ObjectivesThe high prevalence and severity of caries among Canadian First Nations children is a growing concern. Dental surgery in hospital is often necessary to treat the signs of decay but does not address the underlying factors contributing to its development. The purpose of this study was to determine the prevalence and risk factors of caregiver-reported Baby Bottle Tooth Decay (BBTD), or Severe Early Childhood Caries (S-ECC), among preschool children recruited in Phase 2 of the First Nations Regional Longitudinal Health Survey (RHS).Study DesignCross-sectional study including interviews with caregivers.MethodsThis study was limited to data from Manitoba First Nations participating in the RHS Phase 2 (2008–10). Data were restricted to caregiver interviews for their child <72 months of age. The main variable of interest was caregiver-reported BBTD, an antecedent term for S-ECC. Data analysis included descriptive statistics and bivariate analyses; p≤0.05 was significant.ResultsOverall, caregivers of 431 preschool children responded. According to caregiver reports, 102/410 (24.9%) children had S-ECC. Further, 65.0% responded that their child had already undergone treatment for caries. Children with S-ECC were significantly older than those without. S-ECC was also associated with paternal education levels and employment status, and maternal smoking during pregnancy. Breastfed children were less likely to have S-ECC, while consuming drink crystal beverages in bottles, and daily intake of soft drinks, juice, sweets and fast food were associated with increased risk. Those who reported that healthcare services were not available and were not culturally appropriate were significantly more likely to have children with S-ECC.ConclusionsCaregiver reports suggest that nearly 1 in every 4 children has been affected by S-ECC. Identified risk factors for Manitoba First Nations children included age, education and employment, dietary practices, access to care, and disruption to family and culture. This local evidence can be used to help inform future caries prevention activities in these Manitoba communities.