The aim of this study was to describe the onset, development and arrest of dental caries in Brazilian 1- to 5-year-old children with limited access to dental care. The sample represented 40% of all children in these age groups attending public nursery school in the Federal District of Brazil. A total of 1465 children who benefited from fluoridated water soon after birth were examined for caries. For all teeth and tooth surfaces, the examination recorded whether they were sound, showing active or arrested lesions (non-cavitated or cavitated), filled or indicated for extraction. The onset of dental caries was identified at an early age; 89% of children were free of caries at the age of 1 year, decreasing to 28% at the age of 5 years. Non-cavitated lesions (active and arrested) accounted for 71% (<2 years), 58% (3 years), 47% (4 years) and 40% (5 years) of the total number of surfaces showing caries experience. The corresponding values for cavities were 28%, 38%, 47% and 47%, respectively. Maxillary incisors and molars disclosed the highest caries experience in all ages. For children older than 1 year, both mean deft and defs scores not including non-cavitated lesions were significantly different from those for which non-cavitated lesions were taken into account (t-test, P < 0.0001). At the age of 5 years, defs scores were 5.5 and 8.8, respectively. This study documented that the onset and development of dental disease started at an early age in the population studied, leading to a considerable need for dental care.