Table 2.

Selected references on 3D (bio)printing strategies in craniofacial bone and periodontal tissue engineering

Reference	Materials	Advantages/Disadvantages	Most Relevant Findings
[94]	PCL	(+) production of resorbable membranes and tunable porosity	3D printed PCL with 30% porosity showed improved mechanical properties and osteogenic differentiation.
[82]	PCL/PLGA/Collagen	(+) short- or long-term release of BMP-2 can be achieved depending on the polymer used	Scaffold loaded with rhBMP-2 showed higher osteoinductivity compared to PCL/PLGA/gelatin loaded with rhBMP-2 or individual scaffold.
[93]	PLA	(−) requirement of the use of a post-modification method	CaP treatment of printed scaffold increased the roughness and hydrophilicity thereby positively impacting the proliferation of the osteoblasts.
[85]	PCL/PLGA/β-TCP	(+) similar levels of biocompatibility and bone regeneration as collagen membranes	3D printed membrane showed bone regeneration performance similar to that of collagen membranes during a GBR procedure performed in peri-implant defects.
[96]	PEU and HA	(+) capability of printing various types of polymers	3D printed HA-containing PEU composites promote higher bone regeneration compared to pure HA scaffold.
[99]	PLLA and β-TCP	(+) readily incorporation of bioactive tricalcium phosphate	In vivo bone formation driven by the PLLA + TCP30 scaffold with MG-63 cells was significantly greater than PLLA or TCP30 with MG63.
[100]	PCL/β-TCP/	(+) phlorotannin made the composites hydrophilic	Phlorotannin composites showed higher initial cell attachment and mineralization than non-phlorotannin composite.
[103]	PCL-50 wt% of 45s5 bioglass or strontium substitute bioactive glass	(+) biaxially rotating bioreactor cellular homogeneity throughout the scaffolds.	Release of ions (Sr, Zn, Mg, and Si) from scaffold accelerate angiogenesis and stimulate the osteogenic differentiation of mesenchymal stem cells (MSCs)
[84]	PCL-poloxamine	(+) tunable bioerosion rate and DEX release	Varying osteogenic activities from human mesenchymal stem cells cultured onto scaffolds composed of the various blends are demonstrated.
[104]	PLA	(−) difficulty in achieving biomimetic nano resolution	Angiogenesis and osteogenesis are successively induced by delivering dual growth factors with sequential release using PLA.
[83]	PCL/PLGA/β-TCP	(+) slow release of BMP-2	3D printed GBR membrane loaded rhBMP-2 exhibited significantly greater amount of new bone in the rabbit calvarial defect model compared to the membrane without rhBMP-2.
[112]	PCL	(+) combination of melt and solution electrospinning	The multiphasic construct with large and small pores electrospinning to develop biphasic scaffolds to supporting bone formation and cell sheets.
[106]	PCL, HA	(+) multiphasic scaffold to imitate native periodontium (−) ectopic peridontium formation	3D printed seamless scaffold with region-specific microstructure and spatial delivery of proteins resulted into putative dentin/cementum, PDL, and alveolar bone complex regeneration
[30]	PCL-PLGA	(+) printing complex structures by combination of FDM and electrospinning	Triphasic scaffold by combination of 3D printing (FDM) and electrospinning exhibited enhanced ALP activity and GAG amount.
[108]	PCL	(−) polymer of choice is limited because of the high melting point and biodegradability	MEW scaffold coated with calcium phosphate enhanced the osteogenic gene and protein expression of hOBs.
[109]	PLA-PEG_PLA and PLA	(+) tailoring scaffold architectures with high precision	5% BG did not affect the processing adversely.
[110]	PCL and HA	(+) precise and complex porous 3D fibrous structures & tunable porosity	Incorporation of HA in PCL increased the cell spreading and migration.
[111]	P-(Є-CL-co-AC)	(+) production of fibrous scaffolds with sinusoidal patterns and micron-sized diameter mimicking the ligament and tendons	MEW printed P-(Є-CL-co-AC) is cytocompatible and qualitatively mimicked the mechanical characteristics of tendon and ligament tissue.
