The study of flexural strength of various zirconia ceramics

Park, Jae Hong; Hwang, Jung Won; Shin, Sang Wan

Abstract

STATEMENT OF PROBLEM: Increasing demand of esthetic restorations made lots of kinds of ceramic materials. Among them, zirconia has been being focused by many dentists. But, mechanical properties of zirconia were still unclear. PURPOSE: The purposes of this study were to analyze the flexural strength of various zirconia ceramics which had been currently used for clinic i.e., In-Ceram Zirconia(Vita Zahnfabrik, Bad Sa ckingen, Germany), Celay Zirconia(Vita Zahnfabrik, Bad Sa ckingen, Germany) and CAD/CAM Zirconia(Adens Zi-Ceram, Seoul, Korea). MATERIAL AND METHODS: The four point bending test(ASTM C1161) was used to measure the flexural strength of a specimen before and after circular heat treatment and fatigue loading. RESULTS: 1. The average value of flexural strengths of CAD/CAM Zirconia, Celay Zirconia, In-Ceram Zirconia in dry condition were 806.5 MPa, 669.9 MPa, 605.6 MPa, respectively. There was a statistically significant difference in strength among the types(P<0.05). 2. After thermocycling, the average flexural strengths of CAD/CAM Zirconia, Celay Zirconia, In-Ceram Zirconia were 791.2 MPa, 604.2 MPa, 605.4 MPa, respectively. CAD/CAM Zirconia showed statistically significant higher strength(P<0.05). The others showed no significant difference after thermocycling(P>0.05). 3. After fatigue loading in wet condition, the average flexural strengths of CAD/CAM Zirconia, Celay Zirconia, In-Ceram Zirconia were 806.0 MPa, 674.9 MPa, 601.7 MPa, respectively. There was a significant difference in strength among the types(P<0.05). 4. There was no statistically significant difference in strength of the specimens according to experimental methods except for before and after thermocycling in Celay Zirconia(P>0.05). CONCLUSION: Besides high esthetic quality, zirconia had sufficiently high mechanical strength.