Sugar solutions on the surface of exposed dentine cause water to be drawn out of the dentinal tubules causing which distorts the odontoblast causing pain.
[医务英语]《专业语—腔语O2(英文详解)》正文: Osmotic pressure - Water tends to move towards dense concentrations of ions.
Dentin matrix protein 1 (DMP1) is expressed in both pulp and odontoblast cells and deletion of the Dmp1 gene leads to defects in odontogenesis and mineralization.
The outer wall of the pulp, contains odontoblasts which are cells that secrete a bonelike substance called dentin, which is filled with protein and minerals.
The odontoblasts have long processes, or arms, that lay within tiny tubules in the dentin - like an octopus sticking it's arms through a block of cement.
Having both cell types seemed to be crucial: when odontoblasts were present alongside ameloblasts, genes coding for enamel proteins were more strongly expressed than with ameloblasts alone.