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The Effects of Torsional Preloading on the Torsional Resistance of Nickel-titanium Instruments
- Source :
- Journal of Endodontics. 43:157-162
- Publication Year :
- 2017
- Publisher :
- Elsevier BV, 2017.
-
Abstract
- This study evaluated the effect of torsional preloading on the torsional resistance of nickel-titanium (NiTi) endodontic instruments.WaveOne Primary (Dentsply Maillefer, Ballaigues, Switzerland) and ProTaper Universal F2 (Dentsply Maillefer) files were used. The ultimate torsional strength until fracture was determined for each instrument. In the phase 1 experiment, the ProTaper and WaveOne files were loaded to have a maximum load from 2.0 up to 2.7 or 2.8 Ncm, respectively. In the phase 2 experiment, the number of repetitions of preloading for each file was increased from 50 to 200, whereas the preloading torque was fixed at 2.4 Ncm. Using torsionally preloaded specimens from phase 1 and 2, the torsional resistances were calculated to determine the ultimate strength, distortion angle, and toughness. The results were analyzed using 1-way analysis of variance and Duncan post hoc comparison. The fracture surfaces and longitudinal aspect of 5 specimens per group were examined under a scanning electron microscope.All preloaded groups showed significantly higher ultimate strength than the unpreloaded groups (P .05). There was no significant difference among all groups for distortion angle and toughness. Although WaveOne had no significant difference between the repetition groups for ultimate strength, fracture angle, and toughness, ProTaper had a higher distortion angle and toughness in the 50-repetition group compared with the other repetition groups (P .05). Scanning electron microscopic examinations of the fractured surface showed typical features of torsional fracture.Torsional preloading within the ultimate values could enhance the torsional strength of NiTi instruments. The total energy until fracture was maintained constantly, regardless of the alloy type.
- Subjects :
- Dental Instruments
Toughness
Materials science
Post hoc
Scanning electron microscope
Torsion, Mechanical
02 engineering and technology
Endodontics
03 medical and health sciences
0302 clinical medicine
Nickel
Ultimate tensile strength
otorhinolaryngologic diseases
Forensic engineering
Humans
Composite material
Total energy
General Dentistry
Titanium
Torsional strength
030206 dentistry
musculoskeletal system
021001 nanoscience & nanotechnology
Equipment Failure Analysis
Nickel titanium
Microscopy, Electron, Scanning
Fracture (geology)
Equipment Failure
0210 nano-technology
Subjects
Details
- ISSN :
- 00992399
- Volume :
- 43
- Database :
- OpenAIRE
- Journal :
- Journal of Endodontics
- Accession number :
- edsair.doi.dedup.....a209fe04699ffc78a7f17ec9e56413e6