Abstract
Considerable amount of research has been focused on dentin mineralization, odontoblast differentiation, and their application indental tissue engineering. However, very little is known about the differential role of functionally and spatially distinct types of dentalepithelium during odontoblast development.
Here we show morphological and functional differences in dentin located in the crownand roots of mouse molar and analogous parts of continuously growing incisors. Using a reporter (DSPP-cerulean/DMP1-cherry)mouse strain and mice with ectopic enamel (Spry2+/;Spry4/), we show that the different microstructure of dentin is initiated inthe very beginning of dentin matrix production and is maintained throughout the whole duration of dentin growth.
This phenom-enon is regulated by the different inductive role of the adjacent epithelium. Thus, based on the type of interacting epithelium, weintroduce more generalized terms for two distinct types of dentins: cementum versus enamel-facing dentin.
In the odontoblasts,which produce enamel-facing dentin, we identified uniquely expressed genes (Dkk1,Wisp1, andSall1) that were either absent ordownregulated in odontoblasts, which form cementum-facing dentin. This suggests the potential role of Wnt signalling on the dentinstructure patterning.
Finally, we show the distribution of calcium and magnesium composition in the two developmentally differenttypes of dentins by utilizing spatial element composition analysis (LIBS). Therefore, variations in dentin inner structure and elementcomposition are the outcome of different developmental history initiated from the very beginning of tooth development.
Takentogether, our results elucidate the different effects of dental epithelium, during crown and root formation on adjacent odontoblastsand the possible role of Wnt signalling which together results in formation of dentin of different quality.