Table 1.

Examples of tissue engineering strategies for tooth repair and regeneration

Material	Cell type	Results	Reference
PGA-PLLA	Pig tooth bud cells	This study demonstrated the first successful use of adult dental stem cells for the generation of tooth crowns containing dentine and enamel and suggested the presence of dental epithelial and mesenchymal stem cells in pig third molar tooth tissues	Young et al., 2002
Alginate hydrogels	DPCs	TGFβ1 containing alginate hydrogels upregulated dentine matrix secretion and induced odontoblast-like cell differentiation, with subsequent secretion of regular tubular dentine matrix on cut pulpal surfaces	Dobie et al., 2002
Collagen	–	Collagen scaffold induced successful regeneration of the periodontal tissues in a short period of time in dogs. Epithelial downgrowth and root resorption occurred and the defects were filled with connective tissue	Nakahara et al., 2003
PGA and PLGA	Pig/rat tooth bud cells	Cell-seeded PGA or PLGA scaffolds were grown in the omenta of adult rat hosts for 12 weeks. Bioengineered pig tooth crowns containing dentine, pulp, and enamel formed in 25–30 weeks. Rat tooth crowns formed in just 12 weeks	Duailibi et al., 2004
PGA-PLLA	Pig tooth bud cells	3D computer modelling demonstrated a spatial organization of enamel, dentine and pulp resembling that of natural teeth	Young et al., 2005b
PGA/PLGA	Pig tooth bud cells and BMSCs	Tooth implants were generated from pig third molar tooth bud cells seeded onto PGA and PLGA scaffolds, and grown for 4 weeks in the omenta of adult rat hosts. Bone implants were generated from osteoblasts induced from bone marrow progenitor cells obtained from the same pig, seeded onto PLGA fused wafer scaffolds. The results showed that tooth development is not dependent on bone formation	Young et al., 2005a
Collagen and PGA	Pig molar tooth cells	Comparison of collagen and PGA scaffolds seeded with pig third molar tooth cells in vitro and in vivo. The in vivo results showed that the collagen scaffold allows tooth production with a higher degree of success than PGA scaffolds	Sumita et al., 2006
Chitosan	Osteoblast	Chitosan monomer promoted tissue regeneration on dental pulp wounds	Matsunaga et al., 2006
PGA	Embryonic tooth germs	Embryonic day 14 (E14) mice tooth germs were seeded into a PGA 3D scaffold and implanted under a kidney capsule in adult mice. The initial cell-proliferation patterns of the tissue-engineered teeth were similar to that at the cap and early bell stages in natural teeth	Iwatsuki et al., 2006
PGA	Canine tooth bud	Cells were harvested from canine first molar tooth buds and the heterogeneous cell population was seeded on a PGA scaffolds and implanted into the same sockets after extracting the tooth buds. The biological results showed formation of dentine and bone, but enamel tissue and dental root formation were not observed	Honda et al., 2006
Collagen	Pig dental epithelium and mesenchyme cell	Mesenchymal cells were seeded onto the surface of the scaffold and epithelial cells were seeded on top to allow the direct contact of the two cell types. The results showed that the tooth morphology in vivo was similar to that of natural tooth, and only one tooth structure formed in each scaffold	Honda et al., 2007
Chitosan-coral	Human PDLC	Chitosan-coral composites combined with plasmid encoding platelet-derived growth factor B were evaluated in vitro and in vivo in athymic mice. Results demonstrated the potential of the scaffold as a good substrate candidate in periodontal tissue regeneration	Zhang et al., 2007
PLLA	SHED	SHED seeded in PLLA scaffolds prepared within human tooth slices were transplanted into immunodeficient mice. The resulting tissue presented architecture and cellularity that closely resemble those of a physiological dental pulp	Cordeiro et al., 2008
Peptides	SHED and DPSC	SHED and DPSCs were cultured in peptide-amphiphile hydrogel scaffolds. The results showed that both cells proliferate and differentiate within the scaffolds, but distinct differences could be observed. The hydrogel scaffolds were easy to handle and could be introduced into small defects	Galler et al., 2008
PGA-PLLAPLGA	Rat tooth bud cells	Comparison of bioengineered dental tissues grown in the mandible vs the omentum revealed both similarities and differences. Both implant sites supported the formation of bioengineered dentine, enamel, pulp and periodontal tissues. However, omental implant dental tissues seemed more organized than those grown in the mandible	Duailibi et al., 2008
Collagen	DPSCs	Triad of DPSCs, collagen scaffold and DMP1 induced an organized matrix formation similar to that of pulpal tissue in vivo	Prescott et al., 2008
Collagen	DPCs	Dental pulp stem cells (DPCs) collagen scaffolds can completely restore human mandible bone defects	d’Aquino et al., 2009
PGA-PLLAPLGA	Pig BMSC, DMCs, DECs	Tooth and bone constructs were prepared from third molar tooth tissue and iliac crest bone marrow-derived osteoblasts isolated from, and implanted back into, the same pig as an autologous reconstruction. Small tooth structures were identified and consisted of organized dentine, enamel, pulp and periodontal ligament tissues, surrounded by new bone	Abukawa et al., 2009
P(EMA), P(HEA), P (EMA-HEA)-silica	–	The tubular porous scaffolds resembled natural dentine with regard to its structure and properties and induced the precipitation of apatite on their surfaces in vitro	Lluch et al., 2009
PGA-PLLA	Epithelial and mesenchymal DSCs	In vivo results showed the formation of small tooth-like structures consisting of organized dentine, enamel, pulp, cementum and periodontal ligament and surrounded by regenerated alveolar bone, suggesting the possibility of tooth regeneration and associated alveolar bone in a single procedure	Zhang et al., 2009
