Reduced flow (oligosialia) or the complete absence of saliva (xerostomia) decrease the quality of life. While patients suffering from xerostomia are painfully aware of their condition, oligosialia all too often remains unnoticed. The causes of reduced saliva flow are manyfold: somatic or psychosomatic disease, medication, medical therapy, dehydration, age, to name a few. The respective patients suffer from thirst, difficulties in speaking (dysphonia), chewing, tasting (dysgeusia), swallowing (dysphagia) and are at a very high risk for caries as well as for bacterial, viral or fungal infections of the oral mucosa. Early diagnosis and care of oligosialia is mandatory Oral prophylactic care for and dental therapy of xerostomic patients are challenging both for the patients and the dental professionals.