title: Study of force loss due to friction comparing two ceramic brackets during sliding tooth movement.
abstract: OBJECTIVE
  To compare the percentage of force loss generated during canine sliding movements in newly introduced ceramic brackets with metal brackets.
  
  
  METHODS
  Two types of ceramic brackets, namely polycrystalline alumina (PCA) ceramic brackets (Clarity Advanced) and monocrystalline alumina (MCA) ceramic brackets (Inspire Ice) were compared with stainless steel (SS) brackets (Victory Series). All bracket groups (n = 5 each) were for the maxillary canines and had a 0.018-inch slot size. The brackets were mounted on an Orthodontic Measurement and Simulation System (OMSS) to simulate the canine retraction movement into the first premolar extraction space. Using elastic ligatures, 0.016 × 0.022″ (0.40 × 0.56 mm) stainless steel archwires were ligated onto the brackets. Retraction force was applied via a nickel-titanium coil spring with a nearly constant force of approximately 1 N. The OMSS measured the percentage of force loss over the retraction path by referring to the difference between the applied retraction force and actual force acting on each bracket. Between group comparisons were done with one-way analysis of variance.
  
  
  RESULTS
  The metal brackets revealed the lowest percentage of force loss due to friction, followed by the PCA and MCA ceramic bracket groups (67 ± 4, 68 ± 7, and 76 ± 3 %, respectively). There was no significant difference between SS and PCA brackets (p = 0.97), but we did observe significant differences between metal and MCA brackets (p = 0.03) and between PCA and MCA ceramic brackets (p = 0.04).
  
  
  CONCLUSIONS
  PCA ceramic brackets, whose slot surface is covered with an yttria-stabilized zirconia-based coating exhibited frictional properties similar to those of metal brackets. Frictional resistance resulted in an over 60 % loss of the applied force due to the use of elastic ligatures.
authors.affiliation: Department of Pediatric Dentistry and Orthodontics, College of Dentistry, King Saud University, Riyadh, Saudi Arabia.
authors.forename: Mai
authors.initials: M
authors.lastname: AlSubaie
authors.affiliation: Department of Pediatric Dentistry and Orthodontics, College of Dentistry, King Saud University, Riyadh, Saudi Arabia.
authors.forename: Nabeel
authors.initials: N
authors.lastname: Talic
authors.affiliation: Endowed Chair of Oral Technology, School of Dentistry, University of Bonn, Welschnonnenstr 17, 53111, Bonn, Germany.
authors.forename: Said
authors.initials: S
authors.lastname: Khawatmi
authors.affiliation: Endowed Chair of Oral Technology, School of Dentistry, University of Bonn, Welschnonnenstr 17, 53111, Bonn, Germany.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Alobeid
authors.affiliation: Endowed Chair of Oral Technology, School of Dentistry, University of Bonn, Welschnonnenstr 17, 53111, Bonn, Germany. bourauel@uni-bonn.de.
authors.forename: Christoph
authors.initials: C
authors.lastname: Bourauel
authors.affiliation: Department of Orthodontics, School of Dentistry, University of Alberta, Edmonton, Canada.
authors.forename: Tarek
authors.initials: T
authors.lastname: El-Bialy
mesh_terms: D002516:Ceramics / Q000737:chemistry*; D003481:Cuspid / Q000502:physiology*; D003764:Dental Materials / Q000737:chemistry; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis / Q000379:methods*; D019544:Equipment Failure Analysis; D017276:Friction; D006801:Humans; D066298:In Vitro Techniques; D009038:Motion; D016910:Orthodontic Brackets; D013314:Stress, Mechanical; D014086:Tooth Mobility / Q000503:physiopathology*; D014087:Tooth Movement Techniques / Q000379:methods*
chemical_list: D003764:Dental Materials
keywords: Arch-guided tooth movement; Ceramic brackets; Force loss; Friction