Application and Development of Modern 3D Printing Technology in the Field of Orthopedics

Table 2

Summary of additive manufacturing materials: advantages and disadvantages.

Material types	Composition	Advantages	Disadvantages	Ref.
Metal	Titanium alloy, copper alloy, Ti6Al4V alloys, CoCrMo alloys	(i) Good toughness; (ii) Antibending fatigue performance; (iii) Biocompatibility; (iv) Excellent processing performance; (v) Good corrosion resistance; (vi) Easy to manufacture expensive materials with complex geometries or materials that are difficult to process	(i) Pure titanium easily leads to a stress barrier; (ii) Potential biological safety; excessive metal ions such as Zn^2+ show cytotoxicity; (iii) The use of metals may lead to some rare consequences, such as allergies or genotoxicity; (iv) Poor adhesion on the surface of inert implants such as titanium alloys; (v) Metal stent printing needs to be performed under high-temperature conditions, and the stent printing cannot be synchronized with the coating of biologically active molecules or mixed printing of cells	[7, 55, 74–76]
Bioceramics	Hydroxyapatite (HA), calcium phosphate (CaPs), tricalcium phosphate, MgP, alumina, zirconia	(i) Good biocompatibility; (ii) Biodegradability; (iii) Strong resistance to pressure; (iv) Achieve very high structural resolution; (v) Strong osteoinductive ability; (vi) Alumina and zirconia have good toughness and wear resistance and high mechanical strength; (vii) Alumina and zirconia’s low thermal conductivity and nondegradability	(i) Ceramic stents need to be printed at high temperatures, and stents cannot be simultaneously coated with bioactive molecules that promote bone formation or anti-infective drugs; (ii) High brittleness; (iii) Poor toughness; (iv) Weak shear stress	[77–79]
Polymer materials	Polycaprolactone, polylactic acid-glycolic acid, polyglycolic acid, collagen, alginate, silk fibroin, chitosan	(i) Biocompatibility; (ii) Biodegradability; (iii) Good thermoplasticity; (iv) Natural polymer material with natural porous structure and good hydrophilicity; (v) Increasing the roughness of the scaffold can improve the adhesion ability of cells	(i) Natural polymer materials are difficult to obtain in large quantities, degrade quickly, and have insufficient biomechanical strength; (ii) Viscosity-dependent fluidity of polymers; (iii) Biodegradation will produce lactic acid and carbon dioxide, and the local pH will decrease, thereby creating an acidic environment that is conducive to inflammation rather than healing; (iv) The lowering of the pH value of the local environment can accelerate the hydrolysis of the ester bond of the polymer material, promote the degradation of the polymer material, and affect the biomechanical effect of the stent; (v) The polymer scaffold printed with cells has weak resistance to compression and cannot meet the compression requirements of human bones	[80–83]
Composite materials	Polylactic acid-glycolic acid; copolymer/tertiary calcium phosphate; PCL/DCPD/nanoZIF-8; polycaprolactone mixed with β-tricalcium phosphate	Combined with the advantages of the above materials		[55, 70, 84, 85]