Purpose:
To compare torsional properties of conventionally twisted k-files to machined k-files.
Materials/Methods:
- n=280 files
- file sizes #10-40 were subjected to torsional load in clockwise and counterclockwise directions independently
- inspected with a microscope at 30x before and after failure
Results:
- Rotation at failure in a CW and CCW direction was significantly greater for the twisted files than machined files. Thus, Machined files exhibited less ductility than twisted files.
- In a CCW direction, twisted files showed a decrease in rotation at failure with increasing file size, while the machined files had the same rotation at failure for all file sizes.
- Both machined and twisted files exhibited significantly greater rotation at failure in CW than CCW torsion.
- There was no difference in torsional strength between the twisted and machined files.
- Machined files showed less visible deformation prior to failure than the twisted files in both rotation directions.
Clinical Significance:
Machined files exhibit less ductility vs. twisted files and may be more susceptible to torsional failure clinically.