Stability of The Mental Foramen And Its Potential Use As A Landmark For Three-Dimensional Superimposition of Human Mandibles on Cone-Beam Computed Tomograms

Abstract

The purpose of this study was to examine the mental foramina as possible stable landmarks for three-dimensional superimposition of 2 cone-beam computed tomography (CBCT) images of the same human mandible taken during a long period of growth. The ultimate goal was to use the mental foramina as landmarks in a superimposition protocol. This retrospective study used CBCT scans taken at the University of Minnesota’s Department of Orthodontics, which were oriented and measured using Dolphin 3D Imaging software. 55 patients were selected. For each CBCT, the distance between the two mental foramina as well as the distance between protuberance menti (PM) and each mental foramen were measured. Differences in these measurements between the earlier (T1) scan and the later (T2) scan were then tested for statistical significance using a paired t-test. The results showed a significant distal movement of the mental foramen in growing patients, enough to hamper superimposition accuracy. The increase in the distance between each mental foramen and PM was symmetrical. Therefore, it can be concluded that the mental foramina are not suitable landmarks for three dimensional superimposition of the mandible in growing patients. However, the symmetry in the increase in the distance between PM and each mental foramen is a significant finding and indicates that the mental foramina can be used indirectly for 3D superimposition, helping to detect and quantify posterior mandibular growth asymmetry.