15.3 New Developments |
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•Additive manufacture without loss of unprocessed material
•Fabrication of:
––Defined roughness
––Graded porosity
––Lattice structures for realization of adapted stiffness
In addition to the medical aspects, the economic aspects are of great importance for custom made implants. The construction and manufacture of individual implants for craniofacial application are time-consuming and costly. The cost-dominating factors are the expenses for design, construction, and manufacturing, particularly for large defects. Design and manufacturing comprise several processing steps:
•Tooling
•Forging
•Casting
•Forming
•Machining
•Finishing
Costs are mainly determined by speed and effort of design and manufacturing, and both processes need an exact tuning and optimization in order to meet the demands of the surgeons. In comparison with conventional implant manufacturing, the production time needed for an SLM implant can be reduced by about 50%.
Potential advantages are reduced operating costs due to shorter operation times and shorter hospitalization.
Considering the overall objective of specialized medical centers, an implementation and certification of an effective and integrated process chain to plan and manufacture customized implants within 48 h seems to be possible today (Fig. 15.9). On the basis of the SLM process, new designs and material applications will become possible. Porous surfaces with a drastic reduction of the metallic content of the implant by creating three-dimensional spongious structures will allow material compositions with biomaterials without reduction in stability and precision.
15.3.2 PEEK-Implants
Polyetheretherketone (PEEK) is a semi crystalline thermoplastic polymer with biophysical properties similar to that of human bone (Jahur-Grodzinski 1999). The physical characteristics of the material combine good strength and stiffness similar to that of bone with excellent thermal and chemical properties. Its excellent biocompatibility makes this material ideal for long-term medical implant applications. With a continuous use temperature of 260°C, this polymer is suitable for every clinical sterilization method. The manufacture of
Patient
Manufacturing by selective Laser Melting
CT Micrograph /
Medical Requierements
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Implant design and |
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preparing of data |
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Fig. 15.9 Process chain for individual implant manufacture