3.41 Teeth Facts

Teeth are the hard bony structures in the mouth used to chew food. Discover the different types of teeth, how many teeth are in the human mouth, and the parts of a tooth, such as the enamel, dentin, and pulp.

What Do Teeth Do?

If you touch your teeth with your tongue you will notice that they are not all alike. Some teeth feel pointy and sharp, while some feel flat. These different kinds of teeth work together, like a set of tools, to perform the main function of teeth – chewing food. Since your teeth help break down the food you eat, they are part of your digestive system.

Different Types of Teeth

Humans have four different types of teeth. Just like each tool in a toolbox has a unique shape and function, each type of tooth has a different shape and job to do when you chew. The flat front teeth are called incisors. Incisors cut food into smaller pieces just like scissors cut paper. (Scissor and incisor even sound similar!)

Next to the incisors are the pointy and sharp canines. Canines tear food apart. Premolars are the larger, flatter teeth next to the canines. When you run your tongue over these teeth you feel ridges. These ridges make premolars great tools for grinding up the food we eat. Last but not least, the largest teeth way in the back of your mouth are molars. Since molars are big, flat and have sharp ridges, they are perfect for crushing and grinding up food.

1. Main points:

Teeth, varying in shape and function, are essential for chewing food and are part of the digestive system. There are four types: incisors (cutting), canines (tearing), premolars (grinding), and molars (crushing and grinding).

2. Questions:

• Content Analysis: What are the different types of teeth and their specific functions?
• Contextual Analysis: How do the various shapes of teeth contribute to their function in the digestive process?
• Linguistic Analysis: What words in the text emphasize the specialized roles of different teeth?

3. Further Discussion:

Why is it important for our teeth to have different shapes and functions?

4. Answers:

• Content Analysis: "Incisors cut food… Canines tear food apart… Premolars… great tools for grinding up the food… Molars… perfect for crushing and grinding up food."
• Contextual Analysis: The different shapes of teeth, like "flat front teeth," "pointy and sharp canines," "larger, flatter premolars," and "big, flat molars with sharp ridges," contribute to their specific functions in chewing and digestion.
• Linguistic Analysis: Words like "cut," "tear," "grind," and "crush" emphasize the specialized roles of different teeth.

How Many Teeth Do We Have?

Since teeth are such important tools, humans get two sets. Our first set of teeth start to grow when we are just 6 months old and are called primary teeth. These are the teeth that fall out as we grow. This first set contains 20 primary teeth. By the time you turn 13 years old, all of your primary teeth will have fallen out, but not to worry, primary teeth are replaced by a second set of teeth called permanent teeth. Human adults have 32 permanent teeth, which is 12 more teeth than the first set of primary teeth.

What Is a Tooth Made of?

When you smile the part of your tooth that you can see is called the crown. The crowns of your teeth sit on top of your gums, just like a crown sits on top of a king’s head. Since we use the crowns of our teeth every day to chew, they are made out of the toughest material in the human body – enamel. Enamel protects the parts of your teeth you can’t see.

Right under the enamel is a layer of dentin. Like enamel, dentin is a very hard, bone-like material. These two tough layers act like guards protecting the softer innermost layer of the tooth, called the pulp. When you get a toothache it’s the pulp that hurts, because the pulp is where the nerve and blood supply for each tooth is found. The pulp not only fills up the innermost part of the crown of your tooth, it also fills the roots. We can’t see the roots of our teeth because they are below our gums, just like the roots of tress are below the ground. However, they play the important role of keeping our teeth in place. Roots anchor our teeth to our jawbone.

1. Main points:

Humans have two sets of teeth: 20 primary teeth that fall out by age 13, and 32 permanent teeth. Teeth are made of enamel, dentin, and pulp, with the enamel and dentin protecting the pulp, which contains nerves and blood supply, and roots anchoring the teeth to the jawbone.

2. Questions:

• Content Analysis: What are the two sets of human teeth and their numbers?
• Contextual Analysis: Why are teeth made of different materials like enamel, dentin, and pulp?
• Linguistic Analysis: What words in the text describe the structure and function of the different parts of a tooth?

3. Further Discussion:

How does the structure of teeth support their function in eating and speaking?

4. Answers:

• Content Analysis: "Our first set of teeth… are called primary teeth… This first set contains 20 primary teeth… Human adults have 32 permanent teeth."
• Contextual Analysis: "Enamel protects the parts of your teeth you can’t see… dentin is a very hard, bone-like material… the pulp is where the nerve and blood supply for each tooth is found."
• Linguistic Analysis: Words like "toughest," "guards," "protects," "anchor," and "nerve and blood supply" describe the structure and function of the different parts of a tooth.

Lesson Summary

The main job of your teeth is to chew food. Humans get two sets of teeth throughout their lifetime. Kids have 20 teeth that fall out during childhood (called primary teeth), and adults have 32 teeth that they’ll keep for their lifetime (called permanent teeth). Humans have four different types of teeth: incisors, canines, premolars, and molars.

The three layers of a tooth are called:

• Enamel, which protects the parts of your teeth you can’t see
• Dentin, a hard, bone-like material; and
• Pulp, where the nerve and blood supply are located

The two main parts of the tooth are the crown, which you can see in your mouth, and the roots, which lie below the gums. The pulp is what’s deep inside and contains the nerve and blood supply for the tooth.