Biomechanical evaluation of an orthodontic miniimplant used with revolving (translation and rotation) temporary anchorage device by finite element analysis and experimental testing

PURPOSE: To evaluate the biomechanical interactions of a miniimplant using a temporary anchorage device (TAD) for orthodontic traction. MATERIALS AND METHODS: A miniimplant was designed with dual thread (DT) with a TAD that can be connected optionally onto the miniimplant with 60-degree switching unit and an extended arm for tying orthodontic wire. Finite element analysis was used to calculate the relative miniimplant displacement and bone strain under immediate load (500 gW) on behalf of the maximum lateral force during orthodontic treatment. The TAD removal forces were measured by pullout testing. RESULTS: Simulated results showed that the maximum von Mises bone strain concentrated at the cervical regions around the miniimplant. The corresponding strain value in DT miniimplant assembled with TAD was greater than those for DT and single-thread implants with 2.24 and 1.73 times, respectively. Small relative miniimplant displacement (<20 μm) was found in all cases. The TAD removal force remained larger than 2 times the finger-pulling force (9.3 N) after 5 repeated removal tests. CONCLUSION: The DT miniimplant connected with TAD can provide translation and rotation features to change the angles and directions of orthodontic tractions for most effective anchorage preparation.