An adult usually has 32 permanent teeth, though some individuals only have 28 permanent teeth as the wisdom teeth either never emerge or need to be removed.
Not all these teeth are identical. The back molars are different to the front incisors, as are the canine teeth between them teeth. But the underlying structure of the teeth are basically the same. All teeth have a central nerve, a surrounding pulp, a mid layer of dentin, and an outer layer of hard enamel.
We can only see the top part of the tooth that is above the gum. Beneath this outer visible section of the tooth is the root, hidden in the gum. This root varies in size between individuals, but is often larger then the outer section. It provides the anchor for the tooth and allows blood to flow into the tooth’s central nerve. The root is attached to the jawbone via the periodontal ligaments.
The visible part of the tooth has several layers behind the hard outer enamel. If the hard outer layer is damaged, perhaps by decay, then these inner layers are exposed. This is a serious problem, with the tooth almost always continuing to get worse till it fails completely. The tooth itself will probably be painful at this stage, and sensitive to hot and cold temperatures.
The layer immediately beneath the outer enamel is the dentin. This dentin layer is slightly yellow in colour, and less rigid, less brittle than the outer enamel. It is necessary for support of the tooth, as the outer enamel is too brittle for this. Dentin is a mixture or organic and mineral components.
Dentin provides some of the colour of the tooth as the outer enamel is semi-transparent. We see some of the colour of the dentin when looking at a healthy tooth.
If the dentin is exposed to the outside, when the enamel is damaged, the tooth becomes sensitive to hot and cold temperatures. This is because the channels through the dentin conduct the heat/cold directly to the nerve inside the tooth. The enamel is needed to provide some insulation for the tooth nerve.
Diligent brushing and flossing goes a long way to preventing dental decay and gum problems. Use of mouthwash also helps, though this does not replace brushing and flossing.
Our teeth have a much better chance of staying healthy if we look after then every day.