[113]	Star PEG heparin hydrogel/PCL	(+) multiphasic scaffold design in combination with different human cell type	Tissue-engineered periosteum constructs loaded with HUVECs and BMMSC enhance the vascularization and retained the BM-MSCs in undifferentiated state in vivo.
[78]	PCL	(+) heterogenous porosity of scaffold increase cell attachment (−) study needs to be confirmed in an appropriate in vivo model	MEW scaffold with gradient pore size and fiber offset significantly improved the osteogenic potential.
[114]	PEOT, PBT, PCL	(+) designing structural porosity gradients	The construct with a discrete gradient in pore as a strategy to support differentiation supported the osteogenic differentiation of hMSCs.
[12]	PCL and GelMA	(+) reinforcing effect of meshes could be further (−) lack of detailed cross-linked kinetics of GelMA modified AMP.	Fiber-reinforced (PCL meshes processed via MEW) membranes in combination with therapeutic agent(s) embedded in GelMA offer a robust, highly tunable platform to amplify bone regeneration not only in periodontal defects, but also in other craniomaxillofacial sites.
[38]	GelMA, PCL	(+) convergent approach to combine extrusion-based printing of hydrogels and MEW	Mechanically stable constructs with the spatial distributions of different cell types without compromising cell viability and differentiation.
[127]	Calcium silicate	(+) low-temperature rapid prototyping of C3S offers drug/GF incorporation during in printing process	Controllable nanotopography of printed structure into phosphate aqueous solution improve bone regeneration in vivo.
[134]	HA and Gelatin	(+) shape can be easily adjustable, in wet conditions, to that of the bone defect during surgery.	The osteogenic differentiation of MC3T3-E1 on silicon-doped HA scaffold was higher compared to HA only.
[102]	13–93 Bioactive glass/alginate	(+) tunable pore size and porosity	With increase in BG/SA mass ratio, the pore size and porosity also increased. Furthermore, scaffolds exhibited in vitro apatite mineralization and osteogenic differentiation of rBMSCs.
[29]	PCL	(+) Printed membrane-supported periodontal ligament fibrous cell sheets under both stationary and dynamic fluid conditions (−) standardized cell source for preparing the decellularized cell sheets.	Printed scaffolds improve the handling of the cell sheet during decellularization protocols.
[135]	Sr-MBG	(+) Microfill perfusion assay to determine blood vessel. (−) in depth understanding of synergistic osteogenic/angiogenic effect of Sr and Si ions released.	Sr-ions from scaffolds create a better microenvironment activating the angiogenesis and osteogenesis pathway for the enhanced in vitro and in vivo bone formation.
[136]	βTCP-collagen	(+) heterophasic construct design	Scaffold allowed the proliferation of DPC and increased the differentiation towards osteoblasts.
[137]	Akermanite- βTCP	(+) repair of load-bearing bone defects.	Akermanite had better mechanical properties and a higher rate of new bone formation than the pure TCP scaffold.
[141]	Sodium alginate, Pluronic F-127, Bredigite bioceramic	(+) Better oxygen and nutrient delivery for cell activity	Enhanced vascularized bone formation due to synergistic effect of 3D printed hollow-pipe structure and release of bioactive ions.
[125]	Akermanite, Sodium alginate, Pluronic F-127	(+) scaffold developed with different raw materials including ceramics, metal and polymer.	Lotus root-like biomimetic materials significantly improved in vitro and in vivo osteogenesis and angiogenesis.
[144]	Calcium Phosphate	(+) fabrication of humidity-set scaffold	CPC containing VEGF maintains hMSC viability and bioactivity of HDMEC.
[145]	βTCP, Alginate and Gelatin	(+) Printable bioink at room temperature to load drugs/GF	Cell adhesion and ALP expression was enhanced by scaffold containing PLGA microspheres with VEGF.
[147]	Collagen, chitosan, HA	(+) tailored scaffold property for long-term controlled drug release and bone regeneration	The bone regeneration capacity of HA scaffold coated with collagen/chitosan microsphere with rhBMP-2 was higher than the HA scaffold coated with collagen or pure HA.
