Understanding Optimum Fluoride Intake from Population-Level Evidence.

Policy on fluoride intake involves balancing caries against dental fluorosis in populations. The origin of this balance lies with Dean's research on fluoride concentration in water supplies, caries, and fluorosis. Dean identified cut points in the Index of Dental Fluorosis of 0.4 and 0.6 as critical. These equate to 1.3 and 1.6 mg fluoride (F)/L. However, 1.0 mg F/L, initially called a permissible level, was adopted for fluoridation programs. McClure, in 1943, derived an "optimum" fluoride intake based on this permissible concentration. It was not until 1944 that Dean referred to this concentration as the "optimal" concentration. These were critical steps that have informed health authorities through to today. Several countries have derived toxicological estimates of an adequate and an upper level of intake of fluoride as an important nutrient. The US Institute of Medicine (IOM) in 1997 estimated an Adequate Intake (AI) of 0.05 mg F/kg bodyweight (bw)/d and a Tolerable Upper Intake Level (UL) of 0.10 mg F/kg bw/d. These have been widely promulgated. However, a conundrum has existed with estimates of actual fluoride intake that exceed the UL without the expected adverse fluorosis effects being observed. Both the AI and UL need review. Fluoride intake at an individual level should be interpreted to inform more nuanced guidelines for individual behavior. An "optimum" intake should be based on community perceptions of caries and fluorosis, while the ultimate test for fluoride intake is monitoring caries and fluorosis in populations.

Review of Fluoride Intake and Appropriateness of Current Guidelines.

Since the classical epidemiological studies by Dean, it has been known that there should be an optimum level of exposure to fluoride that would be able to provide the maximum protection against caries, with minimum dental fluorosis. The "optimal" daily intake of fluoride for children (0.05-0.07 mg per kilogram bodyweight) that is still accepted worldwide was empirically determined. In the present review, we discuss the appropriateness of the current guidance for fluoride intake, in light of the windows of susceptibility to caries and fluorosis, the modern trends of fluoride intake from multiple sources, individual variations in fluoride metabolism, and recent epidemiological data. The main conclusion is that it is very difficult to think about a strict recommendation for an "optimal" range of fluoride intake at the individual level in light of existing knowledge of 1) the mechanisms of action of fluoride to control caries, 2) the mechanisms involved in dental fluorosis development, 3) the distinct factors that interfere in the metabolism of fluoride, and 4) the windows of susceptibility to both dental caries and fluorosis development. An "optimal" range of fluoride intake is, however, desirable at the population level to guide programs of community fluoridation, but further research is necessary to provide additional support for future decisions on guidance in this area. This list includes the effect of factors affecting fluoride metabolism, clinical trials on the effectiveness of low-fluoride dentifrices to prevent caries in the primary dentition, and validation of biomarkers of exposure to fluoride.

Current Guidance for Fluoride Intake: Is It Appropriate?

The purpose of this report is to examine critically the appropriateness of the current guidance for fluoride intake in the population (0.05-0.07 mg F/kg bodyweight/d), consider whether changes to the current guidance are desirable, and suggest further research that will strengthen the evidence base for future decisions on guidance/advice in this area. The benefits and the risks of using fluoride particularly concern preschool children because it is at this age that excessive fluoride intake may result in dental fluorosis. Data from mostly cross-sectional studies show a wide variation in exposure and a considerable variation in the amount of fluoride ingested. Fluorosis, mostly mild, is commonly observed. For considering changes in current guidance, there is a need for more knowledge on the relationship between exposure to fluoride at an early age and the development of fluorosis. For that, prospective epidemiological studies with sufficiently large and representative samples of children are required. It is also important to study children in communities both with and without water fluoridation and to include populations where salt or milk fluoridation is used. There is also a need for professional agreement on acceptable levels of mild and moderate/severe fluorosis and a more comprehensive knowledge on the appreciation of mild fluorosis among the public.

