ABSTRACT
PURPOSE: Torque control in lingual orthodontics is key to obtain optimal esthetic results. The aim of this in vitro experimental study was to verify the efficiency of the ligature-archwire-slot system in torque control using a customized lingual appliance. METHODS: An idealized cast with eight extracted human teeth was created and a set of customized lingual brackets was obtained. Tests were performed with the following wires: 0.016â³â¯× 0.022â³ nickel-titanium (NiTi), 0.016â³â¯× 0.024â³ stainless steel (SS), 0.017â³â¯× 0.025â³ ßIII titanium (ßIIITi), 0.0182â³â¯× 0.0182â³ ßIIITi, 0.018â³â¯× 0.025â³ SS, 0.018â³â¯× 0.025â³ NiTi, 0.018â³â¯× 0.025â³ ßIIITi, and three types of ligatures were tested using a universal testing machine to calculate the efficiency in torque control. A blind statistical analysis was performed. RESULTS: Based on post hoc multiple comparisons, differences were found for two of the three ligatures when using the 0.016â³â¯× 0.022â³ NiTi wires (pâ¯< 0.001 for both ligatures). When considering all ligatures, 0.018â³â¯× 0.025â³ SS and 0.018â³â¯× 0.025â³ ßIIITi were significantly different from all other wires (pâ¯< 0.001 in all cases). With a moment of 5â¯Nmm, the 0.016â³â¯× 0.022â³ NiTi wire developed median angles of 26.7, 29.8, and 38.7° with the three ligatures, respectively, while the 0.018â³â¯× 0.025â³ SS developed median angles of 12.9, 10.7, and 12.7°, respectively. CONCLUSIONS: The ligature type and geometry did not affect the efficiency of torque control, except for the 0.016â³â¯× 0.022â³ NiTi wire. The wires generating the greatest moments were the 0.018â³â¯× 0.025â³ SS and 0.018â³â¯× 0.025â³ ßIIITi.
