title: Frictional resistance in monocrystalline ceramic brackets with conventional and nonconventional elastomeric ligatures.
abstract: BACKGROUND
  The objective of this study was to compare the frictional forces generated by three types of monocrystalline ceramic brackets coupled with conventional elastomeric ligatures (CEL) and nonconventional elastomeric ligatures (NCEL) during the alignment of apically displaced teeth at the maxillary arch.
  
  
  METHODS
  All tests (a total of 480 tests) were carried out in a dry state on a universal testing machine with a testing model consisting of three 0.022-in. monocrystalline ceramic preadjusted brackets (from the maxillary right second premolar through the right central incisor). The canine bracket was bonded to a sliding bar that allowed for different vertical positions. The frictional forces generated by a 0.012- and 0.014-in. superelastic nickel titanium wire (SENT) with conventional and nonconventional ligatures at various amounts of canine misalignment (1.5, 3.0, 4.5, and 6.0 mm) were recorded. Comparisons between the different types of bracket-wire-ligature systems were carried out by means of analysis of variance on ranks with Tukey's post hoc test (P<0.05).
  
  
  RESULTS
  No significant differences were assessed among the three types of monocrystalline brackets with NCEL when coupled with 0.012-in. SENT. Radiance brackets with NCEL coupled with 0.014-in. SENT showed significantly greater frictional force than Inspire Ice brackets and Pure brackets with NCEL. A significantly greater amount of frictional force was generated with CEL when compared with NCEL for all the tested variables, with the exception of the Pure brackets with 0.012-in. SENT at 1.5 and 3.0 mm of canine misalignment where similar frictional forces were found.
  
  
  CONCLUSIONS
  Nonconventional elastomeric ligatures are able to reduce friction in monocrystalline ceramic brackets.
authors: Department of Orthodontic, University of Florence, Via Ponte di Mezzo 46/48, Florence, 50100, Italy. matteo_camporesi@yahoo.it.
authors: Mariana Bulhoes
authors: MB
authors: Galvão
authors: Matteo
authors: M
authors: Camporesi
authors: André
authors: A
authors: Tortamano
authors: Gladys Cristina
authors: GC
authors: Dominguez
authors: Efisio
authors: E
authors: Defraia
mesh_terms: D001641:Bicuspid / Q000473:pathology; D002516:Ceramics / Q000737:chemistry*; D003460:Crystallization; D003481:Cuspid / Q000473:pathology; D003722:Dental Alloys / Q000737:chemistry; D003799:Dental Stress Analysis / Q000295:instrumentation; D020724:Elastomers / Q000737:chemistry*; D017276:Friction; D006801:Humans; D007180:Incisor / Q000473:pathology; D008422:Materials Testing; D009532:Nickel / Q000737:chemistry; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D013314:Stress, Mechanical; D014025:Titanium / Q000737:chemistry; D014087:Tooth Movement Techniques / Q000295:instrumentation
chemical_list: D003722:Dental Alloys; D020724:Elastomers; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium