Systematic Evidence Review of Community Water Fluoridation - American Academy of Family Physicians

Key Points

• Discusses critically a recently published review of the effectiveness of h2o fluoridation.

• Highlights the lost opportunity to evaluate the vast majority of recent studies on h2o fluoridation to answer the inquiry questions.

• Suggests modernistic and advisable methods for systematic evaluation of the effectiveness of water fluoridation.

Abstract

The Cochrane Review on water fluoridation for the prevention of dental caries was published in 2015 and attracted considerable interest and comment, especially in countries with extensive water fluoridation programmes. The Review had two objectives: (i) to evaluate the effects of water fluoridation (artificial or natural) on the prevention of dental caries, and (two) to evaluate the effects of water fluoridation (bogus or natural) on dental fluorosis. The authors ended, inter alia, that there was very little contemporary bear witness, meeting the Review'southward inclusion criteria, that evaluated the effectiveness of water fluoridation for the prevention of dental caries. The purpose of this critique is to examine the conduct of the above Review, and to put information technology into context in the wider body of show regarding the effectiveness of water fluoridation. While the overall conclusion that water fluoridation is effective in caries prevention agrees with previous reviews, many important public health questions could non be answered by the Review considering of the restrictive criteria used to judge adequacy of study blueprint and risk of bias. The potential benefits of using wider criteria in social club to attain a fuller understanding of the effectiveness of water fluoridation are discussed.

Introduction

The Cochrane Review¹ on water fluoridation for the prevention of dental caries was published in 2015 (referred to in this article as the Cochrane Review) and attracted considerable interest and comment, especially in countries with extensive customs water fluoridation programmes. The Cochrane Review had two stated objectives: (i) to evaluate the effects of h2o fluoridation (artificial or natural) on the prevention of dental caries, and (ii) to evaluate the effects of water fluoridation (bogus or natural) on dental fluorosis. The authors concluded that the initiation of water fluoridation results in reductions in caries which translate into a 35% reduction in primary teeth and a 26% reduction in permanent teeth, with an increase of 15% in the pct of children free of decay experience in master teeth and an increment of fourteen% in the percentage of children free of decay experience in permanent teeth. However, they found that there was very picayune recent or contemporary bear witness, coming together the Cochrane Review's inclusion criteria, that has evaluated the effectiveness of water fluoridation for the prevention of dental caries. They said that around seventy% of the studies they reviewed pre-dated the introduction of fluoride-containing toothpaste in the mid to late 1970s. They also reported that in that location is insufficient show to decide whether water fluoridation results in a change in disparities in caries levels across socio-economic status (SES) groups (although this was not a stated review objective). The authors did not place whatever bear witness, coming together the Review's inclusion criteria, to make up one's mind the effectiveness of h2o fluoridation for preventing caries in adults; they argued that there was insufficient information to determine the event on caries levels of stopping water fluoridation programmes; and that there was a significant clan betwixt dental fluorosis and fluoride level in water supplies up to five mg/L.

The stated intention of the Cochrane Review was to update the systematic review on the same topic by the NHS Eye for Reviews and Dissemination, York University, published in 2000 (conventionally known as the York Review).^two However, the Cochrane Review had simply ii of the v original objectives of the York Review. The study protocol for the Cochrane Review published in 2013³ stated 'The effectiveness of fluoridated water (artificially or naturally) is well documented (McDonagh 2000; NHMRC 2007; Truman 2002) and culling fluoride sources such as toothpastes and varnishes have also been proven to exist constructive (Marinho 2013; Walsh 2010).' The protocol also stated: 'Given the connected interest in this [water fluoridation] topic, from both wellness professionals, policy makers and the public, it is important to update and maintain a systematic review of the available bear witness.'

