Biomechanical response of the human mandible to impacts of the chin.

The purpose of this study was to determine the force-time and force-displacement response of the human mandible under direct loading at the chin. Sub-fracture response of the mandible and temporomandibular joint (TMJ) were analyzed from 10 cadavers that were impacted at the chin with a 2.8-kg mass at drop heights of 300, 400 and 500 mm and a 5.2-kg mass at 500 mm. Motion of radio-opaque markers adhered to the surface of the bone was recorded at 1000 Hz by a bi-planar X-ray and converted to three-dimensional coordinates. Peak force ranged from 0.90 to 4.54 kN causing chin displacement of 1.2-4.4 mm. A bi-linear response was observed with stiffness of 475.1+/-199.8 kN/m for chin displacement resulting from loading up to 0.6 kN and 2381.6+/-495.7 kN/m for loads from 0.6 to 3.25 kN. This defines the biomechanical response of the mandible for chin motion under impact loading. The response of different segments of the mandible and TMJ are also documented. Force-time and force-displacement response corridors for the mandible can be used for finite element model and/or the development and validation of a biomechanical surrogate.