[The impact of tap water fluoridation on human health]. / Consecuencias de la fluoración del agua potable en la salud humana.

The purpose of this review is to describe the osteological, neurological, endocrine and dermatological effects of fluoride ingestion. Additional aims are to evaluate whether the Chilean tap water fluoridation program has had any impact on dental health, and analyze the basis for the Chilean elementary school milk fluoridation program, which is targeted at children living in places where tap water has a fluoride concentration less than 0.3 mg/L, without any artificial fluoridation process. We discuss the finding that both public measures have no direct or remarkable effect on dental health, since topical dental hygiene products are the main and most effective contributors to the prevention of dental decay. We also suggest that the permanent and systematic ingestion of fluorides imposes health risks on the population. Therefore, we recommend reevaluating the national fluoridation program for public tap water and the elementary school milk program.

Global water fluoridation: what is holding us back?

Artificial water fluoridation was introduced more than 60 y ago as a public health intervention to control dental caries. Despite wide recommendations for its use from the World Health Organization (WHO) and studies showing the benefits of water fluoridation, many countries have opted out. Currently, only 25 countries, including the United Kingdom, the United States, and Australia have schemes for artificial water fluoridation. The issues faced in efforts to promote the global uptake of water fluoridation and the factors that affect the decision to implement it are unique in both developed and developing countries and must be explored. This article addresses the benefits and challenges of artificial water fluoridation. Further, it tackles the complexities faced with uptake of water fluoridation globally, such as ethical and political controversies and the use of alternative fluoride therapies. Potential future strategies to encourage the uptake of artificial water fluoridation are also discussed.

Consistency of information on the provision of water fluoridation in Brazil.

OBJECTIVE: This study aimed to assess the consistency of data regarding the provision of fluoridation in Brazilian municipalities with water supply systems. METHODS: Official data from the National Basic Sanitation Survey and the National Information System on Sanitation for 2017 were compared. RESULTS: Out of 5,570 municipalities in Brazil, 4,546 (81.6%) had water supply systems. The agreement between data sources was 84%, with a Kappa of 0.668, indicating substantial agreement. However, the estimates of fluoridation provision exhibited an average discrepancy of 8.1 percentage points, ranging from 1.2 points in the Central-West region to 21.4 points in the Northeast region. CONCLUSION: To address these inconsistencies, it is essential to enhance information sources, ensuring more reliable data for health, sanitation authorities, and society at large.

The importance of substate surveillance in detection of geographic oral health inequalities in a small state.

CONTEXT: Considering that 42% of children and adolescents and 91% of dentate adults experience dental caries, oral disease is a public health problem. Although the population's oral health is improving, certain subgroups remain at increased risk for dental disease. OBJECTIVE: To assess the oral health status at the substate level and explore the possibility of geographic oral health inequalities in New Hampshire while building upon existing surveillance data sets. DESIGN: We used the Third Grade Oral Health and NH Behavioral Risk Factor Surveillance System surveys. We ensured the availability of substate level data and compared county/region specific estimates. SETTING: New Hampshire. PARTICIPANT: Adults and third-grade students in public schools. MAIN OUTCOME MEASURES: The prevalence of dental caries, untreated caries, and dental sealants among children; and the insurance status, utilization of dental services, and edentulism among adults. RESULTS: Of the 10 counties, the northernmost Coos County had consistently worse outcomes when compared with other counties. Only 64% of adult Coos County residents reported a dental visit in the past year; of these, 66% reported dental cleaning. Among adults 65 years and older, 29% were edentulous. In comparison with the state overall, these estimates were 76%, 77%, and 19%, respectively. Coos County third-grade students had the highest prevalence of dental caries experience (64% compared with 44% in New Hampshire) and untreated caries (31% compared with 12%), and only 24% had dental sealants (state prevalence is 60%). CONCLUSIONS: Overall oral health status in our state is favorable and comparable with the nation, yet significant geographic inequalities exist among children and adults. The oral health status of disparate groups can be improved using tailored interventions such as community water fluoridation or expansion of school-based dental sealant programs. Surveillance at the substate level is an essential part of the planning, targeting, and progress monitoring.

