The Leveling Effectiveness of Self-ligating and Conventional Brackets for Complex Tooth Malalignments

Abstract

The transfer of forces and moments between the bracket and archwire is decisive in the multi-band/bracket technique. New developments in bracket design and ligation method aim to optimize the transfer of forces and moments and improve leveling effectiveness. We thus aimed in this study to investigate whether leveling behavior is influenced by different bracket systems, or by the ligation method. The baseline situation for this examination was a complex tooth malalignment. Using the orthodontic measurement and simulation system (OMSS), we tested the leveling effectiveness of nine self-ligating bracket systems made by various manufacturers (Forestadent-Quick, in active and passive variants, Dentsply GAC In-Ovation, adenta TIME, Ormco Damon 2 and Damon 3MX, UP-Dental Opal-M and Opal-2, Strite SPEED) in the 0.022 inch slot system. A conventional bracket system (Dentaurum discovery) was used for reference purposes. We also used a multistranded steel archwire (Ormco Tripleflex, 0.44 mm round) and four nickel-titanium archwires of various diameters (Forestadent BioStarter 0.30 mm round, BioStarter 0.40 mm round, Titanol Low Force 0.40 x 0.40 mm(2) and Titanol Low Force 0.40 x 0.56 mm(2)). The leveling task consisted of correcting a complex malalignment (infraocclusion and vestibular displacement, each of 2 mm) of tooth 21. We analyzed the forces and torque movements that arose during the leveling phase. The test of the ten bracket systems revealed no significant difference in terms of their leveling effectiveness. Both selfligating brackets and conventional brackets behaved similarly, and we observed roughly 80% of the infraocclusions to have been corrected. Vestibular displacement was corrected with all the bracket systems by as much as 100% or even more due to a developing torque movement. The influence of wire material and wire diameter became apparent in relation to existing forces durconvening the leveling stage; those factors' influence was clearly greater than that of the ligation method. This study's results demonstrate that bracket selection has a negligible influence on leveling effectiveness. Although self-ligating brackets are easier for the orthodontist to manipulate and provide patients with esthetic and wearing comfort advantages, they are not superior to conventional brackets in terms of their biomechanical characteristics.