Objectives: To better understand the function of dentin sialophosphoprotein(DSPP) during tooth develolpment and biomineralizaton. Methods: Antisense oligodeoxynucleotide(AS-ODN) strategy was carried out in vitro. In the control experiment, explants of tooth germs from embryo day 17 mice were cultured in semi-solid agarose medium under serum-free and chemically defined conditions for 16ds and 10ds,respectively, examined by H&E, von Kossa staining and transmisson electron microscopy. Other explants were cultured with 15bp antisense or sense ODN targeted to DSPP mRNA. Results: Both the control and the sense-treated explants grew well, while antisense-treated explants were smaller in size. Von Kossa staining was observed between enamel and predentin in control germs but not in the AS-ODN germs. Ultrastructural analysis showed large cisternae of the rough endoplasmic reticulum(RER) in the odontoblasts at the tip of the cusp of the antisense-treated explants.The average thickness of dentin matrix was thinner than in control explants and collagen fibers in the extracellular matrix were disorganized . Conclusions: These findings provide direct experimental evidence indicating that arrested DSPP translation in cultured tooth germs might result in delay in tooth development as well as inhibition of dentin mineralisation.This suggests that DSPP has an important role in tooth development maintaining odontoblast secretory activity.Thus,it may control collagen fiber structure and orientation as well as subsequent mineralization of the matrix. .

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