title: The effect of 3 torque delivery systems on gold screw preload at the gold cylinder-abutment screw joint.
abstract: OBJECTIVE
  This study measured the gold screw preload at the gold cylinder-abutment screw joint interface obtained by 3 torque delivery systems.
  
  
  METHODS
  Using a precalibrated, strain-gauged standard abutment as the load cell, 3 torque delivery systems tested were shown to have significant differences in gold screw preload when a gold cylinder was attached.
  
  
  RESULTS
  Mean preloads measured were 291.2 N for hand torque drivers set at 10 Ncm, 340.3 N for electronic torque controllers at low setting/10 Ncm, 384.4 N for electronic torque controllers at high setting/10 Ncm; and 140.8 N for hand-tightening with a prosthetic slot screwdriver. Significant differences in screw preload were also found between operators using a hand torque driver.
  
  
  CONCLUSIONS
  Hand-tightening delivered insufficient preload and cannot be recommended for final gold screw tightening. Different electronic torque controller units set at 10 Ncm induced mean gold screw preloads that ranged from 264.1 N to as high as 501.2 N.
  
  
  CONCLUSIONS
  Electronic torque controllers should be regularly recalibrated to ensure optimal output.
authors.affiliation: Department of Restorative Dentistry, Faculty of Dentistry, National University of Singapore, Republic of Singapore. rsdtanbc@nus.edu.sg
authors.forename: Keson B
authors.initials: KB
authors.lastname: Tan
authors.forename: Jack I
authors.initials: JI
authors.lastname: Nicholls
mesh_terms: D000704:Analysis of Variance; D002138:Calibration; D000044:Dental Abutments; D017267:Dental Prosthesis Design / Q000295:instrumentation*; D017268:Dental Prosthesis Retention / Q000295:instrumentation*; D019094:Dental Prosthesis, Implant-Supported; D003799:Dental Stress Analysis; D006047:Gold Alloys; D018737:Hand Strength; D006801:Humans; D003765:Models, Dental; D018709:Statistics, Nonparametric; D019415:Torque
chemical_list: D006047:Gold Alloys