Materials for rapid prototyping techniques
Calcium phosphates are popular implantation materials for hard tissue regions due to their similarities to the mineral part of human bone and their osteoconductive properties. They are currently used the clinical medicine in form of granulates, hardening cements or prefabricated shapes of simple geometry, however they are barely applied as patient-specific implants of an individually adjusted form.
That is why we are working on the development of powder-binder systems, which can be applied to manufacture stable three-dimensional forms with a given geometry using conventional three-dimensional (3D) printing processes. As powder component we use calcium phosphates (tri- or tetra-calcium phosphate) solitary or in blend with other substances. If an aqueous hardening solution has impact on certain places of the powder layer, a chemical reaction takes place and a bonding between neighbouring powder particles and abutting layers materializes. Phase analysis of hardened samples is carried out by X-ray diffraction.
Applying optimized systems, complex 3D forms can be printed with conventional 3D printing technologies. The capability of the process was demonstrated on the example of manufacturing forms with crossing channels along the x, y and z axes as well as filigree structures of the viscerocranium. The mechanical stability of the printed porous structures could be increased by sintering and infiltration with a biocompatible radically cross-linkable macromere, respectively. The cytocompatibility of the printed and treated structures has been proven by in vitro investigations using selected cell lines and by in vivo experiments with rabbit cranial bone.