As the smell whiffs in from the kitchen, saliva starts pooling in your mouth. And sometimes, all it takes is thinking about a favourite meal. These emotional signals cue the body’s six salivary glands to get going.

Two of the glands are located in pairs below and to the front of the ear, two more are on the inside of the lower jawbone and two under the tongue.

“Plus, there are a plethora of smaller salivary glands that populate the entire oral mucosa, such as the lips, cheeks, palate or tongue,” explains Dr Cornelius Klein of the German Society of Oral and Maxillofacial Surgery.

The main purpose of saliva is to make food digestible. But it also keeps the mouth hygienic, helping with dental care. “Saliva is an essential body fluid,” says Dr Dietmar Oesterreich, vice-president of the German Dental Association.

It helps reduce bacteria in the mouth and to weaken acidic compounds. “And it helps to repair teeth by balancing mineral loss,” the dentist explains. As long as the glands are working perfectly, most people pay them zero attention.

But keeping them in good health means good oral hygiene and staying hydrated. Individuals with constant dry mouth can stimulate production of saliva by chewing on gum or enjoying a hard candy.

But when things really get bad, people start to notice how important they are. Salivary glands are susceptible to a number of common problems: inflammation, infections, salivary stones, tumours or cysts.

The nature of the pain says a lot about the problem: “In an acute inflammation, no matter whether bacterial or virus-related, the patients feel a non-stop, throbbing pain.” The affected area hurts, swells and reddens.

It is different if there is a salivary gland stone, which clogs the gland duct and this causes discomfort when salivation starts. “Then saliva forms, but because of the stone it cannot drain – and causes pain,” Dr Oesterreich says,

If a gland obstructs saliva, it must be removed. The remaining glands compensate for the missing gland. But when several glands are out of order, things get tougher. This is why removal of glands is a last resort option. – dpa