Ranked 4th global scourge behind cancer, cardiovascular diseases and AIDS, tooth decay is an infectious post eruptive disease, which remains worrying. In children, it involves eating, sleeping and behaviour disorders. Thus, we conducted a descriptive cross-sectional study, on children in toddler's small dwelling of Dakar area. The objective was to determine the prevalence of tooth decay among children of three toddler's small dwelling functional in Dakar. The majority of children was female (57%) and they were more children aged 61 to 73 months in the toddler's small dwelling of Sahm notary located in the suburbs. The prevalence of tooth decay was important for girls in the age group 49 to 60 months and in Toddler's small dwelling located in popular or suburban areas: 78% to Colobane, 68% Sahm notary, with a significant difference. The DFT (decayed, filled teeth) was lowest in Mermoz (residential area). Efforts to improve the oral health must be strengthened by good prevention policy involving people playing a role in educating and guiding children: parents, teachers, organizations, practitioners.