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Topographic Analysis of HyFlex(®) Controlled Memory Nickel-Titanium Files
1Associate Professor, Department of Restorative Dental Sciences, Division of Endodontics, College of Dentistry, King Saud University, Riyadh, Saudi Arabia.
Journal of International Oral Health : JIOH
|January 29, 2015
Summary
HyFlex CM rotary instruments show unwinding and curving defects after use, but most regain their original shape after autoclaving. Smaller file sizes are more prone to deformation and less likely to recover fully.
Area of Science:
- Endodontics
- Dental Materials Science
- Biomaterials Engineering
Background:
- HyFlex controlled memory (CM) rotary instruments are designed for multiple uses post-sterilization.
- Assessing surface defects and shape recovery after autoclaving is crucial for instrument safety and efficacy.
Purpose of the Study:
- To analyze surface defects on HyFlex CM instruments after clinical use.
- To evaluate the ability of these instruments to return to their original shape following autoclaving.
Main Methods:
- Micro-computed tomography was used to scan 24 new HyFlex files before use, after visible defect formation, and post-autoclaving.
- Surface analysis identified and categorized defects such as unwinding and curving.
- Superimposition of scans assessed shape recovery, with data analyzed using Chi-square and t-tests.
Main Results:
- All used files exhibited unwinding (100%), with some showing curving defects.
- Defect incidence, particularly curving, was significantly dependent on file size, with smaller files (#20/0.04, #20/0.06) showing higher rates.
- 79% of files successfully restored their original shape after autoclaving, though smaller files had a higher rate of incomplete recovery.
Conclusions:
- HyFlex CM nickel-titanium rotary instruments demonstrate a significant capacity to regain their original shape after sterilization.
- While most files recover, smaller sizes may exhibit persistent deformation, necessitating careful consideration during clinical application.
