TABLE 1.

Recent development of osteogenic coatings on titanium implants

Category	Main methods or substances	Species of cell	Osseointegration function	References
Surface morphology coatings	Microarc oxidation (MAO)	MC3T3-E1 pre-osteoblasts	↑Adhesion, proliferation, differentiation, and mineralization	Zhao et al. (2020a)
	Dealloying	EA.hy926	↑Early osseointegration in vivo	Bai et al. (2017), Bai et al. (2018a), Bai et al. (2018b)
	3D printing	RAW 264.7	↑Biological activity of Ti implants	Wang et al. (2021a)
	Selective laser melting	BMSCs	↓Inflammatory response of macrophages	Ma et al. (2018)
	Porous/nanoporous	Human 1.19 fetal osteoblast-like (hFOB)	↑Osteoimmunomodulation to facilitate osteo/angiogenesis	Yu et al. (2020a), MacBarb et al. (2017)
			↑Angiogenesis, osteogenesis, and osteointegration	Song et al. (2019)
	Electrochemical anodizationNanotubes	MC3T3-E1	↑Proliferation of the osteoblast cells	Yao et al. (2020)
		HMSCs	↑Cell differentiation	Hu et al. (2020)
		BMSCsMice bone marrow-derived macrophages (BMDMs)	Nanotubes with different nanostructure of 80–100 nm were more likely to induce macrophages to the M1 phenotype, while nanotubes with smaller diameters of 30 nm were prone to induce macrophages to the M2 phenotype	Wang et al. (2018b)
	Alkali treatment nanonetwork structures (TNS)	rBMMSCs MG63 cell	↑Early cell adhesion and proliferation	Zeng et al. (2019)
			↑Osteogenesis and osseointegration	Yin et al. (2019)
			↑Osteogenic gene expression and mineralization	Huang et al. (2019b)
			↑Osteoprotegerin secretion
	Vacuum diffusion bonding of titanium meshes	rBMMSCs	↑Cell adhesion, proliferation, and differentiation	Chang et al. (2016)
	Porous scaffolds with a variety of pore size and porosity
	Template-assisted plasma spraying technique	BMSCs RAW 264.7	↑Polarization of macrophage to anti-inflammatory type M2	Zhang et al. (2018c)
	Patterned surface		↑Mineralization
			↑Osteogenesis
			↑Osteoimmunomodulatory properties
	Microsecond laser direct writing and femtosecond laser-induced methods	MC3T3-E1	↑Cell adherence, alignment, and proliferation ↑Osteointegration	Li et al. (2020a)
	Micro-hexagons and nano-ripples
	Acid etching and anodization	BMSCs	Nanotubes with different nanostructure of 80–100 nm were more likely to induce macrophages to the M1 phenotype, while nanotubes with smaller diameters of 30 nm were prone to induce macrophages to the M2 phenotype	Wang et al. (2018b)
	Nanotubes with different nanostructure	Mice bone marrow-derived macrophages (BMDMs)
Inactive coatings	Mg/Ag/HA	Primary human osteoblasts	↑Adhesion, proliferation, and differentiation	Huang et al. (2018b)
		Human osteoblastic SaOS-2 cells	↑Osteogenic	Yao et al. (2021)
		Murine C3H10T1/2 cells
				Ke et al. (2019)
	MPs-Sr	MC3T3-E1	↑Attachment and spreading of preosteoblast MC3T3-E1 cells	Zhang et al., 2018a
			↑Collagen secretion and matrix mineralization levels of cells
			↑Osteogenic properties
	Cu	RAW 264.7 Human osteoblastic SaOS-2 cells	↑Polarize to M1 phenotype	Huang et al. (2018a)
			↑Pro-inflammatory cytokines
			↑Macrophage-mediated osteogenesis
	Reduced graphene oxide	hMSCs	↑Proliferation and osteogenic differentiation of hMSCs	Jin et al. (2015), Kang et al. (2021)
			↑Cell adhesion and protein adsorption
			↑Matrix mineralization
	Glutamic acid/dopamine methacrylamide	MC3T3-E1	↑Calcium phosphate (CaP) formation with a Ca/P ratio close to that of natural hydroxyapatite	Long et al. (2020)
			↑Mineral deposition
			↑Adhesion and proliferation of osteoblasts
Bioactive coatings	BMSCs/BMP-2	rBMSCs	↑Biocompatibility and osteogenic differentiation ability	Bai et al. (2020)
			↑Osseointegration efficacy
	Physisorption of fibronectin	MG63 cell	↑Osteoblast compatibility	Chen et al. (2020a)
	ADSC-EV		↑Osteoinductive activity
	CaP-BMP2	Murine bone marrow mesenchymal stem cell line D1	↑Osteogenesis and angiogenesis	Teng et al. (2019)
			↑Bone formation
	BMP-9	MC3T3-E1	↑Osteoblast proliferation and differentiation	Souza et al. (2018)
		BMSCs	↑Osseointegration	Zhu et al. (2021)
	Nerve growth factor (NGF)	—	↑Osseointegration	Lee et al. (2015)
			↑Nerve regeneration of peri-implant tissues	Ye et al. (2021)
	GO/IL-4	BMSCs	↑Biocompatibility	Li et al. (2020b)
		RAW 264.7	↑Macrophages polarization to the M2 phenotype in vitro
			↑Proliferation, migration, and osteogenic differentiation of BMSCs
	OGP-NAC	RAW 264.7	↓Important transcription factors for osteoclastogenesis	Liu et al. (2019)
			↑Osteoblast proliferation and differentiation