Teeth

Emer has researched and prepared another informative article about ....TEETH!  Well done Emer! 

The teeth help to prepare food for digestion by cutting and grinding it up. Each tooth is set into the jaw, which has a soft tissue covering called gum. During our lives we have two sets of teeth baby teeth (20) and later permanent teeth (32).

Parts of a tooth;

Enamel: A substance similar to the bone, though it is harder (the hardest substance in the body) and has no living cells. It consists of tightly-packed crystals of apatite, a mineral which contains calcium, phosphorus and fluorine.
Dentin: A yellow substance which forms the second layer inside a tooth. It is not as enamel but, like it, has many of the same constituents as bone. It also contains collagen fibres and strands of cytoplasm. These run out from the pulp cells in the pulp cavity. 
Cervix: The part of a tooth just below the surface, lying between the crown and the root.
Enamel: A substance similar to bone, through it is harder and has no living cells. It consists of tightly- packed crystals of apatite, a mineral which contains calcium, phosphorus and fluorine.
Cement: A bone- like substance, similar to enamel but softer. It forms the thin surface layer of the root and is attached to the jaw by the periodontal ligament.
Pulp cavity: The central area of the tooth, surrounded by dentin. It is filled with a soft tissue called pulp, which contains blood vessels and nerve fibre endings. These enter at the base of a root canal. The blood vessels supply food and oxygen to the living tissue, and the nerve fibre endings are pain receptors.
Different types of teeth and their functions:

Wisdom teeth: Four molars ( the third ones in line), lying at the end points of the jaws. They appear last of all, when a person is fully mature. Often there is no room for them to come through and they get stuck in the jawbone, or impacted. A few people never develop wisdom teeth.


Sources: The Usborne Illustrated Dictionary of Science