title: The effect of repeated torque and salivary contamination on the preload of slotted gold implant prosthetic screws.
abstract: BACKGROUND
  Screw loosening and/or fracture is common and has been attributed to many factors, including improper torque and preload. Purpose. This study evaluated the effect of repeated preload torque and salivary contamination on the preload of the slotted gold implant prosthetic screw.
  
  
  METHODS
  Fifteen slotted gold prosthetic screws were tested in an unused stack of components consisting of an implant, an abutment cylinder, and a screw and gold cylinder. A custom load frame and load cell and associated electronics were used. The component stack was lubricated with human saliva. Each screw was tightened to 10 Ncm with a hand-held torque wrench fitted with strain gauge electronics and then removed 10 times. Preload values at the first (Group 1X), fifth (Group 5X), and tenth (Group 10X) repetition were measured. Repeated-measures 1-way analysis of variance (P<.05) and paired comparisons were used to analyze the data.
  
  
  RESULTS
  The mean preload value increased from Group 1X (184.3 N +/- 28.9) to Group 5X (202.5 N +/- 27.7) to Group 10X (220.2 N +/- 29.0). The differences among these groups were significant (P=.004).
  
  
  CONCLUSIONS
  Within the limitations of this study, higher preload was achieved after the repeated use of a saliva-lubricated gold prosthetic retaining screw.
authors.affiliation: School of Dentistry and College of Engineering, Marquette University, Milwaukee, WI 53201, USA.
authors.forename: George K
authors.initials: GK
authors.lastname: Tzenakis
authors.forename: William W
authors.initials: WW
authors.lastname: Nagy
authors.forename: Raymond A
authors.initials: RA
authors.lastname: Fournelle
authors.forename: Virendra B
authors.initials: VB
authors.lastname: Dhuru
mesh_terms: D000704:Analysis of Variance; D000044:Dental Abutments; D015921:Dental Implants; D017268:Dental Prosthesis Retention / Q000295:instrumentation*; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D017276:Friction; D006047:Gold Alloys; D006801:Humans; D008153:Lubrication; D011897:Random Allocation; D012463:Saliva; D018709:Statistics, Nonparametric; D013718:Tensile Strength; D019415:Torque
chemical_list: D015921:Dental Implants; D006047:Gold Alloys