Alternating versus Continuous Rotation: A Comparative Study of the Effect on Instrument Life

Purificación Varela-Patiño, Adalce Ibañez-Párraga, Berta Rivas-Mundiña, Giuseppe Cantatore, Xosé Luis Otero, Benjamin Martin-Biedma

Research output: Contribution to journalArticlepeer-review


Introduction: Rotary nickel-titanium instruments have multiple advantages but with the risk of more fractures because of flexure or torsion. Alternating rotation appears to be an alternative to continuous rotary movement. The objective of this study was to determine the influence of the type of instrument rotation on the frequency of fractures or deformation. Methods: Instrumentation was performed on 120 molar root canals with an angle of curvature greater than 30° using alternating rotation (group A: 60° clockwise, 45° counterclockwise) and continuous rotation (group B). Results: The results indicate that instruments used with alternating rotation have a higher mean number of uses (13.0) compared with the continuous rotation group (10.05); this difference was statistically significant (p <0.05). Conclusions: The ProTaper shaping instruments (S1 and S2) are those that achieved the greatest difference in use with alternating rotation, with S2 being the most resistant to fracture or deformation with the two types of movement used.

Original languageEnglish
Pages (from-to)157-159
Number of pages3
JournalJournal of Endodontics
Issue number1
Publication statusPublished - Jan 2010


  • Alternating rotation
  • continuous rotation
  • fracture
  • nickel-titanium file

ASJC Scopus subject areas

  • Dentistry(all)


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