Odontoblast Processes: New Insights into Its Role in Dentin Mineralization

The formation of dentin is a highly regulated and well-controlled process, in which odontoblasts form a massive dentin tubular system with one main stalk. These tubules secrete collagenous proteins followed by the deposition of inorganic calcium phosphate in the form of mineral crystals. Two non-collagenous matrix proteins (dentin matrix protein 1, DMP1; and dentin sialophosphoprotein, DSPP) play an important role in the control of mineralization. The current theory, named “mineralization front,” is that minerals are deposited at the edge of the dental pulp and the dentin. In this chapter, we briefly introduced an overall background on dentin mineralization and key roles of DMP1 and DSPP. We then focus on two new findings in researches of dentin mineralization: a recent breakthrough in mineralization mechanism studies because of applications of mineral labeling in a cell lineage-tracing line (the Gli1-creERT2; R26RtdTomato) and the 2.3 Col1a1-GFP reporter line; and discoveries of a novel function of bone morphogenetic protein 1 (BMP1) and tolloid-like 1 (TLL1) proteinase in control of DMP1 and DSPP during dentinogenesis. These findings challenge the current dogma and will shed new light on our understanding of dentin structure and function as well as the mechanisms of mineralization.