Fluoride retention in infants living in fluoridated and non-fluoridated areas: effects of weaning.

Limited knowledge is available on total fluoride exposure, excretion and retention in infants, despite the first year of human life being the critical period for dental development and risk of dental fluorosis. This study investigated total daily fluoride intake (TDFI), excretion (TDFE) and retention (TDFR) in infants living in fluoridated and non-fluoridated water areas at pre- and post-weaning stages of development. Healthy infants, aged 0-12 months, were recruited and their TDFI (mg/kg body weight (BW) per d), from diet and toothpaste ingestion, was assessed over a 3-d period using a dietary diary and tooth-brushing questionnaire. TDFE (mg/kg BW per d) was estimated by collecting 48-h urine and faeces. TDFR (mg/kg BW per d) was estimated by subtracting TDFE from TDFI. A total of forty-seven infants completed the study: sixteen at pre-weaning and thirty-one at post-weaning stages, with a mean age of 3·4 and 10·0 months, respectively. TDFI was lower in the non-fluoridated area (P<0·001) and at the pre-weaning stage (P=0·002) but higher in formula-fed infants (P<0·001). TDFE was mainly affected by type of feeding, with higher excretion in formula-fed infants (P<0·001). TDFR was lower in the non-fluoridated area (P<0·001) and at the pre-weaning stage (P<0·001) but higher in formula-fed infants (P=0·001). In conclusion, a relatively large proportion of fluoride intake is retained in the body in weaned infants. This is an important consideration in fluoride-based prevention programmes, with goals to maximise caries prevention while minimising the risk of dental fluorosis.

Comparison of total ionic strength adjustment buffers III and IV in the measurement of fluoride concentration of teas.

BACKGROUND: Tea is the second most consumed drink in the UK and a primary source of hydration; it is an important source of dietary fluoride (F) for consumers and also abundant in aluminium (Al). Varying ranges of F concentrations in teas have been reported worldwide which may be, in part, due to differences in analytical techniques used to measure this ion. AIM: The effect of using total ionic adjustment buffers (TISAB) III or IV when measuring F concentration of black teas available in the UK was investigated and compared. Based on this evaluation, the effects of three different infusion times, 1 min, 10 min and 1 h, caffeine content and tea form on the F contents of the tea samples were investigated. METHODS: The F concentrations of 47 tea samples were measured directly using a fluoride ion-selective electrode (F-ISE), TISAB III and IV and infusion times of 1 min, 10 min and 1 h. RESULTS: Mean (SD) F concentration of tea samples for all infusion times was statistically significantly higher ( p < 0.001) measured by TISAB IV (4.37 (2.16) mg/l) compared with TISAB III (3.54 (1.65) mg/l). A statistically significant positive correlation ( p < 0.001) was found between Al concentration (mg/l) and differences in F concentration (mg/l) measured using the two TISABs; the difference in F concentration measured by the two TISABs increased with the magnitude of Al concentration. CONCLUSION: Due to higher concentrations of F and Al in teas and their complexing potential, use of TISAB IV facilitates more accurate measurement of F concentration when using an F-ISE and a direct method.

Fluoridated toothpaste: usage and ingestion of fluoride by 4- to 6-yr-old children in England.

Fluoridated toothpaste is effective for dental caries control, yet may be a risk factor for dental fluorosis. This study aimed to quantify fluoride ingestion from toothpaste by children and to investigate the effects of age, gender, and social class on the amount of fluoride ingested per toothbrushing session. Sixty-one children, 4-6 yr of age, were recruited: 38 were from low socio-economic (LSE) areas of Newcastle, UK, and 23 were from high socio-economic (HSE) areas of Newcastle, UK. All expectorated saliva, rinse water (if used), and residual toothpaste were collected after brushing at home and were analysed for fluoride. Of the children, 74% and 69% from HSE and LSE areas, respectively, claimed that they brushed twice per day. The mean (SD) weight of toothpaste dispensed was 0.67 (0.36) g. The mean (SD) amount of fluoride ingested per toothbrushing session and per day was 17.0 (14.7) and 29.3 (32.8) µg kg(-1) of body weight, respectively. Daily fluoride intake per kilogram of body weight did not differ significantly between children from LSE and HSE areas. Fluoride intake per toothbrushing session was significantly influenced by weight of toothpaste, its fluoride concentration, and the child's age. Whilst the average amount of toothpaste used per toothbrushing session was more than twice the recommended amount (of 0.25 g), only one child had a daily fluoride intake that exceeded the tolerable upper intake level of 0.1 mg kg(-1) of body weight for this age group.

Total daily fluoride intake and fractional urinary fluoride excretion in 4- to 6-year-old children living in a fluoridated area: weekly variation?