The purpose of this critique is to examine the methods and assumptions used in the 2015 Cochrane Review and to put the Review into context in the wider trunk of evidence regarding the effectiveness of water fluoridation. While the overall conclusion that water fluoridation is effective in caries prevention is consistent with previous reviews, many important public wellness questions could not exist answered past the Cochrane Review because of the restrictive inclusion criteria used to approximate adequacy of written report design and risk of bias. The potential benefits of using wider criteria in society to achieve a fuller understanding of the effectiveness of water fluoridation are discussed.

The nature of water fluoridation programmes

Water fluoridation is an intervention to benefit public health at the population level, involving adjusting the fluoride concentration in public water supplies for total geographical communities. Equally a population intervention information technology differs from measures to benefit health aimed at individuals. For private clinical interventions, decisions to treat are based on knowledge of the proven efficacy and effectiveness of the drug or other technology equally demonstrated in randomised controlled trials (RCTs) and on the clinical sentence of the prescriber based on his or her knowledge of the individual patient being treated. With public health interventions things are different. In that location will simply sometimes be RCTs demonstrating efficacy and effectiveness. In that location are ofttimes no such trials considering the highly circuitous practical, upstanding and financial factors involved mean that RCTs are not feasible. Consequently, when determining whether a public wellness intervention is cost effective, evidence has to exist drawn from a broad multifariousness of other scientific methods and research designs including cross-sectional ones and process evaluations.^4,v In the case of water fluoridation, this may involve, for example, an assessment that would indicate how well the preparatory and operational stages of a plan of h2o fluoridation have fared. In many cases it is only impossible to brand recommendations for public wellness interventions and policy if reliance is merely placed on RCTs. Farther, with public health interventions, the issue is not nearly individual patient benefit only whether the population as a whole will benefit. So, for example, reducing population level salt intake past irresolute the composition of candy foods has the effect of reducing population levels of hypertension with correspondingly fewer strokes. Not all individuals do good equally from public wellness interventions and some people will nonetheless suffer strokes, but the population as a whole benefits because there are fewer strokes overall. Water fluoridation is non a clinical intervention washed to an private. It is a population level intervention and should be judged as such.^{half-dozen,7,8,nine,10,11,12,thirteen,14,15}

Therefore, measurement of the touch on of h2o fluoridation is not like a clinical intervention for the post-obit reasons. First, the context in which water is fluoridated is circuitous:^16,17 its introduction and maintenance requires legislation, installation and maintenance of equipment, technical preparation of water treatment plant operators, evolution and adherence to procedures and processes, and continuity of supply and regular monitoring. 2d, its touch on is more than just change in 'dmft/DMFT' scores. The effectiveness of water fluoridation can potentially be seen in reductions in caries incidence (both coronal and root caries), as well as reductions in edentulousness, dental pain, dental abscesses, prescription of antibiotics, and dental handling for children under general anaesthetics and admissions to hospital. It reduces costs to the individual and community, and helps to improve people'south quality of life. While the 'percentage caries-gratis' and 'mean dmft/DMFT' in the community as a whole are useful statistics, there is as well a demand to assess the impact of h2o fluoridation in those with the highest caries experience, since this group presents the biggest challenge in dental public health and dental exercise.

The crusade-and-effect human relationship between water fluoridation and caries prevention is confounded past the diff distribution of disease risk and preventive behaviours in society, in particular, variations in use of other sources of fluoride, mainly from toothpaste, and diet, particularly sugar consumption. In many societies, these are closely linked to SES, and evaluation should also measure and control for these explanatory factors and interactions. H2o fluoridation should exist evaluated using gimmicky methods which are appropriate for evaluating public health interventions with such complexities, and systematic reviews should take this into account.

