Purpose <p>The aim of the present study was to identify the prevalence of lack of maternal control of the daily toothbrushing of children up to 6 years of age receiving care at a School of Dentistry in Southern Brazil, as well as its associated factors.</p> Methods <p>A cross-sectional study. Data were obtained through a structured questionnaire administered to the mothers. The outcome of interest was maternal control of their children’s daily toothbrushing, and the exposure variables were related to both the mother and the child. Descriptive and multiple regression analyses were performed.</p> Results <p>A total of 156 mother-child pairs were evaluated. The percentage of children whose daily toothbrushing was not controlled by their mothers was 14.8%. After adjusted regression analysis, lack of dietary control (PR = 2.74; 95% CI 1.15–6.50; <i>p</i> = 0.023) and maternal stress symptoms (PR = 3.74; 95% CI 1.56–8.96; <i>p</i> = 0.003) remained associated with the outcome.</p> Conclusion <p>The percentage of children whose daily toothbrushing was not controlled by their mothers was 14.8%. Factors, such as the presence of maternal stress symptoms and the absence of dietary control for the child, directly influenced the lack of maternal control of children’s daily toothbrushing.</p>