|0093 Dynamic Fatigue Testing of Titanium Dental Implants|
D.A. RUNYAN, United States Army Dental Research Detachment, Great Lakes, IL, USA, and G.A. THOMPSON, United States Army Dental Research Detachment, Great Lakes, IL, USA|
Objectives: Titanium implants have demonstrated fatigue failure when subjected to cyclic, low stress loading during the chewing cycle. Under normal loading conditions, fatigue cracks initiate near singularities and mechanical strength decreases. Growth of fatigue cracks at low cyclic stresses ultimately leads to failure. Fatigue testing can be extremely time consuming. Loading a titanium dental implant at 2Hz to 5,000,000 cycles takes 29 days. Accelerating the cycling rate to 15Hz shortens each test to 4 days. However, decreasing the testing time also decreases the exposure time of the fatigue crack tip to the aqueous environment. The purpose of this study is to measure effects of increased cycling speed on the fatigue strength of titanium dental implants in different environments. Methods: Titanium dental implants were tested at 2Hz and 15Hz in air, 37 deg C distilled water and 37 deg C 0.85% sodium chloride. 5,000,000 cycles was considered a successful test. Results: Fatigue strength when measured at 2Hz in air was 225 N, in water 225 N and in sodium chloride 225 N. There was no statistically significant difference in fatigue strength of titanium dental implants in aqueous environments when tested at 2Hz. When tested at 15Hz the fatigue strengths were 275 N in air, 300 N in water and 300 N in sodium chloride. There was a statistically significant increase in fatigue strength of titanium dental implants in aqueous environments when tested at 15Hz. There was a statistically significant increase in fatigue strength in all environments when tested at 15 Hz when compared to 2Hz. Conclusions: The increase in fatigue strength at 15Hz in aqueous environments could be a result of increased heat dissipation overcoming the corrosive effects at the crack tips. This would also indicate the 2Hz fatigue test more accurately duplicates the fatigue characteristics of the oral environment.
|Seq #17 - Mechanical Implant Studies|
2:00 PM-4:00 PM, Wednesday, 10 March 2004 Hawaii Convention Center 327