The primary aims were to investigate the total number of radiographs and the reason for dental radiography in children and adolescents in the Public Dental Health Service. Secondary aims were to study the influence of caries experience and orthodontic treatment on the number of radiographs. For this retrospective study, 544 adolescents regularly attending three Public Dental Health clinics in the county of Västerbotten, northern Sweden were selected. The number of radiographs exposed each year from 3 to 19 years of age was registered. Information on reason for the radiographic examination was extracted from dental records as well as the caries experience at 19 years of age. The attrition rate was 7% due to incomplete data. The total mean number of radiographs exposed was 23+/-6 of which 1+/-2 were extra-oral radiographs. Bitewing radiographs for caries registration constituted 87% of the intra-oral radiographs with a mean number of 19+/-4 exposures. There was a statistically significant difference (p<0.01) between subjects with caries experience (20+/-4) and those with no caries (16+/-4). No gender-related differences were displayed. During preschool ages, bitewing radiographs were taken in less than 10% of the children. Children treated at specialist clinics in orthodontics displayed higher number of radiographic examinations than non-referred children (p<0.01). CONCLUSION: A mean of 23 radiographs were exposed and bitewings for caries detection were the most common radiographic examination. Fewer bitewing radiographs were exposed in caries-free subjects over time but its use during the preschool ages was low. Orthodontics treatment increased the frequency of radiography significantly.