[Table/Fig-3]:

Summary of advantages and limitations of alternative cell source

Alternative Cell source for ameloblasts	Advantages	Limitations
Epithelial cell rests of Malassez	ERM are direct lineage from HERS, which are derived from the enamel organ through the cervical loop structures, hence ERM retain their original ability to secrete a matrix conducive to generating enamel. ERM cells from HERS can differentiate into ameloblasts and produce enamel-dentin complexes when combined with non-cultured dental pulp cells.	In vitro subcultured ERM expressed ameloblast related genes like ameloblastin and tuftelin but not amelogenin and are inconsisitent when compared to EOE cells. ERM cells showed the enamel regeneration only if it is associated with dental pulp cells
Bone marrow stroma cells	Bone marrow stromal cells are differentiated into ameloblasts when cocultured with dental epithelial cells.	Bone marrow cells alone, without dental epithelial cells and dental mesenchyme cannot differentiate into ameloblasts. So far studies have shown with association of embryonic dental epithelial cell which is practically not feasible
Oral keratinocytes	One day postnatal palatal epithelial cells form enamel dentin complex when associated with dental mesenchymal cells	There are no studies to prove the efficacy of more than 2 days old palatal epithelial cells
Human embryonic stem cell derived epithelial cells	Human embryonic stem cell derived epithelial cells expressed cytokeratins which is comparable to ameloblast lineage cells proving as a potential source for ameloblasts	Sourcing of stem cells is problematic
Skin epithelial cells	1 day postnatal skin epithelial cells were able to regenerate tooth germ like structure	Requires studies to prove the older postnatal skin epithelial cells capable of proliferation and differentiation