BACKGROUND: Forensic investigations have been reported regarding the loss of consciousness and cardiac arrests resulting from direct mandible impact. However, the mechanisms by which the forces are transferred to the skull through direct mandible impact remain unclear. We conducted a study regarding direct mandible impact on the level of energy required to create a mandible fracture and on the energy dispersion phenomenon to the skull and to the brain.
METHODS: This study combines an experimental and numerical approach. Mandible strike was studied using experimental trials performed on post-mortem human subjects. A finite element model of the head and face of a male was also developed based on tomodensitometry scans. The model was validated with literature data and experimental trials. A parametric study was then performed to study the effect of diverse variables such as the dentition integrity, cortical bone thickness, etc.
RESULTS: The forces measured on our reference model were 3000 N on the chin, 1800 N at the condyles, and 970 N in the occiput. Of all the results, we observed a decrease of approximately one-third of the efforts from the chin to the base of the skull and a lower half of the still forces at the occiput, except in the edentulous and for the lateral and frontal impact where the force is transmitted directly to the skull base area.
CONCLUSIONS: This study allowed us to create a 3D model of the mandible and face bones to better understand the force transfer mechanisms into and from the mandible. The parameters of the model may be modified to suit the individual characteristics for forensic investigations and legal matters.

This study compares the performances of three numerical approaches [Lagrangian (LAG), arbitrary Lagrangian-Eulerian (ALE) and control volume (CV)] for modelling the response of a short cylindrical pipe representing a portion of the intestines subjected to large and rapid compressions. While not being able to simulate sustained fluid flow, the LAG approach provided similar results as the ALE for moderate levels of compression. However, it was the stiffest approach for larger levels and had numerical issues for extreme compressions. While the ALE did not have these issues, its computing cost was very high, which would be problematic for large models. The CV approach had the lowest computing cost and seemed promising for larger compressions. However, its response was the softest and further investigations are needed to define its dependency to modelling parameters.