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The Human Body:
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Teeth
Teeth are essential for one to chop up food into smaller pieces in order for it to be easily swallowed. There are 3 types of teeth of each jaw. Firstly the incisors, which are found at the front of the mouth. They have flat sharp edges to cut into food. Secondly, canine which are fang-like and are next to the incisors. The hold on to tough food like eat and enables one to tear it apart. Thirdly are the premolars and molars. They occur at the sides of the mouth behind the canines. They grind food to make it easier to swallow.
Each tooth has 2 main parts, the crown and the root. The crown sticks up out of the gum. The root is buried in the hum. Incisors and canines only have 1 root while the pre-molars have 2 and the molars have 3. Roots sit in the cavities in the jaw bone known as tooth sockets/alveoli. A bone-like layer of tissue, the cementum sticks the roots into place and keeps it secure.
In the crown, the first layer is the enamel, the whitish part that one can see for protection. Enamel is mostly made up of calcium salts and is the hardest substance in the body. It provides a large biting surface and prevents wear and tear. The layer immediately below it, is the ivory/dentine, a yellow bone-like substance which makes up the crown and the root. It is made of 70% calcium salts and also has ossein which is found in the bone. The cavity inside is made of tissue known as the pulp. The pulp contains blood vessels which supply the tooth with food and oxygen and nerves allow one to feel.
The number of teeth one has changes with age. The first set that one has is called the baby teeth that starts developing in the mother’s womb and are fully formed by 6-8 months of age and which is temporary. A full set consists of 20 teeth. At the age of 6-7, these baby teeth will start to fall to be replaced by the permanent teeth. A full set is 32 which consists of 8 incisors, 4 canines, 8 premolars and 12 molars. So, meanwhile the jaws grows in order to accommodate for the extra number of teeth in adulthood. The last four molars are otherwise commonly known as the wisdom teeth which only appear in the late teens or twenties.
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