THE STRUCTURE AND FUNCTION OF OUR MOUTH AND TEETH
   
Structure of teeth
   
Scientifically speaking, our teeth (Latin: dentes) are symmetrically arranged formations of bone-like consistency, embedded in special recesses in the jaw, which crush food and form sounds for speech.

Teeth are divided into three areas; the crown (the visible part), the neck (at the gum line) and the root (hidden in the jaw bone).

A tooth is made up of many layers formed around a core. The first layer consists of very hard material, the enamel. The second layer is comprised of yellowy dentine, which surrounds the dental pulp containing the nerves. Finally, the cementum covers the root and anchors the tooth in the jaw bone.
       
Enamel
   
In a set of teeth, the visible part is the white or yellowy enamel. This is the hardest material in the human body, consisting of calcium phosphate, fluorine, protein and water. Thanks to this combination, the enamel optimally protects the interior of each tooth from temperature differences, bacteria and acids, as well as from the pressure required to chew food.

Dentine
   
The largest component of the tooth is comprised of dentine—the second barrier for protecting the dental pulp. In contrast to the enamel, it is made up of less compacted material and is thereby more susceptible to acids and bacteria. Dentine contains many tiny canals, through which run the nerve fibers. When a tooth is carious, the nerve fibers send impulses to the brain. We feel pain and go to the dentist.

Pulp
   
The pulp lies in a hollow chamber that is surrounded on all sides with dentine. It is comprised of blood vessels, connective tissue and cells. Appendages of the cells and nerves rise into the dentine; they supply it with nourishment, deposit dentine and transfer impulses.

The pulp is also responsible for the highly complex process of tooth formation. Before baby teeth or permanent teeth break into the oral cavity, pulp cells form dentine and enamel.
   
Cementum
   
In the jaw bone, the root is surrounded by cementum. It is interspersed with tiny connective fibers, which anchor the tooth into its socket with some degree of flexibility. The tooth is actually suspended from fibers which connect the bone to cementum. It is, therefore, not directly attached to the bone.
       
How many and what kind of teeth do I have in a full set?
   
Children and babies possess only twenty teeth, because the jaw still needs to grow. This process begins as a baby and is completed by around the age of two. The upper and lower jaw and complete set of teeth are usually fully developed by around 17 years old. They contain 32 permanent teeth: four incisors, two canines, four premolars and six molars. These teeth have different functions: The incisors tear solid food and therefore mostly appear wedge-shaped. The canines, which are ideal for gripping food, are tapered off and have a long, distinctive root. The premolars are good for gripping larger pieces of food and for breaking down food into smaller pieces. They possess a broad, double-ridged chewing surface. The molars are good at crushing food as well, due to interlocking bumps in their surface that interlock like a cogwheel.
       
What happens in the oral cavity?
   
Food is softened with the help of saliva, of which a person produces between 1 and 1½ liters a day. Food can then be broken down more easily. Enzymes in saliva prepare for the final digestion of food in the stomach. Saliva also contributes to the cleaning of the teeth. A multitude of bacteria—or tiny, microscopic creatures—live in the oral cavity. This bacterial coexistence can be altered, for example, by poor oral hygiene or during food consumption, at which point the proportion of harmful bacteria and aggressive acids that harm the enamel can rapidly increase.