Anatomy Of Tooth
The purpose of this article is to help patients understand the anatomy of a tooth.
Each tooth has:
- A crown
- A root or roots
- Supporting structures
What makes up a tooth?
Enamel covers the whole of the crown of a tooth. The enamel can be up to 2.5mm thick and is extremely hard. It is normally thinnest near the gum level and thicker on the biting surfaces of teeth.
Enamel is strong because it consists of rods of calcified tissue cemented tightly together. Enamel has no nerve supply or living cells associated with it and so cannot be considered to be living tissue. Once the enamel is formed it cannot be replaced if it is damaged due to dental decay or trauma.
Enamel is so hard that it decays at a much slower rate than dentine. Enamel that becomes unsupported by decayed dentine will easily break.
Dentine makes up the bulk of the crown and root of a tooth. In the crown, it is covered by enamel and in the roots, a thin layer of cementum covers it. Dentine is softer than enamel and is yellow in colour.
Dentine consists of hollow calcified tubes called dentinal tubules. These tubules are associated with cells called odontoblasts and can transmit pain. It is because of thickening of dentine throughout life that teeth appear to yellow with age- the colour of a tooth is largely determined by the colour of the dentine shining through the enamel.
Cementum forms the outer covering of the dentine in the root of a tooth and its hardness is similar to that of bone. Some people say it is a bone-like substance. Cementum is also a living tissue and it thickens gradually throughout life.
The dental pulp, or pulp as it is most commonly called, is a type of loose connective tissue with nerves, blood vessels, tissue fibres and other tissue cells.
The pulp occupies the pulp chamber inside the crown of a tooth and the pulp canals within the root or roots.
The function of the pulp is to nourish the dentine and to act as a sensory organ that responds to damaging stimuli such as invasion from micro-organisms, chemical irritations, heat, cold and other irritations. These stimuli are generally interpreted as pain by the nerve ending in the pulp. The pulp decreases in size throughout life due to the increasing thickness of dentine.
The periodontal ligament is fibrous tissue, with fibres running from the cementum to the alveolar bone of the toothâ€™s socket.
The periodontal ligament has the following functions:
- Holds the tooth in the socket
- Acts as a shock absorber
- Acts as a shock absorber
- Protects the nerves and blood vessels from strangulation at the tip of the root at the apical foramen.
- Tells us, by sensitivity, where our teeth are when in contact with one another
- Protects teeth from damage caused by excessive force
- Supplies nutrients to the cementum
As with other bony tissue, alveolar bone has an outer layer of compact bone known as the cortical plate with the bulk of the bone being made up of cancellous or spongy bone.
The gingiva is the mucous membrane that covers the alveolar ridge and forms a cuff around the neck of each tooth.
For more information on the anatomy of teeth feel free to contact our team at Harbour Drive Dental. Watch out for next weekâ€™s article on Tooth Decay.