title: Evaluation of esthetic brackets' resistance to torsional forces from the archwire.
abstract: BACKGROUND
  The aim of this study was to evaluate the resistance to deformation or fracture of esthetic brackets produced by archwire torsion.
  
  
  METHODS
  Six types of maxillary right central incisor brackets were analyzed: traditional ceramic brackets (cer); ceramic brackets reinforced with a stainless steel slot (cer/ss); ceramic brackets reinforced with a gold slot (cer/gold); traditional polycarbonate brackets (poly); polycarbonate brackets reinforced with a stainless steel slot (poly/ss); and polycarbonate brackets reinforced with ceramic fillers and a stainless steel slot (poly/cer/ss). Stainless steel wire segments were used, and the testing instrument (Emic DL 10000, São José do Rio Preto, PR, Brazil) was moved at a rate of 1 inch per minute to generate the wire torsion.
  
  
  RESULTS
  The brackets showed deformation or fracture resistance values (gf x mm) in decreasing order as follows: cer/ss (3528.1 +/- 516.6), cer/gold (2858.7 +/- 611.6), cer (2424.0 +/- 352.1), poly/cer/ss (2279.5 +/- 174.5), poly/ss (2142.0 +/- 275.7), and poly (1463.6 +/- 193.3). The cer/ss ceramic brackets showed the greatest statistically significant (P <0.01) values of resistance to fracture, and the poly brackets had the lowest statistically significant (P <0.01) values of resistance to deformation. The cer brackets showed no significant differences (P >0.01) from the cer/gold, the poly/cer/ss, and the poly/ss brackets.
  
  
  CONCLUSIONS
  This suggested that the stainless steel slot might enhance resistance to deformation or fracture, although gold slots and ceramic fillers are ineffective for reinforcing esthetic brackets.
authors.affiliation: Department of Orthodontics, Universidade do Estado do Rio de Janeiro, Brazil. nishiocla@gmail.com
authors.forename: Clarice
authors.initials: C
authors.lastname: Nishio
authors.forename: Alvaro de Moraes
authors.initials: Ade M
authors.lastname: Mendes
authors.forename: Marco Antonio de Oliveira
authors.initials: MA
authors.lastname: Almeida
authors.forename: Eiji
authors.initials: E
authors.lastname: Tanaka
authors.forename: Kazuo
authors.initials: K
authors.lastname: Tanne
authors.forename: Carlos Nelson
authors.initials: CN
authors.lastname: Elias
mesh_terms: D002516:Ceramics / Q000737:chemistry; D003722:Dental Alloys / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry; D004868:Equipment Failure; D004955:Esthetics, Dental; D006047:Gold Alloys / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D011076:Polycarboxylate Cement / Q000737:chemistry; D013193:Stainless Steel / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D054159:Torsion, Mechanical
chemical_list: D003722:Dental Alloys; D003764:Dental Materials; D006047:Gold Alloys; D011076:Polycarboxylate Cement; D013193:Stainless Steel; C005506:polycarbonate