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

The insert (Fig. 3) is the part against which the patient presses the lips to generate a
counter-resistance force. It has an elliptical shape with parabolic curvature and a lateral
dimension of 60 mm, and was made with biocompatible polymers by rapid prototyping.
Fig. 3 – Frontal (A) and lateral (B) view of the insert.
The insert is connected to the load cell by a steel wire. The load cell has a capacity of 50
N and generates an analog signal when pulled in traction. A head support was used to
prevent the person from generating the force with the head instead of the lips. The
transmission, processing and storage system was composed of a data acquisition board
(Ontrak), an electronic coupling system and a personal computer. From the obtained
force x time results it is possible to obtain relevant data such as maximum and average
force and variations that characterize the lips force of the subject in time.
Measurements were made in 10 young women, aged 21 to 33 years with normal lips
force on the qualitative evaluation. The device was fit into the oral cavity and after one
minute of acclimatization, the participants were instructed to pull the device with the
lips towards the teeth as hard as they could for 10 seconds. Three trials were performed
with one-minute intervals between them. Average and maximum forces were analyzed.
4. RESULTS
4.1 Simulation
The evolution of the deformed mesh shape was obtained for different time increments
during the contraction process. The duration of the simulation, 0.25 s, represents the
period between the beginning of contraction and the moment when contraction reached
its maximum.
The maximum resulting displacement in the y-direction was 7.2 mm and occurred at the
top and bottom regions of the mesh. A nearly symmetric displacements field was
observed in the x-direction with a maximum of 3.9 mm at the internal lips region.
Finally, in the z-direction, the maximum displacement was 5.1 mm, and it could be
observed at the tips during the opening movement of the lips.
4.2 Lips force measurement
The results of maximum and average lips force, for each trial, are shown in Table 1.