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The International Journal of Oral & Maxillofacial Implants



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Int J Oral Maxillofac Implants 30 (2015), No. 3     19. May 2015
Int J Oral Maxillofac Implants 30 (2015), No. 3  (19.05.2015)

Page 526-533, doi:10.11607/jomi.3733, PubMed:26009903

Comparison of Design and Torque Measurements of Various Manual Wrenches
Neugebauer, Jörg / Petermöller, Simone / Scheer, Martin / Happe, Arndt / Faber, Franz-Josef / Zoeller, Joachim E.
Purpose: Accurate torque application and determination of the applied torque during surgical and prosthetic treatment is important to reduce complications. A study was performed to determine and compare the accuracy of manual wrenches, which are available in different designs with a large range of preset torques.
Materials and Methods: Thirteen different wrench systems with a variety of preset torques ranging from 10 to 75 Ncm were evaluated. Three different designs were available, with a spring-in-coil or toggle design as an active mechanism or a beam as a passive mechanism, to select the preset torque. To provide a clinically relevant analysis, a total of 1,170 torque measurements in the range of 10 to 45 Ncm were made in vitro using an electronic torque measurement device.
Results: The absolute deviations in Ncm and percent deviations across all wrenches were small, with a mean of -0.24 ± 2.15 Ncm and -0.84% ± 11.72% as a shortfall relative to the preset value. The greatest overage was 8.2 Ncm (82.5%), and the greatest shortfall was 8.47 Ncm (46%). However, extreme values were rare, with 95th-percentile values of -1.5% (lower value) and -0.16% (upper value). A comparison with respect to wrench design revealed significantly higher deviations for coil and toggle-style wrenches than for beam wrenches.
Conclusion: Beam wrenches were associated with a lower risk of rare extreme values thanks to their passive mechanism of achieving the selected preset torque, which minimizes the risk of harming screw connections.

Keywords: complications, dental equipment reliability and validity, immediate dental implant loading, torque