Journal of Endodontics
Volume 31, Issue 2 , Pages 120-123, February 2005

Analysis of Torque and Force with Differently Tapered Rotary Endodontic Instruments In Vitro

  • Charlotte Schrader, Dr Med Dent
    • ,
  • Ove A. Peters, PD, Dr Med Dent, MS, FICD

      Affiliations

    • Corresponding Author InformationAddress request for reprints to Dr. Ove Peters, Clinic for Preventive Dentistry, Periodontology and Cariology, Center of Dental and Oral Medicine and Cranio-Maxillofacial Surgery, University of Zürich, Plattenstr. 11, CH-8028 Zurich, Switzerland;

From the Clinic for Preventive Dentistry, Cariology, Periodontology, and Endodontology, University of Zürich, Zürich, Switzerland; and Endodontic Division, Department of Preventive and Restorative Dental Sciences, University of California San Francisco, San Francisco, CA.

Abstract 

The aim of this study was to compare torques and forces developed by two sequences of nickel-titanium rotary instruments, using only .04 taper instruments or a combination of .04 and .06 tapers, respectively. Curved canals in plastic blocks were shaped in a torque-testing device; torque, force, contact areas and numbers of working rotations were determined. Analysis of variance and Pearson correlation coefficients were used to compare the two sequences. Mean torque ranged from 0.2 ± 0.03 to 3.19 ± 0.28 Ncm and was higher for instrument sizes 25 to 45 in group A. Mean vertical forces ranged from 1.49 ± 0.54 to 12.0 ± 3.5 N; there were significant correlations between torque and force as well as between torque and contact areas. Numbers of rotations were lower in the combined .04 and .06 sequence. An instrumentation sequence encompassing various tapers seems to be safer regarding torsional and fatigue failure compared to a sequence that used one single taper. However, the former sequence requires the use of more instruments.

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PII: S0099-2399(05)60035-0

doi:10.1097/01.don.0000137634.20499.1d

Journal of Endodontics
Volume 31, Issue 2 , Pages 120-123, February 2005

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