[Analysis of water fluoride concentration in Curitiba, Brazil: comparison of techniques]. / Análise da concentração de flúor na água em Curitiba, Brasil: comparação entre técnicas.

OBJECTIVE: To evaluate the adequacy of fluoride levels in the public water system in Curitiba, state of Paraná, Brazil, as determined by two techniques (colorimetric and electrometric). METHODS: Data from independent measurements of fluoride in the public water system in Curitiba routinely performed by the city government were obtained for the period between January 2000 and July 2008. Mean levels of fluoride concentration were calculated for each of these years. After that, fluoride concentrations measured in 1 470 samples by the state water utility (SANEPAR) using the electrometric technique in 2006 and 2007 were compared with the corresponding levels measured by the city using the colorimetric method. The rate of samples meeting the standard for the city (0.8 ppmF), and below and above the standard, was calculated for both methods. Fluoride levels were compared between sanitary districts, months for the period between December 2007 and July 2008, and water treatment facilities. RESULTS: The overall mean fluoride level between 2000 and 2008 was 0.7 ppmF based on the independent measurements. The comparison between techniques showed a higher mean fluoride level with the electrometric technique (0.743 ppmF ± 0.133) vs. the colorimetric technique (0.637 ppmF ± 0.164). The rate of samples meeting the ideal standard of 0.8 ppmF was 15.05% for the colorimetric and 63.97% for the electrometric technique; 62.03% and 22.85% of the samples were below that standard and 21.10% and 13.18% were above that standard, respectively. Fluoride levels were statistically significant (P < 0.001) for the comparison between sanitary districts and months. CONCLUSIONS: The choice of technique significantly influences the resulting levels of fluoride. Independent monitoring of fluoride levels should employ the same technique used by the water utility. Further studies should aim at defining which technique is the most adequate to determine fluoride concentration in public water systems.

Predictive tool for estimating the potential effect of water fluoridation on dental caries.

OBJECTIVE: To provide a tool for public health planners to estimate the potential improvement in dental caries in children that might be expected in a region if its water supply were to be fluoridated. BASIC RESEARCH DESIGN: Recent BASCD (British Association for the Study of Community Dentistry) dental epidemiological data for caries in 5- and 11-year-old children in English primary care trusts in fluoridated and non-fluoridated areas were analysed to estimate absolute and relative improvement in dmft/DMFT and caries-free measures observed in England. Where data were sufficient for testing significance this analysis included the effect of different levels of deprivation. RESULTS: A table of observed improvements was produced, together with an example of how that table can be used as a tool for estimating the expected improvement in caries in any specific region of England. Observed absolute improvements and 95% confidence intervals were: for 5-year-olds reduction in mean dmft 0.56 (0.38, 0.74) for IMD 12, 0.73 (0.60, 0.85) for IMD 20, and 0.94 (0.76, 1.12) for IMD 30, with 12% (9%, 14%) more children free of caries; for 11-year-olds reduction in mean DMFT 0.12 (0.04, 0.20) for IMD 12, 0.19 (0.13, 0.26) for IMD 20, 0.29 (0.18, 0.40) and for IMD 30, with 8% (5%, 11%) more children free from caries. CONCLUSIONS: The BASCD data taken together with a deprivation measure are capable of yielding an age-specific, 'intention to treat' model of water fluoridation that can be used to estimate the potential effect on caries levels of a notional new fluoridation scheme in an English region.

External control of fluoridation in public water supply systems in the state of Goiás, Brazil. / Heterocontrole da fluoretação da água de abastecimento público em cidades do estado de Goiás, Brasil.

