Teeth

§Humans have two sets of teeth in their life:
1.Milk (baby) teeth
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2.These are the first set of teeth to grow. They start growing between six and ten months of age. A child will have around 20 baby teeth by the time he or she is three years old.
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3.Permanent (adult) teeth
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4.Baby teeth should begin to fall out by the age of six, leaving space for adult teeth to grow. An adult can grow up to 32 permanent teeth.


§Humans have three main types of teeth:
§a. Canines - used for tearing and ripping food.
§b. Incisors - help you bite off and chew pieces of food.
§c. Premolars - help you crush and grind food.
§d. Molars




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:

• 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 cavity : 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.


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


§What do you think causes tooth decay?


§Saliva is normally slightly alkaline. When we eat, bacteria in our mouth feed on sugar and turn it into acid. The sugar starts to attack the enamel and wear it away.


Looking after teeth
§Sugar left in the mouth is eaten by bacteria. The bacteria make acid that rots teeth and cause tooth decay.
§Taking care of our teeth prevents tooth decay. You can take care of your teeth by:
§brushing twice a day
§eating the right foods (not too many sugary ones)
§visiting the dentist regularly

Posted in: Biology