Bad breath is a very common problem and there are many different causes. Persistent bad breath is usually caused by the smelly gases released by the bacteria that coat your teeth and gums.
However, strong foods like garlic and onions can add to the problem. Smoking is also one of the main causes of bad breath, along with certain illnesses such as nasal and stomach conditions. Bits of food that get caught between the teeth and on the tongue will rot and can sometimes cause an unpleasant smell. So correct and regular brushing is very important to keep your breath smelling fresh.
The bacteria on our teeth and gums (plaque) also cause gum disease and dental decay.