Science · Year 4 · Animals, including humans · Summer Term

Tooth Decay and Oral Hygiene

Learn about the science behind tooth decay and explore the best ways to keep your teeth and gums healthy throughout your life.

TL;DR:Uncover the science behind every smile and explore the battle that happens in our mouths every day.

• National Curriculum Attainment Targets
• National Curriculum for England: Science Year 4: Animals, including humans

About This Topic

This topic aligns with the Year 4 Science curriculum in England, specifically within the 'Animals, including humans' strand. Pupils are expected to describe the simple functions of the basic parts of the digestive system, including identifying the different types of teeth in humans and their simple functions. This unit extends that statutory requirement by exploring the practical application of this knowledge: the science of tooth decay and the importance of oral hygiene. It provides a vital, real-world context for understanding scientific processes and promotes positive health and wellbeing choices.

The lessons should focus on the cause-and-effect relationship between diet, bacteria, and dental health. Pupils will investigate how bacteria in the mouth feed on sugars, producing acid which then attacks the tooth's enamel, leading to decay. This provides an excellent opportunity to reinforce scientific enquiry skills through simple comparative tests, such as observing the effect of acidic and sugary liquids on eggshells. By contextualising this scientific knowledge within daily routines like brushing teeth and visiting the dentist, pupils can develop a lasting understanding of how to care for their bodies.

Key Questions

1. Explain how sugary foods and drinks can cause tooth decay.
2. Identify three key actions for maintaining healthy teeth.
3. Justify the importance of brushing your teeth twice a day.

Learning Objectives

• Identify the different types of human teeth and their simple functions.
• Explain the process of tooth decay, involving sugar, bacteria, and acid.
• Describe at least three key actions for maintaining good oral hygiene.
• Relate the consumption of sugary foods and drinks to an increased risk of tooth decay.
• Understand the importance of regular dental check-ups.

Key Vocabulary

Enamel	The hard, protective outer layer of a tooth.
Plaque	A sticky, colourless film of bacteria that constantly forms on our teeth.
Decay	The damage to a tooth's surface, or enamel, caused by acids produced by bacteria.
Gums	The soft tissue that surrounds the base of the teeth.
Fluoride	A mineral found in toothpaste that helps to strengthen tooth enamel and prevent decay.

Watch Out for These Misconceptions

Common Misconception

Sugar itself directly rots your teeth.

What to Teach Instead

It is not the sugar itself, but the acid produced by bacteria in your mouth when they eat the sugar. This acid is what dissolves the tooth's protective enamel.

Common Misconception

Fruit juice is healthy, so it must be good for my teeth.

What to Teach Instead

While fruit contains vitamins, fruit juice is very high in sugar and acid. Both of these can cause significant tooth decay, so it should be consumed in moderation and preferably with a meal.

Common Misconception

Baby teeth don't matter because they fall out anyway.

What to Teach Instead

Baby teeth are very important. They help children chew food properly, speak clearly, and hold the correct space in the gums for the adult teeth to grow into.

Common Misconception

You only need to brush the front teeth that people can see.

What to Teach Instead

It is crucial to brush all surfaces of every tooth, including the back, front, and chewing surfaces, as plaque builds up everywhere.

Active Learning Ideas

Experiential Learning

The Eggshell Decay Experiment

Hard-boil several eggs and place them in different liquids like cola, orange juice, water, and milk. Observe the eggs over several days to see how the acidic and sugary drinks stain and weaken the eggshell, which acts as a model for tooth enamel.

45 min·Small Groups

Experiential Learning

Plaque Attack!

Use plaque-disclosing tablets (with parental consent) to show pupils the invisible plaque on their teeth. After chewing the tablet, the plaque is stained a bright colour, revealing the areas they miss when brushing, followed by a session on correct brushing technique.

30 min·Individual

Experiential Learning

Healthy Smile Campaign

In groups, pupils design a poster or a short presentation aimed at younger children. The campaign should explain the causes of tooth decay and give three simple rules for keeping teeth healthy.

60 min·Small Groups

Real-World Connections

• Reading and understanding food labels to identify 'hidden sugars' in everyday foods and drinks.
• Making informed choices about snacks and meals to promote better dental health.
• Establishing a personal daily routine of brushing and flossing based on scientific understanding.
• Understanding the advice given by dentists and dental hygienists during a check-up.
• Recognising the importance of public health initiatives, such as water fluoridation in some areas.

Assessment Ideas

Exit Ticket

Use an exit ticket where pupils must write down one cause of tooth decay and one way to prevent it before leaving the lesson.

Quick Check

Pupils complete a labelled diagram of a tooth, indicating where enamel is and how decay can form. They could also write a short paragraph explaining the process.

Quick Check

Pupils use a simple checklist to reflect on their own weekly oral hygiene habits, such as brushing twice a day and limiting sugary snacks.

Frequently Asked Questions

What is fluoride and why is it in my toothpaste?

Fluoride is a natural mineral that helps to strengthen your tooth enamel, making it more resistant to the acid attacks that cause tooth decay. It's a key ingredient for protecting your teeth.

How often should I go to the dentist?

Most people should visit the dentist for a check-up every six months to a year. The dentist can spot problems early and clean your teeth in ways you can't do at home.

Why do my gums sometimes bleed when I brush my teeth?

Bleeding gums can be a sign of gum disease, which is caused by a build-up of plaque. It's a sign that you need to brush more carefully and regularly, especially along the gum line, and see a dentist if it doesn't improve.