Oral health among 35-year-olds in Oslo, Norway. A summary of time trends 1973-2003

Background: Oral health conditions have been investigated in 35-year-old Oslo citizens in four cross-sectio-nal, age-specific epidemiological studies performed in 1973, 1984, 1993 and 2003. The main aim of the series of investigations was to monitor changes in oral health, including dental caries and endodontic and periodontal conditions. Data will give clues to what extent the documented improvements in oral health among children and adolescents also have been maintained into adulthood. Methods: Random samples of 200-250 35-year-olds were selected from The Norwegian Bureau of Statistics database and invited to participate. They completed a self administered questionnaire and were examined clinically and radiographically. The attendance rate varied between 64 % and 80%. Findings: The results presented are based on time-trend analyses. Caries prevalence, measured as the mean DMFS scores, was high and stable from 1973 (DMFS=68.2) to 1984 (DMFS=66.5), but decreased from 1984 (DMFS=40.9) to 2003 (DMFS=26.1), indicating a 62 % reduction in caries and treatment experience. During the whole period, the prevalence of root filled teeth and prevalence of apical periodontitis decreased, but no improvement from 1993 to 2003 could be demonstrated. Assessment of periodontal status showed that the proportion of persons with one or more periodontal pockets ≥6mm decreased from 22 % in 1984 to 8 % i