Methods: A 3-dimensional mesh model of the cranium with associated maxillary sutures was developed using CT images and Mimics modeling software. To compare transverse expansion stresses in RPE and MiRPE, expansion forces were distributed to differing points on the maxilla and evaluated with ANSYS simulation software.
Results: The stresses distributed from forces applied to the maxillary teeth are distributed mainly along the trajectories of the three maxillary buttresses. In comparison, the MiRPE showed tension and compression directed to the palate, while showing less rotation, and tipping of the maxillary complex. In addition, the conventional hyrax displayed a rotation of the maxilla around the teeth as opposed to the midpalatal suture of the MiRPE. This data suggests that the MiRPE causes the maxilla to bend laterally, while preventing unwanted rotation of the complex.
Conclusions: The MiRPE may be beneficial for hyperdivergent patients, or those that have already experienced closure of the midpalatal suture, who require palatal expansion and would worsen from buccal tipping of the teeth or maxillary complex.
Keywords: Bone, Finite analysis, Mini Implant, Orthodontics and Stress