Many of the early on evaluations of the effectiveness of water fluoridation were repeated cross-sectional studies in both the community about to implement water fluoridation and also in a control (or reference) community receiving drinking water with an unadjusted, low fluoride concentration. Evaluations took place before fluoridation began (baseline) to determine comparability betwixt the two communities, and afterwards a suitable number of years (very often five years). This design is known as a not-randomised, concurrent-control, earlier-and-after study. These early studies, conducted in the 1940s, 50s, 60s and 70s, showed clearly that fluoridation of drinking water was effective at reducing the burden of dental caries, and many wellness regime followed national policy by introducing water fluoridation on the basis of these studies. Over time, in many countries, coverage of the population with water fluoridation schemes was nearly complete, at least to the limits of public wellness requirements and technical feasibility. In such jurisdictions, the priority for health authorities was to monitor the continued effectiveness of existing schemes. Virtually recent evaluations of h2o fluoridation take been of this blazon, using the most appropriate design, which is a single cross-sectional survey of fluoridated and non-fluoridated groups with control for confounding factors. 1 of the critical problems with the 2015 Cochrane Review is that these data have been excluded from the Review. This important point will be discussed farther below.

Surveillance and evaluation of water fluoridation programmes are routinely carried out on behalf of the assistants overseeing the programme, be information technology a local authority or a Government agency. Publication in bookish journals is not the goal of such agencies. Systematic reviews should recognise this reality and ensure that such evaluations are identified and reviewed. Similarly, in such cases where the evaluation is published, reviewers should determine whether the evaluation is more comprehensively described in a full written report written for administrators/managers of the fluoridation programme. While this 'grey literature' was sought in the York Review, there is no record that this was done in the 2015 Cochrane Review.

Criteria for including studies and quality assessment

Requirement for 'at to the lowest degree 2 points in time'

The Cochrane Review states: 'For caries data, we included only prospective studies with a concurrent control, comparing at to the lowest degree two populations, one receiving fluoridated water and the other non-fluoridated water, with at least two points in fourth dimension evaluated. Groups had to exist comparable in terms of fluoridated water at baseline.' The purpose of this requirement appears to be to obtain a measure of alter in caries experience in the fluoridated community from before implementation of fluoridation to quondam after, and to compare this change with any alter in the control (or reference) customs over the same fourth dimension period. This is similar to a method used to evaluate the effectiveness of self-administered fluoride agents at an private-level (such every bit fluoride-containing toothpastes) and, commonly, these trials last for three years so that 3 year caries incidence and increments in intervention and reference groups may be compared. Notwithstanding, trials follow the aforementioned individuals, whereas the studies included in the Cochrane Review virtually ever follow the same communities. The authors of the Cochrane Review infer that, in a not-randomised trial, recording caries experience in both communities earlier offset of water fluoridation and finding similar caries experience in the ii communities before water fluoridation, the communities would remain similar over time. This is surprising, since the Cochrane Review inclusion criterion stipulates that the baseline examination should exist within three years of implementation of water fluoridation: an acknowledgement that the communities may, mainly through population change, lose comparability after three years. While this assumption of similarity may be reasonable over a brusk period, it becomes less tenable as the menstruum between baseline and final examinations increases. This comes advert extremis in the Cochrane Review, in identifying the effect in adults. Thus, for an evaluation of the possible benefits for 50-yr-olds, baseline information on the caries experience of people of this age would be required in the community to be fluoridated and in a comparable reference customs, too as data to exist collected 50 years later on the caries experience of people from the same age group in the same communities which have continued to remain fluoridated or not-fluoridated for the whole of that very long period. Such requirements are unfeasibly stringent given the potential for community demographic characteristics to modify over time, and render fifty twelvemonth historical comparability of intervention and reference communities meaningless for nowadays-mean solar day comparisons.

Even in shorter-term studies (for case, the evaluation of the health of 5-yr-olds subsequently 5 years of water fluoridation), the requirement for baseline and follow-up caries experience data in both the intervention and reference communities, equally well as recording of possible confounding factors, could be questioned. As already mentioned, near evaluations of h2o fluoridation over the by xv to xx years have involved surveillance of existing h2o fluoridation programmes. The nearly advisable study pattern for this purpose is a single cross-sectional study with controls and does not require examination 'at two time points'. Besides the obvious advantage in a greater number of opportunities for study, including a greater number of populations served, the value of this approach in estimating the touch of an intervention has increased with the comeback of study design and data collection, the mainstreaming of powerful and fast computing and the application of new more than sophisticated statistical methods. Cross-sectional studies can now address many of the methodological weaknesses which compromised their value in the past. The main business is controlling for confounding factors and quantifying the amount of the difference between or among groups that is due to the intervention of involvement.

