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 (alpha = 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.