Impact of Fluoride on Associations between Free Sugars Intake and Dental Caries in US Children.

OBJECTIVE: Dental caries is the most prevalent chronic disease in US children, with the highest burden among Black and Hispanic youth. Sugars are a primary risk factor, but few studies have specifically measured intakes of free sugars and related this to dental caries or explored the extent to which water fluoride mitigates the cariogenicity of free sugars. Furthermore, the cariogenicity of certain free sugars sources, such as extruded fruit and vegetable products, is unclear. METHODS: Using cross-sectional data on 4,906 children aged 2 to 19 y in the US National Health and Nutrition Examination Survey 2013-2016, we examined associations of free sugars intake with counts of decayed or filled primary tooth surfaces (dfs) and decayed, missing, or filled permanent surfaces (DMFS) in negative binomial regressions. Stratified models examined these associations in children with home water fluoride above or below the Centers for Disease Control and Prevention (CDC)-recommended level of 0.7 ppm. RESULTS: Free sugars accounted for 16.4% of energy, primarily contributed by added sugars. In adjusted models, a doubling in the percentage of energy from free sugars was associated with 22% (95% confidence interval [CI], 1%-47%) greater dfs among children aged 2 to 8. A doubling in energy from added sugars was associated with 20% (95% CI, 1%-42%) greater dfs and 10% (95% CI, 2%-20%) greater DMFS in children aged 6 to 19 y. Beverages were the most important source of added sugars associated with increased caries. Other free sugars were not associated with dfs or DMFS. Associations between free sugars and caries were diminished among children with home water fluoride of 0.7 ppm or greater. CONCLUSIONS: Free sugars intake, especially in the form of added sugars and specifically in sweetened beverages, was associated with higher dental caries. Water fluoride exposures modify these associations, reducing caries risk in the primary dentition of children whose home water meets recommended fluoride levels. KNOWLEDGE TRANSFER STATEMENT: Intake of free sugars, especially in the form of added sugars and specifically in beverages, was associated with higher dental caries in US children in this study. Water fluoride exposure at CDC-recommended levels protected against caries, especially in the primary dentition. These findings suggest that household water fluoridation at CDC-recommended levels protects against the cariogenic potential of free and added sugars during childhood.

Fractional urinary fluoride excretion and nail fluoride concentrations in normal, wasted and stunted 4-5 year-old children in Nepal.

INTRODUCTION: It has been suggested that undernourished children are more likely to develop dental fluorosis. We investigated the effects of nutritional status on systemic fluoride metabolism including the proportion of ingested fluoride excreted through urine (i.e. fractional urinary fluoride excretion - FUFE) and fluoride concentration in nail clippings in children, aged 4-5 years, in Nepal. METHODS: Nutritional status was evaluated using weight-for-age (wasting) and height-for-age (stunting) indices. Total daily fluoride intake (TDFI) was estimated from diet and toothpaste ingestion and 24 -h urine collected to assess daily urinary fluoride excretion (DUFE). FUFE was calculated by dividing DUFE by TDFI. Nail clippings (finger and toe) were collected and analysed for fluoride concentration. RESULTS: Of the 100 children who participated, 89 provided information to assess FUFE and 51 children provided nail samples. Overall, 86.5 % of the 89 children were wasted and 39.3 % were stunted. When the samples were pooled into binary (affected and non-affected) categories, mean TDFI and mean DUFE were statistically significantly higher in the 77 wasted children (57.7 and 29.7 µg/kgbw/d, respectively) than the 12 non-wasted children (39.4 and 17.0 µg/kgbw/d, respectively). TDFI and DUFE were also statistically significantly higher in the 35 stunted children (65.1 and 34.5 µg/kgbw/d, respectively) than in the 54 non-stunted children (48.8 and 23.7 µg/kgbw/d, respectively). However, mean FUFE was similar in all groups. There were no statistically significant differences in fluoride concentration of either fingernails or toenails among the different categories of wasting, while mean fingernail fluoride concentration was statistically significantly higher in stunted (5.4 µg/g) than in non-stunted children (3.5 µg/g). CONCLUSION: Our study found no significant effect of nutritional status on the proportion of ingested fluoride excreted in urine (and consequently the proportion retained in the body). These findings suggest that nutritional status may be less likely to be a main risk factor for the development of dental fluorosis than children's dietary habits or total fluoride intake.

