Effect of different ligation methods of orthodontic brackets on frictional resistance during sliding mechanics: in vitro study

Document Type : Original Article

Authors

1 Orthodontics Department, Faculty of Dentistry, Suez Canal University.

2 Orthodontic Department, Faculty of Dentistry, Suez Canal University.

3 Orthodontics, Faculty of Dentistry, Suez Canal University.

Abstract

Many factors can contribute to the frictional resistance of edgewise appliances including brackets, wire materials , cross-section and surface conditions of the archwires, torque at the wire-bracket interface, inter bracket distance, functions of the oral environment , type and force of ligation. The aim was to evaluate and compare the frictional resistance (static and dynamic) of different ligation methods during sliding mechanics. Methods: Fifty canine brackets of three types; conventional (4 wings), Synergy (6 wings) and passive self ligating brackets system [SLBs]. Different ligation techniques (conventional elastomeric [CEL], unconventional elastomeric ligatures [UEL] and stainless steel ligatures [SS]) were used in a simulation for canine retraction in a curved path using 0.017X0.025" NiTi wire. Frictional resistance of the bracket/wire/ligation combinations was measured using experimental model mounted on a universal testing machine with 5KN load cell. Each sample was tested 10 consecutive times in dry state. Results: Large frictional forces were found for wires secured with SS ligatures and CEL in standard (4 wings) brackets. Conventional elastomeric ligatures tied on the  middle wings only of the Synergy (6 wings) brackets or the use of SLBs produced the lowest frictional forces. Unconventional elastomeric ligatures as well reduced frictional forces to a significant level in comparison with conventional brackets with SS or CEL. Conclusion: large variations in frictional forces were noticed when archwires were ligated in different bracket designs as well as when similar brackets and different ligation techniques were used. Unconventional elastomeric ligatures can be considered a valid alternative for low friction biomechanics.

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