Table 2.

Overview of various BTE strategies.

Approach	Materials	Origin	Benefits	Limitations	Refs.
Scaffold-based	Metal	Synthetic	• Biocompatibility • Material strength • Mechanical properties	Biodegradability Release of ions	[80,81]
	Fibrin Collagen Chitosan Silk HA Starch	Natural	• Biocompatibility • Biodegradability • Biofunctionality • Low immunogenicity • Biomimetic	Mechanical properties Endotoxins	[82,83,84,85,86,87]
	PHA PGA PLLA PEG PCL	Synthetic	• Biocompatibility • Wide material range • Control over physical properties	Acidic degradation Hydrophobicity	[88,89,90,91,92,93]
	Bioceramics	Synthetic	• Osteoinductivity • Host–tissue similarities • Delivery of bioactive molecules	Brittleness Biodegradability	[94,95]
	Bioglass	Synthetic	• Osteoinductivity	Brittleness Manipulation	[96]
Spheroid-based	MSCs Osteoblasts iPSCs Combination of cells Cell lines	Natural	• Biocompatibility • Biomimetic • Low immunogenicity • Cells and own ECM • Easy to produce/handle • Implementation of various cell types	Mechanical properties Necrotic center	[97,98,99,100,101]
Scaffold- and Spheroid-based		Synthetic and natural	• 3D bioprinting • Variety of composites • Morphology	Nutrient supply Vascularization Necrotic center	[101,102]
Continuative Systems	MSCs Osteoblasts iPSCs Combination of cells Cell lines Implementation of non-bone cells	Natural	• Nutrient support • Vascularization • Crosstalk of tissues • More systemic approach	Work in progress	[103,104]