Saliva is a very multifaceted fluid with many different functions and it plays an essential role in oral health. With an aging population, dental professionals will increasingly be confronted with patients with reduced saliva secretion (hyposalivation) or dry mouth (xerostomia). Clinical symptoms as a result of dry mouth vary from mild to severe damage to the hard and soft tissues. Therefore it is important to establish whether a patient is suffering from hyposalivation and if so, whether the patient is able to activate the saliva secretion. Based on saliva testing, hyposalivation and dry mouth can be diagnosed in the general dental practice and be taken into account in prevention and treatment plans.