The aim was to investigate whether oral hygiene habits and parent-related factors, recorded in early childhood, have a predictive value in relation to approximal caries experience (including initial caries lesions) at the age of 15 years (n = 568). Data were selected from examinations, interviews and questionnaires at 1 and 3 years and bitewing radiographs at 15 years. Four levels of cut-off points for the statistical analysis were used: DFa = 0, > 0, ≧4 and ≧8. In the final logistic regression analyses, mother’s self-estimation of her oral health care being less good remained statistically significant and predicted a caries experience of DFa > 0 at 15 years. The following four variables predicted DFa ≧4: (1) female gender, (2) plaque on maxillary incisors at 1 year, (3) mother’s self-estimation of her oral health care being less good and (4) father being less satisfied with his social situation. Two variables predicted DFa ≧8: (1) toothbrushing with fluoride toothpaste just once a day, and (2) father being less satisfied with his social situation. Furthermore, children who failed to attend the examination at 1 year of age had 6.95 ± 5.36 (mean ± SD) DFa at 15 years compared with 3.10 ± 3.85 for children who were examined at 1 year of age (p < 0.01). To conclude, factors explaining good dental health at 15 years of age pertained to both children and parents. Thus, it seems that good oral hygiene habits, established in early childhood, provide a foundation for a low experience of approximal caries in adolescents.