Food s and drinks contain sugars and starches that the bacteria in the mouth use as food. The bacteria produce acids from the sugars and starch and it is this acid that attacks, and dissolves away the teeth.
Every time food enters the mouth acid is produced and attacks the teeth for about 2 hours. After this time the teeth recover repair themselves. If more food, and hence another acid attack takes place before the recovery is complete then the teeth decay.
There are 5 ways
Brushing of the teeth will remove the bacteria that produce the acids. (It may even be a good idea to brush the teeth BEFORE EATING rather than afterwards) !!!
Reduce the number of times that the teeth are exposed to food and drink (reduce between meal eating & drinking)
The teeth can be treated with fluoride to make them more resistant to decay.
Decay prone areas, such as the fissures in the molars, can be sealed with plastic.
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Regular dental check ups will allow any early decay to be spotted and treated early.