Development and Validation of a Three-Dimensional Finite Element Model of the Face

Abstract

A detailed three-dimensional finite element model of the face is presented in this paper. Bones, muscles, skin, fat, and superficial muscoloaponeurotic system were reconstructed from magnetic resonance images and modeled according to anatomical, plastic, and reconstructive surgery literature. The finite element mesh, composed of hexahedron elements, was generated through a semi-automatic procedure with an effective compromise between the detailed representation of anatomical parts and the limitation of the computational time. Nonlinear constitutive equations are implemented in the finite element model. The corresponding model parameters were selected according to previous work with mechanical measurements on soft facial tissue, or based on reasonable assumptions. Model assumptions concerning tissue geometry, interactions, mechanical properties, and the boundary conditions were validated through comparison with experiments. The calculated response of facial tissues to gravity loads, to the application of a pressure inside the oral cavity and to the application of an imposed displacement was shown to be in good agreement with the data from corresponding magnetic resonance images and holographic measurements. As a first application, gravimetric soft tissue descent was calculated from the long time action of gravity on the face in the erect position, with tissue aging leading to a loss of stiffness. Aging predictions are compared with the observations from an "aging database" with frontal photos of volunteers at different age ranges (i.e., 20-40 years and 50-70 years).

Insertion Area in the Mandible Masticatory Muscles for use in Finite Element Analyses

“…Changes in the insertion areas of each muscle may cause alterations of the muscle loads and, consequently, affecting the final results obtained through the FEA (Gröning et al). A research by Barbarino et al (2009) described an anatomically detailed finite element model of the face, which includes the masticatory muscles reconstructed from the magnetic resonance. However, they do not report quantitatively any information about the distribution of the insertion area in the mandible of the masticatory muscles.…”

Experimental Characterization and Simulation of Layer Interaction in Facial Soft Tissues

“…These measurements could form part of a diagnostic tool to quantify the impact of dermatological diseases such as fibrosis. Additionally, our experimental findings will be incorporated in the finite element model of the face [3] to simulate the tissue response during facial expression and mastication.…”

“…The lower part of the face is included in this model for visualization purposes. The forehead model introduced here was generated similar to the procedure presented in [3].…”

“…In recent papers we have demonstrated the implementation of advanced active and passive constitutive models of face tissue [15,16], as well as the accurate representation of anatomical features, and realistic boundary conditions [3]. Our model allows to simulate facial expressions and wrinkling by incorporating experimentally quantified interaction properties of individual tissue layers.…”

“…Our work aims at improving with respect to existing FE models [3,17,14] in terms of physical relevance of soft tissue geometry and mechanical response.…”