Last revised by Craig Hacking on 25 Jan 2023

The teeth (singular: tooth; collective term: dentition) can be both primary and secondary, with the eruption of permanent teeth occurring over a long period between the ages of 6 and 24 years. When an individual has a complete set of teeth, they are said to be dentate, if some are missing they are partially dentate. Complete absence of the teeth is termed edentulism, if only a few teeth are remaining then partial edentulism.

There are twenty deciduous (primary) teeth in young children, with ten per jaw and five in each quadrant, which consist of (distal to mesial):

  • two molars

  • one canine

  • two incisors

    • central incisors are the first to erupt, around 6 months of age

The deciduous (primary) teeth start erupting at six months (lower central incisor) and are completely erupted by around 3 years of age. They are then progressively replaced by permanent (secondary) teeth from the age of six with the final eruption of the third molar between 18-24 years 5.

There are normally a total of 32 permanent (secondary) teeth in adults, with 16 per jaw and eight in each quadrant, which consists of (distal to mesial) 3

  • three molars

    • "wisdom teeth" refer to the third molars

  • two premolars

  • one canine

  • two incisors

The dental arch describes the crescentic formation of teeth on each jaw.

The tooth sits in alveolar processes of the upper jaw (maxilla) or lower jaw (mandible). Each tooth is mainly composed of dentin and is made up of several parts 1-3:

  • crown: portion of the tooth projecting out of bone

    • dentin is covered by enamel

  • root: portion of tooth embedded in bone

    • composed of cementum

  • pulp chamber and root canal: lie centrally within the tooth and contain neurovascular structures

  • apical foramen: lies at the apex of the tooth root

The periodontal ligament connects the tooth root to the underlying lamina dura, which itself is the cortical bone which lines the tooth socket. This joint between a tooth and alveolar bone is a fibrous joint called a dentoalveolar syndesmosis.

Arterial supply to the teeth is derived from the maxillary artery, a branch of the external carotid artery, via the:

Venous drainage of the teeth is into either the:

via vessels that generally follow the arteries.

The teeth do not have any lymphatic vessels.

The teeth are well visualized on these modalities 1-3:

  • enamel: most radiopaque part, hardest tissue in the human body

  • dentin and cementum are less radiopaque than the enamel and are indistinguishable on these modalities

  • pulp chamber and root canal are lucent and positioned centrally

  • periodontal ligament is a linear lucency between the tooth and the lamina dura

ADVERTISEMENT: Supporters see fewer/no ads

Cases and figures

  • Figure 1
    Drag here to reorder.
  • Figure 2
    Drag here to reorder.
  • Figure 3: tooth names
    Drag here to reorder.
  • Figure 4: ADA Universal notation
    Drag here to reorder.
  • Figure 5: FDI/ISO notation
    Drag here to reorder.
  • Figure 6: Palmer notation
    Drag here to reorder.
  • Figure 7: UK alphanumeric notation
    Drag here to reorder.
  • Figure 8: ADA notation on CT
    Drag here to reorder.
  • Figure 9: FDI notation on CT
    Drag here to reorder.
  • Case 1: normal permanent dentition
    Drag here to reorder.
  • Case 2: normal primary dentition
    Drag here to reorder.
  • Case 3: supernumerary teeth
    Drag here to reorder.
  • Updating… Please wait.

     Unable to process the form. Check for errors and try again.

     Thank you for updating your details.