Tooth enamel (enamelum) is the outermost layer over the so-called tooth crown, the part of the tooth that protrudes from the gums into the oral cavity. Enamel is one of the most resistant and hardest tissues in our body and protects the tooth from irritation and damage.
What is enamel?
Schematic structure of the tooth and its components. Click to enlarge. Enamel gives a tooth a shell that must withstand a great deal of pressure as it crushes food. It protects the tooth from damage and wear and is the hardest substance in the human body due to its fluorine compounds, hydroxyapatite. Due to this hardness, the enamel can only be worked on by the dentist with rotating instruments equipped with diamond grains. Tooth enamel is arranged in hexagonal prisms held together by a putty substance. Due to this crystalline structure, the enamel shines. Because it does not bleed through, enamel once destroyed cannot be rebuilt.
Anatomy and structure
Enamel is made up of a composition of various mineral components and normally has a thickness of up to 2.5 millimeters. The crystalline material hydroxyapatite, consisting of calcium and phosphate, is the main component of tooth enamel. It ensures that water-soluble substances and fluoride can penetrate the enamel. Fluoride, in turn, converts the hydroxyapatite into the much harder substance fluorapatite and is therefore also used in toothpaste. Tooth enamel is neither supplied with blood nor does it have nerves, which is why there is no pain when caries merely destroys the enamel. It is already formed in the jawbone, even before the tooth breaks through into the oral cavity. On the surface of the enamel, the enamel cuticle (cuticula dentis) is formed again and again from saliva.
Function and tasks
Healthy enamel can withstand almost any stress due to its exceptional hardness. This extraordinarily resistant substance protects the tooth from wear as well as decalcification caused by acids contained in food. The enamel compensates for temperature fluctuations and prevents the tooth from being attacked by bacteria. The hardness of the enamel is based on the respective content of calcium phosphate and fluorine. The more the enamel contains of these two substances, the better it is resistant to external attacks. The enamel epidermis, an invisible coating on the enamel, is formed from components of saliva. When teeth are brushed, this coating is brushed away, only to form again. It has a protective and repair function.
Diseases and ailments
Tooth enamel may be extremely hard and therefore able to withstand most mechanical stresses. But acids and bacteria manage to remove the substances calcium and phosphate from the enamel, softening it and making the tooth susceptible to decay. This happens as bacteria that produce acid from the sugars (carbohydrates) in food attach themselves to the enamel’s cuticle. Especially where the toothbrush or tongue reaches less, the layer of bacteria thickens and plaque or biofilm forms. Acid exposure also roughens the enamel epithelium, allowing thicker and thicker layers of plaque to gradually accumulate on the teeth. Saliva contains all the substances that can repair the damage caused to the enamel after an acid attack. However, these substances can also be deposited in the plaque, causing calcification and thus tartar. The development of caries or tooth decay is favored by tartar. At the beginning, caries does not cause pain. Discomfort only occurs when the enamel is already damaged. To save the tooth, the carious substance must be removed by the dentist and the hole must be filled again. Regular and careful brushing is essential to protect the enamel and thus the teeth. Interdental spaces should be cleaned with brushes or dental floss. Acidic fruit juice and fruit consumption roughen the enamel and make it more vulnerable, which is why you should wait a while before brushing your teeth after eating them until the coating has built up again through saliva.