Effect of altitude on urinary, plasma and nail fluoride levels in children and adults in Nepal.

INTRODUCTION: A greater prevalence of dental fluorosis has been reported in higher- versus lower-altitude communities. This study, for the first time, examined several aspects of fluoride metabolism in children, aged 4-5 years, and their parent, living at lower altitude (<78 m) and higher altitude (>1487) areas in Nepal. METHODS: The study assessed total daily fluoride intake (TDFI), 24 h urinary fluoride excretion (UFE), and fluoride concentrations of toe- and finger-nail (FCtoenail, FCfingernail) in children and parents as well as fluoride concentration of plasma (FCplasma) in parents. Fractional urinary fluoride excretion (FUFE) was calculated as the ratio between UFE and TDFI. FCtoenail, FCfingernail and FCplasma were normalised for TDFI by dividing the variables by TDFI and the ratio was reported as the percentage. RESULTS: In total, 89 children and 80 parents took part in the study: 42 children and 41 parents from the lower altitude area; 47 children and 39 parents from the higher altitude area. Fluoride concentration of drinking water was significantly (P < 0.001) higher at lower altitude (0.395 mg F/l) than at higher altitude (0.104 mg F/l). TDFI was significantly (p < 0.001) higher in both children and parents living in lower altitude than those living at higher altitude. There was a statistically significant (p = 0.044) difference in the mean FUFE of children living at lower altitude (53%) and higher altitude (46%). However, no significant difference in FUFE was found between parents living at lower altitude (47%) compared with higher altitude (41%). In both children and parents, no statistically significant differences in normalised FCtoenail, FCfingernail were found between the two altitude areas. However, normalised FCplasma was statistically significantly (P = 0.005) higher in parents living at higher altitude (0.15%) compared with those living at lower altitude (0.11%). CONCLUSION: The results suggest that higher altitude living results in decreased urinary fluoride excretion, and consequently increased fluoride retention in children for a given dose (amount) of fluoride.

Fluoride intake and urinary fluoride excretion in 4- and 8-year-old children living in urban and rural areas of Southwest Nigeria.

OBJECTIVES: To estimate and compare total daily fluoride intake (TDFI), daily urinary fluoride excretion (DUFE), daily fluoride retention (DFR), fractional urinary fluoride excretion (FUFE) and fractional fluoride retention (FFR) in 4- and 8 year-old Nigerians and explore associations between these outcomes to improve understanding of fluoride metabolism. METHODS: Using a cross-sectional observational study, 72 four-year-olds and 72 eight-year-olds were recruited from nursery and primary schools (respectively) in lower and higher water F areas of urban and rural localities in Oyo State, southwest Nigeria. TDFI from diet and toothpaste ingestion was assessed using a validated Food Frequency Questionnaire and visual scale of toothpaste used during toothbrushing. DUFE was measured by collecting a 24-hour urine sample, FUFE estimated as the ratio between DUFE and TDFI, DFR estimated as TDFI-TDFE (where TDFE = DUFE + estimated faecal F excretion (ie TDFI × 10%), and FFR was estimated as [(TDFI-DFR)/TDFI] × 100. Data were analysed using ANOVA with post hoc tests and Student's t tests and strengths of associations between key variables measured. RESULTS: Mean (SD) TDFI, DUFE, DFR, FUFE and FFR were 0.137 (0.169) mg/kg bw/d, 0.032 (0.027) mg/kg bw/d, 0.091 (0.147) mg/kg bw/d, 44% (44%) and 46% (44%), respectively, for 4-year-olds. Corresponding values for 8-year-olds (n = 63) were 0.106 (0.130) mg/kg bw/d, 0.022 (0.017) mg/kg bw/d, 0.073 (0.107) mg/kg bw/d, 36% (30%) and 54% (30%), respectively. Dietary contribution to TDFI was 79% and 75% (respectively), for 4- and 8-year-olds. Mean (SD) TDFI from toothpaste ingestion was 0.021 (0.013) mg/kg bw/d in 4-year-olds, 0.014 (0.010) mg/kg bw/d in 8-year-olds (P = .002) but with no differences between areas. Differences in dietary F intake determined the main differences in F exposure between areas. The positive correlation between TDFI and DUFE was weak for 4-year-olds (r = +.29) and strong for 8-year-olds (r = +.64). A strong positive correlation was observed between TDFI and DFR for both age groups: (r) = +.98 for 4-year-olds and (r) = +.99 for 8-year-olds. CONCLUSION: Fluoride intake in these 4- and 8-year-old Nigerians was much higher than the "optimal range" of 0.05-0.07 mg/kg bw/d in rural, higher F water areas, with diet as the main contributor. F retention was similar in both age groups, with almost half of TDFI retained in the body. In terms of risk vs benefit for fluorosis and dental caries, this finding should be considered when mitigating against excessive fluoride exposure and planning F-based prevention.

