One of the factors that significantly impinges on the quality of life among elderly people is a decrease in salivary flow (hyposalivation) and a dry mouth (xerostomia). The prevalence of xerostomia increases with age and affects approximately 30% of people aged 65 or older. Xerostomia leads to problems with speech, taste digestion, mastication and swallowing, and a high incidence of dental caries and candida. There is no cure but chewing gum and artificial saliva are used to relieve the symptoms in many cases. Given the large numbers of sufferers, and the potential increase in incidence given our aging population, it is important to understand the mechanisms that drive xerostomia so that new therapies can be found. Xerostomia can be caused by a number of different factors. Certain medicines cause xerostomia as a side effect, while xerostomia is also a central feature of the auto-immune disease Sjögren Syndrome, which affects up to 3-4% of older adults. Xerostomia is also a feature of some genetic disorders that affect the salivary glands, such as LADD syndrome and ALSG, and is frequently a side effect of head and neck radiotherapy. We aim to study xerostomia using various mouse models of gland dysfunction and regeneration. This application aims to combine knowledge of salivary gland development with knowledge of salivary gland stem cells from mouse and translate these findings into humans. This is possible through combining research from basic scientists in the UK and clinical researchers in Brazil, with the ultimate goal of creating innovative methods to treat xerostomia.