Background: It has been suggested that the small bonding pads and prominent profiles of self-ligating brackets may lead to high failure rates when compared with conventional edgewise brackets.
Aims: To compare the bond failure rates of a self-ligating bracket (Speed, Strite Industries, Cambridge, Canada) and a twin edgewise bracket (Mini-Diamond, Ormco, Orange, CA, U.S.A.) bonded with different adhesives (Sequence, Ormco, Orange, CA, U.S.A.; Transbond XT, 3M Unitek, Monrovia, CA, U.S.A.); to compare the bond failure rates of a self-ligating bracket bonded with different adhesives (Enlight, Ormco, Orange, CA, U.S.A.; Lightbond, Reliance, Itasca, IL, U.S.A.); and to compare the bond failure rates of molar attachments (Speed, Strite Industries, Cambridge, Canada) using different adhesives (Enlight, Ormco, Orange, CA, U.S.A.; Lightbond, Reliance, Itasca, IL, U.S.A.; Sequence, Ormco, Orange, CA, U.S.A.; Transbond XT, 3M Unitek, Monrovia, CA, USA).
Methods: This retrospective study covered 17 years. Study A (1991-99): Speed and Mini-Diamond brackets were bonded in both arches with either Sequence (Group 1) or Transbond-XT (Group 2) adhesives and the number of bond failures compared. Study B (2000-07): Speed brackets were bonded with either Lightbond (Group 3) or Enlight (Group 4) adhesives and the total number of bond failures (first-time and re-failures) compared. In Study C (1991-2007) Speed upper molar mini-brackets, upper molar tubes or ER brackets were used in the upper arch, and Speed lower buccal tubes were used in the lower arch. The failure rates of the molar attachments were compared.
Results: In Study A the failure rates with Sequence adhesive were: Speed 7.3 per cent, Mini-Diamond 11.9 per cent (p = 0.05). With Transbond XT adhesive the failure rates were: Speed 5.9 per cent, Mini-Diamond 6.4 per cent (p > 0.05). The teeth with the highest failure rates (central incisors and second premolars) were similar for both appliances. In Study B the failure rates were: Group 3 (Speed/Lightbond) 4.2 per cent; Group 4 (Speed/Enlight) 6.9 per cent; Group 3 vs Group 4, p = 0.05. In Study C the failure rate of Speed upper molar mini-brackets was markedly higher than the failure rates of the molar tubes.
Conclusions: The failure rates of the Speed brackets reduced over time, possibly because of improvements in the adhesives. The small bonding pads and prominent profiles of Speed brackets did not result in high failure rates.