The Effects of Partial Demineralization and Fibronectin on Migration and Growth of Gingival Epithelial Cells on Cementum in vitro

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Abstract
The capacity of mineralized cementum to support epithelial cell migration and growth and the effect that fibronectin and partial demineralization of cementum have on these processes were assessed in vitro. Dog gingival explants, 1 x 2 mm, were cultured on the cementum surfaces of pig root pieces in a defined medium consisting of DMEM and F12 (1V/1V, transferrin, insulin, epidermal growth factor, cortisone, selenium, and high-density lipoprotein. Sixty root pieces were divided into four equal groups according to the treatment: (1) untreated mineralized cementum; (2) treated with 5 μg of fibronectin; (3) partially demineralized in 18% EDTA for 30 min; and (4) both partially demineralized and fibronectin-treated as above. Epithelial cell migration and growth on each of the four differently treated cementum surfaces were assessed histomorphometrically by means of scanning electron microscopy. The defined culture medium supported the selective migration and growth of epithelial cells from the gingival explants onto the mineralized cementum. This was confirmed by the positive immunostaining of these cells with antikeratin antibodies. Partial demineralization of cementum inhibited epithelial migration and growth by 83% and 91%, respectively. Fibronectin treatment did not affect epithelial cell migration and growth on mineralized cementum, but it decreased the degree of epithelial cell migration and growth inhibition on partially demineralized cementum to 57% and 43%, respectively. The results indicate that: (i) mineralized cementum may consist of components that are recognized by gingival epithelial cells and support their migration and growth in vitro; (ii) these components can be removed by demineralization; and (iii) fibronectin partially restores epithelial cell migration and growth on partial demineralized cementum in vitro.