Are there good reasons for fluoride labelling of food and drink?

This opinion piece highlights the importance of controlling systemic fluoride intake from food and drink in early childhood to minimise risk of dental fluorosis whilst maximising caries prevention; the wide range of fluoride contents found in a study of commercially-available food and drinks; and the need for comprehensive fluoride labelling on food and drink products in the UK, particularly those used by infants and young children.

Using Normalisation Process Theory to investigate the implementation of school-based oral health promotion.

Despite the considerable improvement in oral health of children in the UK over the last forty years, a significant burden of dental caries remains prevalent in some groups of children, indicating the need for more effective oral health promotion intervention (OHPI) strategies in this population. OBJECTIVE: To explore the implementation process of a community-based OHPI, in the North East of England, using Normalisation Process Theory (NPT) to provide insights on how effectiveness could be maximised. METHODS: Utilising a generic qualitative research approach, 19 participants were recruited into the study. In-depth interviews were conducted with relevant National Health Service (NHS) staff and primary school teachers while focus group discussions were conducted with reception teachers and teaching assistants. Analyses were conducted using thematic analysis with emergent themes mapped onto NPT constructs. RESULTS: Participants highlighted the benefits of OHPI and the need for evidence in practice. However, implementation of 'best evidence' was hampered by lack of adequate synthesis of evidence from available clinical studies on effectiveness of OHPI as these generally have insufficient information on the dynamics of implementation and how effectiveness obtained in clinical studies could be achieved in 'real life'. This impacted on the decision-making process, levels of commitment, collaboration among OHP teams, resource allocation and evaluation of OHPI. CONCLUSIONS: A large gap exists between available research evidence and translation of evidence in OHPI in community settings. Effectiveness of OHPI requires not only an awareness of evidence of clinical effectiveness but also synthesised information about change mechanisms and implementation protocols.

Erosive characteristics and fluoride content of cola-type drinks.

AIM: Excessive consumption of carbonated soft drinks is detrimental to general and oral health. This study determined endogenous pH, titratable acidity (TA) and fluoride (F) ion concentration of cola-type drinks available in the UK. Subsidiary aims were to compare: (i) endogenous pH and TA of drinks upon opening (T0) and after 20 minutes (T20); (ii) endogenous pH, TA and F ion concentration of diet vs regular and plastic bottle vs canned drinks. METHODS: Endogenous pH, TA (mls 0.1M NaOH) and F ion (mg/L) of 71 products were measured using a pH meter and F-ISE. A Wilcoxon Signed Ranks Test compared pH and TAs at T0 and T20; a Mann-Whitney U test compared pH, TAs and F ion concentration for; a) regular vs diet drinks; and b) plastic bottle vs canned drinks. RESULTS: Mean (±SD) pH for regular and diet drinks was 2.44 ± 0.12 and 2.83 ± 0.33 respectively (p = 0.001). Mean NaOH (ml) to raise pH to 5.5 and 5.7 was 5.49 ± 0.76 and 6.40 ± 0.78 (regular drinks); 5.17 ± 1.03 and 6.03 ± 1.07 (diet drinks). Diet (p = 0.040) and regular (p = 0.041) drinks had higher TA to pH 5.7 at T0 compared with T20; at T20 regular drinks had higher TA to pH 5.5 (p = 0.026) and pH 5.7 (p = 0.030) than diet drinks. There was no difference in F ion concentration between regular vs diet drinks (p = 0.754) and no significant container effect. CONCLUSION: Erosive characteristics were similar between manufacturers, but higher erosive potentials were evident at T0 compared with 20 minutes later and for regular compared with diet drinks. F ion concentration of drinks was low.

Estimation of daily dietary fluoride intake: 3-d food diary v. 2-d duplicate plate.

