Evaluation of the Hybrid Rapid Maxillary Expander Assisted With Micro-osteo Perforation (MOPs) in Adults: A Prospective Clinical Study

Transverse maxillary deficiencies are common orthodontic issues observed by professionals. It is estimated that 9.4% of adult orthodontic patients have a transverse maxillary deficiency in combination with a posterior cross bite. A normal transverse skeletal relationship between basal bones is fundamental to achieving a satisfactory and stable occlusion.

Therefore, to correct a maxillary transverse deficiency, palatal expanders are needed. Since Haas popularized this technique in the early 1960s, rapid palatal expanders are the most popular devices of choice, characterized by safety, predictability and efficiency.

The rapid process of activation reduces dental movements (side effects) thus enabling skeletal expansion. Surprisingly, only 30% of the expander opening seems to result in suture opening, whereas one-third reflects alveolar bending and another 30% dental movement.

During activations of traditional tooth-borne rapid palatal expansion devices, heavy transverse forces are generated in a short period of time, causing disruption of the inter sutural tissue thus producing midpalatal suture opening.

On many occasions, these expansion forces in-vivo are in the range of 75-120 N, measured at the level of the hyrax screw of the connecting stainless-steel wire arms at the buccal crowns. In vitro skeletal hybrid expanders, before plastic deformation, demonstrated expansion force values from 67 ± 13 N to 183 ± 48 N when tested on the mini-implant's reinforced bone-anchored wire arms .With these forces, the opening of the palatal suture in adolescents or young adults can be frequently unsuccessful.