How snacks affect your smile

• Use the safety checklist to help you plan and risk assess your activity. Take a look at our guidance to help you carry out your risk assessment, including examples.  
• Make sure all young people and adults involved in the activity know how to take part safely.
• Make sure you’ll have enough adult helpers. You may need some parents and carers to help if you’re short on helpers. 

Planning and setting up the activity

• This activity dives into the real science of tooth decay and how sugar messes with your mouth. You’ll learn why what you eat matters and how you can protect your teeth. Before running this activity, be familiar with the Stephan Curve. This shows how sugar affects your mouth’s pH level over time. You can check out this short guide.
• Make sure you have a way to draw your graph and any equipment you need. If you're using plain paper, draw the axis or grid lines in advance.

Running the activity

1. Ask everyone what they think causes tooth decay. When you’ve finished the discussion, explain that there are four key factors. The four factors are the tooth’s surface, bacteria (from plaque), sugar (bacteria’s food, turns into acid) and time (so how long the acid sits on teeth).
2. Ask everyone which of the four factors they can try to control. Sugar and time are two key ones.
3. Now, take paper, pens and draw the Stephan Curve.
4. Label the Y-axis with pH, ranging from 3 pH to 8.5 pH.
5. Label the X-axis with time, ranging from 6am to midnight.
6. Draw a line through 5.5 pH across the graph. This is the critical pH at which teeth start dissolving.
7. Label anything below 5.5 pH as the danger zone. This is where tooth enamel is safe and doesn’t dissolve.
8. Label anything above 5.5 pH as the safe zone. This is where tooth enamel is safe and doesn’t dissolve.
9. Plot three short dips below pH 5.5 (representing the impact of three meals). These dips should be brief and show how pH drops after eating but returns quickly to the safe zone. These dips represent the acidic environment that temporarily occurs after meals, when food and drink lower pH in the mouth.
10. Plot several longer dips below pH 5.5 for frequent snacking. These dips should be more prolonged than the meal-related dips and may extend over a longer period.
11. Shade the area below pH 5.5 on the graph to show when teeth are exposed to acid and at risk of damage.
12. Now, you’ve finished the Stephen Curve.
13. Ask everyone what they think the graph shows about snacking habits. Frequent snacks cause pH to stay in the danger zone for extended periods, increasing the potential for enamel erosion.
14. Ask if anyone would want to change anything about how often you eat sugary snacks or drinks. What swaps could you make, such as water instead of high-sugar drinks or having fewer snacks? What kind of things might have lots of sugar in them, such as fizzy drinks or fruit juices?