Suitability of orthodontic brackets for rebonding and reworking following removal by air pressure pulses and conventional debracketing techniques.
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.
Knösel
Michael
M
Department of Orthodontics, Georg-August-University, Göttingen, Germany. mknoesel@yahoo.de
Mattysek
Simone
S
Jung
Klaus
K
Kubein-Meesenburg
Dietmar
D
Sadat-Khonsari
Reza
R
Ziebolz
Dirk
D
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
D005899:Glass Ionomer Cements; D019279:Resin Cements