Table 1.

Features of Various Medical Imaging, Additive Manufacturing, and Bioreactor Technologies Utilized in Bone Tissue Engineering Applications

Technology	Description	Advantages	Disadvantages	References
Medical imaging technologies
Computerized tomography	Utilizes an X-ray source that is variably attenuated when crossing tissues with different densities	Short scanning time. High contrast in cortical bone	Exposure to radiation. Limited contrast in newly formed bone	13,61
Magnetic resonance imaging	Utilizes magnetic fields that induce variable rates of oscillation of hydrogen atoms generating contrast between different tissues	No exposure to radiation. Enables visualization of newly formed bone	Long scanning time. Limited contrast in cortical bone	61,62
Additive manufacturing technologies
Fused deposition modeling	Extrusion of molten material from a nozzle forming a thin filament that is laid down layer-by-layer over a deposition surface moving over three axes relative to the extrusion nozzle	Self-supportive structures do not require support material. Multimaterial prints possible	Material usually needs to be preprocessed into filament format	30
Selective laser sintering	Fusion of particles contained in sequentially stacked layers of powder material by means of directed laser radiation	Degree of detail mainly dependent on powder grain size. Easily prints, blends composite materials by mixing material powders	Utilizes support material that may be difficult to remove. Limited to single material prints	28,29
Bioprinting	Extrusion of materials such as gels and/or cellular aggregates from a nozzle forming a thin filament that is laid down layer-by-layer over a deposition surface moving over three axes relative to the extrusion nozzle	Ability to utilize gels and cells as deposition material. Multimaterial prints possible	Utilizes support material that may be difficult to remove. Produced structures are very delicate	31
Bioreactor technologies
Perfusion bioreactor	Fluid forced through scaffold generates shear stress, which stimulates cells by deforming their structure	Can perform cellular seeding. Very simple and inexpensive systems	Requires a fluid circulation circuit	38–40,42,43
Direct mechanical compression bioreactor	Mechanical compression/relaxation of scaffolds deforms cells attached to scaffold surfaces	Closely mimics compressive forces felt by native tissues during movement	Requires the utilization of complex mechanical actuators. Exerts forces over cells indirectly	44
Hydrostatic compression bioreactor	Compressed fluid generates mechanical forces, which directly deform the membranes of cells contained in scaffolds	Self-contained. Exerts forces directly over cellular membrane	Requires the utilization of high-pressure equipment	45