Requirement for a positive reference community when evaluating the effect of abeyance of water fluoridation

Fluoridation of water has been stopped in a number of communities worldwide and the effect on caries experience in these communities has been reported. The authors of the Cochrane Review introduced a new requirement for including such evaluations into their analysis. They required the existence of a positive (fluoridated) reference community during the menses of time from cessation of water fluoridation to the evaluation – for example, v years afterwards cessation – with information on caries experience in both communities before abeyance and after cessation. Reasons for abeyance of water fluoridation vary but often information technology is due to regional or national policy. Thus, all fluoridation programmes in the region would cease, ruling out the possibility of a comparable positive reference community. Examples of this occurred in Scotland; the furnishings of abeyance of water fluoridation in both Wick and Stranraer were evaluated, but not against positive reference communities since national policy ensured none existed. The authors of the Cochrane Review did not accept the concept of a negative reference community, although information technology had previously been accepted by the authors of the York Review. While the deviation in caries experience between the previously fluoridated community and the positive control customs at follow-upwardly examination would be a measure of disbenefit, since this is in practise difficult if non impossible to obtain, modify in caries experience in a non-fluoridated reference customs between baseline and follow-up examination is a measure of change in groundwork caries experience, allowing an estimate of decline in do good in the previously fluoridated customs. This approach was accepted in the York Review which examined data on the effect of cessation of water fluoridation in 22 analyses (eight studies). In 14 of these, 'stopping h2o fluoridation led to an increase in caries in the previously fluoridated surface area compared to the never-fluoridated expanse.' The Cochrane Review analysed just one of these studies.

A systematic review sometimes involves a trade-off between methodological excellence and purity, and meaningful and useful data for policy makers, the public and politicians. Testify, even that produced past the most pristine methods, never speaks for itself or tells you exactly what to practise; it always requires interpretation.¹⁷ If methodological excellence blinds the states to the power of data, imperfect though it may be, about which nosotros can make an cess and a sentence, this may be a serious deficiency. Nosotros believe that has happened in the 2015 Cochrane Review.

Exclusion of mod methods of surveillance of water fluoridation programmes

In many countries with water fluoridation programmes, surveillance of existing schemes is a public health priority and mandated in legislation. For example, the 'Health (Fluoridation of H2o Supplies) Deed, 1960', Government of Ireland,¹⁸ which permitted fluoridation of water in Ireland, requires 'the Government minister [for Wellness] to conform from fourth dimension to time for such surveys every bit appear to him to be desirable to be fabricated equally respects the wellness [...] of persons [...] in the functional area of a health potency.' Such surveillance¹⁹ has also been recommended in other countries including Australia, New Zealand, the The states, Canada, Israel and England.^20,21 In all of these countries, scientifically robust evaluations have been made and published, recording the continued effectiveness of h2o fluoridation. These are cross-sectional studies, which accept compared the caries feel of people, of various ages, with a history of exposure, fractional exposure, or no exposure to water fluoridation. Multivariable analyses take controlled for possible confounding factors, allowing an unbiased estimate to be fabricated of the forcefulness of association of water fluoridation with dental caries.²² Yet, because of their lack of 'baseline' data, these studies were excluded from the Cochrane Review.

