title: A Comparative Study of Three Types of Rapid Maxillary Expansion Devices in Surgically Assisted Maxillary Expansion: A Finite Element Study.
abstract: OBJECTIVE
  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.
  
  
  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.
  
  
  CONCLUSIONS
  The pivoting effect is least with the hybrid appliances.
authors.affiliation: Professor, Department of Orthodontics, Narayana Dental College, Nellore, Andhra Pradesh, India.
authors.forename: Gowri Sankar
authors.initials: GS
authors.lastname: Singaraju
authors.affiliation: Post-graduate Student, Department of Orthodontics, Narayana Dental College, Nellore, Andhra Pradesh, India.
authors.forename: Dhyanisree
authors.initials: D
authors.lastname: Chembeti
authors.affiliation: Professor and Head, Department of Orthodontics, Narayana Dental College, Nellore, Andhra Pradesh, India.
authors.forename: Prasad
authors.initials: P
authors.lastname: Mandava
authors.affiliation: Professor, Department of Orthodontics, Narayana Dental College, Nellore, Andhra Pradesh, India.
authors.forename: V Karunakar
authors.initials: VK
authors.lastname: Reddy
authors.affiliation: Professor and Head, Department of Orthodontics, KVG Dental College, Sullia, Karnataka, India.
authors.forename: Sharath Kumar
authors.initials: SK
authors.lastname: Shetty
authors.affiliation: Professor and Head, Department of Orthodontics, Government Dental College, Thiruvananthapuram, Kerala, India.
authors.forename: Suja Ani
authors.initials: SA
authors.lastname: George
keywords: Displacement; finite element; rapid maxillary expansion; stress; surgically assisted rapid maxillary expansion