ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

LIPS CONTRACTION SIMULATION AND FORCE MEASUREMENT
SYSTEM
T.V.C. Perilo 1 , J. Grasa 2 , M.D.C. Magalhães 3 , A.R. Motta 4 , A.F. Valentim 5 ,
R.M.M.M. Furlan 6 , M. Doblaré 7 , E.B. Las Casas 8
1. ABSTRACT
Introduction: Human lips are formed by the muscle orbicularis oris and its contraction
is essential for different oral functions. The purpose of this study is to describe an
ongoing research project that includes the simulation of the lip muscle mechanical
behavior and the measurement of lip forces obtained by a device developed specifically
for that purpose. Methods: The 3D geometric model of the orbicularis oris was
obtained via MRI from a healthy female subject. The hyperelastic transversally isotropic
material model used in the analysis was based on an energy function that is uncoupled
for active and passive behavior. The instrument to measure lips force is composed of an
elliptical shaped insert mechanically coupled to a steel cable, connected to a force
transducer type load cell that is connected to a data acquisition system. Ten young
women were evaluated. Results: The evolution in time of the model displacements was
obtained for the contraction process. The period between the beginning and peak
contraction was 0.25s. The maximum resulting displacement happened in y-direction
(7.2 mm), but it also in x and z directions. As for experimentally measured forces, an
average of 9.2N was obtained and a maximum value of 10.9N. Conclusion: The finite
element model allowed a realistic simulation of lip contraction, corresponding to its real
deformation, and the instrument permitted knowing lips forces. Values for characteristic
lip forces were measured. Next steps include the development of a numerical model of
the experimental process for the individual used for the generation of the geometric
model in order to calibrate and validate the finite element simulation.
2. INTRODUCTION
The orbicularis oris muscle is a facial muscle responsible for the lips shape and
function. It is elliptical, and consists of upper and lower fibers composing the upper and
lower lips that interact in the region of the labial commissure. Lips contraction is
essential functions, such as speech, food prehension and swallowing, as it produces
closure of the mouth. Lips also participate in the actions of blowing, sucking, kissing
and whistling (Figún and Garino, 2003).
1,3,5,6,8 Mechanical and Structural Engineering Graduate Programs, Biomechanical Engineering Group,
Universidade Federal de Minas Gerais (MECBIO). Av Antônio Carlos, 6627, Campus Pampulha, 31270-
901, Belo Horizonte, Brasil.
2,7 Group of Structural Mechanics and Materials Modeling (GEMM), Universidad de Zaragoza, Spain and
Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-
BBN) Betancourt Bldg. María de Luna s/n, Campus Río Ebro, 50018, Zaragoza, Spain.
4 Speech Pathology Department, Universidade Federal de Minas Gerais, Belo Horizonte, Brasil.