The aim of this study was to compare changes in periodontal status of a Swedish population over a 10-year period expressed as frequency distributions of individuals according to severity of periodontal disease experience. The study involved 600 randomly selected individuals evenly distributed into age groups 20, 30, 40, 50, 60 and 70 years, examined in 1973 and another randomly selected group of 597 individuals similarly age distributed and examined in 1983. Based on clinical data and full mouth intraoral radiographs all individuals were classified into 5 groups according to severity of periodontal disease experience. In 1983, 23% of the individuals were classified as having healthy periodontal tissues, group 1, compared to 8% in 1973. The changes were most pronounced in the age groups 20 and 30 years, among whom 58% and 35%, respectively, were registered as having healthy periodontium in 1983. The prevalence of individuals with gingivitis without signs of lowered periodontal bone level, group 2, was 22% in 1983 compared to 41% in 1973. In all, 49% of the dentate population in 1973 and 45% in 1983 showed no marginal alveolar bone loss. Moderate periodontal bone loss, group 3, was found in 41% of the population in 1983 compared to 47% in 1973. Among 30-, 40-, and 50-year-olds, there were more, and among 60- and 70-year-olds, fewer individuals in this group in 1983 compared to 1973. 96% of the dentate population were classified as belonging to groups 1, 2 or 3 in 1973 compared to 86% in 1983.(ABSTRACT TRUNCATED AT 250 WORDS)