title: Friction behavior of ceramic injection-molded (CIM) brackets.
abstract: OBJECTIVE
  Bracket material, bracket design, archwire material, and ligature type are critical modifiers of friction behavior during archwire-guided movement of teeth. We designed this in vitro study to compare the friction losses of ceramic injection-molded (CIM) versus pressed-ceramic (PC) and metal injection-molded (MIM) brackets-used with different ligatures and archwires-during archwire-guided retraction of a canine.
  
  
  METHODS
  Nine bracket systems were compared, including five CIM (Clarity™ and Clarity™ ADVANCED, both by 3M Unitek; discovery(®) pearl by Dentaurum; Glam by Forestadent; InVu by TP Orthodontics), two PC (Inspire Ice by Ormco; Mystique by DENTSPLY GAC), and two MIM (discovery(®) and discovery(®) smart, both by Dentaurum) systems. All of these were combined with archwires made of either stainless steel or fiberglass-reinforced resin (remanium(®) ideal arch or Translucent pearl ideal arch, both by Dentaurum) and with elastic ligatures or uncoated or coated stainless steel (all by Dentaurum). Archwire-guided retraction of a canine was simulated with a force of 0.5 N in the orthodontic measurement and simulation system (OMSS). Friction loss was determined by subtracting the effective orthodontic forces from the applied forces. Based on five repeated measurements performed on five brackets each, weighted means were calculated and evaluated by analysis of variance and a Bonferroni post hoc test with a significance level of 0.05.
  
  
  RESULTS
  Friction losses were significantly (p < 0.05) higher (58-79 versus 20-30 %) for the combinations involving the steel versus the resin archwire in conjunction with the elastic ligature. The uncoated steel ligatures were associated with the lowest friction losses with Clarity™ (13 %) and discovery(®) pearl (16 %) on the resin archwire and the highest friction losses with Clarity™ ADVANCED (53 %) and Mystique (63 %) on the steel archwire. The coated steel ligatures were associated with friction losses similar to the uncoated steel ligatures on the steel archwire. Regardless of ligature types, mild signs of abrasion were noted on the resin archwire.
  
  
  CONCLUSIONS
  The lowest friction losses were measured with rounded ceramic brackets used with a stainless-steel ligature and the resin archwire. No critical difference to friction behavior was apparent between the various manufacturing technologies behind the bracket systems.
authors.affiliation: Endowed Chair for Oral Technology, Rheinische Friedrich-Wilhelms-University of Bonn, Welschnonnenstrasse 17, 53111, Bonn, Germany. susanne.reimann@uni-bonn.de.
authors.forename: Susanne
authors.initials: S
authors.lastname: Reimann
authors.affiliation: Endowed Chair for Oral Technology, Rheinische Friedrich-Wilhelms-University of Bonn, Welschnonnenstrasse 17, 53111, Bonn, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Bourauel
authors.affiliation: Endowed Chair for Oral Technology, Rheinische Friedrich-Wilhelms-University of Bonn, Welschnonnenstrasse 17, 53111, Bonn, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Weber
authors.affiliation: Endowed Chair for Oral Technology, Rheinische Friedrich-Wilhelms-University of Bonn, Welschnonnenstrasse 17, 53111, Bonn, Germany.
authors.forename: Cornelius
authors.initials: C
authors.lastname: Dirk
authors.affiliation: , Neulingen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Lietz
mesh_terms: D002516:Ceramics / Q000737:chemistry*; D003481:Cuspid / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis / Q000379:methods*; D019544:Equipment Failure Analysis; D017276:Friction; D006801:Humans; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D011312:Pressure; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D003764:Dental Materials
keywords: Archwires; CIM brackets; Ceramic brackets; Friction behavior; In vitro techniques