The age changes in dentin include:

The age changes in dentin include the formation of sclerotic dentin and dead tracts. Hydroxyapatite crystals are laid down in the intertubular dentin and within dentinal tubules to block the tubules, against the entry of bacteria, etc. The dentin then becomes transparent in transmitted light, hence often called transparent dentin. Permeability of dentin becomes reduced ,while hardness increases in these regions. Breakage of apical thirds of roots during extraction of teeth of elderly is due to the brittle nature of sclerotic dentin. Dead tracts are areas containing degenerated dentinal tubules, which appear dark in transmitted light. These are often seen in attrited or abraded teeth or below the carious lesions.