A Comparative Study of Three Types of Rapid Maxillary Expansion Devices in Surgically Assisted Maxillary Expansion: A Finite Element Study

OBJECTIVES: The aim of this study was to analyze the displacement pattern and stress distribution during surgically assisted rapid maxillary expansion (RME) with three different types of RME devices by constructing a finite element model. MATERIALS AND METHODS: A finite element model is constructed from the computerized tomography scans. According to the type of RME device, 3 groups were simulated on this mesh model. The experimental groups were as follows; Group I (tooth borne appliance), Group II (bone borne appliance), and Group III (hybrid appliance). A Le fort I osteotomy with bilateral pterygomaxillary disjunction and midpalatal split osteotomy cuts were incorporated in all the groups. The displacement pattern and stress distribution for each 1 mm of activation of appliance up to 10 mm is noted and analyzed. The data were analyzed using Student’s t-test, Analysis of Variance and Duncan new multiple range test. RESULTS: Tooth borne appliance has more rotational tendencies. The bone borne and the hybrid appliance exhibited similar stress patterns for the dissipation of the forces produced by RME appliances. The pivoting effect decreased with the hybrid and the bone borne appliance and can be utilized in patient with hyper divergent growth. CONCLUSION: The pivoting effect is least with the hybrid appliances.