Effect of mandibular advancement on symphyseal form

Much research has been done to understand the complex process of facial growth and development for decades. Recently, the form and function of the human mandibular symphysis has been of interest. The human symphysis theoretically experiences three types of strains during function, lateral transverse bending, vertical bending, and shearing, which may influence symphyseal shape and development. These forces are influenced by the size and position of the mandible relative to the muscles that act upon it. The purpose of this study is to determine whether an increase in mandibular length through surgery leads to increased skeletal indicators of resistance to wishboning forces. We retrospectively collected a sample of 47 subjects who had undergone mandibular advancement surgery and compared their pre- and post-surgical radiographs to examine for any changes. The results of our analysis did not provide any evidence to suggest increased wishboning resistance as a result of surgical lengthening. Perhaps there were truly no changes in the symphysis, or that we were unable to detect them due to limitations of using two-dimensional images on an adult population with a relatively short follow-up. Further research is needed to understand the role of function in the form of the human mandibular symphysis.