Biomedical Engineering Reference
In-Depth Information
a
c
b
Fig. 7.7
Metal implant structure to support an entirely new set of dentures. Courtesy of Layerwise
Fig. 7.8
Porous structure in
tantalum with a pore size
somewhat less than 1 mm and
strut size of about 200
m
A second example is the dental framework shown in Fig.
7.7
: (a) the manufac-
tured metal support, (b) the ceramic-coated implant, (c) the final result.
Recently, we successfully realized the manufacturing of tantalum porous struc-
tures. One example of a structure with cubic pores of 1
1
1mm is shown in
Fig.
7.8
. The strut size is about 200
m.
7.4
Stereolithography of Polymers
Machine Layout
The foregoing techniques started from solids either metals, ceramics or polymers.
Objects are built up layer by layer by melting or sintering. A third technique,
although chronologically the one it all started with, consists of curing or polymeriz-
ing a liquid monomer by a focused laser beam. The laser beam is scanning over the
liquid surface curing a thin slice (Fig. 7.9). The scanning is monitored in a way sim-
ilar to the two former techniques. After finishing one layer, the supporting platform
is lowered to start curing the following slice. The monomers are a blend of epoxies
and acrylates, whose composition is kept secret by the suppliers. Biocompatibility
for surgical guides is not a problem but is not sufficient for endoprostheses.
