title: Comparison of frictional resistance between self-ligating and conventional brackets tied with elastomeric and metal ligature in orthodontic archwires.
abstract: OBJECTIVE
  To compare the frictional resistance between self-ligating and conventional brackets tied to different types of wire.
  
  
  METHODS
  Abzil Kirium Capelozza (Pattern I) and Easy Clip (Roth prescription) incisor brackets were used. An elastomeric ligature or a 0.10-in ligating wire was used to ligate the wire to the Abzil bracket. Three types of orthodontic archwire alloys were assessed: 0.016-in NiTi wire, 0.016 x 0.021-in NiTi wire and 0.019 x 0.025-in steel wire. Ten observations were carried out for each bracket-archwire angulation combination. Brackets were mounted in a special appliance, positioned at 90 degrees in relation to the wire and tested in two angulations. Frictional test was performed in a Universal Testing Machine at 5 mm/min and 10 mm of displacement. The means (MPa) were submitted to ANOVA and Tukey's test set at 5% of significance. The surfaces of wires and brackets were observed at SEM.
  
  
  RESULTS
  Steel-tied brackets (16.48 ± 8.31) showed higher means of frictional resistance than elastomeric-tied brackets (4.29 ± 2.16 ) and self-ligating brackets (1.66 ± 1.57) (P < 0.05), which also differed from each other (P < 0.05). As for the type of wire, 0.019 x 0.025-in steel wire (5.67 ± 3.97) showed lower means (P < 0.05) than 0.16-in NiTi wire (8.26 ± 10.92) and 0.016 x 0.021-in NiTi wire (8.51 ± 7.95), which did not differ from each other (P > 0.05). No statistical differences (P > 0.05) were found between zero (7.76 ± 8.46) and five-degree (7.19 ± 7.93) angulations.
  
  
  CONCLUSIONS
  Friction was influenced not only by the type of bracket, but also by the ligating systems. Different morphological aspects were observed for the brackets and wires studied.
authors.forename: Vanessa Vieira
authors.initials: VV
authors.lastname: Leite
authors.forename: Murilo Baena
authors.initials: MB
authors.lastname: Lopes
authors.forename: Alcides
authors.initials: A
authors.lastname: Gonini Júnior
authors.forename: Marcio Rodrigues de
authors.initials: MR
authors.lastname: Almeida
authors.forename: Sandra Kiss
authors.initials: SK
authors.lastname: Moura
authors.forename: Renato Rodrigues de
authors.initials: RR
authors.lastname: Almeida
mesh_terms: D000497:Alloys / Q000737:chemistry; D003722:Dental Alloys / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D020724:Elastomers / Q000737:chemistry*; D017276:Friction; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D009532:Nickel / Q000737:chemistry; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D013193:Stainless Steel / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry
chemical_list: D000497:Alloys; D003722:Dental Alloys; D003764:Dental Materials; D020724:Elastomers; C040654:titanium nickelide; D013193:Stainless Steel; C013616:nitinol; D009532:Nickel; D014025:Titanium
keywords: Dental brackets; Friction; Self-ligating; Wires