> Developmental dental toxicity of dioxin and related compounds--a
> review.
TCDD specifically reduces mRNA for the mineralization-related dentin
sialophosphoprotein in cultured mouse embryonic molar teeth.
Previous studies show that the most toxic dioxin congener, 2,3,7,8-
tetrachlorodibenzo-p-dioxin (TCDD), interferes with mineralization of
the dental matrices in developing mouse and rat teeth. Culture of
mouse embryonic molar teeth with TCDD leads to the failure of enamel
to be deposited and dentin to undergo mineralization. Lactationally
exposed rats show defectively matured enamel and retardation of dentin
mineralization. To see if the impaired mineralization is associated
with changes in the expression of dentin sialophosphoprotein (Dspp),
Bono1 and/or matrix metalloproteinase-20 (MMP-20), thought to be
involved in mineralization of the dental hard tissues, we cultured
mouse (NMRI) E18 mandibular molars for 3, 5 or 7 days and exposed them
to 1 microM TCDD after 2 days of culture. As detected by in situ
hybridization of tissue sections, localization and intensity of Bono1
and MMP-20 expression showed no definite difference between the
control and exposed tooth explants, suggesting that TCDD does not
affect their expression. On the contrary, TCDD reduced or prevented
the expression of Dspp in secretory odontoblasts and decreased it in
presecretory ameloblasts. The results suggest that the retardation of
dentin mineralization by TCDD in mouse molar teeth involves specific
interference with Dspp expression. PMID: 16926037
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