The addition of fluoride to the public water supply is a method used for reducing tooth decay. In this sense, the control of fluoridation is important for maintaining its efficiency and, at the same time, for avoiding the risk of fluorosis as a result of the consumption of water with excess of fluoride. The objective of this study was to evaluate the adequacy of fluoride levels in the water distributed to populations of the state of Goiás, Brazil. Towards this aim, 5,039 water samples collected between 2011 and 2013 in 225 municipalities of the state of Goiás were analyzed for fluoride level. The results were assessed with regard to season, type of water source and geographic location. Fluoride levels were found to vary between complete absence and 2.5 mg F/L, with 28.2% of the samples being between 0.6 and 0.8 mg F/L, and 39.1% between 0.55 and 0.84 mg F/L. The rainy season produced a greater number of atypical results and higher values than the dry period. The systems supplied by groundwater sources were shown to have a limited control of fluoride concentration compared to systems supplied by surface water sources. Lower concentrations of fluoride were found in samples collected in the North and East Mesoregions of Goiás, with less than 7.5% being between 0.6 and 0.8 mg F/L, which systems are mainly supplied by groundwater sources with fluoride addition .

A adição do flúor na água é um método empregado na redução de cárie dentária. O controle da fluoretação é importante para manter a sua eficiência e, ao mesmo tempo, evitar o risco de ocorrência de fluorose, fruto do consumo de água com flúor em excesso. O objetivo deste trabalho foi avaliar a adequação dos níveis do fluoreto na água distribuída à população do estado de Goiás, Brasil. Foram analisadas 5.039 amostras de água coletadas em 225 municípios de Goiás, entre 2011 e 2013. Os resultados foram analisados por sazonalidade, tipo de manancial e localização geográfica. Ocorreu uma variação entre ausência e 2,5 mg F/L, com 28,2% das amostras entre 0,6 e 0,8 mg F/L e 39,1% entre 0,55 e 0,84 mg F/L. No período de chuva ocorreu um maior número de resultados atípicos e maiores valores quando comparados ao período da seca. Verificou-se que os sistemas abastecidos por água proveniente de mananciais subterrâneos possuem um menor controle de fluoreto quando comparados a sistemas provenientes de mananciais superficiais. Observou-se menores concentrações nas amostras coletadas no Norte e Leste goianos, com menos de 7,5% entre 0,6 e 0,8 mg F/L, para aquelas coletadas de sistemas de abastecimento que utilizam água de manancial subterrâneo com adição de fluoreto, existindo dificuldades na manutenção dos seus teores.

Knowledge and Attitudes Towards Fluoride Supplementation: A Survey of Pediatric Medical and Dental Providers in the State of Hawai'i.

Hawai'i has the lowest rate of community water fluoridation in the nation, which has contributed to poor oral health for children statewide. When properly prescribed, the benefits of fluoride supplementation for oral health outweigh any potential side effects to the body. Official recommendations give pediatric healthcare providers the authority to prescribe fluoride supplements and guide parents in daily usage. However, knowledge of actual practice and adherence for both providers and patients have never been examined in Hawai'i. This study aims to evaluate pediatric healthcare providers' attitudes, knowledge, and practices, regarding fluoride supplementation. A 37-item survey was developed investigating these domains, and was distributed to pediatric dentists, family practitioners, and pediatricians in the state. One hundred and three responses were collected during the time period of May 2014 through May 2015. Descriptive and bivariate associations with several outcomes were assessed. The majority (87%) reported at least some knowledge of the official guidelines. There was uncertainty in knowledge of fluorosis and the seriousness of the health risk. A recent educational session on fluoride was associated with more knowledge of the guidelines and the signs and symptoms of fluorosis. The majority of providers started fluoride at the recommended age whereas there was more variablility on stopping fluoride. On the patient side, providers reported that 67% of the parents forget to administer and 53% reported that their child does not like the taste. This study provides some information regarding the clinical use of fluoride supplementation in children. More efforts are needed to raise awareness in a consistent manner by both the dental and medical communities on the importance of fluoride supplementation to promote oral health in children while addressing concerns of professionals and the community.

Fluoride concentration in drinking water samples in Fiji.

