Suitability of orthodontic brackets for rebonding and reworking following removal by air pressure pulses and conventional debracketing techniques

Aim: 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. Method: 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 (MonoLok2; 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 (Corona Flex; 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 Corona Flex 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). Conclusion: With regard to bracket reusability, the SC and the BRP cannot be recommended for debonding brackets, especially in combination with a composite adhesive. (Angle Orthod. 2010;80:649-655.)