Requirements for recording confounding factors

Avoiding and minimising methodological bias in belittling epidemiology is important and it is mostly accepted that research studies accept to demonstrate that bias has been considered and controlled for as far equally reasonably possible. Yet, for studies to be rated equally having a 'low' risk of bias, the Cochrane Review required that information on four possible misreckoning factors be recorded and included in analyses: 'carbohydrate consumption/dietary habits, SES, ethnicity, and use of other fluoride sources.' The Cochrane Review gave no justification for requiring all 4 of these requirements. While there is good show that all four influence caries evolution, there is likewise skilful evidence that dietary habits and home utilize of fluoride products are strongly related to SES in many communities.^23,24 It may, therefore, be unnecessary to record nutrition and employ of fluoride products if SES is recorded, and the requirement to record many potential confounders needs to be considered carefully, especially as dietary habits are notoriously difficult to tape and quantify. Indigenous differences are relevant in some communities only. Information technology should be noted in Table 2 of Rugg-Gunn and Practice²⁵ that the percent caries reductions recorded both before and later on aligning for confounding factors by multivariable analyses were very similar in seven out of the eight studies identified in that review. Thus the insistence on the requirement to include the above four confounding factors may be misguided. While in many countries, low income and limited education are positively associated with caries development, this is not and so in some countries.²⁶ Potential misreckoning factors should exist decided at a local level, with justification of their relevance.

Blueprint of study

The Cochrane Review maintained that the RCT would be the best design for evaluating the effectiveness of water fluoridation, while simultaneously acknowledging its impracticability in this instance. Although RCTs are the method of choice for evaluating the effectiveness of medicines and some clinical interventions, literature published during the by twenty years has indicated that they are inappropriate for evaluating public health preventive programmes and other complex interventions.^{6,seven,8,9,10,11,12,13,fourteen,fifteen} Using water fluoridation as an example, information technology is not possible to randomly assign individuals to fluoridated and non-fluoridated water supplies. RCTs may have high internal validity, merely they besides may have poor external validity. As Petticrew¹⁵ pointed out, public health scientific discipline has moved on from saying 'what works' to exploring 'what happens'. At that place is a stark contrast in arroyo when the Cochrane Review on water fluoridation is compared with the recent World Health Arrangement (WHO) systematic review of dietary sugars and dental caries.^27,28 National nutrition guidelines and h2o fluoridation are both public health bug. While the one-time (Cochrane) review'southward requirements for written report blueprint were very restrictive, the latter (WHO) included studies with a variety of designs: of the 55 studies eligible for inclusion, three were intervention, eight cohort, 20 population, and 24 cross-sectional.^27,28 Both the Cochrane Review¹ and the WHO review²⁸ used the Course method for assessing the quality of evidence.

The role of cross-sectional studies with concurrent controls to monitor the differential in caries between long fluoridated and negative reference sites should have been explored for its potential to accost the research question of the connected effectiveness of water fluoridation in an environment of other fluoride sources. The issue of the length of follow-up required, peculiarly amidst adults, should have prompted consideration of cohort studies, whether true prospective studies built around differing exposure to h2o fluoridation or historical cohort studies which can be derived from cantankerous-sectional comparisons. Ecological studies tin can besides be in the mix due to the population-level implementation of water fluoridation, leading to the possible utilise of multilevel modelling in analysis. Instead, the Cochrane Review has attempted to respond all the supplementary research questions through prove from non-randomised, concurrent and negatively controlled before-and after-studies. This, it could be argued, led to what is termed 'an empty review'. The Cochrane Review's decision that 'at that place is very lilliputian contemporary evidence. that has evaluated the effectiveness of water fluoridation for the prevention of caries' is cocky-fulfiling due to its omission of gimmicky studies designed for surveillance of public wellness programmes.

Dental fluorosis

The Cochrane Review has a second stated objective of evaluating the effect of water fluoridation (bogus or natural) on dental fluorosis. This basically repeats an evaluation of the dose-response relationship between fluoride in h2o supplies and dental fluorosis that Dean and others documented in the 1930s and 1940s.²⁹ This objective explains the inclusion of natural fluoride concentrations well higher up those used in adjusted water fluoridation programmes. It is also a repeat of the analyses presented in the York Review.

