It is a good practice to brush your teeth after food, especially if you are wearing braces or have crown or bridge work done. You do not want the food trap to cause plaque accumulation on your teeth, causing gum problems and decay problems.
For the rest of you, it is advisable to wait for at least 30 mins to 1 hour before you actually start brushing. The rationale behind this principle is simple.
Nowadays, most food are acidic in nature, with a pH of less than 7 when ingested in the mouth. This become more critical if you just had a bowl of hot and spicy laksa or some citrus fruits such as oranges and kiwi. The acid can cause mild to moderate erosion of the teeth. If you brush your teeth straight after a meal and with the added mechanical action, the harm is increased.
Usually, our saliva act as a buffer against the acid resulting from food. The surface minerals on the enamel ( outer protecting layer ) can be replaced by the ions in our saliva. But if you brush the surface directly after food intake, you may slow down or stop this ‘self regeneration’ process.
This recommendation of waiting for 30 mins before brushing is very important if you already have general teeth sensitivity or teeth erosion. Some of you may have gastric reflux and this practice can help you in preventing more dental damage.