Alvin Silverstein - Handy Health Guide to Your Teeth

KEEP SMILING

We all face health problems once in a while. Maybe you have come down with the flu or you have a cavity. Perhaps you have asthma or diabetes. Some people need glasses to see better or are allergic to bee stings. These handy guides teach you about your health and how all the parts of your body work together to keep you healthy most of the time.

About the Author

Dr. Alvin Silverstein is a retired professor of biology at the College of Staten Island, City University of New York. Virginia Silverstein translates scientific Russian and is a professional author. Together they have written more than 200 books for young people. Laura Silverstein Nunn has coauthored more than 100 books with her parents.

If you take care of your teeth, you can have a healthy smile your whole life.

Say Cheese! Thats what people say when they want to take your picture. You give a big, wide smile for the camera to show that youre happy. And when you smile, you show off a nice set of pearly white teeth.

Your teeth arent there just to make your smile look good. Teeth have a very important job to dothey chew up the food you eat into little pieces so you can swallow it more easily. Actually, you start to digest the food right in your mouth, while you are chewing it.

To help your teeth do their job, you need to take good care of them. If you do, your teeth can last a lifetime.

You can tell a lot about an animal by looking at its teeth. For example, some animals eat only plant foodsleaves, roots, fruits, or seeds. Many plant eaters have very good cutting teeth. Their front teeth are large and sharp so they can snip off leaves and stems or bite off roots with ease. A beavers front teeth are so big and strong that it can even gnaw through tree trunks. Grazing animals such as horses and cows are plant eaters, too. Their large back teeth are good for grinding up leaves or grains.

Some animals eat mainly meat. They hunt other animals for food. Their teeth are very different from those of plant eaters. Dogs, cats, and other meat eaters have long, pointed fangs. They use them to bite into their prey and tear the meat into pieces small enough to swallow. They have cutting and grinding teeth too, but those are not very big or strong. (If you watch a pet cat or dog eating, you may notice that it does not chew its food very well. It just swallows it down in chunks.)

Look at a mirror and check out the inside of your own mouth. Your front teeth are not as strong as a beavers cutting teeth, but they are good enough to take a bite out of an apple or a carrot. Your back teeth are not as big or wide as those of a horse, but you can still crunch vegetables and mash them into a soft pulp. And you dont have long fangs like a cat or a dog, but your teeth can handle meateven a tough piece of steakpretty well. People eat both plant foods and meat, so you have teeth that are good for chewing many different types of foods.

Meat eaters, such as this gray wolf, use their fangs to tear flesh into pieces that are small enough to swallow.

Plant eaters, such as this beaver, use their large front teeth to gnaw on branches, stems, and roots.

Think of all the different types of food on a slice of pizzacheese, sausage, pepperoni, mushrooms, onions, peppers, tomatoes. Your teeth can chew them all.

What do you call animals that eat mainly meat? Carnivores. What about animals that eat mainly plants? They are herbivores. Some animals eat both meat and plants. They are called omnivores.

What about people? People are omnivores. We can eat all kinds of foods. But what about people that choose not to eat meat? They are still omnivores. Whether or not they eat meat, they were born with teeth that were made for eating both meat and plant foods.

Babies are born without any teeth showing at all. At first they can drink only liquids like milk, water, or juice. After a few months, they may eat some soft foods like applesauce, ground-up bananas, or mashed peas.

The first teeth, called milk teeth, appear when an infant is about six months old. One by one they pop out of the gumsfirst the cutting teeth in front, then some grinding teeth and tearing teeth. It takes about two years for all 20 milk teeth to come in.

This baby has no teeth. Her first teeth will appear when she is about six months old.

A crocodile can replace lost teeth throughout its life.

When a child is about five or six years old, the milk teeth start to fall out. These baby teeth are replaced, one at a time, by larger ones called permanent teeth. There are 32 teeth in a complete set of permanent teeth. These are the teeth that we keep for the rest of our lives.

Why do people grow two sets of teeth? A complete set of permanent teeth cant fit into a babys tiny mouth. Thats why they come later, when a child is a little bigger.

Animals such as cats and dogs have two sets of teeth, just like people do. Reptiles and fish may have many sets of teeth during their lives. Crocodiles and sharks, for example, can keep on replacing their teeth their whole life.

This boy is missing a front tooth. You see the permanent tooth just under the surface of the gum.

Did the tooth fairy visit your home when you were young? In the United States, when kids lose a baby tooth, they put it under their pillow. When they wake up the next morning, they find that the tooth fairy took the tooth and left money in its place. In some other countries, children put their baby teeth where a tooth mouse can find them. They hope their new teeth will be as strong and sharp as a mouses teeth.

You have several kinds of teeth in your mouth. Each type of tooth has a special job to do. When you look in the mirror and smile, you see two rows of flat, squared-off teeth right in the front of your mouth. There are four on top and four smaller teeth below. These front teeth are called incisors. They are sharp and act like knives to slice and bite off chunks of food. (Look at your toothprint after you bite into an apple to see how broad and sharp your teeth are.)