title: Influence of interbracket distances on the resistance to sliding of orthodontic appliances.
abstract: BACKGROUND
  The influence of interbracket distance (IBD) on the resistance to sliding (RS) was evaluated.
  
  
  METHODS
  Commercially pure titanium brackets (CP-Ti; 0.018- and 0.022-in slots, width = 0.14-in) were tested against 0.016 x 0.022-in rectangular stainless steel (SS), nickel titanium (Ni-Ti), and beta-titanium (beta-Ti) archwires in the dry and wet (human saliva) states. With a custom testing apparatus that simulated a 3-bracket system, the RS was measured at a normal force of 300 cN and at second-order angles (theta) ranging from -9 degrees to +9 degrees. Twenty-three pairs of IBDs (written as IBD1_IBD2) were varied to simulate clinically relevant biomechanical scenarios with IBD ranging from 16 to 7 mm.
  
  
  RESULTS
  In the dry state, the kinetic frictional coefficients (micro(k)) were equal to 0.12, 0.23, and 0.24 for the SS, Ni-Ti, and beta-Ti archwires against the CP-Ti brackets, respectively. The presence of saliva slightly increased micro(k). The RS was inversely proportional to the total IBD (IBD(T) = IBD1 + IBD2) regardless of archwire alloy or bracket slot. Elastic binding (BI = RS - frictional force in the passive region) did not depend on the order of the IBDs in the IBD1_IBD2 pair.
  
  
  CONCLUSIONS
  For a specific archwire-bracket couple, the BI of an IBD1_IBD2 pair is equal to any other pair with an equal IBD(T). Although no significant difference was found between the coefficients of binding (micro(BI)) for SS and beta-Ti archwires, the micro(BI)'s of Ni-Ti archwires were lower and significantly different. The micro(BI) was linearly related (P<.01) to IBD(T) and total archwire beam length (L(T)).
authors.affiliation: Dental Research Center, School of Dentistry, University of North Carolina, Chapel Hill, NC 27599-7455, USA.
authors.forename: John Q
authors.initials: JQ
authors.lastname: Whitley
authors.forename: Robert P
authors.initials: RP
authors.lastname: Kusy
mesh_terms: D003722:Dental Alloys; D003799:Dental Stress Analysis / Q000706:statistics & numerical data; D004548:Elasticity; D017276:Friction; D006801:Humans; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D019516:Orthodontic Space Closure / Q000295:instrumentation; D009969:Orthodontic Wires; D012044:Regression Analysis; D013193:Stainless Steel; D014025:Titanium