Abstract:

Objective　To investigate more deeply the function and mechanism of DSPP during tooth development.Meth- ods　Explants of tooth germs from embryonic 17 th day mice were divided into two groups. In the control experiment, explants were cultured in agarose semi-solid medium under serum-free and chemically defined conditions, while explants in the other group were cultured with 30μmol/L, 15 bp antisense oligodeoxynucleotide targeted to DSPP mRNA. After 10 ds, the explants were ex- amined by transmission electron microscope. The width of dentin matrix at the tip of the cuspswere then measured and statistically analyzedwith Studentt-test.Results　Ultrastructure analyses showed that large cisternae of the rough endoplasmic reticulum (RER) existed in the odontoblasts at the tip of the cusps of antisense-treated explants and the average thickness of dentin matrix (2.5μm) was thinner compared to the control ones (3μm,P<0.001). In addition, the collagen fibers in extracellular matrix were disorganized.Conclusion　These findings indicated that DSPP played an important role in keepingtooth normal development, as well as in dentin mineralization by maintaining odontoblasts′secreting ability and controlling fiber structure and orientation.

Key words: dentin sialophosphoprotein(DSPP), antisense oligodeoxynucleotide, tooth germ, ultrastructure