Evaluation of the effects of surgically assisted and two different types of micro-implant supported rapid maxillary expansion devices by finite element analysis

Aim: There is a need for micro-implant supported rapid maxillary expansion (MARPE) studies, which can be an alternative to surgical-assisted rapid maxillary expansion (SARME) methods, and will reduce invasive procedures in adults. The aim of the study is to evaluate the effects of SARME and two different types of MARPE appliances on the nasomaxillary complex in a finite element adult skull model with finite element analysis. Methods: In this study, 34-year-old individual finite element skull model was created by accepting the craniofacial sutures as closed. Surgically assisted tooth-supported (4- and 6-band) conventional hyrax appliance (Type A), tooth-supported (6-band) monocortical screw-located MARPE appliance (Type B), and tooth-supported (6-band) bicortical screw-located MARPE appliance (Type C) were modeled. Median suture and lateral osteotomy were performed in the type A model. Finite element analysis of Von mises stresses at 0.25 mm expansion, and displacements at 5 mm expansion was applied. Results: At the end of the study, more parallel expansion was observed in the transverse direction in Type B and Type C models, while a 'V' shaped opening was observed on midpalatal suture in the Type A model. In the type A model, negligible movement is observed in the pterygomaxillary region and lateral movement was observed in the pterygomaxillary region in the Type B and Type C models. Von mises stress values in Type B and Type C models showed higher values than Type A models. Conclusions: More parallel transversal expansion was achieved with the MARPE appliance. In addition, it might be recommended to perform SARME treatment in adults. Key words: Surgical Assisted Rapid Maxillary Expansion (SARME), Micro-implant (mini screw) Assisted Rapid Palatal Expander (MARPE), Finite Element Analysis (FEA)