I agree with your dentist that your son should be using a fluoridated toothpaste to help with your decay prevention efforts.
There are specially formulated children's toothpastes with different levels of fluoride depending on age group. A good example is Elgydium.
To minimize the risk of swallowing, these tips may help:
1) Brush teeth using a DRY toothbrush
This helps to cut down on the foaming that may make it difficult for your child to cope with. Less foam means less accidental swallowing!
2) Use less toothpaste
A small smear of toothpaste that is enough to wet the toothbrush bristles is sufficient. Avoid using large quantities of toothpaste to minimize foaming and inadvertent swallowing.
3) DO NOT rinse out after brushing
Teach your son to spit out the residual foam as many times as he likes. Children below 8 years old should not use mouthrinses because their swallowing reflex is not yet fully developed. Rinsing the mouth with water after brushing dilutes the toothpaste (remember, toothpaste is a topical medicine for the teeth!) and increases the risk of ingestion.
If your son swallows a small amount of toothpaste accidentally, there is minimal risk of toxicity. Higher concentrations of fluoride may cause tummy upsets.
If large amounts of fluoride are ingested over a long period of time, this may affect the development of his adult tooth enamel which have already started to form within the jawbones from birth. Fluoride may also come from other sources like tap water and tea grown in certain regions of the world with high fluoride in the soil. Ingestion of small amounts of fluoride during tooth development may be beneficial in growing strong enamel that is more decay-resistant. As you can see, fluoride in small amounts is beneficial and it is the dose that makes the poison.
Apart from relying on fluoridated toothpaste, drinking tap water, thorough brushing and flossing of the teeth, and reducing frequent consumption of sweetened food, beverages (cordial, fizzy drinks, fruit juices, yoghurt drinks) or infant formula will go a long way in preventing further tooth decay. Fluoride is just a small part of the picture.
