ORIGINAL ARTICLE https://doi.org/10.1007/s00056-019-00190-w J Orofac Orthop Torque efficiency of a customized lingual appliance Performance of wires with three different ligature systems Marco Migliorati 1 · Daniela Poggio 1 · Sara Drago 1 · Alberto Lagazzo 2 · Roberto Stradi 3 · Fabrizio Barberis 2 · Armando Silvestrini-Biavati 1 Received: 31 July 2018 / Accepted: 2 July 2019 © Springer Medizin Verlag GmbH, ein Teil von Springer Nature 2019 Abstract Purpose Torque 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 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: 0.016 00 × 0.022 00 nickel-titanium (NiTi), 0.016 00 × 0.024 00 stainless steel (SS), 0.017 00 × 0.025 00 βIII titanium (βIIITi), 0.0182 00 × 0.0182 00 βIIITi, 0.018 00 × 0.025 00 SS, 0.018 00 × 0.025 00 NiTi, 0.018 00 × 0.025 00 βIIITi, 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 0.016 00 × 0.022 00 NiTi wires (p < 0.001 for both ligatures). When considering all ligatures, 0.018 00 × 0.025 00 SS and 0.018 00 × 0.025 00 βIIITi were significantly different from all other wires (p < 0.001 in all cases). With a moment of 5Nmm, the 0.016 00 × 0.022 00 NiTi wire developed median angles of 26.7, 29.8, and 38.7° with the three ligatures, respectively, while the 0.018 00 × 0.025 00 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 0.016 00 × 0.022 00 NiTi wire. The wires generating the greatest moments were the 0.018 00 × 0.025 00 SS and 0.018 00 × 0.025 00 βIIITi. Keywords Lingual orthodontics · Orthodontic brackets · Mechanical properties · Torque control · Esthetics Marco Migliorati, DDS, MS, PhD marco.migliorati@gmail.com Daniela Poggio, DDS dada.poggio@gmail.com  Sara Drago, MSc, DDS sara.drago.laffi@gmail.com Alberto Lagazzo, MSc, PhD alberto.lagazzo@unige.it Roberto Stradi, MD, DDS roberto.stradi@tin.it Fabrizio Barberis, MSc, PhD fabrizio.barberis@unige.it Armando Silvestrini-Biavati, MD, DDS armando.silvestrini@tin.it 1 Orthodontics Department, School of Dentistry, University of Genova, largo Rosanna Benzi 10, 16132 Genova, Italy 2 Section of Materials Engineering, Department of Civil, Chemical and Environmental Engineering (DICCA), University of Genova, via Opera Pia 15, 16145 Genova, Italy 3 School of Orthodontics and Temporomandibular Disorders, University of Naples Federico II, Via Pansini 5, 80131 Naples, Italy K