title: Comparison of design and torque measurements of various manual wrenches.
abstract: OBJECTIVE
  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.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.forename: Jörg
authors.initials: J
authors.lastname: Neugebauer
authors.forename: Simone
authors.initials: S
authors.lastname: Petermöller
authors.forename: Martin
authors.initials: M
authors.lastname: Scheer
authors.forename: Arndt
authors.initials: A
authors.lastname: Happe
authors.forename: Franz-Josef
authors.initials: FJ
authors.lastname: Faber
authors.forename: Joachim E
authors.initials: JE
authors.lastname: Zoeller
mesh_terms: D003758:Dental Implantation, Endosseous / Q000295:instrumentation*; D003762:Dental Instruments; D004867:Equipment Design; D012016:Reference Values; D019415:Torque