title: Suitability of orthodontic brackets for rebonding and reworking following removal by air pressure pulses and conventional debracketing techniques.
abstract: OBJECTIVE
  To test the null hypothesis that there are no significant differences in the reusability of debonded brackets with regard to debonding technique and adhesive used.
  
  
  METHODS
  Ninety-six osteotomed third molars were randomly assigned to two study groups (n = 48) for bonding of a 0.018-inch bracket (Ormesh, Ormco) with either a composite adhesive (Mono-Lok2; RMO) or a glass ionomer cement (GIC; Fuji Ortho LC;GC). Each of these two groups were then randomly divided into four subgroups (n = 12) according to the method of debonding using (1) bracket removal pliers (BRP; Dentaurum), (2) a side cutter (SC; Dentaurum), (3) a lift-off debracketing instrument (LODI; 3M-Unitek), or (4) an air pressure pulse device (CoronaFlex; KaVo). The brackets were subsequently assessed visually for reusability and reworkability with 2x magnification and by pull testing with a 0.017- x 0.025-inch steel archwire. The proportions of reusable brackets were individually compared in terms of mode of removal and with regard to adhesives using the Fisher exact test (alpha = 5%).
  
  
  RESULTS
  The null hypothesis was rejected. Not taking into account the debonding method, brackets bonded with GIC were judged to a significant extent (81%; n = 39; P < .01) to be reworkable compared with those bonded with composite (56%; n = 27). All brackets in both adhesive groups removed with either the LODI or the CoronaFlex were found to be reusable, whereas 79% (46%) of the brackets removed with the BRP (SC) were not. The proportion of reusable brackets differed significantly between modes of removal (P < .01).
  
  
  CONCLUSIONS
  With regard to bracket reusability, the SC and the BRP cannot be recommended for debonding brackets, especially in combination with a composite adhesive.
authors.affiliation: Department of Orthodontics, Georg-August-University, Göttingen, Germany. mknoesel@yahoo.de
authors.forename: Michael
authors.initials: M
authors.lastname: Knösel
authors.forename: Simone
authors.initials: S
authors.lastname: Mattysek
authors.forename: Klaus
authors.initials: K
authors.lastname: Jung
authors.forename: Dietmar
authors.initials: D
authors.lastname: Kubein-Meesenburg
authors.forename: Reza
authors.initials: R
authors.lastname: Sadat-Khonsari
authors.forename: Dirk
authors.initials: D
authors.lastname: Ziebolz
mesh_terms: D000399:Air Pressure; D002484:Cementation / Q000379:methods; D017005:Dental Debonding / Q000295:instrumentation / Q000379:methods*; D003799:Dental Stress Analysis; D017743:Equipment Reuse; D005899:Glass Ionomer Cements; D006801:Humans; D008964:Molar, Third; D016910:Orthodontic Brackets; D019279:Resin Cements
chemical_list: D005899:Glass Ionomer Cements; D019279:Resin Cements