Maternal report underestimates the amount of dentifrice used by children during toothbrushing: a cross-sectional study

Purpose This study investigated whether the report of mothers about the amount of dentifrice applied on a toothbrush could be a reliable method to estimate the inadvertent use of dentifrices. Methods A cross-sectional study was conducted in a randomly selected sample of 334 mothers of children enrolled in public day care centres of a city in the Brazilian northeast. Initially, the mothers chose the figure corresponding to the amount of dentifrice used during their children’s daily toothbrushing. Then, they simulated real-life conditions with the toothbrush routinely used to brush the children’s teeth. The amount of dentifrice on toothbrush was weighted using an analytical scale. Data were analysed by the Kruskal–Wallis followed by the Dunn test ( α = 0.05). Results The weight of dentifrice on the toothbrush was high (> 0.3 g), mainly considering the categories ‘covered only’ and ‘completely covered’ that showed no statistical difference ( p > 0.05). The proportion of agreement between the mothers’ reports and the weight of dentifrice on the toothbrush was 0.23 (CI 0.18–0.28). Conclusion The mothers’ report regarding the amount of dentifrice on the toothbrush by demonstrative figures was not a reliable method to estimate the inadvertent ingestion of fluoride from dentifrices.