The 3-d food diary method (3-d FD) or the 2-d duplicate plate (2-d DP) method have been used to measure dietary fluoride (F) intake by many studies. This study aimed to compare daily dietary F intake (DDFI) estimated by the 3-d FD and 2-d DP methods at group and individual levels. Dietary data for sixty-one healthy children aged 4-6 years were collected using 3-d FD and 2-d DP methods with a 1-week gap between each collection. Food diary data were analysed for F using the Weighed Intake Analysis Software Package, whereas duplicate diets were analysed by an acid diffusion method using an F ion-selective electrode. Paired t test and linear regression were used to compare dietary data at the group and individual levels, respectively. At the group level, mean DDFI was 0·025 (sd 0·016) and 0·028 (sd 0·013) mg/kg body weight (bw) per d estimated by 3-d FD and 2-d DP, respectively. No statistically significant difference (P=0·10) was observed in estimated DDFI by each method at the group level. At an individual level, the agreement in estimating F intake (mg/kg bw per d) using the 3-d FD method compared with the 2-d DP method was within ±0·011 (95 % CI 0·009, 0·013) mg/kg bw per d. At the group level, DDFI data obtained by either the 2-d DP method or the 3-d FD method can be replaced. At an individual level, the typical error and the narrow margin between optimal and excessive F intake suggested that the DDFI data obtained by one method cannot replace the dietary data estimated from the other method.

The fluoride contents of commercially-available soya milks in the UK.

BACKGROUND: In some parts of the world, soya milks are found to be a significant source of fluoride (F). Among western commercial markets, although there has been a sustained increase in soya milk products available for purchase, there are limited data on their F content. OBJECTIVE: To determine the F content of soya milk products available in the UK market including fresh and ultra-high temperature products in addition to sweetened and unsweetened soya milks. MATERIALS AND METHODS: Fifty-two traditional and UK-produced soya milk samples commercially available in northeast England were analysed to determine their F concentration using a modified hexamethyldisiloxane-facilitated diffusion method with a F-ion-selective electrode coupled to a potentiometer. RESULTS: The median F concentration of all products was 0.293 µg/ml ranging from 0.015 µg/ml to 0.964 µg/ml. The median F concentration of ultra-high temperature (UHT) (n = 42) milks was 0.272 µg/ml lower than 0.321 µg/ml obtained for fresh (n = 10) soya milks. Organic soya milks contained less F compared with non-organic for sweetened and unsweetened categories. CONCLUSION: Commercially available soya milks in the UK do not pose an increased risk for dental fluorosis development. Further research is necessary into the manufacturing process of soya milks, which may influence the overall F content of the end product.

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.

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.

Fluoride balance in infants and young children in the U.K. 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 U.K. 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.

Urinary fluoride excretion in 6- to 7-year-olds ingesting milk containing 0.5 or 0.9 mg fluoride.

Effectiveness of 0.5 mg fluoride (F) milk ingestion in preventing caries has been termed only 'moderate'. In this 3-arm partial cross-over intervention, 32 children aged 6-7 years in a non-F area were recruited and urinary F excretion (UFE) measured before and after ingestion of 0.5 or 0.9 mg F milk. Maintaining customary dietary and oral hygiene habits, children underwent a 2-week 'wash-in' with non-F milk, providing a 24-hour urine sample on day 4 of non-F (baseline) and F milk ingestion containing either (i) 0.5 mg or (ii) 0.9 mg F (intervention). A comparative group of thirteen 6- to 7-year-olds living in fluoridated areas provided a 24-hour urine sample on day 4 of daily non-F milk ingestion, following a 2-week non-F milk wash-in. Valid urine samples were analysed for F and UFE estimated from corrected 24-hour urine volume and F concentration. For the 24 test children providing 2 valid urine samples, mean (95% CI) change in corrected 24-hour UFE was 0.130 (0.049, 0.211) and 0.153 (0.062, 0.245) mg/day for 0.5 mg (p < 0.007) and 0.9 mg F (p < 0.001) groups, respectively. Post-intervention, mean (SD) corrected 24-hour UFE was 0.437 (0.153) mg/day and 0.420 (0.188) mg/day for the 0.5 and 0.9 mg F groups, respectively, which were lower than the WHO provisional standards (0.48-0.60 mg F/day). F milk consumption significantly increased UFE; however, the F content of 0.5 and 0.9 mg F milk may be too low to achieve WHO provisional UFE standards concomitant with optimal F exposure in children aged ≥6 years.

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. Pearson's 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 %). Pearson's 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 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.

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 microg 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 x 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.