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AIM: To assess the effect of the application of fluoride gels on the acid resistance of occlusal enamel in primary molars. STUDY DESIGN: Forty-five primary second molars were randomly assigned to three groups: a) control (pH-cycling); b) 2% NaF gel/pH-cycling; and c) 1.23% APF gel/pH-cycling. METHODS: Specimens were longitudinally sectioned in the buccal-lingual direction and used for cross-sectional microhardness testing. Knoop hardness values were converted into vol.% mineral and mineral loss (ΔZ) was then calculated. STATISTICS: The response variables were vol.% mineral and ΔZ. Data were tested using parametric tests at a significance level of 5%. RESULTS: No statistically significant differences were found between groups regarding vol.% mineral or ΔZ. CONCLUSIONS: A single application of a high concentration fluoride compound does not promote greater resistance to demineralisation in enamel pits and fissures, regardless of the product used.

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The aim of this study was to assess the reliability and external validity of the Previous Day Food Questionnaire (PDFQ) designed to obtain a report of the foods eaten on the previous day by schoolchildren. Participants were 7-10-year-old school children of the first four grades of a public school in Southern Brazil (N=227). Test-retest reliability was evaluated by kappa coefficient for two administrations of the PDFQ on the same day to the same children. External validity of the PDFQ was evaluated via sensitivity, specificity, and positive and negative predictive values (PPV and NPV, respectively) using trained observers of the food eaten on the previous day as gold standard. The association between responses from observed food intake with those from reported food intake on PDFQ was evaluated by multivariate logistic regression, controlled for school grade, gender, time of the eating, and the variation between first and second PDFQ applications. For the reliability study, the analyses stratified by school eating occasions (3 a day) indicated that agreement level was moderate or better for all food categories. PDFQ's sensitivity ranged from 57.1% (vegetables) to 93.3% (rice), whereas its specificity ranged from 77.8% (bread/pasta) to 98% (meats). Both, PPV and NPV were reasonably high. PDFQ was highly associated with observed food intake, with effect magnitude several times larger than any other factor analyzed for all foods. PDFQ also showed good test-retest reliability, suggesting that it may generate reliable and valid data for assessing food intake at the group (school) level.

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Waist circumference (WC) is a measure of central adiposity related to elevated risk factor levels in children and adolescents. The aim of the present study was to describe WC percentiles in 7- to 10-year-old Brazilian children and to compare frequencies of obesity and overweight as defined by BMI and frequencies of excess and at risk of abdominal adiposity as defined by WC to the corresponding age and sex data from British references. A representative sample of 2919 schoolchildren of the city of Florianopolis (southern Brazil) was examined. Smoothed WC percentiles were derived using the least mean square method. Frequencies of overweight and obesity and of excess and at risk of abdominal adiposity were assessed using the 91st and 98th centiles of the British references as cut-off points. WC increased with age in both boys and girls, with higher values for boys at every age and percentile level. Nutritional status categories of children assessed by the 91st and 98th British BMI and WC centiles showed moderate agreement (weighted kappa = 0.58). Overweight was more frequent in Brazilian than British children: 15.1 % of girls and 20.1 % of boys were above the 91st percentile of the 1990 BMI for age British references. About one-quarter (22.0 % of girls and 26.9 % of boys) exceeded the 91st percentile of WC British references. The present data could be used to compare WC in children in other populations and may serve as a baseline for future studies of temporal trends in WC in Brazil.

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OBJECTIVE: To assess the prevalence of obesity, overweight (including obesity) and thinness in children of the city of Florianopolis (southern Brazil). DESIGN: Cross-sectional study. SUBJECTS: Representative sample of 7-10-y-old schoolchildren of the first four grades of elementary schools (1432 girls, 1504 boys). METHODS: Measurements of weight, height and triceps skinfold thickness (TSF) were taken following standard techniques. The body mass index (BMI) was computed as weight/height2. Nutritional status was defined using two references: (1) the Must et al reference for BMI and TSF to define thinness, overweight and obesity (5th, 85th and 95th percentiles, respectively); (2) the International Obesity Task Force (IOTF) BMI cutoffs to define overweight and obesity. RESULTS: Using BMI, according to the Must et al, and IOTF references, the prevalence of obesity was 10.6 and 5.5%, respectively; overweight (including obesity) affected 26.2 and 22.1% of children, respectively. According to the Must et al reference, the prevalence of thinness was 3.2%. Using TSF rather than BMI, according to the Must et al references, fewer children were classified as obese (8.0%) or overweight (20.2%) and more children were classified as thin (4.9%). CONCLUSION: This study supports the previously reported high frequencies of childhood overweight and obesity in developing countries. The data allow comparisons with other studies carried out in Brazil and other parts of the world.

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