P. Nanavati*, S. Alapati, J. Babcall, B. Johnson University of Illinois at Chicago, Illinois
The objective of this study is to compare cyclic fatigue (CF) life of Edge Taper Platinum IM (ETP) and ProTaper® Gold (PTG) Nickel-Titanium (NiTi) rotary instruments in as-received, after one and three simulated clinical uses.
Materials and Methods: Total of 160 simulated root canals (30° curvature) in clear resin blocs were divided into two groups ETP and PTG. Each file set consist of sizes S1, S2, F1, and F2 files 25 mm length (n=10/size) and randomly selected to prepare either one or three resin blocs under simulated-clinical conditions. Files were subjected to Cyclic Fatigue testing (CF) using a special curved metallic testing fixture (ISO 3630-1) driven by motor (per manufacturer instructions) in continuous motion until the instrument separates. CF was calculated by product of time (seconds) to failure and rotations per minute (RPM). Data analysis was done using ANOVA and Tukey-Kramer (p=<.05).
Results: CF for both instruments tested one-use and three-uses was significantly higher than that of control as-received (p<0.001). ETP instruments had significantly greater number of cycles to failure than PTG instruments in all groups (p<0.001). There was a significant decrease in cyclic fatigue resistance after one-use and three-uses in ETP group. The CF resistance remained consistent in the PTG group. Conclusions: ETP instruments decreased considerably in their cyclic fatigue resistance after use. The fatigue resistance of ETP instruments was higher than that of PTG instruments after one-use and three-uses. Multiple usages of files demonstrated a decrease in efficiency and decrease in fracture resistance from cyclic fatigue.
