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Alternating versus continuous rotation: a comparative study of the effect on instrument life
Purificación Varela-Patiño1, Adalce Ibañez-Párraga, Berta Rivas-Mundiña
1Department of Operative Dentistry and Endodontics, School of Dentistry, University of Santiago de Compostela, Santiago de Compostela, Spain. puri.varela@usc.es
Journal of Endodontics
|December 17, 2009
Summary
Alternating rotation of nickel-titanium endodontic instruments significantly increases their lifespan and resistance to fracture compared to continuous rotation. This method enhances the durability of ProTaper shaping instruments, particularly S2, reducing procedural risks.
Area of Science:
- Endodontics
- Dental Materials Science
- Biomaterials Engineering
Background:
- Rotary nickel-titanium instruments offer advantages in endodontic procedures but are susceptible to fracture from flexure or torsion.
- Alternating rotation presents a potential alternative to continuous rotary motion to mitigate these risks.
Purpose of the Study:
- To investigate the impact of alternating versus continuous rotation on the fracture and deformation frequency of endodontic instruments.
- To compare the durability and lifespan of nickel-titanium instruments under different rotational modes.
Main Methods:
- 120 molar root canals with curvatures exceeding 30 degrees were instrumented.
- Instrumentation was performed using either alternating rotation (60° clockwise, 45° counterclockwise) or continuous rotation.
Main Results:
- Instruments utilized with alternating rotation demonstrated a statistically significant higher mean number of uses (13.0) compared to those in continuous rotation (10.05).
- ProTaper shaping instruments (S1 and S2) showed the most significant improvement in use with alternating rotation.
Conclusions:
- Alternating rotation enhances the cyclic fatigue resistance and lifespan of nickel-titanium endodontic instruments.
- The S2 ProTaper shaping instrument exhibited superior resistance to fracture and deformation irrespective of the rotation type used.
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