The aim of the present study was to compare data on dental care habits and knowledge of oral health in three cross-sectional studies carried out in 1973, 1983, and 1993. The 1973 study constituted a random sample of 1000 individuals evenly distributed in the age groups 3, 5, 10, 15, 20, 30, 40, 50, 60, and 70 years. The same age groups with addition of a group of 80-year-olds were included in the 1983 and 1993 studies which comprised 1104 and 1078 individuals, respectively. A questionnaire (23-101 questions) about dental care habits and knowledge of oral health was used in connection with a clinical and radiographic examination. The same questions were used in all the three studies. An addition to the 1993 investigation was questions concerning ethnographic background. In 1993 approximately 95% of all individuals were visiting the dentist on a regular basis every or every second year. The 30-year-olds, however, did not visit a dentist as regularly in 1993 as in 1983. The 70- and 80-year-olds visited a dentist more regularly in 1993 than in 1983. An increased number of adults in all age groups, except for the 70-year-olds, received their dental care in the Public Dental Service in 1993 compared to 1983 and 1973. Most 40-year-olds and older, however, received their dental care by private practitioners. About 80% of all adults in 1993 were enrolled in a recall system on the dentist's initiative while in 1973 most appointments were based on the patient's own initiative. The number of individuals who felt discomfort at the prospect of an appointment with the dentist was more or less the same in 1973, 1983, and 1993. The knowledge of the etiology of dental diseases has not changed much between 1973 and 1993. The frequency of toothbrushing has increased since 1973 and in 1993 more than 95% of all individuals brushed their teeth daily. The use of dental floss and toothpicks as well as disclosing tablets decreased in 1993 compared to 1983. Almost all individuals in 1993 used fluoride toothpaste. The use of topical fluorides and fluoride tablets in children had decreased considerably in 1993 compared to 1983.