This book provides a concise account of the pathological processes involved in periodontal disease. The first chapter gives a broad overview of periodontal disease and is followed by accounts of the periodontium in health and disease. The book then deals with the micro-organisms implicated in periodontal disease and evaluates their significance. The host responses to factors present in dental plaque are discussed, followed by an account of the interactions between bacteria and the host which cause tissue damage. This leads to a consideration of the different clinical manifestations of the disease, including those associated with HIV infection. In the final chapter, a rational approach to treatment is presented, based on an understanding of the disease mechanisms discussed in the book. Although written principally for dental undergraduates, this book should also be useful to postgraduate students, including those preparing for the Fellowship Examinations of the Royal Colleges. It may be valuable, too, for those practising dentists who wish to update their knowledge of this important subject.