Corpus: Tooth

Teeth are part of the masticatory apparatus. They consist mainly of the hard substances enamel and dentin, which are made up of collagen and hydroxyapatite.

Teeth serve to break down food and prepare it for subsequent digestion in the gastrointestinal tract.

The permanent dentition of adults generally contains 32 permanent teeth (dentes permanentes). These include:

• Incisors
• Canines
• Premolars
• Molars, which include the wisdom teeth (dentes serotini)

The human deciduous dentition, in contrast, consists of 20 deciduous teeth (dentes decidui).

The shape of the teeth is determined by their function during the chewing process. Incisors are wedge-shaped to enable biting off solid food, while premolars and molars have chewing surfaces with cusps and fissures suitable for crushing and grinding food.

Teeth are arranged in four quadrants, with the border running between the incisors. Each quadrant in the permanent dentition consists of:

• 2 incisors
• 1 canine tooth
• 2 premolars
• 3 molars

The third molar, or wisdom tooth, is often not fully developed or only partially erupts due to a lack of space.

The tooth formula, based on the incisors, shows the structure of a quadrant in the upper and lower jaw:

• Tooth formula for the permanent dentition: 2-1-2-3/2-1-2-3 (x2) = 32
• Tooth formula for the primary dentition: 2-1-2/2-1-2 (x2) = 20

A single tooth is structured as follows:

• Tooth crown (Corona dentis): The part of the tooth covered by enamel
• Tooth neck (Collum/Cervix dentis): The border zone between enamel and cementum
• Tooth root (Radix dentis): The part of the tooth anchored in the bone and covered with cementum. There can be one to three roots, each ending in an apical foramen. The division point of the tooth roots is called a furcation.
• Tooth cavity (Cavitas dentis): Contains the dental pulp

Each tooth consists of four types of tissue:

• Enamel
• Dentin
• Pulp
• Cementum

The teeth of the upper jaw are innervated by branches of the maxillary nerve V₂ (superior alveolar nerve). The mandibular nerve V₃ (inferior alveolar nerve) innervates the teeth of the lower jaw.

The most well-known and significant diseases of the teeth and periodontium include caries and periodontitis.