[148]	Mesoporous silica/calcium phosphate	(+) well-interconnected macropores and ordered mesopores	MS/CPC/rhBMP-2 scaffolds induced the osteogenic differentiation and vascularization in vitro and in vivo.
[149]	β-TCP	(+) use of large translational animal model	Delivery of dipyridamole improved the osseoconduction in sheep calvarial defect model resulting in significant increase in bone formation.
[140]	Alginate, Pluronic F-127, bioceramic	(+) migration of cells in the inner part of the scaffolds due to high porosity and surface area	HSP demonstrated more new bone formation compared with a solid-struts-packed scaffold.
[126]	β-TCP, Wollastonite, Bredigite	(+) Scaffold stable in aqueous medium for a long period of time.	CSi-Mg10 scaffolds displayed improved flexural strength and higher osteogenic capability in rabbit mandibular defect.
[124]	β-TCP	(+) scaffold strut and porosity designed to elicit bone-healing behavior.	3D printed beta-TCP induce new bridging bone formation in full-thickness mandibulectomy defects after 8 weeks without the use of osteogenic inducers.
[156]	PLGA-TCP	(+) Bone was able to remodel under physiological loading	Phyto-molecule icariin exhibited improved biodegradability, biocompatibility, and osteoinductivity both in vitro and in vivo.
[36]	Calcium phosphate, Alginate and Methylcellulose	(+) post-plotting regime, to prevent microcrack formation inside CPC strands	Biphasic scaffold showed migration of cells towards CPC from alg/mc after 7 days.
[153]	Alginate, Lutrol F-127, Poloxamer 407, Matrigel, Agrose, Methylcellulose	(+) two distinct cell populations printed within a single scaffold	No difference in cell proliferation and viability of 3D printed and unprinted hydrogel scaffolds.
[31]	α-TCP and type 1 collagen	(+) two step printing process to develop cell-loaded bioceramics scaffold.	3D printed scaffold showed improved physical properties, metabolic activity and mineralization, compared with those of the controls.
[13]	AMP and synthetic peptide gel	(+) Fast degradation of AMP microparticles	AMP-modified constructs favored in vitro and in vivo mineralization without the use of a chemical inducer.
[163]	Collagen, β-TCP	(+) unique fibrillogenesis of collagen to produce a bioink laden with cell and bioceramics	hASC-laden composite structure (20 wt% of β-TCP) demonstrated significant osteogenic gene expression compared to control cultured using an osteogenic media
[164]	GelMA,k- Carrageenan,Laponite	(+) NICE bioink produce fabricate patient specific, 3D implantable scaffold	bone tissue formation was a result of endochondral differentiation of hMSCs
[32]	PCL, Alginate	(+)MtoBS is a promising system for regeneration of heterogeneous tissue	Multi-Arm BioPrinter enabling dispensing of human chondrocytes and MG63 cells to biofabricate osteochondral tissue.
[152]	Agrose hydrogel	(+) computationally designed spatial patterns of cells	3D printed constructs with specific spatial pattern and varying cell densities improves cell viability
[37]	PCL, Alginate, Collagen, HA	cytocompatible multi-layered construct formed by stacking different types of printable extracellular matrix (ECM) bioink	3D printing of construct with different types of ECM hydrogels encapsulated stem cells allowed the differentiation towards chondrogenic and osteogenic lineages
[182]	Alginate, chitosan	The coating improved the retention and release efficacy of drug	The coating of 3D printed alginate construct with chitosan improved cell proliferation and result into elongated cells.
[177]	β-TCP	(+) Scaffold preserved the cranial suture patency.	Large scaffold pore (500 νm) coated in 1000 μM dipyridamole yielded the most bone growth and faster degradation within the defect.
[14]	PCL	(+) first clinical case of 3D printed scaffold for periodontal regeneration. (−) Slow scaffold resorption, at 13 months, the scaffold became exposed	The implanted 3D scaffold showed n signs of chronic inflammation or dehiscence upto 12 months.
