Dental decay affects many children, especially those from the lower socioeconomic classes. In this cross-sectional study designed to investigate the role played by sociodemographic factors, parental attitudes, and monitoring points, which are an indicator of personal perception of what controls individual health, on the prevalence of tooth decay among 5-year-old pre-school children living in a midsized city in São Paulo, Brazil. The ceo-d index of 426 children was assessed; the parents reported sociodemographic characteristics and completed two questionnaires concerning monitoring points and parental attitudes. The results show that 52.35% of the children had decay; higher levels of severe decay were observed among lower E-F socioeconomic classes. Higher socioeconomic status and low externality appear to be protective factors. Low parental internality emerged as a risk factor for decay in primary teeth, possibly because the mother expects or delegates the action to others, delaying care. Parental perceptions of control over a child's health seem to impact preventive care and, consequently, the level of tooth decay among children.