settlers who were taking land from
Indians. As a boy during the American
Revolution, he helped the British attack
American colonists. Later he united
Indian tribes to fight Americans. He
worked with his brother Tenskwatawa, a
religious leader.
Tecumseh saw the War of 1812 as a
chance for his people to recover the land
they had lost. The war was between
Great Britain and the United States.
Tecumseh and his warriors helped the
British. They hoped a British victory
would allow the Indians to take back
their land.
British and Indian forces captured
Detroit, Michigan. Later Tecumseh’s
army invaded Ohio with the British.
After failing to capture a fort near
Toledo, they crossed into Canada. The
British and the Indians were defeated
near the Thames River in Ontario on
October 5, 1813. Tecumseh was killed
in the battle.
#More to explore
Shawnee •War of 1812
Teeth
Many vertebrates, or animals with backbones,
have teeth inside their mouths.
Teeth are hard, bony structures that
grow from the jawbone. Humans and
other animals use their teeth to bite and
to chew food.
Types of Teeth
Teeth of different shapes do different
jobs. Front teeth, called incisors, bite
and cut. Pointed teeth, called cuspids or
canines, tear and shred. Teeth with two
points, called bicuspids, tear and grind.
Back teeth, called molars, crush and
grind.
Humans have two sets of teeth during
their lives. The first set consists of 20
teeth. These are called primary, or baby,
teeth. When a child is about 6 years old,
these teeth begin to loosen and fall out.
Over the next eight years 28 permanent
teeth replace all the baby teeth. When a
person is around age 20, four more
Tecumseh led American Indians
in a losing struggle to keep their
land.
30 Teeth BRITANNICA STUDENT ENCYCLOPEDIA
molars, called wisdom teeth, grow in.
Many people have their wisdom teeth
removed to keep their other teeth
straight.
Tooth Structure
The visible part of a tooth is called the
crown. Several layers make up the
crown. The outer layer is a hard white
covering called enamel. Enamel protects
the tooth from wear and tear. Below the
enamel is dentin. This yellow, bonelike
material is softer than enamel. Dentin
makes up the largest part of the tooth.
The center of a tooth is called the pulp.
The pulp is soft tissue that contains
blood and nerves. Nerves in the teeth
send signals to the brain about heat,
cold, or pain.
The soft tissue around the base of each
tooth is called the gum. The roots of the
teeth lie below the gums. A tooth has
between one and three roots. A gluelike
substance called cementum coats the
roots. Cementum keeps the teeth stuck
in the jawbone.
Problems with Teeth
A common problem with teeth is tooth
decay, or cavities. Cavities can form if a
sticky film called plaque is allowed to
build up on the teeth. Germs in plaque
eat away the tooth and cause pain and
infection. Dentists fill cavities to prevent
further damage. Plaque can also make
gums red, sore, and weak. Over time,
weakened gums can wear down so far
that the teeth fall out. People can keep
teeth healthy by brushing and flossing
teeth and visiting the dentist.
Sometimes the teeth do not bite
together properly. Dentists called orthodontists
can straighten teeth.
#More to explore
Dentistry • Mouth
The tusks of
elephants and
walruses are
enlarged
upper teeth.
A diagram shows the teeth of people at two
different ages. Humans have two sets of
teeth during their lives. The first set is called
the primary teeth. At about age 6, one’s
primary teeth begin to fall out. The second
set, called the permanent teeth, replaces
them.
BRITANNICA STUDENT ENCYCLOPEDIA Teeth 31
Tegucigalpa
Population
(2007 estimate)
944,400
Tegucigalpa is the capital of Honduras,
a country in Central America. The city
lies on the Choluteca River. It is located
in a hilly region surrounded by
mountains. It is the largest city in
Honduras.
Tegucigalpa is one of the main industrial
centers in Honduras. Factories in the
city make cloth, clothing, processed
foods such as sugar, and other goods.
The Honduras region was once part of a
Spanish colony. Spanish conquerors
founded Tegucigalpa in 1578. They
built the city as a center for mining silver
from the nearby mountains.
Honduras became an independent
country in 1838. For much of the
1800s the country’s capital shifted back
and forth between Tegucigalpa and the
city of Comayagua. Tegucigalpa became
the permanent capital of Honduras in
1880.
A strong hurricane hit Honduras in
1998. Tegucigalpa was severely damaged.
..More to explore
Honduras
Tehran
Population
(2007 estimate)
7,873,000
Tehran is the capital of Iran, a country
in the Middle East. The city lies in the
Elburz Mountains. It is Iran’s largest city
by far. It is also a center of education
and industry.
Factories in Tehran make such products
as cloth, cement, food products, and
medicines. A factory near the city processes
oil. Many people in Tehran work
in government offices.
Iran has a long history. For most of that
history Tehran was not a very important
city. In ancient times the city of Rayy
Many houses sit on hilly ground in Tegucigalpa,
Honduras.
