A New Oral salIvary equivAlent Compared to Two moisturizinG Mouth sprAys in Patients With xeRostomiA: NIAGARA Study

Inclusion Criteria: Patients: * Aged 18 years or more, * Clinical diagnosis of xerostomia by a severe reduction of salivation, as detected by patient's answers to few specific questions and measured by saliva volume at screening visit (test of saliva weight absorbed ≤ 0.1g/min) * Any medical condition or treatment leading to a severe reduction of salivation related to either: * Head and neck radiation therapy for cancer, * Gougerot-Sjögren syndrome * Medications known to induce xerostomia (psychotropic drugs, antihypertensive drugs) * Dehydration, hypothyroidism, Parkinson's disease and/or diabetes mellitus * Female patients must be post-menopausal or using a highly effective method for avoidance of pregnancy throughout the whole study duration, if childbearing potential. * Able to understand and comply with the protocol procedures * Willing and able to give their written informed consent * Affiliated to the French National Health Insurance Program Exclusion Criteria: * Known hypersensitivity to one of the study products or to one of their components * Any planned change in dosing of all known medications inducing mouth dryness * Concomitant treatment for xerostomia symptoms without a scheduled 3 to 7-day withdrawal window * Oral candidiasis as diagnosed by a microbiological test obtained from an unstimulated whole saliva sample until 3-week period from disease release * Oral ulceration * Alcohol (\>2 glasses of wine/day), smoking (\>10 cigarettes/day), caffeine and/or theine intake (\>4 cups/day) * Patients unable to fill out the questionnaires or to comply with the study protocol * Dental infection * Patients participating to another clinical trial at the time of the study entry or within 30 days prior to study enrolment * Life-threatening condition at the time of the study * Pregnant or lactating women and women of childbearing potential refusing to use adequate contraception.