Prevalence of dental caries and influencing factors, time trends over a 30-year period in an adult population. Epidemiological studies between 1983 and 2013 in the county of Dalarna, Sweden

Objective: The aim of this study was to investigate the prevalence of dental caries in an adult population using four different cross-sectional studies over a 30-year period and to assess its possible associations with socio-economic and socio-behavioural factors. Materials and methods: Four cross-sectional epidemiological studies were performed in the county of Dalarna, Sweden, in 1983, 2003, 2008 and 2013. Random samples of 1012-2244 individuals, aged 20-85 years, who answered a questionnaire about socio-economic and socio-behavioural factors, were radiographically and clinically examined. Results: The proportion of individuals with at least one decayed surface (DS) was 58% in 1983 and significantly lower, 34% in 2008 (p<0.05) and 33% in 2013; the mean number of DS was 2.0 in 1983 and 1.1 in 2013 in the age group 35-75 (p<0.05). In the age group 85, the mean number of DS was 1.2 in 2008 and 2.4 in 2013. Adjusted for age and number of teeth, irregular dental visits, limited financial resources for dental care, smoking, education below university, male gender, daily medication and single living were positively and statistically associated with manifest caries. Conclusion: The declining trend in the prevalence of manifest caries seems to be broken. In the oldest age group mean number of DS was higher in 2013 compared with 2008, indicating a possible beginning of an increase. This needs special attention as this group increases in the population, retaining natural teeth high up in age. Manifest caries was found to be associated with socio-economic and socio-behavioural factors.