Evaluation of the Hybrid Rapid Maxillary Expander Assisted With Micro-osteo Perforation (MOPs) in Adult.

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.

Therefore, conventional expanders, under high loads, deform prematurely or create excessive molar tipping or mucosa soreness before

reaching midpalatal suture opening. If these expansion forces are not able to open the suture, surgically assisted rapid palatal expansion (SARPE) is suggested.

In addition, scientific papers do not provide information of the amount of force at the level of the midpalatal suture and the limit of plastic deformation. Solely anchored on orthodontic mini-implants (OMIs) and placed in the anterior-middle palate. These bone anchored expanders seem to improve the aforementioned drawbacks and provide greater expansion forces to facilitate midpalatal suture opening even in adult patients so as to avoid SARPE.

Major areas of resistance to hybrid rapid maxillary expansion are mid palatine suture and the pterygomaxillary articulation. With increasing the age, the interdigitation at sutures increases making the site more rigid. The concept of regional acceleratory phenomenon (RAP) can be used for such clinical challenges by using mild surgical trauma induced by Micro-osteo perforation (MOPs) to produce localized inflammation with the mid palatine suture being the only sight easily accessible for intervention, minimally invasive procedures like Micro-osteo perforation (MOPs) can be used to disrupt the mid palatine suture to make it more pliable to expansion forces.

Micro-osteo perforation (MOPs) along the mid palatal suture which will induce rapid acceleratory phenomenon which would accelerate the bone turnover and reduce the regional bone density leading to transient osteopenia and thus bringing out changes in the transverse dimension.

Cone beam computed tomography (CBCT) allows better imaging at low radiation dosages and presents a clear view of bony structures, tooth position, and type of palatal suture fusion with minimal image distortion. Although hybrid rapid maxillary expansion and minimally

invasive surgical techniques are often used in orthodontic clinical practice, only a few studies have been published in the literature on large groups of patients that present possible complications that may occur after practicing this method of orthodontic treatment.