Normal Mouth and Teeth- must know

The teeth are the hardest substances in the human body. Besides being essential for chewing, the teeth play an important role in speech. Parts of the teeth include:The crown of each tooth projects into the mouth and The root of each tooth descends below the gum line, into the jaw.

• 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. Dentin 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.

A normal adult mouth has 32 teeth, which (except for wisdom teeth) have erupted by about age 13:

• Incisors (8 total): The middlemost four teeth on the upper and lower jaws.
• Canines (4 total): The pointed teeth just outside the incisors.
• Premolars (8 total): Teeth between the canines and molars.
• Molars (8 total): Flat teeth in the rear of the mouth, best at grinding food.
• Wisdom teeth or third molars (4 total): These teeth erupt at around age 18, but are often surgically removed to prevent displacement of other teeth.