| 0425 Flexural Strength of Zirconia Frameworks Fatigued Under Simulated Oral Conditions | ||
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J.E. EVERTS, J. MENG, and D.G. GRATTON, University of Iowa, Iowa City, USA Objectives: Limited data exists regarding the stress corrosion properties of yttrium tetragonal zirconia polycrystalline (Y-TZP) fixed partial denture frameworks. This study evaluated the stress corrosion properties of Y-TZP frameworks, fabricated using KaVo EverestŪ CAD/CAM technology, cyclically loaded under simulated oral conditions. Methods: Fifteen cylindrical frameworks (24x3.15x3.15mm) were milled from partially sintered zirconium oxide, then fully sintered at 1100°C for 9 hrs and randomly assigned to one of three groups. A 3-point bend test (20mm between supports, load applied in center) was used to fatigue and determine flexural strength of the frameworks. The control group was statically loaded to fracture in a dry environment, a second group was cyclically fatigued and then loaded to failure in a dry environment (cycled-dry), the third group was cyclically fatigued and then brought to failure immersed in artificial saliva (cycled-wet). Cyclic load was applied to each framework with a universal loading machine; load magnitude varied from 10-350N for 106 cycles at 15Hz, using a sinusoidal duty cycle. Results: The mean flexural strengths (MPa) were: control 796.1+/-59.73, cycled-dry 800.7+/-26.83, and cycled-wet 687.4+/-31.7. One-way ANOVA provided evidence of significant interaction among the groups (p=0.0015). The mean flexural strength of cycled-wet group was significantly less than mean flexural strength of both the control and cycled-dry groups. No significant difference was found between the control and the cycled-dry groups (Tukey's Multiple Comparison Test, p<0.01). Conclusions: Cyclical loading of Y-TZP-ZrO2 milled and sintered bars in artifical saliva resulted in a 14% reduction in the flexural strength over a simulated 1 year life cycle, suggesting that Y-TZP based fixed partial denture frameworks are susceptible to stress corrosion. Supported by KaVo America and the University of Iowa, College of Dentistry. | ||
| Seq #77 - Ceramics and FRC in Fixed Prosthodontics 2:00 PM-4:00 PM, Thursday, 10 March 2005 Baltimore Convention Center Exhibit Hall E-F | ||
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