[183]	PCL	(+) scaffolds combined hierarchical mesoscale and microscale features can align cells in vivo.	Combination of gene therapy and topographical guidance cues showed osseous tissue formation and oriented collagen fibers for treatment of periodontal osseous defects.
[77]	GelMA, PCL	(+) convergence of MEW and bioprinting, for fabrication of flat to anatomical relevant structures.	MEW process allowed the fabrication of a complete condyle-shaped biological construct.
[101]	PCL, MBG-58S	(+) use of clinically relevant post-menopausal mode; for bone regeneration	MBG-PCL scaffold promoted new bone formation at both the peripheral and the inner parts of the scaffolds with thick trabeculae and a high vascularization degree.
[123]	PCL, Mesorporous calcium silicate and bioactive glass	(+) two different scaffolds with highly properties to avoid the interference of the comparing osteogenic potential	MBG/PCL scaffolds exhibited better bioactivty than MCS/PCL scaffolds for bone regeneration.
[129]	Magnesium phosphate	(+) DAHP solution eliminate the conventional sintering process to extend the usefulness of loading drug	MgP scaffold showed good pore structural conditions, mechanical property and cell affinity.
[131]	α-TCP	(+) fabrication of thermally instable and degradable matrices of secondary calcium phosphates	The printed sample strength increase after treatment of phospharic acid give rise to brushite with minor phases of unreacted TCP.
[130]	TCP, DCPA	(+) complete conversion of all components involved in the production process (raw powder and binder solution) to a cement matrix minimizing risk of harmful residues	Scaffolds was printed with >96.5% of dimensional accuracy. Cell proliferation was higher on biphasic calcium phosphate when compared to HA.
[166]	CaP, PCL, GelMA	(+) Multi-material, multi-scale 3D printing approach (hydrogel-thermoplastic-bioceramic composite)	multi-scale composite osteochondral plugs results in the formation of cartilage-like matrix in vitro with 3.7-fold increase in strength of the interconnection at the bone-cartilage interface.
[172]	Calcium silicate, β-TCP	(+) engineering of pro-angiogenic microenvironment in vitro	Co-culture of HUVECs and hBMSCs on porous 5% CS/β-TCP accelerates vascularization and osteogenesis in ectopic bone formation model.
[175]	GelMA	(+) hollow, stackable miniaturized microcage modules, resembling the features of toy interlocking building blocks	3D printed microcages loaded with microgels supplemented with growth factors enhanced cell invasion into the core of assembled constructs in a controllable manner, thus accelerating the process of new tissue formation and healing.
[176]	β-TCP	(+) scaffolds do not cause premature closure of sutures and preserve normal craniofacial growth	Regeneration of vascularized bone with mechanical characteristics comparable to native bone.
[184]	PCL	(+) high adaptability to the created defect geometry	The ligament cells displayed highly predictable and controllable orientations along microgroove patterns on 3D biopolymeric scaffolds.
[178]	β-TCP	(+) Dipyridamole as a viable cost-effective osteogenic agent	Resorbable, β-TCP scaffolds treated with DIPY increased bone regeneration qualitatively and quantitatively.
[174]	Akermanite	(+) Development of Haversian bone–mimicking scaffolds (−) multicellular synergistic including bone-resident cells such as osteoblasts, osteoclasts, and macrophages need to be explored	The scaffold showed the potential for multicellular delivery by inducing osteogenic, angiogenic, and neurogenic differentiation in vitro and accelerated the ingrowth of blood vessels and new bone formation in vivo.
[133]	TCP and anhydrocus dicalcium phosphate	(+) discrete deposition of pharmaceutical agents on bioceramics scaffold using multijet 3D printing	rhBMP-2 and vancomycin by loading the drug within the 3D printed scaffold.
[173]	PCL	(+) deferoxamine loaded PCL showed mechanical property similar to cancellous bone	The deferoxamine-printed scaffold had no effect on cell attachment or proliferation, but it significantly increased vascularization, which was accompanied by increased bone growth.