Validity of 5-year-old children's oral hygiene pattern referred by mothers.

OBJECTIVE To determine the validity of oral hygiene questions for children, as commonly used in epidemiological studies, and assess their validity by family income and mother's education. METHODS A subsample of 1122 children from the 2004 Pelotas Birth Cohort, Southern Brazil (who had participated in a 2009 oral health study) was analyzed. The children received dental examinations, and their mothers were interviewed at home. The gold standard for oral hygiene was the Simplified Oral Hygiene Index; from its total score, the outcome was dichotomized into the absence (total score = 0) or presence (total score ≥ 1) of dental plaque. The mothers answered questions related to their child's oral hygiene, including daily toothbrushing, toothbrushing before sleeping and the combination of the two (oral hygiene). These responses were dichotomized into regular and irregular. The validity was determined by calculating the percentages and respective 95% confidence intervals for sensitivity, specificity, positive predictive value and negative predictive value. RESULTS The overall prevalence of dental plaque was 37.0%. The following sensitivities, specificities, positive predictive values and negative predictive values were observed: 29.6%, 82.5%, 49.8% and 66.6%, respectively, for irregular daily toothbrushing; 41.8%, 64.6%, 40.9% and 65.5%, respectively, for irregular toothbrushing before sleeping; and 48.8%, 60.8%, 42.2% and 67.0%, respectively, for irregular oral hygiene. The validity of the oral hygiene reporting varied across different levels of family income and mother's education. The sensitivity and positive predictive values were higher among children with lower incomes and less educated mothers, while opposite associations were observed for specificity and negative predictive value. CONCLUSIONS Oral hygiene questions answered by mothers of five year-old children are not an appropriate substitute for direct oral hygiene assessment by the clinical examination of dental plaque.