OBJECTIVE: To determine the amount of torque expressed by various self-ligating brackets and to evaluate the influence of active clip designs. MATERIALS AND METHODS: Torque moments were measured for nine different bracket types in combination with a 0.019 × 0.025 inch stainless-steel archwire. All active brackets were measured in an open and a closed configuration to evaluate the influence of the self-ligating spring clip. In addition, slot dimensions were optically measured and compared to the torque expression. RESULTS: Moments between 3.1 Nmm and 22.6 Nmm were observed at an angulation of 30° between archwire and slot. The amount of torque contributed by the spring clip of active self-ligating brackets was approximately 1 Nmm; 10 Nmm of torque was achieved with most brackets with a 20°-25° angulation between archwire and slot. The slot dimensions ranged from 0.0222 inch (0.563 mm) to 0.0241 inch (0.613 mm). CONCLUSION: The influence of the ligature or the active or passive self-ligating mechanism is minimal, and slot dimensions are far more important for the transmission of torque. The amount of torque exerted by the active spring clip is approximately 1/10th of the torquing moments recommended in the literature.
OBJECTIVE: To determine the amount of torque expressed by various self-ligating brackets and to evaluate the influence of active clip designs. MATERIALS AND METHODS: Torque moments were measured for nine different bracket types in combination with a 0.019 × 0.025 inch stainless-steel archwire. All active brackets were measured in an open and a closed configuration to evaluate the influence of the self-ligating spring clip. In addition, slot dimensions were optically measured and compared to the torque expression. RESULTS: Moments between 3.1 Nmm and 22.6 Nmm were observed at an angulation of 30° between archwire and slot. The amount of torque contributed by the spring clip of active self-ligating brackets was approximately 1 Nmm; 10 Nmm of torque was achieved with most brackets with a 20°-25° angulation between archwire and slot. The slot dimensions ranged from 0.0222 inch (0.563 mm) to 0.0241 inch (0.613 mm). CONCLUSION: The influence of the ligature or the active or passive self-ligating mechanism is minimal, and slot dimensions are far more important for the transmission of torque. The amount of torque exerted by the active spring clip is approximately 1/10th of the torquing moments recommended in the literature.
Authors: Hisham M Badawi; Roger W Toogood; Jason P R Carey; Giseon Heo; Paul W Major Journal: Am J Orthod Dentofacial Orthop Date: 2008-05 Impact factor: 2.650
Authors: Juliana F Morais; Birte Melsen; Karina M S de Freitas; Nuria Castello Branco; Daniela G Garib; Paolo M Cattaneo Journal: Angle Orthod Date: 2018-06-18 Impact factor: 2.079