Tooth
Tooth (/'tu:θ/)
Tooth is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores, also use teeth for hunting or for defensive purposes. The roots of teeth are covered by gums. Teeth are not made of bone, but rather of multiple tissues of varying density and hardness.
Etymology
The word "tooth" comes from the Old English tōþ, from Proto-Germanic *tanþs, from Proto-Indo-European *h₁dónts.
Structure
Teeth have numerous structures that contribute to their function. These include:
- Enamel: The hardest, white outer part of the tooth. Enamel is mostly made of calcium phosphate, a rock-hard mineral.
- Dentin: A layer underlying the enamel. It is a hard tissue that contains microscopic tubes. When the enamel is damaged, heat or cold can enter the tooth through these paths and cause sensitivity or pain.
- Pulp: The softer, living inner structure of teeth. Blood vessels and nerves run through the pulp of the teeth.
Types of Teeth
There are four main types of teeth, and their shapes and functions are related to what they do in the process of digestion:
- Incisors: Sharp, chisel-shaped front teeth (four upper, four lower) used for cutting food.
- Canines: Sometimes called cuspids, these teeth are shaped like points (cusps) and are used for tearing and grasping food.
- Premolars: These teeth have two pointed cusps on their biting surface and are sometimes referred to as bicuspids. The premolars are for crushing and tearing food.
- Molars: Used for grinding and chewing food, these teeth have several cusps on the biting surface to help in this process.
Related Terms
- Dental plaque: A biofilm or mass of bacteria that grows on surfaces within the mouth.
- Cavities: Also known as tooth decay or caries, are areas of the tooth that have been permanently damaged and may even have holes in them.
- Gingivitis: A type of gum disease that is usually caused by poor oral hygiene.
- Periodontitis: Serious gum infection that damages gums and can destroy the jawbone.
External links
- Medical encyclopedia article on Tooth
- Wikipedia's article - Tooth
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