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[Thermoelastic analysis of nickel-titanium endodontic files]
E Rapisarda1, T R Tripi, A Bonaccorso
1Università degli Studi-Catania.
Minerva Stomatologica
|January 6, 2010
Summary
Repeated use and sterilization of nickel-titanium endodontic instruments alter their elastic properties. Mechanical stress and autoclave sterilization significantly modify the modulus of elasticity in these vital dental tools.
Area of Science:
- Materials Science
- Biomaterials Engineering
- Endodontics
Background:
- Innovative nickel-titanium (NiTi) endodontic instruments utilize superelastic alloys with reduced elastic moduli.
- Repeated use, mechanical stress, and thermal treatments can significantly alter the elastic properties of NiTi alloys.
- Understanding these property variations is crucial for maintaining instrument performance in challenging root canal anatomies.
Purpose of the Study:
- To investigate the impact of repeated thermomechanical cycles on NiTi alloy properties.
- To analyze the influence of mechanical and thermal stress on martensitic transformation temperatures and deformation recovery.
- To evaluate changes in the internal structure of NiTi alloy after thermomechanical cycling.
Main Methods:
- Thirty ProFile Maillefer NiTi instruments were divided into five groups.
- Groups were subjected to varying conditions: 14 autoclave sterilization cycles, single sterilization cycle, control (new), and clinical use on endodontic simulators (240s and 480s).
- All samples were analyzed using a dynamic mechanical thermal analysis (DMTA).
Main Results:
- Endodontic instruments subjected to simulated clinical use showed modified elastic behavior compared to controls.
- Instrument elasticity decreased proportionally with the number of simulated uses.
- Instruments undergoing 14 sterilization cycles exhibited altered dynamic analysis curves and responses to thermodynamic stress compared to new instruments.
Conclusions:
- Both repeated mechanical stress (simulated use) and autoclave sterilization significantly alter the modulus of elasticity in NiTi endodontic instruments.
- The observed modifications in elastic behavior indicate a degradation of material properties with use and sterilization.
- Instrument taper did not significantly influence the experimental results regarding elastic behavior.
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