R_Bibb_Medical_Modelling_The_Application_of_Adv.pdf

238 Medical modelling
6.89 Cobalt-chrome RPD framework fi tted to patient cast.
Ref. Number 426). The frameworks in their initial form were well formed
but showed a fi ne surface roughness. This roughness was easily removed
by bead blasting. This resulted in a framework that showed similar physical
appearance and surface qualities as the investment cast items typically used
in dental technology. Therefore, the treatment and fi nishing of the framework
from that point onwards was conducted in the same manner as any
other RPD framework, using normal dental laboratory techniques and
equipment.
6.14.4 Results
The successful 316L stainless steel RPD framework was assessed for the
quality of fi t by fi tting it to the plaster cast of the patient’s oral anatomy.
The quality of the fi t was assessed according to normal dental practice by
an experienced dental technician and found to be excellent. The frameworks
showed a quality of fi t that was comparable with investment cast
frameworks. However, repeated insertion and removal from the patient
cast resulted in small but permanent deformation of the clasp components.
The clasp components are the functional parts of the framework and are
designed to grip the teeth to provide a fi rm location of the denture (the
clasps are the elements shown in the close up photographs in Fig. 6.90).
Therefore, the permanent deformation reduces the ability of the framework
to grip the teeth and the denture becomes loose. This meant that after