Research about fluoride in drinking h2o was initially focused on dental fluorosis. Subsequent dose-response inquiry by Dean and others gave an equal consideration to fluorosis and dental caries. The premise behind adjustment of h2o supplies to around 1 mgF/L was that fluorosis at that concentration was of no public wellness consequence. While fluorosis was present, information technology was of both low prevalence and severity. It was considered to be of such express severity that information technology was frequently not discernible by the public and, if discernible, was of minor upshot in relation to the affliction, discomfort and distress that was associated with caries. Hence the early water fluoridation trials and the replications though the 1950s to 1970s did non place as much accent on fluorosis as an outcome equally caries. Reporting tended to ostend the expected low prevalence of whatsoever fluorosis, and its depression severity – mostly questionable and very mild with few cases of mild fluorosis. This was to be contrasted with the presence of fluorosis at an fifty-fifty lower prevalence and severity distribution in not-fluoridated areas.

However, the introduction of other sources of fluoride through fluoride supplements (tablets and drops) and fluoridated toothpaste contradistinct the relationship of near maximal prevention of caries and adequate levels of fluorosis. Fluorosis became a business concern. Through the 1980s, at that place were reports of higher-than-expected prevalence and severity of fluorosis, especially in (but not restricted to) fluoridated areas. Initially, the focus was on fluoride supplement regimens, resulting in recommended doses existence revised downwards before those regimens were phased out every bit a public health measure in many countries. This was followed by a recognition that fluoridated toothpaste was ingested, peculiarly past young children. Research on dental fluorosis increasingly focused on trends in prevalence and severity, and explored take chances indicators/factors and the owing take a chance for fluorosis. In the Cochrane Review, the effect of h2o fluoridation on the prevalence of fluorosis should have been isolated from the confounding effect of other fluorides. The Cochrane Review's analysis of fluorosis studies is silent on the possible contribution of other fluorides, such as fluoridated toothpaste, which risks leaving readers with the impression that all dental fluorosis arises from fluoride in water supplies. Research since 2000 has indicated that a greater proportion of dental fluorosis risk is due to the use (and therefore swallowing) of fluoride-containing toothpastes than to optimally fluoridated water.^30,31

The subject of the Cochrane Review was 'water fluoridation', rather than fluoride in drinking water. In customs water fluoridation programmes, the recommended fluoride concentration is usually in the range 0.5 to 1.0 mgF/L. This target concentration is decided subsequently the climatic temperature and background fluoride exposure accept been taken into account – for example, the recommended concentration is 0.v mgF/L in Singapore and ane.0 mgF/Fifty in Newcastle upon Tyne. Two principles stem from this: first, that it is unnecessary to consider dental fluorosis in communities with fluoride concentrations more than that used in h2o fluoridation programmes (that is 1.0 mgF/Fifty); 2d, that comparisons should be made between dental fluorosis levels in the fluoridated community and the reference (non-fluoridated) community. The difference between these levels is the statistic of interest – the fluorosis risk due to water fluoridation. This comparison between intervention and reference communities was the method used for evaluating caries prevention in the Cochrane Review but, for an unexplained reason, not for the evaluation of dental fluorosis. For communities with lower fluoride concentrations (such equally 0.five mgF/50), their fluorosis levels should be compared with those in the respective reference (non-fluoridated) community. This would overcome the anomaly in the Cochrane Review of, in effect, comparison fluorosis levels recorded in cooler, amend nourished populations (such equally Newcastle upon Tyne) with those in hot, less-well-nourished populations (such every bit India, Saudi arabia and Namibia). Undernutrition is a recognised risk gene for dental enamel defects^32,33 and the severity recorded is substantially different in areas of the world with different levels of evolution. The rationale for including data from communities with water fluoride concentrations higher than those recommended is unclear, and information technology is not applicative to the evaluation of water fluoridation where fluoride concentrations are controlled and maintained within acceptable limits. The highly restrictive approach taken by the Cochrane Review in examining the outcome of community water fluoridation on dental caries seems to accept been abandoned for dental fluorosis. The reason for this difference is unclear.

