This research proposal contains the aims, rationale and procedures for a collaborative project comprising three oral epidemiological studies examining the social impact of oral disease in order adult populations. The aims of the project are: to measure the extent and nature of the social impact of oral disease; to assess the distribution and determinants of oral disease; to investigate the relationships between oral disease and social impact; and to compare the distribution and determinants of social impact among elderly populations in South Australia, North Carolina and Ontario. The procedures for the North American studies are described in subsequent pages. In South Australia, 2004 subjects representative of the populations aged 60+ of fluoridated Adelaide and non-fluoridated Mt. Gambier will be interviewed at baseline after their selection in a two-stage cluster sample; and estimated 1245 of them will receive oral examination. An important part of the interview schedule is a new, empirically derived Oral Health Impact Profile which has been developed by the South Australian investigators. The oral examinations are based on the NIDR protocols used already in North Carolina and Ontario. Subsequent interviews and examinations will be conducted at two and five years (although this application seeks initial funding for three years). Two sub-samples will be identified (at baseline and two years) for more intensive questioning over concurrent one year periods concerning changes in social impact. An additional nested case control study will be examine socio-demographic risk factors in edentulism of one or both jaws. These narrower, more extensive concurrent investigations are intended to supplement the broad ranging group of questions under investigation in the main longitudinal component. Data obtained at baseline will be analyzed to determine the extent of association between socio-demographic characteristics (focussing particularly upon age-groups) and oral disease and social impact. Information describing incidence rates obtained at two and five years will allow a more rigorous analysis of postulated casual relationships between socio-demographic characteristics, oral disease and social impact. The strength and importance of these relationships (assessed through measures of relative and attributable risk) will be examined using both univariate and multivariate techniques, and will provide guidance for the development of rational interventions to prevent and minimize the burden of oral illness. In examining the social impact of oral disorders, this project will provide new information which will be of generic value in numerous population defined by age, race and geography. It is also expected that older adults from these three sites will provide particularly useful information of the examination of the mechanisms of social impact and that this information will enhance public health planning and policy in Australia, the U.S.A. and Canada.