Epidemiological studies demonstrate a high prevalence of advanced destruction but also that relatively few individuals in each age group account for most of the advanced periodontal disease. The available data suggest that three quarters of advanced periodontal disease could be prevented by targeting an effective preventive strategy on the 28% of individuals especially at risk. Questions remain regarding: 1) whether an acceptable cost-effective preventive strategy can be devised; and 2) whether it is possible to establish a simple method of identifying the 'at risk' group. The various risk factors are numerous and include systemic diseases, smoking, drug therapy, hormonal disturbances and genetic factors as well as the more mundane factors such as plaque control and socio-economic and education and attitude factors. Aside from these factors, many patients present with periodontal disease and have no discernible predisposition other than possibly genetic, for which we can not currently test, and for the vast majority of patients there would appear to be no other alternative to periodic thorough examination for all patients, early treatment of all periodontal lesions and appropriate dental health education.