other side.