Verification of a 3D finite element model and evaluation the effect of miniscrew-assisted maxillary expansion of changing various parameters

Abstract

Introduction Rapid palatal expansion (RPE) is an orthodontic method for patients with constricted maxilla Rapid palatal expander is divided into bone-born and tooth-born type types：bone-born expander transmits force to bone screws to further expand maxillary bone；contrarily tooth-born expander passes on force to tooth directly Micro-implant assisted RPE which is one of bone-born expanders has been proved which could expand the maxilla in adult patients successfully and efficiently Most of the studies analyzed the effect of various screw position screw length in micro-implant assisted RME using finite element method (FEM) with different setting of material properties that contribute to opposite results Moreover there are few reports focused on how to create a finite element model and verify the model by clinical results The purpose of our study is to create a finite element model by changing various suture properties to stimulate the clinical results and to evaluate the effect of micro-implant assisted RME with verified FEM Methods A finite element model was constructed from a cone beam computed tomography (CBCT) images of a 24 years male In the first part of study the effects resulting from different suture property setting was evaluated The behavior of the FEM was compared with the findings of patient’s clinical result Comparisons refer to the pattern of suture opening and reaction force of expander In second part using the verified finite element model two clinical situations with varying screw length (9 11 13) were studied in two 3D models: anterior-positioned between first premolars of both sides and posterior-positioned expander between first molars of both sides The expander was activated transversely by b 0 125mm of both side of x-axis Finite element analysis simulations were performed in both 3D models Deformation and reaction force were evaluated for all models Results The findings of this study suggest that mid-palatal suture’s property play an important role in analysis’s results identified from the reaction force of expander It was suggested that practical property of mid-palatal suture was E = 0 1MPa P=0 1 For other maxillary sutures (Pterygo-palatine Zygomatico-temporal Zygomatico-maxillary suture) E = 1370MPa P=0 3 was recommended that contribute to rational opening pattern With the verified model moreover changes in screw length and expander position could not affect the width of expansion but when placing expander anteriorly reaction force of expander increases much more A finite element model should be verified by clinical result first and the results of FEM study would be reliable and applicable to provide more worthy information to clinical doctors

Date of Award	2021
Original language	English
Supervisor	Tzer-Min Lee (Supervisor)