Table 3.

Summary of key findings in studies involving the use of piezoceramics for bone regeneration and their piezoelectric coefficients.

Material	Year	Cell type or animals	Key findings	Piezoelectric coefficient (pC/N)
Barium titanate	2018 [80]	MG-63 cells	Increased cell adhesion, proliferation, and migration into barium titanate scaffolds.	191
	2016 [81]	MG-63 cells	Higher cell density, ALP, and BGP activities on porous barium titanate composites compared to dense titanate composites.
HA (hydroxyapatite)	2007 [87]	MSCs from rabbits and U2OS cells	20 nm HA nanoparticles had the greatest potential for stimulating bone regeneration (MSCs) but inhibited the growth of osteosarcoma cells.	1.5–2.4
	2010 [89]	MC3T3-E1 osteoblast-like cells	Cell attachment, proliferation, and metabolic activities were significantly increased on the charged HA surface.
Boron nitride	2016 [93]	Umbilical cord mesenchymal stem cells (UC-MSCs)	BNNT composite scaffolds promoted osteogenic differentiation of UC-MSCs with more calcium deposition.	0.3
	2016 [94]	MSCs from rats	MSCs had better proliferation, ALP, and osteocalcin activities on boron nitride nanotube layers.
ZnO (zinc oxide)	2017 [100]	SaOS2 cells	Electromechanical reactions between living cells and ZnO nanosheets could stimulate the opening of calcium channels, thus enhancing cell viability, proliferation, and differentiation.	12.4
	2014 [101]	MG-63 cells	Fracture toughness, compressive strength, cell attachment, and proliferation improved when the content of ZnO increased from 0 to 2.5 wt%.

Osteosarcoma cell lines: U2OS, MG-63, SaOS2; MSCs: mesenchymal stem cells; ALP: alkaline phosphatase; BGP: bone gla protein; BNNT: Boron nitride nanotubes