How do teeth and the periodontium work?

Teeth are made up of different “materials.” The main material is a bone-like substance called dentin. It contains minerals and organic tissue such as collagen fibers. On the crown of the tooth, it is covered by a hard outer layer called enamel. Tooth enamel is the hardest substance in the human body. It mainly consists of minerals such as phosphorus, fluoride and calcium. The layer of enamel protects the softer dentin from wear and tear. At the very center of the tooth there's a hollow space with pulp in it. Tooth pulp is soft tissue containing blood vessels and nerves. It supplies the tooth with nutrients.

Each tooth is divided into three parts:

• The crown: This is the upper part of each tooth – the part that you can see when you look inside the mouth. The crown of the tooth is protected by a layer of enamel.
• The root: This is the lower part of the tooth – the part that's embedded in the upper or lower jawbone. Different types of teeth have a different number of roots: Incisors and canine teeth usually have only one root, while molars can have up to four. The tooth's nerves and blood vessels run through the roots.
• The neck: This is where the enamel on the crown of the tooth meets the root. In a healthy tooth, the neck is covered by the gums.

Teeth are sometimes damaged by tooth decay. This happens if bacteria in the mouth produce acid that attacks the tooth enamel. As a result, holes (cavities) may gradually appear on the surface of the teeth. If the tooth decay gets worse, deeper layers of the tooth may also become damaged.

The periodontium surrounds and supports our teeth, keeping them firmly in place. It is made up of four parts:

• the tooth sockets
• the periodontal ligament
• the cementum
• the gums

Tooth sockets (also called dental alveoli) are holes in the jaws that contain the roots of the teeth. The jaws and the walls of the tooth sockets are made up of bone tissue. This part of the periodontium is not usually visible.

The teeth are connected with the walls of the tooth sockets and anchored in the jaws by the periodontal ligament and the cementum. The periodontal ligament is made up of connective tissue and contains collagen fibers. These fibers are especially strong so that our teeth can withstand the great pressure put on them when we chew. The teeth can also move slightly in the ligament to absorb some of the pressure from chewing. As well as connective tissue and collagen fibers, the periodontal ligament contains blood vessels and nerves. The blood vessels supply the ligament with nutrients, and the nerves help you to adjust the amount of force used while chewing.

The actual tooth has an outer layer of cementum around its root. The cementum is mostly made up of minerals, but also contains collagen fibers. It is very firmly attached to the periodontal ligament, binding the root of the tooth to the rest of the periodontium. The outer layer of the tooth gradually changes from cementum to enamel at the neck of the tooth.

The gums (gingiva) cover and protect the periodontal ligament and the neck of the tooth, and are usually the only visible part of the periodontium. They fit tightly around the teeth like a collar. At the point where the gums meet the teeth, they turn slightly inward, forming a narrow groove.

The gum tissue can easily become inflamed, causing it to slightly detach from the neck of the tooth. The space between the tooth and the gum may then get bigger, forming a gum pocket. Bacteria rapidly build up in these pockets. Sometimes inflamed gums ( gingivitis) can lead to periodontitis. This is an inflammation of the periodontium that may attack the gums and the jawbone. Advanced periodontitis can cause teeth to become loose and fall out.