Effects of rapid maxillary expansion on the cranial base--an FEM-analysis.

BACKGROUND AND AIM: Rapid maxillary expansion not only has local effects on the midpalatal suture and the maxillary region, but also on deep anatomical structures of the viscero- and neurocranium. This study's aim was to analyze the distribution pattern of stresses on the juvenile and adult sphenoid by the finite element method (FEM) induced by rapid maxillary expansion. Of special interest were stresses and deformations around the sphenoidal foramina with their vulnerable neural and vascular structures.

MATERIAL AND METHOD: A finite element model of the sphenoid consisting of 19,383 single elements was used for the analysis.

RESULTS: The virtual experiments showed that rapid maxillary expansion leads to moderate stresses and deformations in the juvenile sphenoid, so serious complications are unlikely in this region. The situation is different in adulthood because of decreasing elasticity of the skeletal structures. Due to lateral bending of the pterygoid processes, marked stress develops in the round and oval foramen regions and those of the superior orbital fissure, where fractures causing neural and vascular injury can occur.

CONCLUSION: The surgical separation of the maxilla from the sphenoid is an important means of preventing complications in the region of the cranial base in adults.