Teeth

This lesson covers:

  1. The structure of teeth and how they are fixed to the gums and bone
  2. The different types human teeth and their functions

Ingestion, digestion, and the role of teeth


Ingestion is the first step of the digestive process, in which food and drink are taken into the mouth. 


After ingestion comes physical digestion. Physical digestion (also called 'mechanical digestion') is the breakdown of food into smaller pieces, without the food molecules undergoing a chemical change. This increases the surface area for the next stage of digestion.


Teeth play a key role in physical digestion. They are used to rip, tear, and grind up the ingested food into smaller pieces, increasing the surface area of the food particles. This helps digestive enzymes carry out chemical digestion. 

Tooth structure - crown and root

Diagram showing the structure of a tooth with labels for crown, root, and gumline.

Teeth are considered as having two main parts:

  1. Crown - the exposed part of the tooth that is visible above the gum line.
  2. Root - the part hidden below the gum line. The root is fixed into the gum and jaw bone, and anchors the tooth in place.


Tooth structure - enamel, dentine, and pulp

Illustration showing the structure of a tooth including enamel, dentine, and pulp.

A tooth is made of three distinct layers:

  1. Enamel - the outer layer. Enamel is hard and protects the tooth.
  2. Dentine - the middle layer. Dentine is softer than enamel and forms the main bulk of the tooth.
  3. Pulp - the inner layer. Pulp is softer than dentine, and contains nerves and blood vessels.


How teeth are fixed to the body


In order to withstand the forces caused by chewing, teeth need to be firmly fixed in place. There are three main structures that act to keep a tooth attached to the body.

Diagram showing a tooth fixed to the body with gum and bone structures.

Gums and jaw bone

The tooth is fixed into the gum, which wraps around the tooth's root to secure it in place. The root is also physically embedded into the jaw bone.

Illustration showing how a tooth is attached to the body with cement.

Cement

Cement is a bone-like tissue that covers the root of the tooth and strengthens the bond between the root and gum.

Types of human teeth


There are four types of teeth in humans: incisors, canines, premolars, and molars.

Diagram showing the location of incisors in the human mouth.

1Incisors have a single sharp edge which cuts into food.

What is the name of the hardest, white outer part of the tooth?

Dentine

Enamel

Pulp

Cement

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What is the name of the inner structure of teeth, that contains blood vessels and nerves running through it?

Dentine

Cement

Pulp

Enamel

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1

What is the name of the tissue that binds the tooth firmly to the gum and bone?

Dentine

Enamel

Pulp

Cement

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1

The four types of human teeth are the incisors, canines, and molars.

premolars

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What are the pointy teeth beside the incisors called?

Canines

Premolars

Molars

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1

What is the name of the teeth found in the very front of the mouth?

Incisors

Premolars

Canines

Molars

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1

Which two types of teeth are used to crush food?

Incisors

Molars

Canines

Premolars

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2