This book has come about following a symposium organized by the editor to encourage further research into dry mouth and its causes. The symposium was held at the Pan-European meeting of the IADR, and as a consequence, this book is largely based on contributions from Europeans. This may lead to variations compared to US-based books as there are differences in drug prescribing, irradiation protocols, and even diagnostic criteria that may influence the healthcare professional. Using even the most conservative of estimates, this book will still be relevant to the 30 million dry mouth sufferers in the European region. In trying to stimulate research in this field, a more scientific than clinical approach has been taken although, of course, the two go hand in hand.