Why ceramics?

Advanced ceramics are used more and more for medical applications, such as surgical instruments and patient-specific implants. Patient-specific implants made of biocompatible and bioresorbable ceramics are used for cranio-maxillofacial and hemi-maxillary implants. These implants will be reabsorbed by the body and will be replaced by native bone tissue, meaning that the implant does not need to be removed once the healing process is finished, eliminating the need for otherwise necessary removal of autologous bone, which is often associated with severe pain and complications. In comparison to tricalcium phosphate, hydroxyapatite takes far more time to be absorbed into the body, therefore giving the body more time to heal.

Implementing Additive Manufacturing

Additive manufacturing allows to produce patient-specific implants: by scanning the current situation of the bones of the patient, an optimized geometry for the implant can be defined. Additive manufacturing allows for the production of interconnected scaffolds with defined geometries and sizes. A combination of dense and porous structures in bonetissue engineering facilitates the ingrowth of bone from adjacent tissues.

Using beta-TCP or Hydroxyapatite, it is possible to manufacture patient-specific, bioresorbable implants, which have defined pore structures and geometries. Combinations of functional graded ceramic materials, such as dense and porous structures in a single hemi-maxillary bone-like structures, have been printed and sintered successfully with help of the lithography based additive manufacturing technology provided by Admatec.

The Admaflex Technology

Using the tool-free Admaflex DLP 3D print technology, it is possible to manufacture highly complex geometries, channels, lattice and honeycomb structures with features and wallthicknesses in the range of 100 µm. The Admaflex 3D print technology uses the material much more efficient compared with conventional manufacturing technology such as milling. Unlike injection molding, there is no mold needed, so fast and cost-effective development and production of components for medical devices, surgical instruments and patient-specific implants is possible. The batch-orientated printing process has been optimized for speed and build volume. With currently available build volumes of upto 260 x 220 x 500 mm, on one build platform, relatively big implants can be produced. In case of small implants, many different geometries can be 3D printed simultaneously with the Multi-part printing software, which allows to optimize the production settings of each part individually. Another advantage of 3D printing is the high precision and reproducible macroporosity in connection with the defined surface quality, which could significantly improve for example the cell adhesion.

Future multi-materials for DLP 3D printing

Recent developments are focussing on Multi-materials DLP 3D printing, for example for combination implants for the lower jaw, where a combination of Hydroxyapatite and Zirconia can be used. In case of large bone defect due to a severe trauma or bone tumor, the bone itself is not able to heal the defect without appropriate measures. A possible solution is a cage made of high-strength zirconia or other high strength ceramic, which gives support during the healing phase. The inner volume of the implant could be made of bioresorbable ceramic such as calcium phosphate or hydroxyapatite. The zirconia cage can be left in place due to its outstanding biocompatibility. The calcium phosphate or hydroxyapatite can be resorbed into the cells and replaced by newly formed bone. The combination of design freedom and the ability to use multiple ceramic materials in DLP 3D printing open up many new applications for permanent implants.