The influence of crystalline phase additions on the mechanical properties of dental ceramic materials part 1.1: Ceramic materials reinforced with alumina-based nanocomposites

Abstract

The present study, divided into two parts, aims to evaluate the reinforcing influence of the crystalline phase in dental ceramics subjected to short-time, one-step firing. Parti compares four groups of different types of crystalline Al2O3phase mixed with dental ceramic. In all, nine composite materials of crystalline Al2O3phase and dental ceramic were tested. For this purpose, 20 bars were prepared per material. Strength data were analyzed using a one-way ANOVA with Scheffé post hoc test (ρ=0.05) and Weibull statistics. The average bending strength (MPa) values of Al2O3reinforcements in the four groups were: (1) A2O3platelet-reinforced as DA40133.3b,c,dand DA50124.0b,c;(2) Nanocrystalline Al23-reinforced as DAn30119.6b, DAn40119.1band DAn50148.7d,e;(3) Mixed-size Al2O3-reinforced as DAm30135.4b,c,dand DAm40132.7b,c,dand (4) Fibre-shaped Al2O3-reinforced as DAf30165.0eand DAf40143.2c,d,e;whereas the dental ceramic was 83.4a. Values with the same superscript letters showed no statistically significant difference. Microscopy revealed the relationship between the ceramic matrix and the crystalline phase; the characteristics of the latter were correlated to the strengthening and toughening mechanisms of these Al2O3-reinforced ceramics. Crystalline Al2O3reinforcement is accompanied by a strength increase in the dental ceramic. The crystalline content, porosity, grain size, shape and nanocomposite structures are important in determining the strength of composite materials. The different types of crystalline phase-reinforced Al2O3, especially the fibrous Al2O3and nanocrystalline Al2O3, strongly affect the mechanical properties of the ceramics.