title: Analysis of the characteristics of slot design affecting resistance to sliding during active archwire configurations.
abstract: BACKGROUND
  During orthodontic treatment, a low resistance to slide (RS) is desirable when sliding mechanics are used. Many studies showed that several variables affect the RS at the bracket-wire interface; among these, the design of the bracket slot has not been deeply investigated yet. This study aimed to clarify the effect of different slot designs on the RS expressed by five types of low-friction brackets in vertical and horizontal active configurations of the wire.
  
  
  METHODS
  Five low-friction brackets (Damon SL II, Ormco, Orange, CA, USA; In-Ovation, GAC International, Bohemia, NY, USA; Quick, Forestadent, Pforzheim, Germany; Time 2, AO, Sheboygan, WI, USA; Synergy, RMO, Denver, CO, USA) coupled with an 0.014-in NiTi thermal wire (Therma-Lite, AO) were tested in two three-bracket experimental models simulating vertical and horizontal bracket displacements. A custom-made machine was used to measure frictional resistance with tests repeated on ten occasions for each bracket-wire combination. Design characteristics such as the mesio-distal slot width, slot depth, and presence of chamfered edges at the extremities of the slot were evaluated on SEM images (SUPRA, Carl Zeiss, Oberkochen, Germany) and analyzed in relation to the data of RS recorded.
  
  
  RESULTS
  Time 2 was found to show the higher frictional forces (1.50 and 1.35 N) in both experimental models (p<0.05), while Quick and Synergy brackets showed the lower frictional values in the vertical (0.66 N) and in the horizontal (0.68 N) bracket displacements, respectively. With vertically displaced brackets, the increased mesio-distal slot width and the presence of clear angle at mesial and distal slot edges increase the values of RS. With brackets horizontally displaced, the RS expressed by the wire is influenced simultaneously by the depth of the slot, the mesio-distal slot width, and the presence of clear angle at the extremities of the slot base, the clip, or the slide.
  
  
  CONCLUSIONS
  In order to select the proper low-friction bracket system, clinicians should consider specific characteristics of slot design apart from the wire engaging method.
authors: Riccardo
authors: R
authors: Nucera
authors: Department of Scienze Sperimentali Medico-Chirurgiche ed Odontostomatologiche, Section of Orthodontics and TMJ Disorder, University of Messina, Via Consolare Valeria, Messina, 98123, Italy. nino.logiudice@gmail.com.
authors: Antonino
authors: A
authors: Lo Giudice
authors: Giovanni
authors: G
authors: Matarese
authors: Alessandro
authors: A
authors: Artemisia
authors: Ennio
authors: E
authors: Bramanti
authors: Paolo
authors: P
authors: Crupi
authors: Giancarlo
authors: G
authors: Cordasco
mesh_terms: D003722:Dental Alloys / Q000737:chemistry; D017276:Friction; D006801:Humans; D008422:Materials Testing; D055595:Mechanical Phenomena; D008855:Microscopy, Electron, Scanning; D009532:Nickel / Q000737:chemistry; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets / Q000145:classification; D009969:Orthodontic Wires; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium