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Tooth diagram

Most adults have 32 teeth, including wisdom teeth. Our teeth are one of the hardest parts of the body.

Teeth are essential for chewing food, but what lies beneath the shiny white surface of a healthy tooth?

human_tooth_revised.jpg

 

Parts of the teeth

Parts of the teeth include:

  • Enamel: The hardest, white outer part of the tooth. Enamel is mostly made of calcium phosphate, a rock-hard mineral.
  • Dentine: A layer underlying the enamel. Dentine is made of living cells, which secrete a hard mineral substance.
  • Pulp: The softer, living inner structure of teeth. Blood vessels and nerves run through the pulp of the teeth.
  • Cementum: A layer of connective tissue that binds the roots of the teeth firmly to the gums and jawbone.
  • Periodontal ligament: Tissue that helps hold the teeth tightly against the jaw.

Types of teeth

  • Incisors (eight in total): The middle four teeth on the upper and lower jaws.
  • Canines (four in total): The pointed teeth just outside the incisors.
  • Premolars (eight in total): Teeth between the canines and molars.
  • Molars (eight in total): Flat teeth in the rear of the mouth, best at grinding food.
  • Wisdom teeth or third molars (four in total): These teeth erupt at around the age of 18, but are often surgically removed to prevent displacement of other teeth.

The crown of each tooth projects into the mouth. The root of each tooth descends below the gum line, into the jaw.

Teeth conditions

  • Cavities (caries): Bacteria evade removal by brushing and saliva and damage the enamel and deeper structures of teeth. Most cavities occur in molars and premolars.
  • Tooth decay: A general name for disease of the teeth, including cavities and periodontitis.
  • Periodontitis: Inflammation of the deeper structures of the teeth (periodontal ligament, jawbone, and cementum). Poor oral hygiene is usually to blame.
  • Gingivitis: Inflammation of the surface portion of the gums, around and between the crowns of the teeth. Plaque and tartar build-up can lead to gingivitis.
  • Plaque: A sticky, colourless film made of bacteria and the substances they secrete. Plaque develops quickly on teeth after eating sugary food, but can be easily brushed off.
  • Tartar: If plaque is not removed, it mixes with minerals to become tartar, a harder substance. Tartar requires professional cleaning for removal.
  • Overbite: The upper teeth protrude significantly over the lower teeth.
  • Underbite: The lower teeth protrude significantly past the upper teeth.
  • Teeth grinding (bruxism): Stress, anxiety or sleep disorders can cause teeth grinding, usually during sleep. A dull headache or sore jaw are possible symptoms.
  • Tooth sensitivity: When one or more teeth become sensitive to hot or cold, it may mean the dentine is exposed.

Teeth tests

  • X-rays: X-ray pictures of the teeth may detect cavities below the gum line, or that are too small to identify otherwise.
  • Teeth examination: By viewing and gently manipulating the teeth, a dentist can detect potential teeth problems.
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