OBJECTIVES: Risk of development of dental fluorosis may increase with even a short-term increase in fluoride (F) intake during tooth formation. Considering the wide variations in F concentrations of different food and drinks, it is important to assess short-term differences in F intake and consequently fractional urinary F excretion (FUFE) in children, which provide an indication of F body burden. Therefore, the aim of this study was to investigate weekly variation in total daily F intake (TDFI) and its sources and fractional urinary F excretion (FUFE) in 4- to 6-year-olds living in a fluoridated area in the UK. METHODS: Sixty-one children were surveyed twice with a 1-week gap between surveys. Dietary F intake was assessed by 'food-diary' and 'duplicate-plate collection'. Toothbrushing expectorate (saliva/toothpaste) was collected to estimate F intake from toothpaste ingestion. TDFI was calculated from dietary F intake and toothpaste ingestion. Daily urinary F excretion (DUFE) was estimated by collecting 24-h urine samples and FUFE was calculated from DUFE and TDFI [FUFE = (DUFE/TDFI) × 100]. RESULTS: The overall mean TDFI, DUFE and FUFE for all children were 0.056 (SD 0.036) mg/kgbw/day, 0.018 (SD 0.007) mg/kgbw/day and 39 (SD 20)%, respectively. The mean (95% CI) difference between the 2 weeks studied was 0.004 (-0.004, 0.011) mg/kgbw/day for TDFI, 0.002 (-0.001, 0.004) mg/kgbw/day for DUFE and 1 (-6, 8)% for FUFE. CONCLUSIONS: Mean TDFI and FUFE did not vary statistically significantly with week and therefore one set of data collection from a group of children living in a temperate climate could be sufficient to monitor F exposure and F body burden in community prevention programmes for oral health.

Fluoride content of ready-to-feed (RTF) infant food and drinks in the UK.

BACKGROUND: The level of Fluoride exposure needed to cause dental fluorosis is not known precisely. An awareness of total F intake from all sources, especially during the critical stages of dental development during infancy and early childhood, is important in preventing the development of dental fluorosis. OBJECTIVES: The aim of the study was to measure F content of ready-to-feed (RTF) infant drinks and foods in the UK. METHODS: In total, 122 infant foods were analysed for F concentrations, in triplicate, indirectly by an acid diffusion method and 25 infant drinks analysed directly using an F-ion-selective electrode after addition of TISABIII. RESULTS: The median (range) F concentration was 0.110 (0.030-0.221) µg/g for breakfast cereals, 0.112 (0.040-1.200) µg/g for savoury meals, 0.056 (0.030-0.379) µg/g for desserts, 0.044 (0.020-0.191) µg/g for fruits, 0.196 (0.040-0.397) µg/g for baked goods, 0.069 (0.050-0.148) µg/ml for juices, 0.016 (0.009-0.030) µg/ml for milks and 0.041 (0.022-0.069) µg/ml for waters. The median (range) F concentration of all RTF infant foods and drinks by recommended age of consumption was 0.029 (0.010-0.245), 0.088 (0.020-0.500), 0.108 (0.100-0.510) and 0.108 (0.060-1.200) µg/g for infants from birth, 4+ month, 6+ month and 10+ month, respectively. CONCLUSION: The results suggest that the F concentrations of UK-marketed RTF infant foods, drinks and formula milk are not sufficiently high to be a risk factor for dental fluorosis, if consumption is within the limits recommended for infants and young children.

Impact of water fluoride concentration on the fluoride content of infant foods and drinks requiring preparation with liquids before feeding.

OBJECTIVES: To measure the fluoride (F) content of infant foods and drinks requiring reconstitution with liquids prior to consumption and to determine the impact of water F concentration on their F content, as consumed, by measuring F content before and after preparation. METHODS: In total, 58 infant powdered formula milks, dry foods and concentrated drinks were prepared with deionized water (<0.02 ppm F) nonfluoridated (0.13 ppm F) and fluoridated (0.90 ppmF) water. The F concentrations of drink samples were measured directly using a fluoride-ion-selective electrode after addition of TISAB III, and food samples and formula milks measured indirectly by an acid diffusion method. RESULTS: The overall range of F concentrations of all the nonreconstituted samples, in their prepreparation dry or concentrated forms, was from 0.06 to 2.99 µg/g with the highest F concentration for foods found in the dry 'savoury meals' (a combination of vegetables and chicken or cheese or rice) group. However, when the samples were reconstituted with nonfluoridated water, the mean F concentrations of prepared 'concentrated juices', 'pasta and rice', 'breakfast cereals', 'savoury meals' and 'powdered infant formula milks' were 0.38, 0.26, 0.18, 0.16 and 0.15 µg/g, respectively. The corresponding mean F concentrations were 0.97, 1.21, 0.86, 0.74 and 0.91 µg/g, respectively, when the same samples were prepared with fluoridated water. CONCLUSION: Although some nonreconstituted infant foods/drinks showed a high F concentration in their dry or concentrated forms, the concentration of F in prepared foods/drinks primarily reflected the F concentration of liquid used for their preparation. Some infant foods/drinks, when reconstituted with fluoridated water, may result in a F intake in infants above the suggested optimum range (0.05-0.07 mg F/kg body weight) and therefore may put infants at risk of developing dental fluorosis. Further research is necessary to determine the actual F intake of infants living in fluoridated and nonfluoridated communities using reconstituted infant foods and drinks.