Biomedical Engineering Reference
In-Depth Information
Fig. 11
Boundary condition
applied in FE model
3.3
Boundary Conditions, Validation and Sensibility
The boundary condition presents an important role in the results. For the boundary
conditions the incisor was fixed in three directions but could rotate, and the condyle
could slide on the plane surface of a support as shown in Fig.
11
. The variation
in aspects like mandible size, mandible shape, bone properties, bite forces do not
allow to determine the stress and strain data in a real situation. These variations can
be differentiated by some aspects like gender, age and size.
The loads are included in Table
1
for a mouth opening of 5 mm on the incisor,
which is the condition that causes the most critical situation on the condyle [
27
,
57
],
and which presents most tension and displacement in the condyle compared with the
other two support positions (canine and molar teeth) and different mouth apertures
(5, 10, 15, 20, 25, 30 mm) [
27
].
The muscular actions applied were the ones presented [
32
] and five principal
muscles were included in the loading configuration: deep and superficial masseter,
medial pterygoid, temporalis and medial temporal. The muscle forces were consid-
ered in the same insertion zones and with symmetrical x direction.
These insertions have been observed through MRI images by Mesnard et al.
[
27
] based on dissections made to investigate contact between the condyles and
the temporal bone and the insertion centers of the muscles [
57
]. Calculation of
the muscular force directions was thus computer-assisted for three different sensor
thicknesses (5, 10 and 15 mm). The co-ordinate values used to calculate the articular
forces corresponded to the averages of the values obtained from the four dissections,
and was used in the FE models.
