Manufacturing of SiO2-Coated beta-TCP Structures by 3D Printing using a Preceramic Polymer as Printing Binder and Silica Source

摘要

Tricalcium phosphate (beta-TCP) can be used as bone graft, exhibiting suitable bioabsorption and osteoconduction properties. The presence of silica may induce the formation of a hydroxyapatite layer, enhancing the integration between implant and bone tissue. Preceramic polymers present silicon in their composition, being a source of SiO2 after thermal treatment. Using the versatility of 3D printing, beta-TCP and a polysiloxane were combined to manufacture a bulk beta-TCP with a silica coating. For the additive manufacturing process, PMMA powder was used as passive binder for the beta-TCP particles, and polymethylsilsesquioxane (MK), dissolved in an organic solvent, was used both as a printing binder (ink) and as the source of SiO2 for the coating. Five distinct coating compositions were printed with increasing amounts of MK. The structures were then submitted to heat treatment at 1180 degrees C for 4 h. XRD and FTIR showed no chemical reaction between the calcium phosphate and silica. SEM allowed observation of a silicon-based coating on the structure surface. Mechanical strength of the sintered porous structures was within the range of that of trabecular bones.