Human tooth anatomy

What is the oral cavity?

Simply put, the oral cavity is the interior of the mouth. It is bounded laterally by the cheeks, superiorly by the palate, inferiorly by the floor of the mouth and anteriorly by the lips.

For the most part, the oral cavity is filled by the tongue. The area between the teeth and the lips or cheeks is also called oral vestibule. In a human oral cavity there can be more than 700 species of bacteria, which live in a natural balance without harming the individual. Diseases usually only occur when this balance is disturbed. Caries and gingivitis are among the most common diseases of the oral cavity.

The oral mucosa

The oral mucosa is located on the inside of the oral cavity and covers it completely. The part of the oral mucosa around the teeth is called gum.

The oral mucosa, which consists mainly of connective tissue, contains some lymphocytes (defence cells). The mucosa is covered by a squamous epithelium. The oral mucosa contains sensory cells for temperature, pain and touch. Where the mucosa is subject to greater stress during chewing, it is somewhat harder than in unstressed areas.

Different types of teeth and their function

Our teeth play a crucial role in our daily lives. They enable us to chew our food and contribute to the articulation and shaping of our face.

Function of the teeth

Our teeth have various functions, including crushing and grinding food, which facilitates the digestive process. They also play an important role in pronunciation and facial expression. Accordingly, they have both a health-functional and an aesthetic purpose.

Different types of teeth

There are different types of teeth, each of which fulfils a specific function.

Incisors

The teeth situated at the front of the jaw are called incisors and can be found in both jaws. Incisors are sharp, as they are used to bite and cut food.

Together with the canines, the incisors belong to the front teeth. There are 8 incisors in the human dentition – two central and two lateral incisors in each jaw. The cutting edges of the upper and lower teeth perform a scissor-like motion. The tips of the incisors may appear transparent due to the thinner enamel.

Canines / eye teeth

The canines are situated between the incisors and molars. There are 4 canine teeth in the human dentition. 2 in the upper jaw and 2 in the lower jaw.

In Icelandic, the canine tooth is called Augntönn and in English it is also called eye tooth, which takes its name from the long roots of the upper canine that almost reach the bony eye socket. Inflammations of this tooth therefore often lead to redness and swelling just below the eye.

Premolars

In the human dentition, premolars belong to the molars. In the permanent dentition, there are two premolars per quadrant, situated between the canines and the molars.

Originally, there were 4 premolars in each half of the jaw, but over time, however, these have been reduced to 2. Rodents no longer grow premolars at all. In the human dentition, premolars usually have two cusps and two root canals.

Molars

The molars are situated in the back of the jaw next to the premolars.

The word “molar” comes from the Latin “molaris”, which means millstone. There are 12 molars in the permanent dentition of humans. Most people know the molars at the very back as wisdom teeth.

Wisdom teeth

Wisdom teeth are the most posterior molars. Seen from the centre, it is the 8th tooth on the left and right of the upper and lower jaw.

Generally speaking, every human being has four wisdom teeth. The name wisdom teeth comes from the fact that they only erupt in adulthood, at an age where people are presumably “wiser”. In Latin, they are called dentes intellectus. In many cases, wisdom teeth have to be extracted because there is a discrepancy between the size of the jaw and the number of teeth. These disproportions cause the wisdom teeth not to erupt or to erupt only partially.

Permanent dentition

In the human dentition, the permanent teeth replace the deciduous teeth between the age of 6 and 17. The first permanent tooth is usually the first molar, also called the six-year molar.

The permanent dentition is composed of 32 teeth, 12 teeth more than in the primary dentition.

Deciduous teeth

Deciduous teeth (or baby teeth) are our first teeth, which remain from infancy to early adulthood. We have 20 deciduous teeth in total. The transition from deciduous teeth to permanent teeth is completed between the age of 12 and 17.

Tooth structure

The structure of our teeth is impressive and complex at the same time. They consist of different layers and materials that play an important role in their function.

Enamel

The enamel is the outer layer of the teeth. Tooth enamel is the hardest tissue in the human body, it is acid-soluble and cannot be reproduced. A cavity in the enamel can also cause pain. To protect the enamel from acids, a proper daily oral hygiene and a low-sugar diet are important.

Dentin

The dentin is the main component of our teeth, it consists of mineral and organic materials and lies below the enamel.

Unlike the enamel, dentin can regenerate. The dentin surrounds the pulp and is surrounded by the cementum in the area of the tooth root. Dentin is a bone-like matrix and has a yellowish colour.

Root (of the tooth)

The root is located underneath the tooth crown and anchors the tooth in the dental alveolus.

Blood vessels and nerve fibres penetrate into the roots of the teeth. These vessels and fibres exit through an opening and pass into the alveolar bone. The number of roots depends on the type of tooth: incisors and canines only have one, while molars have two or three.

Neck (of the tooth)

The neck of the tooth is the transition between the crown and the root of the tooth.

The enamel ends around the neck of the tooth with its thinnest part. The neck of the tooth does not form a straight line around the tooth and has different heights: at the point of contact with the adjacent tooth, the neck extends highest towards the crown. In a healthy dentition, the gums cover the necks. Certain diseases or incorrect brushing techniques can cause the gums to flatten and expose the necks of the teeth.

Dental pulp

The dental pulp fills the inside of the tooth. It extends from the tooth crown to the root area. The dental pulp consists of lymphatic and blood vessels, connective tissue and nerve fibres.

Cementum

The cementum is located in the root area of the tooth, it lies on the dentin and it is part of the periodontium.

The cementum surrounds the exterior part of the root area and separates the root of the tooth from the gum and jawbone.

Structure of the dentition

Our dentition is an amazing interplay of different structures that enable us to chew food, speak and form facial expressions.

The main functions of the dentition are:

• Chewing and crushing food: the main function of the teeth is to grind and prepare food so that it can be digested more easily.
• Articulation and pronunciation: our teeth and jaws play a crucial role in the formation of sounds and our ability to speak clearly and intelligibly.

Upper jaw

The upper jaw is a bone of the facial skull and forms the lower end of the eye socket as well as the side wall of the nasal cavity and part of the palate. Part of the upper jaw is formed by the alveolar bone, which contains the gum pockets.

Lower jaw

The lower jaw is a bone of the facial skull and forms the movable part of the masticatory apparatus in humans.

Part of the lower jaw is formed by the alveolar bone, which contains the gum pockets. The lower jaw is attached to the rest of the skull by the temporomandibular joint.

Dental alveolus

The tooth socket, also called alveolus, is the cavity in the jaw in which the roots of the teeth are held.

The part of the jaw where the tooth sockets are located is the alveolar process (also called alveolar bone). There are tooth sockets in the upper and lower jaw. Together with the gums, the dental cementum and the periodontal ligament, the alveolus is part of the periodontium.

Alveolar bone

The alveolar bone is the area in the upper and lower jaw where the tooth sockets (alveoli) are located. The teeth are rooted in the alveoli.

In the case of tooth loss, the alveolar bone is reduced to form a narrow ridge. Without prosthetic treatment, this results in a loss of height of the lower face.

Masticatory muscles and temporomandibular joint

The masticatory muscles and the temporomandibular joint form a remarkable unit in our body that not only enables us to chew food, but also provides precise control over our jaw movements.

Masticatory muscles

The masticatory muscles play a crucial role in chewing and grinding food. These muscles allow us to control the jaw movements required to grind food.

Temporomandibular joint (TMJ)

The temporomandibular joint is a hinge that connects the jawbone to the skull.

In mammals, the temporomandibular joint is formed by the mandibular fossa in the temporal bone and the head of the lower jaw.