Three-dimensional and four-dimensional printing in otolaryngology.

Each year, thousands of patients deal with ear, nose, and throat disorders that can be life threatening such as tracheal stenosis, or impact the psychosocial well-being, such as microtia. These often require surgical intervention using autologous or allogenic grafts. Tissue engineering represents an exciting alternative to substitute the use of human tissues, by fabricating living bioartificial constructs using three-dimensional scaffolds that incorporate or support human cells that can proliferate and mature. The complex geometries of ear, nose, and throat call for advanced fabrication techniques such as bioprinting, which leverages additive manufacturing to fabricate patient-specific scaffolds with a high design freedom and repeatability. Here, we will provide a comprehensive overview on the use of bioprinting technologies to address specific challenges in otolaryngology, with relevant examples from recent literature.