Three dimensional mechanical-mathematical model and algorithm of oral mandibular jaw

The purpose of this paper was to analyze unloaded jaw-opening and Jaw-closing movement in human. The discussion is based on the three fundamental laws of mechanics applied to the various anatomical structures that are part of the masticatory system. In this paper, a dynamical six-degrees-of-freedom biomechanical mathematical model of the human masticatory system was developed. The model incorporated morphology, physiological properties, muscle architecture and dynamical muscle properties. The movements of the human jaw are controlled by the forces produced by the masticatory muscles, whereas passive structures such as ligaments and joint surfaces are considered to be limiting factors. Masticatory muscles consist of the jaw-opening and jaw-closing muscles. Masticatory muscle force and jaw movement influence each other, so we have to study their mutual relationship. The contributions of the individual muscles to jaw movements can be derived from the orientation of their lines of action with respect to the center of gravity of the lower jaw. The mechanical role the muscles play is strongly related to their three-dimensional coordinates of insertion points and orientation in the muscle-bone-joint system.They cause the jaw to linear and angular accelerations with six degrees of freedom. The jaw movement was simulated in the biomechanical model. The resultant force and the moment of force or torque acting on the mandible which were derived as a function of jaw opening angle generate accelerations.The mechanical stimulations of the jaw movement were built up. We use Runge-Kutta method to resolve second-order ordinary different equation of the jaw-opening movement. Various symmetrical jaw-opening and jaw-closing movements were simulated based upon different muscle forces and jaw-opening muscles schemes. The amount of jaw opening was limited by the passive forces of the jaw-closing muscles.

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Recommended citation: Yao Sun. (2008). “ Three dimensional mechanical-mathematical model and algorithm of oral mandibular jaw.” Thesis. 1(3).