Objective: To compare the severity of dental caries in the primary dentitions of children under 7 years (who received comprehensive restorative treatment under general anaesthesia, GA) from an optimally fluoridated area (0.85ppmF) and a low-fluoride area (~0.1ppmF). Research design: Consecutive clinical case series: clinical details (diagnoses and the treatments provided) were recorded for children who had received comprehensive dental care under GA between 2000 and 2009. Age, gender, ethnicity, socio-economic status and fluoridation status (determined from the residential address) were also recorded. Results: Of the 1396 treated children, 55.7% came from fluoridated areas and 52.5% were male. On average, children from low-fluoride areas were 2.4 months younger and presented with more decayed deciduous teeth than those from fluoridated areas (4.9 and 3.9 teeth respectively; p<0.0001). For each tooth type, the mean number of carious teeth at presentation was greater among the children from low-fluoride areas. In the multivariate model, the number of deciduous teeth affected by caries was lower among older children, those residing in a fluoridated area and among those seen after 2001. It was higher among those not living in high-SES areas. Conclusions: Children with severe dental caries had statistically significantly lower numbers of lesions if they lived in a fluoridated area. The lower treatment need in such high-risk children has important implications for publicly-funded dental care. Key words: Dental caries; Children; Fluoridation; Residence characteristics