Bacteria
Bacteria are the most common cause of bad breath. Food particles that remain in the mouth after eating attract bacteria. The most common sites where bacteria collect are the tongue, between the teeth and just below the gums. The surface of the tongue is rough and bacteria can accumulate easily in the cracks and crevices. When teeth are not cleaned properly, the bacteria in the mouth develop into a ‘plaque’ or a sticky, colourless film that forms on teeth, particularly around the gum line. If not brushed away, the plaque is transformed into a hard material called tartar, which harbours bacteria and irritates the gums. Once formed, tartar can only be removed by a dentist. The bacteria produce volatile sulphur compounds (VSC). The VSC escape from saliva into the air and are the cause of the characteristic odour associated with bad breath. Dentists can actually measure the amount of VSC using sulphide monitors.

Dry Mouth
Saliva helps to cleanse the mouth. When saliva flow decreases e.g. during sleep, the mouth dries out and dead bacterial cells accumulate and give off odours. This is often referred to as “morning breath”. Fasting, smoking and some medications also cause dry mouth.

Food
Eating foods that contain volatile oils e.g. onions and garlic are another source of bad breath.