Fracture resistance of commonly used self-drilling orthodontic mini-implants
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© 2015 by The EH Angle Education and Research Foundation, Inc. Objective: To investigate the fracture resistance of six commonly used self-drilling orthodontic mini-implants by comparing their respective fracture torques during insertion. Materials and Methods: Ninety self-drilling mini-implants from six manufacturers (Aarhus, Dual Top, OrthoEasy, Tomas-pin, Unitek, and VectorTAS), with diameters ranging from 1.4 to 1.8 mm, were inserted into acrylic blocks using a custom-made insertion device. Insertion torques were measured using a 6-degree-of-freedom load cell fixed to the base of the acrylic blocks, and peak torques experienced at the time of fracture for each of the mini-implants were recorded. One-way analysis of variance (a 5 .05) was used to compare the fracture torques among the six different groups. Results: Statistical analysis revealed significant differences (P < .05) in the peak fracture torques among mini-implant groups. Mean fracture torques ranked as follows: Unitek (72 Ncm) . Tomaspin (36 Ncm) . Dual-Top (32 Ncm) < VectorTAS (31 Ncm) . OrthoEasy (28 Ncm) . Aarhus (25 Ncm), with significant differences found between all manufacturers, except for Dual-Top and VectorTAS. Conclusions: Mini-implants tested showed a wide range of torque at fracture depending on the manufacturer, with only a weak correlation between mini-implant diameter and fracture resistance. This torque should be considered at the time of mini-implant insertion to minimize the risk of implant fracture, especially in areas of high-density bone without predrilling.