title: Development of a standardized testing system for orthodontic sliding mechanics.
abstract: BACKGROUND
  The primary objective of this study was to develop a computer-controlled three-dimensional friction measuring system, the orthodontic friction simulator (OFS). A clinically-based in vitro experiment considering wet and dry friction for conventionally and self-ligated brackets is presented to elucidate debate surrounding sliding mechanics and illustrate capabilities of the OFS.
  
  
  METHODS
  The OFS was designed and manufactured using sound engineering principles and with the primary concern of being able to measure all forces and moments generated during sliding mechanics. This required the implementation of a six-axis load cell. A variety of translation and rotation stages were also incorporated to allow for precise positioning of the bracket relative to the archwire. Once designed and built, the OFS was then used to compare conventional and self-ligation methods in both the wet and dry state. Damon Q brackets and 0.018″ × 0.025″ stainless steel wires were used for all tests with a sample size of n = 65 for each ligation method. Archwires were pulled at a speed of 0.1 mm/s in 11 increments of 0.1 mm. At each increment, the bracket would be rotated 0.5° resulting in a total archwire travel of 1.1 mm and a second-order bracket angle range of 0°-5°. A repeated measures ANOVA was conducted to determine if ligation method and/or addition of moisture effected resulting orthodontic loads.
  
  
  RESULTS
  The developed equipment for studying orthodontic sliding mechanics was able to measure forces and moments in all three directions; a capability not previously realized in the literature. Additionally, it was found that passive ligation significantly reduced resistance to sliding, P ≤ 0.05, while the dry/wet state did not.
  
  
  CONCLUSIONS
  The OFS certainly proved to be an adequate instrument for the scientific evaluation of orthodontic sliding mechanics. It is capable of measuring loads generated in all directions and is a fully automated apparatus allowing for simple and repeatable friction tests to be conducted. Furthermore, the addition of saliva was not found to significantly influence the loads generated during sliding mechanics regardless of ligation method.
authors.affiliation: Orthodontic Department, School of Dentistry, University of Alberta, Edmonton, AB, Canada, fathiman@ualberta.ca.
authors.forename: Maryam
authors.initials: M
authors.lastname: Fathimani
authors.forename: Garrett W
authors.initials: GW
authors.lastname: Melenka
authors.forename: Dan L
authors.initials: DL
authors.lastname: Romanyk
authors.forename: Roger W
authors.initials: RW
authors.lastname: Toogood
authors.forename: Giseon
authors.initials: G
authors.lastname: Heo
authors.forename: Jason P
authors.initials: JP
authors.lastname: Carey
authors.forename: Paul W
authors.initials: PW
authors.lastname: Major
mesh_terms: D003198:Computer Simulation; D003199:Computer Systems; D003722:Dental Alloys / Q000737:chemistry; D003890:Desiccation; D004548:Elasticity; D020724:Elastomers / Q000737:chemistry; D017276:Friction; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008422:Materials Testing / Q000295:instrumentation*; D016910:Orthodontic Brackets / Q000592:standards*; D009969:Orthodontic Wires / Q000592:standards*; D012399:Rotation; D013193:Stainless Steel / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D019415:Torque; D014867:Water / Q000737:chemistry
chemical_list: D003722:Dental Alloys; D020724:Elastomers; D014867:Water; D013193:Stainless Steel