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Ultrastructure of in-vitro recovery of mineralization capacity of fluorotic enamel matrix in hamster tooth germs pre-exposed to fluoride in organ culture during the secretory phase of amelogenesis

1987; Elsevier BV; Volume: 32; Issue: 2 Linguagem: Inglês

10.1016/0003-9969(87)90053-7

1879-1506

D.M. Lyaruu, M. de Jong, A.L.J.J. Bronckers, J.H.M. Wöltgens,

Dental Trauma and Treatments

The recovery of mineralization capacity of fluorotic enamel matrix was investigated in 3-day-old hamster first molar tooth germs already pre-exposed in organ culture to 10 parts/106 F− for 24 h during the secretory phase. The germs were then cultured for another 24 h in a fresh medium without F−. The unmineralized fluorotic enamel matrix secreted in vitro eventually mineralized in the absence of F− but the orientation of the crystals compared to those in the fluorotic enamel was disturbed, especially in the younger regions of the enamel nearest cervical-loop in which the underlaying fluorotic enamel was most hypermineralized; but least disturbed in the more mature parts of the enamel organ in which the fluorotic enamel was less hypermineralized. The subsequent culture in F−-free medium did not abolish or reduce the degree of hypermineralization induced by F− treatment during the initial 24 h of culture. It seems that in vitro the inhibitory effect of F− on enamel matrix mineralization during the secretory phase is completely reversible when the ion is removed from the matrix environment, i.e. F−-induced synthesis and secretion of defective enamel matrix is not the cause of the lack of matrix mineralization. The F−-induced hypermineralization seems to be irreversible.