The dentition of an adult, if all wisdom teeth (sapiens) are present, consists of 32 teeth, which are divided into four types of teeth: Incisors, canines, anterior molars, and posterior molars, also known as molars. Since the third molars do not erupt until adulthood, they are also called wisdom teeth.
What are wisdom teeth?
Wisdom teeth, also referred to as dentes serotini (= late coming teeth), appear between the ages of 16 and 25, making them the last teeth to develop in the human dentition. There are also cases in which they erupt later or not at all, because often upper and lower wisdom teeth are not established in the jaw. Since they are placed last in the row of teeth, i.e. eighth from the center of the dentition, they are also called eights. The upper wisdom teeth show the most irregularities of all teeth in terms of crown and root shape. Lower wisdom teeth often show tooth position anomalies, so that eruption is often accompanied by complications. In many people, the wisdom teeth are outside the tooth row and are therefore not infrequently the cause of various diseases or complaints.
Anatomy and structure
The wisdom tooth, like all other teeth of the permanent dentition, consists of the tooth crown (corona dentis), the tooth neck (cervix dentis) and the tooth root (radix dentis). A tooth is composed of several layers. The outermost layer, the enamel (enamelum) is the hardest substance found in the human body. It consists of 95 percent crystalline material called hydroxyapatite, whose main components are calcium and phosphate. Tooth enamel is formed by adamantoblasts, enamel-forming cells. The enamel is slightly permeable to water-soluble substances such as calcium, phosphate and fluorides. The dentin, which is the main mass of the tooth, lies directly under the enamel. Two-thirds of the hard substance of the dentin, like the enamel, consists of phosphate and calcium. The last third is composed of protein and water, which is why dentin is less hard and therefore more susceptible to caries than enamel. In addition, dentin is sensitive to pain. Stimuli of touch, cold and heat trigger fluid movements in the dentinal tubules, irritating the cell processes (Tomes’ fibers) of the dentine-forming cells (odontoblasts). Nerve endings associated with the odontoblasts transmit this stimulus to the central nervous system as a sensation of pain. The inner part of the tooth is filled by the pulp, which is also colloquially referred to as the dental nerve. The pulp is permeated by nerve fibers and blood vessels and nourishes the tooth. At the root of the tooth, the dentin is encased by the root cementum, which forms the outer covering of the tooth at this point and anchors it to the jaw.
Functions and tasks
Originally, the wisdom teeth had the task of crushing raw food that humans found in nature. Over the millennia, the dietary shift to cooked food and home cultivation of grains, vegetables, and fruits led to increasing atrophy of the wisdom teeth. At the same time, the human jaw became smaller, so that today they are only considered relics of times gone by. However, if the wisdom teeth erupt completely in the correct position, they are useful chewing elements.
Diseases
Problems with wisdom teeth usually occur when there is insufficient space in the jaw. If it is too narrow, the teeth cannot grow far enough into the oral cavity and become partially or completely stuck in the jaw. Teeth remaining in the jaw can damage or displace neighboring teeth. This can lead not only to aesthetic losses due to tooth misalignment, but also to the formation of niches between the teeth that are difficult to clean and thus susceptible to caries and periodontal disease. The gum pockets, which are formed by wisdom teeth that have only partially erupted, are a veritable hotbed of bacteria, as food residues accumulate there that can only be removed with difficulty or not at all. This often leads to gum inflammation in these areas, which can lead to abscesses or even life-threatening phlegmon.