Teeth

Teeth break food down into pieces, making it easy to swallow. Many vertebrate animals have teeth.

Parts of a tooth

Most types of teeth have three main parts: a crown, a neck, and a root.

Crown – this is the part above the gum. It’s covered with a very hard and often shiny layer of enamel, which protects the inside of the tooth. The soft pulp inside the crown contains nerve endings and the tooth’s blood supply. The rest of the tooth is a tough substance called dentine.

Neck – this holds the tooth in place in the jaw bones. Roots contain nerves and blood vessels. A tooth can have one, two or three roots.

Root – this holds the tooth in place in the jaw bones. Roots contain nerves and blood vessels. A tooth can have one, two or three roots.

Types of teeth

The types of teeth an animal has depends on the food it eats.

Lions are hunters and meat-eaters, so have sharp teeth for killing and eating their food.

Sheep just eat plants. So have flat teeth for grinding.

People can eat both meat and plants. So they have some teeth that are sharp and others that are flat.

Each type of tooth has a different name:

• Molars are broad, square teeth with points and grooves that help animals to chew and grind food.
• Premolars are thin, square teeth with two points. Animals use them to mash and grind food.
• Canines are long, cone-shaped teeth with a sharp point that helps animals to pierce and tear meat.
• Incisors are flat-topped, small, front teeth that help animals to cut food or scrape meat from bones.

Sets of teeth

A set of teeth is all the teeth an animal is using in its mouth. Many animals grow new teeth to replace ones that fall out and some replace whole sets.

Most mammals, like humans, have two sets of teeth during their lives. Young mammals have baby teeth but, as the animals grow their baby teeth gradually fall out and are replaced by bigger, stronger adult teeth.

• A newborn horse’s front baby teeth
• A 15-years-old horse’s front adult teeth

Most sharks have a lot of rows of teeth. A shark’s tooth doesn’t have roots, so breaks off easily usually lasting for about a week before it falls out. They, the tooth behind it moves up to replace it. Sharks keep replacing it. Shark keep replacing their teeth all their lives.

Plaque

Plaque is a sticky covering that forms over teeth. It is made when bacteria in an animal’s mouth feed off sugary foods stuck to teeth. This makes an acid which dissolves teeth and damages gums, causing tooth decay and gum disease.

Tooth decay

1. Acid makes a hole in the tooth’s enamel.
2. If the hole reaches the nerves, the tooth hurts.
3. Decay and infection can rot the whole tooth.

Gum disease

1. Plaque builds up between the teeth.
2. The gum becomes infected. It bleeds.
3. The gum shrinks and the teeth fall out.

Dental hygiene

Dental hygiene means keeping teeth healthy. Wild animals scrape plaque off their teeth when they tear at their food. But people need to brush their teeth using a toothpaste that strengthens enamel and repairs damage caused by plaque.