Jenni Hjerppe1, Timo O Närhi2, Pekka K Vallittu3, Lippo V J Lassila4. 1. Assistant Professor, Department of Prosthetic Dentistry, University of Turku, Turku, Finland. Electronic address: jenhje@utu.fi. 2. Professor, Department of Prosthetic Dentistry, University of Turku, Turku, Finland; and Professor, Clinic of Oral Diseases, Turku University Central Hospital, Turku, Finland. 3. Professor, Department of Biomaterials Science, University of Turku, Turku, Finland; and Professor, City of Turku, Welfare Division, Turku, Finland. 4. Laboratory Manager, Turku Clinical Biomaterials Centre (TCBC), University of Turku, Turku, Finland; and Senior Lecturer, Turku University of Applied Sciences, Faculty of Health and Well-being, Turku, Finland.
Abstract
STATEMENT OF PROBLEM: Different surface treatments are commonly used during the fabrication of zirconia fixed dental prostheses. However, such treatments can affect the properties of the zirconia framework material. PURPOSE: The purpose of this in vitro study was to determine the effect of different surface treatments on the surface roughness and flexural and bend strength of zirconia. MATERIAL AND METHODS: Seventy-two zirconia disks (n=8) and 72 zirconia bars (n=8) were sintered and divided into 9 groups for different surface treatments: sintered control, airborne-particle abraded with 50-μm aluminum oxide, airborne-particle abraded with Rocatec soft (30 μm), airborne-particle abraded with Rocatec (105 μm), grinding dry with a micromotor, turbine grinding under water cooling, grinding with silicon carbide paper, diamond paste polishing, and steam cleaning. The biaxial flexural strength of the disks (diameter 19 mm, thickness 1.6 mm) and 3-point bend test of the bars (thickness 2 mm, height 2 mm, length 25 mm) were measured dry at room temperature. One-way ANOVA followed by the Tukey HSD test (α=.05) and Pearson correlation test were used for statistical analysis. RESULTS: Airborne-particle abrasion and silicon carbide paper grinding increased the flexural and bend strength of zirconia specimens (P<.05). The 3-point bend test gave 20% to 30% higher strength values than the biaxial test, but a strong correlation was shown between the test types. Surface roughness had a statistically significant negative effect on the strength values in the 3-point bend test. CONCLUSIONS: The surface treatments tested affected the strength and surface roughness of zirconia framework material.
STATEMENT OF PROBLEM: Different surface treatments are commonly used during the fabrication of zirconia fixed dental prostheses. However, such treatments can affect the properties of the zirconia framework material. PURPOSE: The purpose of this in vitro study was to determine the effect of different surface treatments on the surface roughness and flexural and bend strength of zirconia. MATERIAL AND METHODS: Seventy-two zirconia disks (n=8) and 72 zirconia bars (n=8) were sintered and divided into 9 groups for different surface treatments: sintered control, airborne-particle abraded with 50-μm aluminum oxide, airborne-particle abraded with Rocatec soft (30 μm), airborne-particle abraded with Rocatec (105 μm), grinding dry with a micromotor, turbine grinding under water cooling, grinding with silicon carbide paper, diamond paste polishing, and steam cleaning. The biaxial flexural strength of the disks (diameter 19 mm, thickness 1.6 mm) and 3-point bend test of the bars (thickness 2 mm, height 2 mm, length 25 mm) were measured dry at room temperature. One-way ANOVA followed by the Tukey HSD test (α=.05) and Pearson correlation test were used for statistical analysis. RESULTS: Airborne-particle abrasion and silicon carbide paper grinding increased the flexural and bend strength of zirconia specimens (P<.05). The 3-point bend test gave 20% to 30% higher strength values than the biaxial test, but a strong correlation was shown between the test types. Surface roughness had a statistically significant negative effect on the strength values in the 3-point bend test. CONCLUSIONS: The surface treatments tested affected the strength and surface roughness of zirconia framework material.