title: The effect of aging on the accuracy of new friction-style mechanical torque limiting devices for dental implants.
abstract: OBJECTIVE
  High variability in delivering the target torque is reported for friction-style mechanical torque limiting devices (F-S MTLDs). The effect of aging (number of use) on the accuracy of these devices is not clear. The purpose of this study was to assess the effect of aging on the accuracy (±10% of the target torque) of F-S MTLDs.
  
  
  METHODS
  Fifteen new F-S MTLDs and their appropriate drivers from three different implant manufacturers (Astra Tech, Biohorizon and Dr Idhe), five for each type, were selected. The procedure of peak torque measurement was performed in ten sequences before and after aging. In each sequence, ten repetitions of peak torque values were registered for the aging procedure. To measure the output of each device, a Tohnichi torque gauge was used.
  
  
  RESULTS
  Before aging, peak torque measurements of all the devices tested in this study falled within 10% of their preset target values. After aging, a significant difference was seen between raw error values of three groups of MTLDs (P<0.05). More than 50% of all peak torque measurements demonstrated more than 10% difference from their torque values after aging.
  
  
  CONCLUSIONS
  Within the limitation of this study, aging as an independent factor affects the accuracy of F-S MTLDs. Astra Tech MTLDs presented the most consistent torque output for 25 Ncm target torque.
authors.affiliation: Dental Research Center, Research Institute of Dental Sciences of Shahid Beheshti University of Medical Sciences, Tehran, Iran ; Associate Professor, Department of Prosthodontics, Dental School, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Aboulfazl
authors.initials: A
authors.lastname: Saboury
authors.forename: Seyed Jalil
authors.initials: SJ
authors.lastname: Sadr
authors.forename: Ali
authors.initials: A
authors.lastname: Fayaz
authors.forename: Minoo
authors.initials: M
authors.lastname: Mahshid
keywords: Aging; Dental Implants; Torque