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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):
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:
"wisdom teeth" refer to the third molars
The dental arch describes the crescentic formation of teeth on each jaw.
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:
inferior alveolar artery: arises from the maxillary artery then enters the mandibular foramen
Venous drainage of the teeth is into either the:
via vessels that generally follow the arteries.
The teeth do not have any lymphatic vessels.
posterior superior alveolar nerve supplies the maxillary molar teeth apart from the mesiobuccal root of the first maxillary molar
middle superior alveolar nerve supplies the mesiobuccal root of the first maxillary molar and premolars
anterior superior alveolar nerve supplies the incisors and canines
hyperdontia: supernumerary teeth
hypodontia: congenital absence of teeth
macrodontia: atypically large teeth
microdontia: atypically small teeth
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
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