The incisors of the human dentition are single-rooted teeth located in the front part of the lower or upper jaw and are often colloquially called “shovel teeth”.
What are incisors?
Incisors (dens incisivus), are the four teeth in the lower or upper jaw that are located between the canines and have a pointed cutting edge or a shovel-shaped form. Incisors do not have an occlusal surface and the lower incisors are smaller than the upper incisors.
Anatomy and structure
The incisor is a so-called front tooth, which is shovel-shaped and can be found in the front of the jaw. At about the safest year of life, the eight deciduous incisors are replaced by permanent teeth. In adolescents, the incisal edge is still divided by two incisions, while in adults these are usually ground down. The crown of the tooth has two marginal ridges on the posterior side, these meet in the so-called tuberculum, a structure that has the shape of a cusp. Above this lies the foramen caecum. In the human dentition, the following incisors can be distinguished in the lower or upper jaw:
- Middle incisor in the lower jaw 31/41.
- Lateral incisor in the lower jaw 22/42
- Central incisor in the upper jaw 11/21
- Lateral incisor in the upper jaw 12/22
The central incisors have three notches, the lateral have two and one notch is visible in the canine region. However, over time, due to tooth wear, tooth erosion or tooth wear, there is wear of the incisal enamel edge. This results in a uniform incisal edge. There are significant differences in size between the lateral and central incisors in the upper jaw, and the incisors found in the lower jaw are also smaller. The lower incisors have only one root, which is strongly flattened. The roots of the incisors are relatively weak and therefore not suitable for post restorations. The lower incisors represent the smallest teeth in the human dentition. Their labial surfaces are smooth and have a basic triangular shape. The tooth necks are pointed and narrow. The lingual surfaces are also triangular, but slightly narrower. The proximal surfaces have the shape of an acute-angled triangle and the curvature feature can be seen on the contour. The lower incisors are also very delicately built and therefore do not qualify for crown replacement. In addition, the crown base is quite narrow, so it is also not possible to grind the teeth without making them thin. For aesthetic reasons, they are also unsuitable as clasp teeth.
Function and tasks
Since incisors have a sharp cutting edge, they are needed for biting off food. Thus, they function like a small knife and do not have a chewing surface. The basis for optimal cutting quality is a sharp contour of the cutting edges, which can, however, be lost due to the aging process. In addition, the incisors also have an optical significance, as they belong to the front teeth. If they are discolored, crooked or broken off, this looks unaesthetic and unattractive. In terms of aesthetics, the central upper incisors dominate, because they are conspicuous due to their size and are also very visible when smiling and speaking.
Diseases
Caries can develop on the incisors, a disease caused by bacterial pathogens. On the front teeth, it is mainly the neck of the tooth that is particularly at risk. Caries is caused by irregular oral hygiene, so that food debris can accumulate in the spaces between the teeth. Due to special end products that are secreted during metabolism, damage to the tooth substance or caries occurs. As a result, toothache and sometimes even loss of the tooth occurs. Furthermore, root inflammation can occur in the incisors. This is also usually caused by caries, as the caries bacteria can attack the tooth nerve if left untreated. The inflammation irritates the nerves and in the worst case the tooth nerve can die. If the bacteria reach the tip of the root, the jawbone may also be affected. The remedy is usually a root canal treatment, in which the tooth is opened with the help of a drill. This allows the pulp and nerve fibers to be removed.Then the dentist rinses the canal with various solutions. In case of severe inflammation, the tooth must rest for a few days, in case of lighter inflammation, the canal is filled with a rubber-like mass and sealed with density cement. Normally, incisors keep their natural color after root canal treatment, but sometimes discoloration may occur due to metabolic products. However, these discolorations can be eliminated with the help of whitening. Misalignments in the area of the incisors are also possible. If, for example, the lower row of teeth is overlapped by the upper incisors by a large distance, this malocclusion is referred to as a backbite of the lower jaw or a forward bite of the upper jaw and can be corrected in children from about nine years of age. A backbite of the upper jaw, on the other hand, is when the upper incisors recede behind the lower incisors. If the lower incisors are not visible when biting down, this type of malocclusion is called a deep bite. Dental anomalies, such as symmetrical hypodontia, in which the upper lateral incisors are missing, are also not uncommon. In a condition called mesiodens, an underdeveloped tooth occurs between the upper central incisors.
Typical and common dental diseases.
- Tooth loss
- Tartar
- Toothache
- Yellow teeth (tooth discoloration)