The Cochrane Review presented information on the prevalence of dental fluorosis in two means – (i) any level of fluorosis, and (ii) fluorosis of aesthetic business organisation. The reason for presenting information for any level of dental fluorosis is unclear, peculiarly since some of the indices used were not specific for dental fluorosis and recorded the total range of developmental defects of enamel; for these there are many causes of the altered enamel other than fluoride.³⁴ An case of this is the DDE index, although almost reports of studies where the DDE index has been used have provided data on the 3 types of enamel defect separately, allowing some comparison with indices of enamel fluorosis.³⁵ In addition, it is at present recognised that the lower grades of dental fluorosis are not detrimental to appearance. Inquiry shows that communities rate questionable and very balmy fluorosis as of amend appearance and higher self-rated oral health than no fluorosis, with some reports stating that moderate fluorosis is judged as no different to teeth without any fluorosis.^36,37,38 This indicates that if a threshold exists for fluorosis of aesthetic business organization, it may be higher than that proposed in the 1990s, which was equivalent to mild fluorosis. The possible explanation for this shift is that enamel opacities classed equally mild fluorosis are a whitening of teeth, a feature that has go socially desirable, as evidenced by the demand for tooth whitening products and procedures. There is recent evidence that the severity of diffuse enamel opacities reduces with further maturation during boyhood.³⁹

The 2015 Cochrane Review within the context of the totality of information on water fluoridation for the prevention of dental caries

Information technology should be emphasised, first, that the Cochrane Review states 'that water fluoridation is constructive at reducing caries levels in both deciduous [primary] and permanent dentition in children.' In this, it agrees with all other administrative reviews.^{2,40,41,42,43,44,45,46,47} The findings and conclusions of the Cochrane Review are at odds, though, with the literature on the effectiveness of water fluoridation in respect of: its effectiveness in adults; its effectiveness in reducing social disparities in oral wellness; and the outcome of cessation of water fluoridation. On these, the Cochrane Review said that there was insufficient prove; it did not say that h2o fluoridation was ineffective in these regards. Information technology is a cardinal premise of interpreting evidence from trials that the absenteeism of prove, or the beingness of poor-quality testify, should not be confused with, or taken to imply, an absence of outcome. In that location is a adventure that the Cochrane Review will be inadvertently, or deliberately, misinterpreted in this mode.

The primeval written report of the effect of fluoridated h2o on the dental wellness of adults was reported in the USA in 1943.⁴⁸ Since and so, many studies have reported lower caries experience in adults who accept lived in fluoridated communities than adults who have lived in communities with low concentrations of fluoride in drinking h2o. In 2007, Griffin and co-workers, working for the The states Centers for Disease Control and Prevention (CDC), published a systematic review⁴⁹ on the effectiveness of fluoride in preventing caries in adults. For the nine studies which satisfied the inclusion criteria, water fluoridation significantly reduced caries experience (p <0.001). For the five studies published afterward 1979, the prevented fraction was 27%. Since the publication of that systematic review, several publications have supported its conclusions.^50,51,52,53

As mentioned earlier, the use of h2o fluoridation to reduce dental health inequalities was non a stated objective of the Cochrane Review, so it is unsurprising that the narrow inclusion criteria neglect to identify any reports. In contrast, the York Review stated: 'There appears to exist some bear witness that water fluoridation reduces the inequalities in dental health beyond social classes in five and 12-year-olds using the dmft/DMFT measure. This effect was not seen in the proportion of caries-gratis children among five-yr-olds.' A recent analysis of national data in England²⁰ concluded that caries prevalence and experience were lower in communities receiving fluoridated h2o than in communities receiving water low in fluoride, and suggested that 'the outcome is greater within the most deprived communities.'

