IADR Abstract Archives
NiTi Rotary Files: Cyclic Fatigue and the Impact of Sterilization
Objectives: Nickel-titanium (NiTi) endodontic instruments have increased file fracture resistance. The cost of these files leads many clinicians to sterilize and reuse them. Whether sterilization impacts file cyclic fatigue resistance was tested in this study. We also measured changes in cross-sectional flute sharpness before and after autoclaving.
Methods: New EdgeGlidePath, WaveOne Gold Glider, ProGlider, and TruNatomy files (n=3/group) were tested. 360° surface scans were made of each file before and after five sterilization cycles (5 minutes, 270°F, 30 min. dry). Cross-sectional area was visualized 3mm from the tip. Repeated measure radius-of-curvature was performed on the flutes. ANOVA tested for significant between-group differences in radius-of-curvature before-after autoclaving. Cyclic fatigue testing was performed with cylinder-radii of 5mm and 7.5mm using manufacturer recommended-settings. Cycles-to-failure were compared with ANOVA and post-hoc Tukey (α=0.05).
Results: ANOVA shows significant effects of group (brand) on the change in radius-of-curvature before-after sterilization (p=0.048). Subsequent DTK test showed this was driven by TruNatomy files, which had larger radius-of-curvature after autoclaving (α<0.05). Within-group variance was high for all samples, indicating the radius-of-curvature did not change uniformly across flutes.
Cyclic fatigue testing with a cylinder-radii of 5mm revealed significantly greater resistance to cyclic fatigue with WaveOne Gold Glider files compared to ProGlider and TruNatomy files (p<0.01). The EdgeGlide Path files demonstrated greater resistance to cyclic fatigue than TruNatomy (p<0.01) and ProGlider (p<0.01) files with both 5mm and 7.5mm cylinder-radii. Testing with 7.5mm resulted in significant differences between WaveOne and ProGlider files (p<0.01).
Conclusions: EdgeGlidePath and WaveOne Gold Glider files had significantly greater resistance to cyclic fatigue compared to the other files tested. This characteristic can enhance the predictability of endodontic therapy. Sterilization can cause surface changes to file shape, which may affect the function of these files after repeated sterilization cycles.
Methods: New EdgeGlidePath, WaveOne Gold Glider, ProGlider, and TruNatomy files (n=3/group) were tested. 360° surface scans were made of each file before and after five sterilization cycles (5 minutes, 270°F, 30 min. dry). Cross-sectional area was visualized 3mm from the tip. Repeated measure radius-of-curvature was performed on the flutes. ANOVA tested for significant between-group differences in radius-of-curvature before-after autoclaving. Cyclic fatigue testing was performed with cylinder-radii of 5mm and 7.5mm using manufacturer recommended-settings. Cycles-to-failure were compared with ANOVA and post-hoc Tukey (α=0.05).
Results: ANOVA shows significant effects of group (brand) on the change in radius-of-curvature before-after sterilization (p=0.048). Subsequent DTK test showed this was driven by TruNatomy files, which had larger radius-of-curvature after autoclaving (α<0.05). Within-group variance was high for all samples, indicating the radius-of-curvature did not change uniformly across flutes.
Cyclic fatigue testing with a cylinder-radii of 5mm revealed significantly greater resistance to cyclic fatigue with WaveOne Gold Glider files compared to ProGlider and TruNatomy files (p<0.01). The EdgeGlide Path files demonstrated greater resistance to cyclic fatigue than TruNatomy (p<0.01) and ProGlider (p<0.01) files with both 5mm and 7.5mm cylinder-radii. Testing with 7.5mm resulted in significant differences between WaveOne and ProGlider files (p<0.01).
Conclusions: EdgeGlidePath and WaveOne Gold Glider files had significantly greater resistance to cyclic fatigue compared to the other files tested. This characteristic can enhance the predictability of endodontic therapy. Sterilization can cause surface changes to file shape, which may affect the function of these files after repeated sterilization cycles.
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