Forces transmission to the skull in case of mandibular impact.
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.
APHM, CHU Timone, Service de Médecine Légale et Droit de la Santé, 13385 Cedex 5 Marseille, France; Aix-Marseille Université, CNRS, EFS, ADES UMR 7268, 13916 Marseille, France. Electronic address: lucile.tuchtan@ap-hm.fr.
Lucile
L
Tuchtan
APHM, CHU Timone, Service de Médecine Légale et Droit de la Santé, 13385 Cedex 5 Marseille, France; Aix-Marseille Université, CNRS, EFS, ADES UMR 7268, 13916 Marseille, France.
Marie-Dominique
MD
Piercecchi-Marti
APHM, CHU Timone, Service de Médecine Légale et Droit de la Santé, 13385 Cedex 5 Marseille, France; Aix-Marseille Université, CNRS, EFS, ADES UMR 7268, 13916 Marseille, France.
Christophe
C
Bartoli
Aix-Marseille Université, IFSTTAR, LBA UMR_T 24, 13916 Marseille, France.
Dominic
D
Boisclair
Aix-Marseille Université, CNRS, EFS, ADES UMR 7268, 13916 Marseille, France.
Pascal
P
Adalian
APHM, CHU Timone, Service de Médecine Légale et Droit de la Santé, 13385 Cedex 5 Marseille, France; Aix-Marseille Université, CNRS, EFS, ADES UMR 7268, 13916 Marseille, France.
Georges
G
Léonetti
Aix-Marseille Université, IFSTTAR, LBA UMR_T 24, 13916 Marseille, France.
Michel
M
Behr
Aix-Marseille Université, IFSTTAR, LBA UMR_T 24, 13916 Marseille, France.
Lionel
L
Thollon
D000368:Aged; D001696:Biomechanical Phenomena; D002102:Cadaver; D005260:Female; D020342:Finite Element Analysis; D044707:Forensic Sciences; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008337:Mandibular Fractures; D008954:Models, Biological
Finite element modelling; Forensic investigations; Mandible; Uppercut