F. V. Zohoori

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 childs 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.

Effect of Rinsing with Mouthwashes after Brushing with a Fluoridated Toothpaste on Salivary Fluoride Concentration

The aim of the study was to determine whether rinsing with a mouthwash after brushing with a fluoridated toothpaste affected oral fluoride (F) retention and clearance compared with an oral hygiene regime without mouthwash. In this supervised, single-blind study, 3 regimes were compared: (A) brushing for 1 min with 1 g of 1,450 μg F/g NaF toothpaste followed by rinsing for 5 s with 10 ml water; (B) as A but followed by rinsing for 30 s with 20 ml of 100 mg F/l NaF mouthwash, and (C) as B but rinsing for 30 s with a non-fluoridated mouthwash. Twenty-three adults applied each treatment once in a randomised order, separated by 1-week washout periods, and used a non-fluoridated toothpaste at home prior to and during the study. Whole saliva samples (2 ml), collected before each treatment commenced and 10, 20, 30, 60, 90 and 120 min afterwards, were subsequently analysed for fluoride by ion-specific electrode. The mean (SD) back-transformed log (area under salivary F clearance curve) values were: A = 2.36 (+3.37, –1.39), B = 2.54 (+2.72, –1.31) and C = 1.19 (+1.10, –0.57) mmol F/l × min, respectively. The values for regimes A and B were statistically significantly greater than that for regime C (p < 0.001; paired t test). These findings suggest that use of a non-F mouthwash after toothbrushing with a F toothpaste may reduce the anticaries protection provided by toothbrushing with a F toothpaste alone. The use of a mouthwash with at least 100 mg F/l should minimise this risk.

Fractional urinary fluoride excretion of 6-7-year-old children attending schools in low-fluoride and naturally fluoridated areas in the UK

F is an important trace element for bones and teeth. The protective effect of F against dental caries is well established. Urine is the prime vehicle for the excretion of F from the body; however, the relationship between F intake and excretion is complex: the derived fractional urinary F excretion (FUFE) aids understanding of this in different age groups. The present study aimed to investigate the relationships between (1) total daily F intake (TDFI) and daily urinary F excretion (DUFE), and (2) TDFI and FUFE in 6-7-year-olds, recruited in low-F and naturally fluoridated (natural-F) areas in north-east England. TDFI from diet and toothbrushing and DUFE were assessed through F analysis of duplicate dietary plate, toothbrushing expectorate and urine samples using a F-ion-selective electrode. FUFE was calculated as the ratio between DUFE and TDFI. Pearsons correlation and regression analysis were used to investigate the relationship between TDFI and FUFE. A group of thirty-three children completed the study; twenty-one receiving low-F water (0·30 mg F/l) and twelve receiving natural-F water (1·06 mg F/l) at school. The mean TDFI was 0·076 (SD 0·038) and 0·038 (SD 0·027) mg/kg per d for the natural-F and low-F groups, respectively. The mean DUFE was 0·017 (SD 0·007) and 0·012 (SD 0·006) mg/kg per d for the natural-F and low-F groups, respectively. FUFE was lower in the natural-F group (30 %) compared with the low-F group (40 %). Pearsons correlation coefficient for (1) TDFI and DUFE was +0·22 (P= 0·22) and for (2) TDFI and FUFE was − 0·63 (P< 0·001). In conclusion, there was no correlation between TDFI and DUFE. However, there was a statistically significant negative correlation between FUFE and TDFI.

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.

Fluoride intake of infants living in non-fluoridated and fluoridated areas

Objectives Data on fluoride exposure of infants are sparse. This study aimed to estimate total daily fluoride intake (TDFI) of infants aged 1-12 months, living in non-fluoridated and fluoridated areas in north-east England.Methods Daily dietary fluoride intake was assessed using a three-day food diary coupled with analysis of fluoride content of food/drink consumed, using a F-ISE and diffusion method. A questionnaire with an interview was used to collect information on toothbrushing habits. TDFI was estimated from diet, plus fluoride supplements and dentifrice ingestion where used.Results Thirty-eight infants completed the study; 19 receiving fluoridated water (mean 0.97 mgF/l) and 19 receiving non-fluoridated water (mean 0.19 mgF/l). Mean (SD) TDFI for the infants living in fluoridated and non-fluoridated areas was 0.107 (0.054) and 0.024 (0.015) mg/kg body weight per day, respectively. Diet was the only fluoride source for 87% of infants and none used fluoride supplements. For infants for whom mouth/teeth cleaning was undertaken, dentifrice contribution to TDFI ranged from 24 to 78%.Conclusions Infants living in fluoridated areas, in general, may receive a fluoride intake, from diet only, of more than the suggested optimal range for TDFI. This emphasises the importance of estimating TDFI at an individual level when recommendations for fluoride use are being considered.

Fluoride concentrations of Ready-to-Feed (RTF) infant foods 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.

