Deformation characteristics of the human mandible in low impact experiments.

A total of 11 human mandibles were subjected to physical impacts under standardised conditions. Two impact sites and directions were tested and the impact load was varied in four steps. Two occlusional strengths were applied and the influence of simulated soft tissue covering was recorded. The deformation of the bones was measured using strain gauge strips located at eight defined sites. In a series of frontal to occipital impacts the frontal areas and the collum showed the largest length changes. Increasing impact intensities led to a proportional increase of the length changes. An increase of the occlusional strength was either protective (at the collum) or it increased the deformation (frontal area). The soft tissue covering was only partly protective. Lateral impact was characterised by a compression on the side of the impact and stretching on the other side only. The intensity and speed of deformation increased with increasing distance from the site of impact. A fixed occlusion caused an increase of compression at the site of impact and an increasing stretching in the frontal part of the bone and at the opposite collum.