A detailed three-dimensional finite element model of a skull, based on CT scans, was constructed to provide insight into the strain and stress distributions in the human facial skeleton due to occlusal loading. Forces and constraints were applied, simulating full arch and unilateral single point occlusal loading in molar, premolar, canine and incisor sites. Resulting strain and stress regimes are presented from Von Mises (VM) failure criteria, extension and compression diagrams. The 3-D FE model provides both descriptive and quantitative information on the relationship between facial architecture and occlusal loading. Results show different patterns of strain distribution between simulated full arch loading and individual loading points. On full maxillary arch loading, even distribution of strain is seen throughout the facial elements. For single tooth points strain trajectories divide into a «V-shaped» pattern, from the loading point into supero-medial and supero-lateral branches with greater VM values in the medial. High VM values are located several mm above the loading point on the facial aspect for all loading points. When the loading point moves from posterior to anterior teeth, VM values increase on all facial areas, the strain increasing, mainly in the alveolar arch and around the rim of the nasal cavity, and becoming more symmetrical. Analysis of the results shows the geometric form of the face as a vertical plate enabling it to withstand occlusal stresses by in-plane loading and bending in its own plane. The most efficient distribution of load is seen on full arch loading with the most unfavourable strain concentrations occurring on loading in the anterior region. The internal plate of the calvaria and some of the facial bones play a significant role in withstanding masticatory loading. Previous biomechanical concepts of vertical pillars, a supraorbital buttress and a pterygoid trajectory were not supported by the present study. The supraorbital region manifests, under all loading conditions, low strain values compared to other parts of the face, under all loading conditions. Also, split lines of the facial bones do not correspond with the masticatory facial stress regime, seen in this model.
|Number of pages||26|
|Journal||HOMO- Journal of Comparative Human Biology|
|State||Published - Jun 2000|