OBJECTIVE: The main aim of this study was to determine the content of fluoride in drinking water from sources within the sampling areas for the National Oral Health Survey (NOHS) 2011 from the Central, Northern, Western and Eastern Divisions in the Fiji Islands. METHOD: Drinking water samples were collected from taps, a waterfall, wells, creeks, streams, springs, rivers, boreholes and rain water tanks in a diverse range of rural and urban areas across the Fiji Islands. A total of 223 areas were sampled between December 2014 and June 2015. Samples were analysed for fluoride using a colorimetric assay with the Zirconyl-SPADNS Reagent. The samples were pre-treated with sodium arsenite solution prior to analysis to eliminate interference from chlorine. RESULTS: Measured fluoride concentrations ranged from 0.01 to 0.35 ppm, with a mean concentration across all samples of 0.03 + 0.04 ppm. No samples achieved the optimal level for caries prevention (0.7 ppm). The Western Division had the highest fluoride levels compared to the other Divisions. The highest single fluoride concentration was found in Valase. The drinking water for this rural area located in the Western Division is from a borehole. The lowest concentrations of fluoride were in reticulated water samples from rural areas in the Central Division, which were consistently less than those recorded in the Northern, Eastern and Western Divisions. CONCLUSION: All samples had fluoride concentrations below the optimum level required to prevent dental caries. Implications for public health: This research forms part of the objectives of the 2011 National Oral Health Survey in Fiji. At present, Fiji lacks water fluoridation and therefore a baseline of the fluoride content in drinking water supplies is essential before water fluoridation is implemented. The results from this study would be beneficial in designing caries-preventive strategies through water fluoridation and for comparing those strategies with caries prevalence overtime.

Feasibility and costs of water fluoridation in remote Australian Aboriginal communities.

BACKGROUND: Fluoridation of public water supplies remains the key potential strategy for prevention of dental caries. The water supplies of many remote Indigenous communities do not contain adequate levels of natural fluoride. The small and dispersed nature of communities presents challenges for the provision of fluoridation infrastructure and until recently smaller settlements were considered unfavourable for cost-effective water fluoridation. Technological advances in water treatment and fluoridation are resulting in new and more cost-effective water fluoridation options and recent cost analyses support water fluoridation for communities of less than 1,000 people. METHODS: Small scale fluoridation plants were installed in two remote Northern Territory communities in early 2004. Fluoride levels in community water supplies were expected to be monitored by local staff and by a remote electronic system. Site visits were undertaken by project investigators at commissioning and approximately two years later. Interviews were conducted with key informants and documentation pertaining to costs of the plants and operational reports were reviewed. RESULTS: The fluoridation plants were operational for about 80% of the trial period. A number of technical features that interfered with plant operation were identified and addressed though redesign. Management systems and the attitudes and capacity of operational staff also impacted on the effective functioning of the plants. Capital costs for the wider implementation of these plants in remote communities is estimated at about $US 94,000 with recurrent annual costs of $US 11,800 per unit. CONCLUSION: Operational issues during the trial indicate the need for effective management systems, including policy and funding responsibility. Reliable manufacturers and suppliers of equipment should be identified and contractual agreements should provide for ongoing technical assistance. Water fluoridation units should be considered as a potential priority component of health related infrastructure in at least the larger remote Indigenous communities which have inadequate levels of natural fluoride and high levels of dental caries.

Dental fluorosis in Brazil: a systematic review from 1993 to 2004.

The current article proposes a reflection on several aspect pertaining to dental fluorosis in Brazil, based on a systematic review of epidemiological surveys. The authors assess the prevalence and degrees of severity found in different studies and show that in methodological terms, there is a need for progress in procedures for population-based studies on fluorosis. Despite the different data collection approaches, there is some consensus among the different studies as to the limited severity of fluorosis in Brazil, as well as its association with the independent variables age and socioeconomic status. The authors also highlight the importance of adding subjective aspects to the normative diagnosis as a contribution to public health policy decisions, since the use of exclusively clinical criteria gives dental fluorosis more space than society ascribes to it. There is a lack of empirical evidence to reassess the fluoride content in public water supplies, a method that is known to be necessary to improve dental caries epidemiological indicators.

