title: Effect of simulated debracketing on enamel damage.
abstract: OBJECTIVE
  A smooth enamel surface after the removal of a bracket from a tooth is essential for both esthetic demands and the prevention of plaque accumulation. The purpose of this study was to evaluate enamel damage caused by three standardized debracketing techniques.
  
  
  METHODS
  We established three standardized test devices based on the principles of the squeezing, shearing, and tensile testing methods, which were simulated using a How Plier (TASK 60-306), a Direct Bond Bracket Remover (TASK 60-335 T), and a Lift-Off Debracketing Instrument (3 M-Unitek 444-761), respectively. Thirty teeth in each group were evaluated after debracketing. An optical stereomicroscope and a CCD camera with a computerized image analysis system were used to ascertain the proportion of remnant adhesive area (RAE) on the enamel surface. Fractography was analyzed using a scanning electron microscope.
  
  
  RESULTS
  The squeezing debracketing method exhibited the highest debonding force (54.3 ± 7.0 N) and the least damage to the enamel surface (RAE = 99.5% ± 2.4%). The tensile debracketing method preserved most of the adhesive on the enamel surface (RAE = 98.7% ± 3.3%) and required the least debonding force (6.8 ± 1.2 N). However, the shearing debracketing method exhibited a significantly higher debonding force (32.0 ± 8.2 N) and smaller RAE (77.3% ± 33.5%) compared to the tensile debracketing method (p < 0.05). Three specimens appeared to have vertical fractures on their enamel prisms when using the shearing method.
  
  
  CONCLUSIONS
  With the proposed method, we conclude that the squeezing and tensile methods are acceptable for clinical use when debracketing, whereas the Direct Bond Bracket Remover may cause shearing failure, leading to a risk for enamel damage.
authors.affiliation: Department of Orthodontics, School of Dentistry, National Taiwan University and National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Ming-Zen
authors.initials: MZ
authors.lastname: Su
authors.forename: Eddie Hsiang-Hua
authors.initials: EH
authors.lastname: Lai
authors.forename: Jenny Zwei-Chieng
authors.initials: JZ
authors.lastname: Chang
authors.forename: Hong-Jiun
authors.initials: HJ
authors.lastname: Chen
authors.forename: Frank Hsin-Fu
authors.initials: FH
authors.lastname: Chang
authors.forename: Yu-Chih
authors.initials: YC
authors.lastname: Chiang
authors.forename: Chun-Pin
authors.initials: CP
authors.lastname: Lin
mesh_terms: D003738:Dental Cements / Q000009:adverse effects; D017005:Dental Debonding / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods*; D003743:Dental Enamel / Q000293:injuries*; D006801:Humans; D008855:Microscopy, Electron, Scanning; D016910:Orthodontic Brackets
chemical_list: D003738:Dental Cements