Dentin sialophosphoprotein knockout mouse teeth display widened predentin zone and develop defective dentin mineralization similar to human dentinogenesis imperfecta type III.

[dentin dysplasia]

Dentin sialophosphoprotein (Dspp ) is mainly expressed in teeth by the odontoblasts and preameloblasts . The Dspp mRNA is translated into a single protein , Dspp , and cleaved into two peptides , dentin sialoprotein and dentin phosphoprotein , that are localized within the dentin matrix . Recently , mutations in this gene were identified in human dentinogenesis imperfecta II (Online Mendelian Inheritance in Man (OMIM ) accession number 125490 ) and in dentin dysplasia II (OMIM accession number 125420 ) syndromes . Herein , we report the generation of Dspp-null mice that develop tooth defects similar to human dentinogenesis imperfecta III with enlarged pulp chambers , increased width of predentin zone , hypomineralization , and pulp exposure . Electron microscopy revealed an irregular mineralization front and a lack of calcospherites coalescence in the dentin . Interestingly , the levels of biglycan and decorin , small leucine-rich proteoglycans , were increased in the widened predentin zone and in void spaces among the calcospherites in the dentin of null teeth . These enhanced levels correlate well with the defective regions in mineralization and further indicate that these molecules may adversely affect the dentin mineralization process by interfering with coalescence of calcospherites . Overall , our results identify a crucial role for Dspp in orchestrating the events essential during dentin mineralization , including potential regulation of proteoglycan levels .

Diseases
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Diseases presenting "irregular mineralization front" symptom

dentin dysplasia

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