A novel magnetic orthodontic bracket system for static magnetic field generation: a finite element analysis

Magnetic forces have the potential to accelerate orthodontic tooth movement. Miniature sized neodymium-iron-boron (Nd-Fe-B) magnets along with biocompatible coating materials are now available enabling a re-evaluation of magnetic usage in orthodontic brackets. The study was done to assess the viability of embedding magnetic material into orthodontic brackets for generating localized static magnetic fields.

An intra-oral scan of a patient with orthodontic brackets was obtained and reconstructed into a three-dimensional dentition model, and exported in STL format. Neodymium-iron-boron (Nd-Fe-B) magnets and soft magnetic iron yokes were designed and positioned on the model. The magnetic elements were placed within the bracket body between the bracket base and archwire slot in an alternating magnet-yoke arrangement, such that one bracket contained only the magnet and the adjacent bracket contained the soft iron yoke. Magnetostatic finite element analysis was performed using Gmsh and GetDP to evaluate magnetic flux density distribution and field propagation.

Finite element simulation displayed creation of localized magnetic field, with a peak magnetic flux density of about 0.72-0.83 Tesla immediately adjacent to the magnetic elements (0.72 T under the primary, locally-oriented magnetization configuration; up to 0.83 T under the supplementary global-axis configuration), decaying by two to three orders of magnitude within a few millimetres; the far-field inter-bracket field values are mesh-sensitive and are therefore reported as provisional.

This study demonstrated the feasibility of establishing a localized static magnetic field around the embedded brackets, with simulated field strength decaying by two to three orders of magnitude within a few millimetres of the bracket surface. This approach may hold potential for influencing biological processes relevant to orthodontic tooth movement. However, its clinical significance requires validation through further clinical studies.