Brushing within half an hour of eating a meal or drinking a cup of coffee could ensure your teeth suffer worse damage. After drinking fizzy or acidic drinks, the acid burns into the enamel of your teeth – and the layer below the enamel, called “dentin”.
Brushing at the “wrong” time – particularly within 20 minutes of finishing a meal – can drive the acid deeper into your teeth, corroding them far faster than they would have rotted by themselves.
Waiting to brush for at least 30 minutes gives your mouth time to produce enough saliva to neutralize the acidity. This saliva helps your teeth to harden and absorb more calcium, which then acts like a coat of armour.
Saliva contains calcium and phosphate ions and teeth also contain these ions, so saliva acts as a reservoir of calcium and phosphate for your teeth. Saliva also contains enzymes and buffers which neutralize acid and return the pH of your mouth to neutral over time.
You especially want to avoid brushing if you’ve consumed anything that contains citric acid, found in fruit, or phosphoric acid, which most soft drinks are filled with. Drinks that combine both of these acids, such as lemon-flavoured fizzy drinks, are harder for saliva to neutralise.