[External control over the fluoridation of the public water supply in Bauru, SP, Brazil]. / Heterocontrole da fluoretação da água de abastecimento público em Bauru, SP, Brasil.

OBJECTIVE: To assess the fluoridation of the public water supply and compare these results with previous data. METHODS: The study was carried out from March 2004-2005 in Bauru, a city of Southeastern Brazil. Every month, on dates established randomly, 60 water samples were collected from the 19 supply sectors of the city, totaling 737 samples. The fluoride concentration in the water samples was determined in duplicate, using an ion-specific electrode (Orion 9609) coupled to a potentiometer. Following analysis, the samples were classified as acceptable or unacceptable according to their fluoride concentration. Descriptive statistical analysis was utilized. RESULTS: The mean fluoride concentration observed in the different collection months ranged from 0.37 to 1.00 mg/l. Around 85% of the samples were classified as acceptable. CONCLUSIONS: One year after implementing external control, an improvement in the water fluoridation conditions was observed in comparison with previous results obtained in the city. The implementation of water supply fluoridation monitoring by means of surveillance systems must be stimulated: this is fundamental for controlling dental caries.

Caution needed in altering the 'optimum' fluoride concentration in drinking water.

The US Public Health Service has finalized its recommendation relating to community water fluoridation (Federal Panel on Community Water Fluoridation, US Department of Health and Human Services, 2015). It recommends an optimal concentration of 0.7 mg/l F based on their argument that this concentration provides the best balance of protection from dental caries while limiting the risk of dental fluorosis. The rationale for this recommendation can be questioned, particularly given the contrasting etiologies and impact on the community. Uncertainty surrounds the key evidence considered by the panel. This study argues that the panel should have exercised more caution and called for further research before reducing the 'optimal' concentration of fluoride in water supplies. Up-to-date data on caries and fluorosis trend by age group or birth cohort, analyses on attributable risk for fluorosis, data on individual and population impact of caries and fluorosis, water intake over an extended period across the seasons, and the curvilinear relationship of fluoride concentration in water supplies and caries protection would have all been desirable to inform the panel, given the foreshadowing of the recommendation in late 2011. Further, a wider range of policy directions to achieve the best balance of protection from dental caries while limiting the risk of dental fluorosis are available from the international literature. Assessment of these should have been more evident. There is a public health policy responsibility to monitor water fluoridation programs so as to achieve a near maximum reduction in dental caries without unacceptable levels of dental fluorosis. However, recommendations to alter existing policy need to be cognizant of the balancing of risk and protective exposures across the entire population and potentially all ages and to be based on recent data that are purposefully collected, critically analyzed and carefully interpreted.

A comparison of results of fluoride determinations by different laboratories.

With water fluoridation imminent in South Africa, the accurate determination of the fluoride content of water is important. The aim of this study was to compare the fluoride content of water reported by 9 laboratories and the laboratory at the South African Bureau of Standards (SABS). The SABS and 9 South African laboratories were asked to determine the fluoride content of five water samples. The fluoride content of the samples was in a range that could be expected in South African waters. The laboratories were requested to disclose their methods for fluoride determination. The results reported by the laboratories were compared to the results reported by the SABS laboratory. Fluoride concentrations of 0.13, 0.22 and 0.58 mg/litre were reproduced to within 0.05 mg/litre by two, six and three laboratories respectively. At the 1.1 and 1.5 mg/litre concentration no laboratory could achieve this accuracy. Four different methods for the determination of fluoride were used. At present laboratories determining fluoride concentrations are not accurate enough to ensure that the process of water fluoridation will be safe. Laboratories will have to check their procedures to ensure better results before water fluoridation can commence.