title: Bond failure of gingivally offset mandibular premolar brackets: a randomized controlled clinical trial.
abstract: BACKGROUND
  The purpose of this randomized controlled clinical trial was to examine the clinical bond failure rate of gingivally offset mandibular premolar brackets and compare it with that of standard mandibular premolar brackets.
  
  
  METHODS
  Eighty-three patients were enrolled in this trial. A total of 240 brackets--120 standard and 120 offset--were bonded in a split-mouth design.
  
  
  RESULTS
  Ten standard brackets and 1 offset bracket debonded during the trial period. Survival times were analyzed by using the Kaplan-Meier nonparametric test, and comparisons between bracket types were made with the Mantel-Haenszel log rank test. These tests showed that the failure rate between the bracket types was statistically significant (P <0.0058).
  
  
  CONCLUSIONS
  Gingivally offset mandibular premolar brackets have a lower bond failure rate than standard mandibular premolar brackets.
authors.affiliation: Aberdeen Royal Infirmary, Aberdeen, United Kingdom. bikrams.thind@nhs.net
authors.forename: Bikram Singh
authors.initials: BS
authors.lastname: Thind
authors.forename: David R
authors.initials: DR
authors.lastname: Stirrups
authors.forename: Sumithra
authors.initials: S
authors.lastname: Hewage
mesh_terms: D000134:Acid Etching, Dental; D000293:Adolescent; D000328:Adult; D001641:Bicuspid; D004868:Equipment Failure; D000431:Ethanol / Q000737:chemistry; D005260:Female; D005881:Gingiva; D006801:Humans; D055115:Light-Curing of Dental Adhesives; D008297:Male; D008310:Malocclusion / Q000145:classification / Q000628:therapy; D008334:Mandible; D008689:Methacrylates / Q000737:chemistry; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets / Q000145:classification*; D019279:Resin Cements / Q000737:chemistry; D013499:Surface Properties; D016019:Survival Analysis; D055815:Young Adult
chemical_list: D008689:Methacrylates; D019279:Resin Cements; C477790:Transbond XT; C458821:Transbond moisture-insensitive primer; D000431:Ethanol