Read and analyze the text very carefully and create a topic outline or a
sentence outline.
Your teeth and the structure of your mouth play important roles in your ability to
eat, speak, and stay healthy. Everyone has several different types of teeth. Each type
has a unique name with specific number of teeth, has development, has a slightly
different shape, and performs different jobs and purpose.
The teeth in the front of your mouth, and the easiest to see, are called incisors.
There are four incisors on the top and four on the bottom. Incisors are usually the first
teeth to erupt — at around 6 months for your baby teeth, and between ages 6 and 8
for your adult set. Incisors are shaped like tiny chisels with flat ends that are sharp.
These teeth are used for cutting and chopping food. They are the first teeth to chew
most food we eat.
The pointed teeth on either side of your incisors are called canine teeth. People
have a total of four canine teeth, two on top and two on the bottom. Primary canines
generally appear between 16 and 20 months, with the upper canines coming in just
ahead of the lower canines. Because they are pointed and sharp, they are used to tear
food.
Next to your canine teeth are the premolars. You have eight premolars in all,
four on top and four on the bottom. The first premolars appear around age 10, with the
second premolars arriving about a year later. They have a completely different shape
than both the incisors and canines. That is because premolars are bigger, stronger,
and have ridges – all of which makes them perfect for crushing and grinding food.
Finally, there are your molars. You have eight of these, four on the top and four
on the bottom. Molars are the toughest of the teeth. They are wider and stronger than
premolars, and they have more ridges. Molars work closely with your tongue to help
you swallow food. The tongue sweeps chewed food to the back of your mouth, where
the molars grind it until it is mashed up and ready to be swallowed.
By age twenty, four more molars grow in the back of the mouth, one in each
corner. These are called the wisdom teeth. They appear between 12 and 28 months,
People do not need wisdom teeth now, but many years ago these teeth were
necessary to help people chew tough plants, which were an important part of the
human diet. Now, many people get their wisdom teeth pulled by a dentist, a doctor
who takes care of teeth, to keep them from crowding their other teeth.