The aim of this study was to analyze stress distribution and displacement of the maxilla and teeth according to different designs of bone-borne palatal expanders using micro-implants. A three-dimensional (3D) finite-element (FE) model of the craniofacial bones and maxillary teeth was obtained. Four designs of rapid maxillary expanders: one with micro-implants placed lateral to mid-palatal suture (type 1), the second at the palatal slope (type 2), the third as in type 1 with additional conventional Hyrax arms (type 3), and the fourth surgically assisted tooth-borne expander (type 4) were added to the FE models. Expanders were activated transversely for 0.25mm. Geometric nonlinear theory was applied to evaluate Von-Mises Stress distribution and displacement. All types exhibited downward displacement and demonstrated more horizontal movement in the posterior area. Type 3 showed the most transverse displacement. The rotational movement of dentoalveolar unit was larger in types 1 and 3, whereas it was relatively parallel in types 2 and 4. The stresses were concentrated around the micro-implants in types 1 and 3 only. Type 2 had the least stress concentrations around the anchorage and showed alveolar expansion without buccal inclination. It is recommended to apply temporary anchorage devices to the palatal slopes to support expanders for efficient treatment of maxillary transverse deficiency.

The palate has been reported to be a suitable skeletal anchorage site in adolescents and adults. This article introduces new treatment modalities for correction of sagittal discrepancies by molar protraction and distalization with a modified palatal anchorage plate appliance. The effectiveness and versatility of this method are demonstrated in 2 adolescent patients.

This article presents a non-extraction orthodontic treatment case using mini-screws and a modified palatal anchorage plate (MPAP) to intrude the maxillary posterior teeth, and distalize the whole arch dentition and control the extrusion of the maxillary posterior dentition during distalization.