Brushing cannot clean between your teeth, but bacteria certainly can live there quite happily, creating enamel-destroying acid 24/7. Rinsing does not remove plaque anywhere, so flossing is a must. Here is an x-ray of a cavity between teeth:
Dentin is the layer of tooth beneath the outer enamel layer and is important for a few reasons:
The color of dentin shows through the enamel and imparts color to the tooth.
In this photo, the dentin is the darker inner layer:
The next two pictures are great examples of what acid in plaque does as it works its way through the outer enamel into the dentin. It turns the enamel frosty white, as acid does to glass, and turns the inner dentin dark brown.
Dentin is flexible and helps prevent fracture of the brittle overlying enamel.
Dentin contains tubules that transmit painful stimuli like cold and sweet. Are your teeth sensitive? Blame it on the dentin.
Dentin allows faster spread of bacteria from the outside of the tooth to the inner nerve (pulp).
That’s dentin in a nutshell.
Love your smile,