Purpose: to investigate the effect of some ignored clinical variables on the torsional properties of one brand Endodontic file.
n= 25 size no. 10, 15, 20, 25, and 30 stainless steel K file (5 samples per each).
- The torsional testing apparatus was used that it is coupled to an Instron testing machine.
- Torsional strength, reported as maximum torque, and ductility, reported as number of revolutions to failure.
- Strain-Rate Sensitivity (effect of torque on strength and ductility), The effect of hot bead sterilization on torsional strength and ductility, also were examined.
- fracture surfaces were analyzed with a scanning electron microscope (SEM).
Most highlighted Results:
- maximum torque increases with increasing file size.
- No significant difference in clockwise and counterclockwise torsional strength except for size 30.
- Endodontic files twisted in a counterclockwise manner were extremely brittle in comparison to those twisted in a clockwise manner (higher ductility) Fig.1
- Endodontic bead sterilization at 425 F has no apparent effect on torsional strength and ductility
- Endodontic files do not exhibit strain-rate sensitivity
great caution should be exercised when backing off an embedded instrument during the preparation of a root canal.
strengths: relatively comprehensive evaluation.
weakness: small sample