HA-coated P(EMA-HEA)-silica	–	Scaffolds were implanted subcutaneously into immunocompromised nude mice for 4, 6 and 8 weeks. The result showed that the scaffold ultrastructural pattern imitates dentinal histological structure	Valles et al., 2010
PGA-PLLA	Epithelial and mesenchymal DSCs	Co-cultured 3D DE-DM constructs maintained their predetermined shape and size. The data analyses suggested that DE and DM cells expressed proper dental tissue markers under both in vitro and in vivo culture conditions	Zhang et al., 2010
Hyaluronic acid	Odontoblastic	Hyaluronic acid scaffold showed an appropriate structure, biocompatibility and biodegradation for dental pulp regeneration	Inuyama et al., 2010
HA-coated P(EMA-HEA)-silica	–	Scaffolds were implanted subcutaneously into immunocompromised nude mice for 4, 6 and 8 weeks. The materials allowed cell colonization and neoangiogenesis. Such materials seem promising in tissue-engineering strategies for dentine regeneration	Valles-Lluch et al., 2010
PCL-gelatin-HA	DPSCs	The performance of dental pulp stem cells on nanofibre PCL-gelatin-HA scaffolds was investigated in vitro and in vivo. The biological results showed that all implants were surrounded by a thin fibrous tissue capsule without any adverse effects and incorporation of nano-HA in nanofibres enhanced DPSCs differentiation towards an odontoblast-like phenotype	Yang et al., 2010
Collagen and chitosan	Epithelial and mesenchymal stem cells	A 3D multilayered co-culture system was developed to study epithelial- mesenchymal interactions that occur during tooth morphogenesis. This system influenced the migration, proliferation and differentiation properties of the epithelial and mesenchymal cells in vitro and also permitted neovascularization in vivo	Ravindran et al., 2010
HA-PCL	–	Dual GFs delivered from a 3D bioprinting scaffold with 200 μm diameter interconnecting microchannels. In vivo implantation results showed the regeneration of tooth-like structures and periodontal integration by cell homing, new bone formation and vessel formation		Kim et al., 2010c
Silk	Human DPCs	Silk porous (500 and 1000 μm diameter) scaffolds, with either RGD or DMP-1 peptide protein modification, were systematically investigated in vitro and in vivo. The biological results demonstrated that all silk scaffolds were well tolerated by host animals, whether they were cell-seeded or not	Zhang et al., 2011
Chitosan	Osteoblast	Alendronate-loaded chitosan scaffolds achieved the dual functions of improvement in osteoblast functions and inhibition of osteoclast differentiation	Kim et al., 2012
Decellularized scaffold	Porcine DMCs	Decellularized porcine tooth bud scaffolds were reseeded with porcine tooth bud matrices. The results indicated that more dense patches of collagen were detected in areas of the reseeded scaffold when compared with unseeded scaffolds. This means that the dental cells established residence in the decellularized scaffold and remodelled the matrix	Traphagen et al., 2012
Alginate hydrogel	PDLSCs and GMSCs	It was developed an injectable and biodegradable scaffold based on oxidized alginate microbeads encapsulating PDLSCs and GMSCs. The biological results showed that alginate is a promising candidate as a non-toxic scaffold for PDLSCs and GMSCs	Moshaverinia et al., 2012
Fibrin	Tooth bud cells	Tooth bud cells were suspended in fibrin glue and the scaffold was autografted back into the original alveolar sockets of a pig. The pig developed a complete tooth with crown, root, pulp, enamel, dentine, odontoblast, cementum, blood vessels and periodontal ligaments in indiscriminate shape	Yang et al., 2012b
PLGA microspheres	Tooth pulp cells	The effect of the controlled release of FGF-2 and TGF/S1 from microspheres on permanent tooth pulp cell proliferation and migration was investigated. The results showed the usefulness of growth factor-controlled release in investigating the early events of pulp/dentine regeneration	Mathieu etal., 2013
Collagen	iPS	The hanging drop method on a collagen scaffold combined with BMP-4-induced mouse iPS cells to form odontoblast-like cells without epithelialmesenchymal interaction	Ozeki et al., 2013
HA-PLGA nanofibres	Epithelial and mesenchymal DSCs	The effects of fibre alignment and HA content in biodegradable electrospun PLGA scaffolds were investigated in vitro. Scaffold porosity was sufficient to allow migration of mesenchymal cells. HA incorporation did not have a positive effect on cell proliferation, especially of epithelial cells, but seemed to promote differentiation	van Manen et al., 2014
Alginate hydrogel	DPSC	DPSCs immobilized in alginate hydrogels exhibit enhanced osteogenic potential while maintaining high cell viability		Kanafi et al., 2014
Decellularized scaffold	DPSCs and PDLSC	Subcutaneous implantation of the decellularized scaffolds containing DPSCs formed dental pulp-like tissue with cells expressing dentine sialoprotein and dentine phosphophoryn	Ravindran et al., 2014

PGA-PLLA, polyglycolate-poly-L-lactate; PLGA, poly-L-lactate-coglycolate; PDLSCs, periodontal ligament stem cells; GMSCs, gingival mesenchymal stem cells; DPCs, dental pulp stem/progenitor cells; DPSCs, dental pulp stem cells; TGFβ1, transforming growth factor-β1; FGF-2, fibroblast growth factor; P(EMA-HEA), polyethyl methacrylate-co-hydroxyethyl acrylate; SHED, stem cells from human exfoliated deciduous teeth; DMCs, dental mesenchymal cells; DECs, dental epithelial cells; PCL-TCP, polycaprolactone-tricalcium phosphate; DMP1, dentine matrix protein 1; HA, hydroxyapatite.