Incisors – structure, function & diseases
Incisors
The incisors of the human dentition are single-root teeth , which are located in the front part of the lower or upper jaw and are often colloquially called “shovel teeth”.
What are incisors?
The four teeth in the lower and upper jaw that are located between the canines and have a pointed cutting edge or a shovel-like shape are called incisors (dens incisivus). Incisors have no chewing surface and the lower incisors are smaller than the upper ones.
Anatomy & Structure
The incisor is what is known as an anterior tooth, which is shovel-shaped and can be found in the front of the jaw. Around the age of five, the eight deciduous incisors are replaced by permanent teeth.
In young people, the incisal edge is divided by two incisions, while in adults these are usually ground down. The crown of the tooth has two marginal ridges on the back, which meet in the so-called tuberculum, a structure that has the shape of a hump. Above this is the foramen cecum. In the human dentition, the following incisors can be distinguished in the lower and upper jaw:
- Central incisor in the lower jaw 31/41
- Lateral incisor in the lower jaw 32/42
- Upper central incisor 11/21
- Lateral incisor in the upper jaw 12/22
The central incisors have three notches, the lateral ones two and one notch in the canine area. However, over time, wear of the incisal enamel edge occurs due to tooth abrasion, tooth erosion or tooth wear. This creates a uniform cutting edge. There are significant size differences 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 severely flattened. The roots of the incisors are relatively weak and therefore not suitable for post restorations. The lower incisors are the smallest teeth in the human dentition. Their labial surfaces are smooth and have a triangular basic shape. The tooth necks are pointed and narrow. The lingual surfaces are also triangular, but somewhat narrower.
The approximal surfaces have the shape of an acute triangle and the curvature feature can be seen on the contour. The lower incisors are also very delicately built and are therefore not suitable for crown replacements. In addition, the base of the crown is quite narrow, so it is also not possible to grind down the teeth without making them thin. They are also unsuitable as clasped teeth for aesthetic reasons.
Function & Tasks
Because the incisors have a sharp cutting edge, they are needed to bite off food. So they work like a small knife and have no chewing surface. The basis for optimal cutting quality is a good contour of the cutting edges, which can be lost due to the aging process.
In addition, the incisors are also of optical importance, since they belong to the front teeth. If they are discolored, crooked or broken off , this has an unaesthetic and unattractive effect. From an aesthetic point of view, the central upper incisors dominate, as they are conspicuous due to their size and are also very visible when smiling and speaking .
Diseases
Caries , a disease caused by bacterial pathogens, can develop on the incisors . In the front teeth, the neck of the tooth is particularly at risk. Tooth decay is caused by poor oral hygiene , which allows food debris to accumulate in the gaps.Due to special end products that are released during metabolism, damage to the tooth substance or caries occurs. The result is toothache and sometimes even tooth loss. Root inflammation can also occur in the incisors. The cause for this is usually caries, since the caries bacteria can attack the nerve of the tooth if left untreated. The inflammation irritates the nerves and in the worst case the dental nerve can die off. If the bacteria reach the tip of the root, it can also infect the jawbone. The remedy is usually 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 rinsesthe channel with different solutions.
In the case of severe inflammation, the tooth must rest for a few days, in the case of milder inflammation, the canal is filled with a rubber-like mass and sealed with dense cement. Normally, the incisors keep their natural color after a root treatment, but sometimes discoloration can also occur due to metabolic products. However, this discoloration can be eliminated with the help of lightening. Malpositions 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 misalignment is referred to as overbite of the lower jaw or overbite of the upper jaw and can be regulated in children from about nine years of age.
On the other hand, one speaks of an overbite of the upper jaw when the upper incisors recede behind the lower ones. If the lower incisors are not visible when biting, this type of misalignment is referred to as a deep bite. Tooth anomalies such as symmetrical hypodontia , in which the upper lateral incisors are missing, are not uncommon. In a so-called mesiodens, an underdeveloped tooth occurs between the upper central incisors.
Typical & common dental diseases
Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.