Fluoride Intake of Japanese Infants from Infant Milk Formula

This study aimed to measure the fluoride (F) content of all infant milk formulas (IMF) available for purchase in Japan and estimate the F exposure of infants whose primary source of nutrition is IMF when reconstituted with different F concentrations of water. Twenty-two commercially available IMFs were purchased from 6 manufacturers in Japan. These IMFs included 21 milk-based products and 1 soy-based product. Each IMF was reconstituted using distilled water and 0.13 µg F/ml fluoridated water according to the manufacturers’ instructions. The F concentrations in each sample were measured using the hexamethyldisiloxane diffusion technique and an F ion-selective electrode. The mean F concentration of all products was 0.41 (range 0.15–1.24) µg/g. There were no statistically significant differences among mean F concentrations of newborn milks, follow-on milks and other milks or among manufacturers. The mean F concentration of all products, when reconstituted with distilled water and 0.13 µg F/ml water, was 0.09 and 0.18 µg/ml, respectively. The mean F intake from IMF ranged from 0.039 to 0.134 mg/day with distilled water and from 0.078 to 0.258 mg/day with 0.13 µg/ml fluoridated water, respectively. These results suggested that F intake of infants from IMFs depended on the F concentration of added water, and therefore the risk of dental fluorosis for most Japanese infants would be small since most Japanese municipal water supplies are low in F. However, there was a possibility to exceed the tolerable upper intake level, even under the limit of the law, especially for infants within the first 5 months of life.

Total fluoride intake and excretion in children up to 4 years of age living in fluoridated and non-fluoridated areas.

Fractional fluoride retention is important during the early years of life when considering the risk of development of dental fluorosis. This study aimed to measure fractional fluoride retention in young children. The objectives were to investigate the relationships between fractional fluoride retention and total daily fluoride intake, age, and body mass index (BMI). Twenty-nine healthy children, up to 4 yr of age, participated; 14 lived in a fluoridated area (0.64 μg ml(-1) of fluoride in drinking water) and 15 lived in a non-fluoridated area (0.04 μg ml(-1) of fluoride in drinking water). The total daily fluoride intake of each child was calculated from the daily dietary fluoride intake and toothpaste ingestion (if fluoride toothpaste was used). Total daily fluoride excretion was measured by collecting voided urine and faeces over a 24-h period, and fractional fluoride retention was calculated by dividing the amount of fluoride retained in the body (total daily fluoride intake minus total daily fluoride excretion) by the total daily fluoride intake. Nine children were excluded from data analysis because of suspected invalid samples. Mean (range) fractional fluoride retention for the remaining 20 children was 0.61 (0.06-0.98). There were no statistically significant correlations between fractional fluoride retention and either age or BMI. However, fractional fluoride retention was correlated with total daily fluoride intake: fractional fluoride retention = 1 - exp (-C × total daily fluoride intake), where C = 28.75 (95% CI = 19.75-37.75). The wide variation in fluoride retention in young children could have important implications when recommendations for fluoride use are being considered.

Effect of exercise on fluoride metabolism in adult humans: a pilot study

An understanding of all aspects of fluoride metabolism is critical to identify its biological effects and avoid fluoride toxicity in humans. Fluoride metabolism and subsequently its body retention may be affected by physiological responses to acute exercise. This pilot study investigated the effect of exercise on plasma fluoride concentration, urinary fluoride excretion and fluoride renal clearance following no exercise and three exercise intensity conditions in nine healthy adults after taking a 1-mg Fluoride tablet. After no, light, moderate and vigorous exercise, respectively, the mean (SD) baseline-adjusted i) plasma fluoride concentration was 9.6(6.3), 11.4(6.3), 15.6(7.7) and 14.9(10.0) ng/ml; ii) rate of urinary fluoride excretion over 0–8 h was 46(15), 44(22), 34(17) and 36(17) μg/h; and iii) rate of fluoride renal clearance was 26.5(9.0), 27.2(30.4), 13.1(20.4) and 18.3(34.9) ml/min. The observed trend of a rise in plasma fluoride concentration and decline in rate of fluoride renal clearance with increasing exercise intensity needs to be investigated in a larger trial. This study, which provides the first data on the effect of exercise with different intensities on fluoride metabolism in humans, informs sample size planning for any subsequent definitive trial, by providing a robust estimate of the variability of the effect.

Fluoride balance in infants and young children in the UK and its clinical relevance for the dental team

This paper provides an overview of the main sources of fluoride (F) in children and discusses the importance of assessing F exposure at an individual and community level. It describes some of the methods used to assess F exposure by estimating F intake and excretion, together with the development and use of biomarkers for F and their importance. The paper focuses on what recent F research has shown in terms of significant sources of dietary F intake in UK infants and young children and the proportion of F intake that derives from F ingestion of toothpaste. This information is considered in the context of clinical dental practice and the implications of this research for oral health discussed.