Objectives: The purpose of the present investigation was to report on caries experience among Norwegian 12-year-olds from 1985 to 2004 and to assess caries incidence from 12 to 18 years of age for birth cohorts 1973 to 1986.
Material and methods: Aggregated data from the Norwegian Public Dental Services and from official statistics were employed. Information was available about the number of subjects, the proportion receiving treatment, sales of fluoride tablets, socio-demographics, caries prevalence, and the number of decayed, missing, and filled teeth (DMFT).
Results: An almost linear decline in caries prevalence and mean D3MFT (dentine level) occurred among 12-year-old children from 1985 until the year 2000, but from 2000 to 2004 an increasing trend was observed. The highest mean 6-year D3MFT increment (age 12-18 years) was 4.1 (cohort 1976), while the lowest was 3.2 (cohorts 1982 and 1983). In multiple linear regression analyses of trend, baseline D3MFT accounted for more than 91% of total explained variance in D3MFT increment (Models I and III). Without baseline D3MFT as predictor (Models II and IV), there was a significant association between education, social assistance, mobility, infant mortality, percentage examined, and the additive interaction terms year + income and year + education and D3MFT increment after controlling for confounding and multicollinearity.
Conclusions: Four consecutive years of increase in caries experience among 12-year-old children after 15 years of decline and evidence of stability or increase of the caries increment from 12 to 18 years of age among Norwegian teenagers give cause for concern.