Objective This study aimed to analyze the oral health status of four different birth cohorts: two cohorts of 60-year-olds born in 1941-1943 and 1954-1955 and 2 cohorts of 81-year-olds born in 1920-1922 and 1933-1934. Material and methods The study was based on data from an ongoing longitudinal population project, The Swedish National Study on Aging and Care (SNAC). Oral health status was repeatedly examined clinically and radiographically in 2001-2003 and 2014-2015, including 60- and 81-year-olds, in total 412 individuals. Statistical analyses were performed using independent-samples t test and Pearson's chi(2) test. Results More individuals were dentate in 2014-2015 compared to 2001-2003 in the two age groups: 60 and 81 years (p < 0.001 for both). The mean number of teeth increased in the 60-year-olds from 24.2 to 27.0 and in the 81-year-olds from 14.3 to 20.2. The numbers of at least one intact tooth increased for both age groups (p < 0.001 and p < 0.004, respectively). In the age groups 81 years, there was an increase in having at least one PPD >= 6 mm (p < 0.016) and bone loss >= 5 mm (p < 0.029) between the two examinations. No such differences were found in the age groups of 60 years. Conclusion Over 13 years, oral health improved for both 60- and 81-year-old age groups. The most significant changes were in the 81-year-olds where oral health had improved except for periodontal status.