Stress distribution analysis during an intermaxillary dysjunction: A 3-D FEM study of an adult human skull

BACKGROUND: With the increased interest in adult orthodontics, maxillary width problems in the nongrowing patients have been encountered with greater frequency. In view of the negative outlook for successful nonsurgical palatal expansion in adult patients it seemed appropriate to evaluate the biomechanical effects of nonsurgical rapid maxillary expansion (RME) in adults using the finite element method (FEM). OBJECTIVES: To evaluate the biomechanical effects of RME on the craniofacial complex as applied to three-dimensional (3D) model of an adult human skull using the finite element method. SETTINGS AND DESIGN: The Department of Orthodontics and Dentofacial Orthopedics at Government Dental College and Hospital, Nagpur. The study was done on an analytical model developed from a dry human skull of an adult female with an approximate age of 20 years. MATERIALS AND METHODS: A 3D finite element analysis of the craniofacial complex was developed from sequential computed tomography scan images. Known transversal (X) displacement with magnitudes of 1, 3, and 5 mm were applied and the displacement and Von-Mises stresses in different planes were studied on different nodes located at various structures of the craniofacial complex. RESULTS: Transverse orthopedic forces not only produced an expansive force at the intermaxillary suture but also high forces on various structures of the craniofacial complex, particularly at the base of the sphenoid bone and frontal process of the zygomatic bone. Lateral bending of the free ends of the pterygoid plates were noted. CONCLUSION: RME must be used judiciously in adults because of its far-reaching effects involving heavy stresses being noted at the sphenoid bone, zygomatic bone, nasal bone, and their adjacent sutures.