AbstractObjectivesThe objective of this study was to estimate the prevalence of deciduous tooth erosion and to identify possible associations with sex, age and toothbrushing frequency in children aged 4–6 years.MethodsThe sample was drawn from attendants (n = 7058) of 57 public preschools in a Brazilian city. Tooth wear index was used to evaluate erosion. Descriptive statistical analysis consisted of the calculation of the prevalence of dental erosion; chi‐squared and Fisher's exact tests were performed to verify the association between dental erosion and sex, age and toothbrushing frequency.ResultsTwo thousand and seven hundred and fifty‐nine preschool students were examined. Deciduous tooth erosion was observed in 0.6% of children and its incidence did not differ between sexes. The highest prevalence was observed in children aged 6 years (58.3%) and the most affected sextants were the fourth (22.86%) and sixth (20.00%), indicating that lingual and occlusal tooth surfaces were most frequently involved. The degree of involvement was classified as incipient in 54.29% of children and moderate in 45.71%. The significance level was set at 5%. No association was found between erosion and sex, age or toothbrushing frequency.ConclusionsThe prevalence of deciduous tooth erosion was low in Brazilian children, and this disorder is not considered a public health problem in this part of the population.