OBJECTIVE To examine the relationship between the presence of enamel defects, dental caries in primary teeth, and exposure to various fluoride technologies and the presence of dental caries in permanent teeth in children with mixed dentition. METHODS A cross-sectional study was conducted in 713 children aged 6-9 years old in 4 elementary schools in Campeche, Mexico through the use of a questionnaire for the mothers and an oral examination in the children. The dependent variable was the prevalence of caries in permanent dentition. RESULTS The mean number of decay, missing or filling teeth in primary dentition (dmft) and in permanent dentition (DMFT) was 2.48 (2.82) (deft > 0 = 58.9%) and 0.40 (0.98) (DMFT > 0 = 18.2%), respectively. The significant caries index (SiC), which is calculated in deciduous dentition, was 5.85 for 6 year-olds. Multivariate logistic regression adjusted for variables related to fluoride exposure revealed that older age (OR = 2.99), a deft of > 0 (OR = 5.46), and lower maternal educational level (OR = 1.57) were significantly associated with a higher number of dental caries in permanent teeth. An interaction between sex and enamel defects was also found. CONCLUSIONS The number of dental caries in both primary and permanent dentitions was relatively smaller than that found in prior studies performed in Mexican populations. The results confirm that the presence of caries in primary dentition is strongly associated with caries in permanent dentition. No significant relationship was found between fluoride exposure and dental caries in permanent dentition.