Teeth

Hard white objects inside the mouth that are used for biting and chewing.

Smile! Show off those teeth. Strong teeth are a sign of good overall physical health. Without them, you can't eat or even speak well. Your teeth are important.

Teeth are like bones. They are alive. They start forming before you are born and continue to develop until you are an adult. Teeth form inside the jaw and are nourished and protected by the pink tissue that surrounds them. That pink tissue is called the gums. The crown is the part of the tooth you can see above the gums, but there is a lot more to your teeth.

The tooth is made up of five parts. The enamel is the white covering on the top. It is the hardest substance in your whole body. The layer under the enamel that you can't see is the dentin. It makes up most of the tooth and isn't as hard as the enamel. The pulp is under the dentin and it is the softest part of the tooth. It is made up of nerves and blood vessels. It is what hurts when you get a toothache. The root is what holds the tooth in place and a thin layer of tissue called the clementum protects it.

Kids have about 20 teeth by the time they turn 3 years old. This first set of teeth are called milk teeth, baby teeth or primary teeth. By the time you are five or six, your first permanent teeth will start coming in. The permanent teeth lie just beneath the roots of the baby teeth.

As a permanent tooth grows, it puts pressure on the baby teeth. That pressure causes the root of a baby tooth to dissolve and the baby tooth falls out. The permanent tooth then moves into place. By the time you are an adult, you should have 32 teeth.

Mammal teeth are called heterodonts, meaning they have two types of teeth — the primary teeth and the permanent teeth. Mammals have four types of teeth, each with a specific task to handle for different kinds of food. Incisors are used for cutting. Canines are for tearing. Premolars are used for crushing, and molars are used to grind up food. Not all mammals have all, or even any, of each kind of tooth. It all depends upon what kind of food the animal eats.

Humans have:

• Eight incisors — four in your upper jaw and four in your lower jaw in the front of your mouth. Incisor means “biting tooth” and these teeth help you bite into your food.
• Four canines — two in your upper jaw and two in the lower jaw. Your canines are located next to the incisors. Canine means “like a dog.” These teeth are pointed and are used to stab and tear at food.
• Eight molars — four in your upper jaw and four in your lower jaw. These teeth in the back of your mouth help you grind your food.

Carnivores need long canine teeth so they can grip and kill prey quickly. Their incisors strip flesh from bones. They don't need molars for grinding food. They have teeth that slice meat — these are called carnassial teeth, not molars.

Herbivores do not have upper incisors because they cut the plants with their lips instead. All herbivores need their molars (the big flat teeth at the back of the mouth) for grinding the mouthfuls of food. A herbivore's molars are big and ridged for better grinding.

Omnivores have teeth that are used for many different things. Like grasping, cutting, grinding, and slicing. This is especially true for humans. Yes, humans are omnivores, meaning they eat meat, fruits, and veggies!

Insectivores have teeth that are square with sharp points that are perfect for tearing up insect bodies.

Ancient Egyptians believed that a mixture of onions, spices, and incense would cure a toothache. Today, we know that toothaches happen when you don't take care of your teeth.

When you eat, bits of food particles are left on your teeth. When sugars combine with bacteria in your mouth, plaque forms. The plaque forms acids that can eat a hole in the tooth. This is called a cavity.

Left untreated, the cavity can spread into the dentin and then into the pulp. If bacteria gets into the pulp, it can cause the blood vessels to swell and press on the nearby nerves. Ouch! Now you have a real toothache. Do animals get cavities? You bet! Especially if they don't take care of their teeth. Even animals get cavities! Check out this horse's cavities!

Plaque can also harden into a chalky substance called tartar. Tarter can cause gum disease. If your gums aren't healthy, they can't protect your teeth. If the gum disease gets really bad, you can lose a tooth. And gum disease can also lead to other health problems like heart disease and strokes. So taking care of your teeth is important for your whole body!

You can prevent cavities and gum disease by brushing at least twice a day. You should use a fluoride toothpaste and a toothbrush with soft, rounded bristles. Brush with short, angled strokes.

Brush the front and back sides of your teeth and don't forget to brush your tongue too! That will help keep your breath fresh. When brushing, you should brush for 2 minutes on your upper teeth and 2 minutes for your bottom teeth. You should brush in the morning, the evening, and after eating meals! Be sure to rinse your brush well and get a new brush every three months.

No time to brush after a meal? Be sure to rinse your mouth out well with water to help clean away as many food particles as possible until you can get to your toothbrush! Besides, germs love a dry mouth. So, if you drink lots of water to help wash away leftover foods, there will be fewer places for bacteria to grow!

Besides brushing, you should also floss once a day. Flossing removes food and plaque from between your teeth — places your toothbrush cannot reach. This is also a great way to help prevent gum disease.

You should also make regular visits to your dentist and eat right. Candy and other sticky, sugary foods are bad for your teeth. Eating a good healthy diet, brushing and flossing often, and visiting your dentist regularly are the best way to keep a healthy smile!

Even if you don't have a toothache, you should visit your dentist at least twice a year to check your teeth. When you visit the dentist she will examine your teeth and gums, and either the dentist or the dental hygienist will clean your teeth to remove the plaque and tartar from your teeth.

Dentists and hygienists use special tools to clean and check your teeth. The dentist will use an explorer to check and clean around your teeth. It is a metal tool with a hook on the end. Dentists also use a small suction tube to suck the water and saliva out of your mouth. The dentist will also use a mirror to help get a better look at all the surfaces of your teeth. If the dentist finds any cavities they will take an X-ray of your teeth, remove the decayed part of the tooth, and put in a filling to prevent further decay. Piece of cake! Well, maybe that's not the best choice of words . . . but going to the dentist is pretty painless these days!

Who has the most teeth?

• On land, the mammal with the most teeth is the Giant Armadillo, which can have as many as 100 teeth in its jaws.
• In the oceans, the real tooth master is the long-snouted spinner dolphin. They can have as many as 252 teeth in their long thin jaws. These teeth are more like reptile teeth because they are all the same basic shape, thin sharp little spears. These teeth are good for catching and holding the little fish that dolphins eat.

Shark lose teeth throughout their life and they grow new ones to replace the lost teeth. As soon as one falls out, another one takes its place.

Poisonous snakes have specialized teeth called fangs. Fangs are hollow teeth that pierce skin and inject poison.

Rats gnaw all the time to help wear down their teeth. If they didn't wear down them down, their bottom teeth would continue to grow longer — potentially right into their brain.

Some animals dig with their teeth, while others use their teeth for self-defense or displays of power, such as when males fight for territory or for females. Wild pigs dig with their tusks, which are actually canine teeth. Even the mighty walrus will use its large canine teeth to anchor itself to ice while sleeping.

Our first president, George Washington, did not have teeth made out of wood, but he did have teeth made out of hippopotamus teeth. He also had teeth made out of ivory, lead, human teeth, and cow and sheep's teeth.

In the early 1600s, Japanese women blackened their teeth. They thought it showed loyalty to their husbands. Eww . . . yuck!

In the ninth century, Mayans filed their teeth into different shapes and decorated them with jewels. Today, some people get “grillz” to impress their friends. What do you think? Think jewelry on your teeth is cool? Maybe, but not if you wear it for an extended period of time — it can cause tooth decay and gum disease. So, if you do add some sparkle to your smile, be sure to take care of the teeth underneath so you don't lose all your shine!