The
Structure: Information about our teeth and surrounding tissues (1/4) - click for the next
The tooth is consisted of enamel, dentin, cementum and pulp.
Enamel: This is the hardest structure in a human body, and it surround the tooth for protection. It does not contain any nerves, therefore it is not sensitive. 97% of it consists of calcium salts. Enamel is formed by hexagonal apatit crystals. The formation of these crystals on our teeth starts in the womb. If the mother takes certain medication that prevents this, or if the child undergoes some illness which harm the crystallization enamel growth may be harmed and the teeth becomes yellow, gray or brown color. Sometimes it may also form missing (hypo-plastic).
Dentin: This is the layer underneath the enamel. 75% of an adult tooth is formed by dentin. Even though it has the same density as the bones, it is sensitive to heat and touch. Thanks to its repair cells, it is able to rebuilt itself. Dentin is covered at the crown part by enamel, and at the root part by cementum. Dentin is a living structure and it is consisted 70% electrolytes, 20% organic material and 10% water. It contains many micro channels, which is filled with extensions of repair cells. The cells that produce dentin are called Odontoblast. Micro dentin channels may reach the amount of 10.000 per mm square. When the tooth is drilled these channels may be exposed and the tooth may become sensitive to cold, hot, sweet or sour.
Pulp: It is the central part of the teeth and the soft tissue in it, which continues until the end of the root. At the root of the tooth there are blood vessels that feeds the pulp. Owing to these vessels the pulp is protected from infections and keeps alive. There are also quite sensitive nerves which makes it sensitive to hot, cold and pressure.
Cementum: It is the bony structure that covers around the root and it is quite thin. It helps the tooth to hold on the the jaw bones. Consists 65% inorganic materials.
Gums surround the teeth and provide a seal around them. Compared with the soft tissue linings of the lips and cheeks, most of the gingiva are tightly bound to the underlying bone and are designed to resist the friction of food passing over them.
Only the marginal part of the gingiva is visible from outside. It covers the teeth and alveolar bone. Gingiva is covered by oral epithelium.
Gums are hard, fibered structures which are well fed with with blood vessels. Healthy gingiva is usually coral pink. Gums are also connected to inner cheeks and lips with a softer tissue, which is called mucosa.
Mouth has an an important guard: Saliva. Saliva is produced in and secreted from the salivary glands, below the chin, underneath the tongue, and frontal ear. These lympf nodes produce almost 1.5 liters of saliva per day. Human saliva is composed mostly of water, but also includes electrolytes, mucus, antibacterial compounds, and various enzymes. As part of the initial process of food digestion, the enzymes in the saliva break down some of the starch and fat in the food at the molecular level. Saliva also breaks down food caught in the teeth, protecting them from bacteria that cause decay. Furthermore, saliva lubricates and protects the teeth, the tongue, and the tender tissues inside the mouth. Salivary glands transfers the saliva thought small channels. Those belonging to the frontal ear opens near the first molar, the others underneath the tongue. Due to the calcium content of the saliva, usually, more tooth calculus (tartar) is gathered on the teeth near the channel openings.
The use of saliva for the mouth and the teeth can be summarized as follows:
- Saliva mechanically cleans the teeth,
- Protects the teeth from decay,
- Protects the mucosa with its enzymes.
Only a newborn baby has a sterile mouth, however in few minutes it is contaminated with bacteria and other microorganisms, and it stays this way the whole life. Nevertheless, the reason why we do not get sick is because of the fact that these bacteria is not the kind that produces illness (saprofite type mucosal bacteria). Only when our immune system drops these can cause illnesses. All of the bacteria exist in the mouth forms the mouth flora.