The objectives of this study are to measure permanent tooth loss and the factors which influence it. The study will be conducted in two (2) phases. The first phase will be independent of the second and will be a complete study without the second phase. Specific aims of Phase I are to describe 1) the biological condition of extracted teeth, 2) the sociodemographic, attitudinal, economic, and dental care-seeking characteristics of individuals who have extractions, and 3) selected characteristics of the dental providers who perform the extractions. Phase II will be conducted after the first phase and will collect information on patients whose teeth were treated with dental services that are alternatives to extraction for given biological conditions. These teeth will be controls for the extracted teeth and will allow the estimation of a model which explains the factors which influence the choice between extraction and its alternatives. The same practices will be used for both phases. Data from both Phases will be used to develop a more complete explanation of the relative significance of these factors for tooth loss. This year the data collection instruments (patient questionnaire and patient examination form) and the sampling strategy have been finalized. The instruments underwent several rounds of focus group pretesting and pilot testing. The sampling strategy was revised from a "quota" sampling approach to one using random probability sampling to improve inference to the general population. In addition, in vivo/in vitro validation studies were carried out to determine the comparability of measurements (e.g. pocket depth) across cases and controls.