An old tooth does not exist on its own; therefore, any decision about a tooth demands knowledge about the elderly patient to whom the tooth belongs. If it is available, one can then evaluate the oral cavity in which the tooth resides. When all this information has been gathered, decisions about the individual tooth can be made. This paper discusses three specific issues: when does one 'patch' an amalgam restoration; when should one crown this restored tooth; and when does one 'patch' the crown, and when does one replace it? A review of the literature indicated that reliable and generally applicable data on these issues do not exist, so that these decisions are still made by clinical judgement based upon experience. In view of the known changes in caries rates, fluoridation of water supplies, and patient attitudes, dentists' judgements of appropriate restorative treatment for older adults based upon past experience may be inappropriate. Longitudinal clinical research is required to develop clinically usable guidelines, especially for the elderly.