Design, 3D Bioprinting, and Testing of Otic Prosthesis

Sammanfattning: The middle ear is a complex organ with multiple functions. It is prone to accidental, genetic, excessive noise exposure, or age-related damage. Its main role is to convey and amplify the mechanical vibrations of the tympanic membrane to the acoustic nerve through three connected small bones, the ossicles; malleus, incus, and stapes. When severely damaged, the most used solution is currently a partial or total ossicle replacement with inorganic titanium prostheses, which are not anatomically similar. However, 3D models derived from micro-CT scans of human ossicular chains are freely available for research and educational purposes in high resolution 3D files. Therefore, these files were scaled to anatomical size and used to print partial models of the malleus and incus using an extrusion contact method using a bioprinter and OsteoInk, a calcium phosphate-based paste sold by the bioprinting company regenHU. The use of this biologically analogous material to 3D print anatomically sized and shaped ossicles is novel. The process and settings for bioprinting the malleus and incus were devised and tested for repeatability. OsteoInk was found suitable to form hard bone-like objects after printing and curing. However, for this process to be successful with OsteoInk, the models required a flat base; the first .560 mm of the virtual model were not printed. A support structure is required for creating complete ossicles, but the hydrogel and polymer structures attempted were not deemed feasible. The support structure could be created by combining the OsteoInk with other biomaterials, or by fibers printed through Melt Electrospinning Writing. The workflow devised in this project is applicable to other bioprinters, and to thus to further the research in the field of bioprinting.