Torque efficiency of a customized lingual appliance

PurposeTorque control in lingual orthodontics is key to obtain optimal esthetic results. The aim of this in vitro experi-mental study was to verify the efficiency of the ligature–archwire–slot system in torque control using a customized lingualappliance.MethodsAn idealized cast with eight extracted human teeth was created and a set of customized lingual brackets wasobtained. Tests were performed with the following wires: 0.01600× 0.02200nickel-titanium (NiTi), 0.01600× 0.02400stainlesssteel (SS), 0.01700× 0.02500βIII titanium (βIIITi), 0.018200× 0.018200βIIITi, 0.01800× 0.02500SS, 0.01800× 0.02500NiTi,0.01800× 0.02500βIIITi, and three types of ligatures were tested using auniversal testing machine to calculate the efficiencyin torque control. A blind statistical analysis was performed.ResultsBased on post hoc multiple comparisons, differenceswere found for two of the three ligatures when usingthe 0.01600× 0.02200NiTi wires (p< 0.001 for both ligatures). When considering all ligatures, 0.01800× 0.02500SS and0.01800× 0.02500βIIITi were significantly different from all other wires (p< 0.001 in all cases). With a moment of 5Nmm,the 0.01600× 0.02200NiTi wire developed median angles of 26.7, 29.8, and 38.7° with the three ligatures, respectively, whilethe 0.01800× 0.02500SS developed median angles of 12.9, 10.7, and 12.7°, respectively.ConclusionsThe ligature type and geometry did not affect the efficiency of torque control, except for the 0.01600× 0.02200NiTi wire. The wires generating the greatest moments were the 0.01800× 0.02500SS and 0.01800× 0.02500βIIITi