What are teeth?
Teeth are the main tools for “chopping” food, i.e. mechanical digestion. They are harder than the bones – the enamel, which is thickest on the chewing surface, is the hardest substance in the body.
Milk teeth and adult dentition
Children’s primary dentition consists of 20 teeth (deciduous teeth, Latin: dentes decidui): Five teeth sit in each quadrant (dentistry divides the dentition into four quadrants). They erupt between the sixth month and the end of the second year of life. Each tooth has a root with which it is anchored in the jaw.
The permanent teeth (dentes permanentes) are already present in the child’s jaw, under and between the roots of the milk teeth. As there is not enough space in the child’s jaw for all the permanent teeth, the molars are located in the lower jaw branch and in the area of the rear wall of the upper jaw. During the growth phase, they must therefore undertake a complicated migration to their final position in the dentition. If this migration is disturbed in any way, the permanent teeth can erupt in the wrong place in the jaw. Some molars are also positioned transversely and cannot erupt at all.
Tooth crown, tooth neck, tooth root
As differently shaped as incisors, canines and molars are, their structure is basically the same: the uppermost part, which protrudes from the gums into the oral cavity, is known as the crown of the tooth. Below this is the neck of the tooth, the thin transition from the crown to the root of the tooth. Normally, the neck of the tooth is barely visible because it is largely surrounded by the gums. The lower two-thirds of the tooth is called the tooth root; this anchors the tooth in the bone. Incisors and canines each have one root, while molars usually have between one and three. The number of roots varies greatly from person to person. In general, the further back the tooth is in the jaw, the more roots it has.
Tooth enamel
The tooth crowns are covered in enamel, the most resistant tissue in the body. It consists mainly of the mineral salts of calcium, phosphate and fluorine. Fluorine compounds are responsible for its extraordinary hardness. Thanks to them, healthy tooth enamel can withstand almost any mechanical stress – but not some chemical and biological substances: acids and bacteria can corrode and soften even the most stable tooth enamel.
Dentin (dentin)
Dental pulp (pulp)
The soft pulp is located inside the tooth. It contains nerve tissue, is well supplied with blood and nourishes the tooth from the inside out. The pulp is connected to the jawbone via a small hole at the tip of the root. Nerve fibers and blood vessels run through the root tip canal from the bone into the pulp.
Periodontium
At the transition from the crown to the neck of the tooth, the gum nestles tightly against the tooth and holds it elastically in place with thin fibers. The jaw has deep bony indentations (alveoli) into which the tooth roots are fitted. There is a microscopically tiny gap between the tooth and the jawbone, which is traversed by retaining fibers that provide a resilient suspension of the tooth in the bony socket. The fibers that pass through the small gap attach to the tooth root on the so-called cementum that covers the root surface. All layers together form the periodontium.
What is the function of teeth?
The teeth have the task of grinding all food so that it can be swallowed mixed with saliva to form a pulp. The teeth also play an important role in the shape of the lower part of the face and in the formation of sounds during speech.
Where are the teeth located?
What problems can teeth cause?
Misalignments and especially the absence of individual teeth can lead to misalignments in the temporomandibular joint, followed by muscle tension in the head area and headaches. Individual missing teeth also cause the neighboring teeth to shift or tilt.
Toothache is also a common problem with the chewing tools in the mouth. How does this pain arise? The teeth are supplied by nerve fibers that come from the fifth cranial nerve (trigeminal nerve). The nerve fibers enter each tooth root from below through openings in the jawbone and lie in the middle of the dental pulp. A protective layer of dentine and enamel surrounding the tooth prevents stimuli such as cold, heat or acid from being perceived as unpleasant. However, if the enamel is damaged (e.g. by caries), toothache can occur.
Exposed tooth necks also often react very sensitively to hot coffee, ice cream and the like. Their main cause is periodontitis – a chronic inflammation of the periodontium that causes the gums to recede further and further, exposing the neck of the tooth. As a result, affected teeth become increasingly loose and can eventually even fall out.
