Table 2.

Studies reporting effects and interactions of SSH on the dental structure.

	Progestagens	Androgens	Estrogens
Enamel
Receptor polymorphisms and effects on the enamel			Genetic polymorphisms in ER are associated with developmental defects of the enamel (98), higher caries experience (99) and a higher incidence of fluorosis in children (100, 101).
Pulp
Receptors	Pulp fibroblasts and odontoblasts expressed PR (102)	Pulp cells expressed AR (103). Freshly isolated pulp tissue expressed AR, which was significantly more abundant in male subjects. Its expression increased when exposed to estradiol or androstenedione, while exposure to testosterone decreased its expression (104).	hDPC expressed ERα, ERβ1 and ERβ2. During osteogenic differentiation of hDPCs, ERβ1 and ERβ2 were upregulated and ERα was downregulated (105). Pulp cells expressed ERα and ERβ (103). Pulp cell cultures expressed ERβ (104). Odontoblasts, endothelial cells and Schwan cells (all derived from pulp tissue) expressed ERα (106). Odontoblasts and endothelial pulp cells expresser ER (107).
Cellular differentiation		DHT upregulated the expression of several genes involved in odontogenesis and odontoblast differentiation in hDPCs (103).	Estradiol enhanced hDPSCs’ ALP activity, mineralization capacity and promoted odonto/osteogenic differentiation (108). It also increased proliferation of hDPCs and upregulated odontoblastic differentiation markers (109). When inducing the overexpression of ERα in hSCAPs ALP activity, mineralization capacity and odonto/osteogenic differentiation were significantly increased (110). hDPSCs, hSCAP and hDFSCs show odonto/osteogenic differentiation potential when supplemented with estradiol (74). Estradiol up-regulated ALP activity, mineralization capacity and odonto/osteogenic markers in hSCAPs (111). Estradiol induced up-regulation of several genes involved in odontogenesis and odontoblast differentiation in hDPCs (103). Estradiol enhanced expression of osteoprotegerin (OPG) in hPDLCs via a membrane-bound receptor (112).

ALP, alkaline phosphatase; AR, androgen receptor; DHT, 5α-Dihydrotestosterone; ER, estrogen receptor; hDPCs, human dental pulp cells; hDPSCs, human dental pulp stem cells; hSCAPs, stem cells from the apical papilla; hDFSCs, human dental follicle stem cells; OPG, osteoprotegerin; PR, progesterone receptor.