Aim: To investigate if active caries disease in the primary dentition can be used as a long-term predictor for active caries disease in the permanent dentition. Study Design: Population-based longitudinal register study. Methods: This study included all those born in 1987 living in Örebro county who came to the clinic for an examination at all three measuring points in 1990, 1993 and 2006 (n = 1,985, panel). The panel consisted of 77.3% of the baseline group (1990) and represented 60.0% of the three-year-olds in the population in 1990. Caries data were compared at the individual level and were broken down into the components of decayed, filled primary teeth (dft) and decayed surfaces (ds) (at three years and six years) and decayed filled permanent teeth (DFT) and decayed surfaces (DS) (at 19 years). DFT (dft) was used as an indicator of caries experience and DS (ds) as an indicator of active caries disease Results: There was a poor correlation between active caries disease at six years of age and active caries disease at 19 years of age. A stronger correlation could be measured between dental caries experience at six years of age (primary dentition) and caries experience at 19 years of age. Statistics: Bivariate analyses were conducted by cross-tabulation and Chi-squared statistics. Multivariate analyses were conducted using binary multiple logistic regression with categorical data. Conclusions: The correlations between active caries disease in the primary dentition and active caries disease at 19 years of age were very low on an individual level. Using early caries disease as a predictive test for later caries disease showed low sensitivity and low specificity over a long time period.