Humans grow two sets of teeth during their lives - baby teeth and permanent teeth. The adult human mouth contains 32 permanent teeth divided into four types that serve different functions: incisors cut food, canines tear food, premolars crush food, and molars grind food. Teeth whitening is an effective way to lighten teeth without removing tooth surface, though the whitening effects typically last many years before teeth start to darken again over time.

1. Teeth
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Prepared by group (D)
Mahmoud Khalil
Dlnia Khalifa
Dunya Tahseen
Farhang Ismat
Hanna Mohammad
Hazher Mawlwd
Hemn Jamil
Kazhin Hamid
Dr.Hiwa Balisane

3. Introduction
Humans grow two sets of teeth during their lives. The first set
has 20 teeth baby teeth. When a child is about 6 years old,
these teeth become loose and fall out. Over the next few
years 28 permanent teeth replace the baby teeth. When a
person is around 20, four more back teeth, called wisdom
teeth grow in.
We have different types of teeth in our mouth. Each one has
a different function.

4. Types of the teeth
The adult human mouth contains 32 permanent teeth. There are
four layers to a tooth. The pulp is the middle of the tooth
made up of soft connective tissue, blood vessels and nerves.
The cementum, made of minerals, covers the pulp and helps
to anchor the tooth. The majority of the tooth is made up of
dentin which gives the tooth its shape. The shiny outer
surface of the tooth is made of enamel, the hardest substance
in the human body according to the Dental Health Site. There
are four types of teeth that work together to help to tear and
chew food needed for nutrition.

5. Types of the teeth
• Incisors
• Canine Teeth
• Pre-Molars
• Molars

6. Incisors
Incisors, also called cutting teeth, have flat surfaces with a straight,
sharp edge. The front 4 top and bottom teeth are incisors, making 8
total incisors in the human mouth. These teeth work to cut and bite
food into small pieces that can be chewed by the other teeth.
Incisors have one long conical root that anchors it into the jaw bone.
The primary (also known as baby teeth) incisors are the first teeth to
erupt. The bottom incisors usually begin to appear between 6 and 10
months of age, according to The Online Knowledge Magazine, while
the top incisors appear between 8 and 12 months of age.

7. Pre-Molars
Behind each canine tooth are two pre-molar teeth, also known as bicuspids.
This makes a total of 8 pre-molar teeth in the adult human mouth. The
pre-molars have a flat upper surface with at least 2 cusps and are used for
chewing and crushing food. The pre-molar teeth have either 1 or 2 roots.

8. Canine Teeth
The canine teeth are the strong, pointed teeth found in the corners of
the mouth. There are 4 canine teeth, two on top and two on bottom.
The canine teeth surround the incisors. These teeth are used to shred
and tear food.
The top canine teeth are often also called the eyeteeth. The canine
teeth are the longest teeth in the mouth and extend beyond the
other teeth. Like the incisors, the canine teeth have one single root.
In addition, the canine teeth are the only teeth with a single cusp
(a rounded projection on the chewing surface of a tooth).

9. Molars
The teeth found furthest back in the mouth are the molars. There are 12 molars in the
adult human body, 3 in each quadrant. The molars have the largest upper surface
providing for the maximum chewing and grinding of the food. This is important
since the molars are the final teeth food meet before swallowing. Molars have
between 2 and 4 roots to anchor them into the jaw bone.
The third molars are also known as the wisdom teeth. These molars are the last to
appear, erupting in the late teens to the twenties. The wisdom teeth are often
removed due to lack of space in the jaw or because of a partial eruption that can
lead to infection.

10. Teeth Whitening
Teeth whitening is a highly effective way of lightening
the natural colour of your teeth without removing
any of the tooth surface.

11. How long will my teeth stay whiter?
The effects of whitening normally last for many years, although this
will vary from person to person. Inevitably with time the teeth will
start to darken again due to drinks and food (and more rapidly if you
are a smoker). Most people like to maintain their whitening effect
by using the gel for one or two nights every three to six months.