The touch of cessation of water fluoridation was considered higher up. It was noted that the York Review concluded: 'The best available evidence from studies following withdrawal of water fluoridation indicates that caries prevalence increases, budgeted the level of the low fluoride group. Again, nonetheless, the studies were of moderate quality (level B) and limited quantity.' The Australian National Health and Medical Research Council (NHMRC) 2007 review⁴³ concurred with the conclusions of the York Review, stating: '[the York Review] also sug gest that cessation of fluoridation resulting in a narrowing of the difference in caries prevalence between the fluoridated and non-fluoridated populations. Only one boosted relevant original report was identified in the current review and this did not change the determination of the existing systematic review.'

Public health policy and decisions in public wellness should exist grounded in the totality of the show with advisable consideration of the quality of that evidence, its context, relevance, applicability and cost. In that location is no doubt that there is a considerable amount of bear witness indicating that h2o fluoridation is effective in caries prevention. This bear witness considers not only oral wellness-related result measures such as dmft/DMFT scores, simply besides dental abscesses, toothache and admission to hospital for full general anaesthetics.^54,55,56 Information technology was listed by the U.s.a. CDC as ane of ten nigh important public health initiatives during the twentieth century.⁵⁷ The Cochrane Review used methods which were very restrictive: the American Academy of Pediatrics commented that the Cochrane Review of community water fluoridation had excluded 97% of the evidence.⁵⁸ Those considering this Cochrane Review or embarking on a farther review of water fluoridation should acquit this in mind.

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Author information

Affiliations

1. Professor Emeritus, Newcastle University

   A. J. Rugg-Gunn

2. Professor Emeritus, University of Adelaide

   A. J. Spencer

3. School of Dentistry, Academy of Leeds

   H. P. Whelton

4. NHS Health Scotland, Edinburgh

   C. Jones

5. Hon Senior Lecturer in Dental Public Wellness, University of Leeds

   J. F. Aggravate

6. Independent communications adviser specialising in health-related topics

   P. Castle

7. Faculty of Dentistry, University of Toronto

   P. 5. Cooney

8. American Fluoridation Lodge

   J. Johnson

9. Senior Visiting Fellow, Institute of Public Health, University of Cambridge

   M. P. Kelly

10. Professor Emeritus, University of Sheffield

    1000. A. Lennon

11. American Dental Association, Chicago

    J. McGinley

12. Professor Emeritus, University College Cork

    D. O'Mullane

13. Hebrew University, Hadassah, Jerusalem

    H. D. Sgan-Cohen

14. President, Ontario Association of Public Health Dentistry

    P. P. Sharma

15. Professor of Epidemiology and Public Health, University of Otago

    West. K. Thomson

16. Specialist in Public Health, The Infringe Foundation

    S. M. Woodward

17. Ministry of Wellness, Jerusalem

    S. P. Zusman

Respective author

Correspondence to A. J. Rugg-Gunn.

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Competing interests

AJRG was a member of the MRC (Great britain) working group on water fluoridation and health and is a trustee of The Borrow Foundation. AJS is a member of the Australian Government Department of Wellness, Nutritional Reference Values Fluoride Expert Working Grouping and the National Health and Medical Inquiry Council Fluoride Reference Group. HPW is Principal Investigator of the FACCT report funded past the Irish Health Research Board and is an evaluation of the touch on of changes in the policy on children's oral health in Ireland. She is an contained counselor to the British Fluoridation Society. CJ is a member of the British Fluoridation Gild, the Cochrane Oral Health Grouping and commented on the Cochrane review protocol. JFB is vice-chairman, British Fluoridation Society. PC is a communications adviser to the National Alliance for Disinterestedness in Dental Health and the British Fluoridation Society. PVC was Chief Dental Officeholder for Canada. JJ is President, American Fluoridation Society. MPK is co-investigator on the CATFISH study of a water fluoridation scheme in Cumbria. MAL was a fellow member of the Advisory Panel for the York Review, a member of the MRC Skilful Grouping and formerly Chair of the British Fluoridation Society. JMcG is manager, Fluoridation Activities, American Dental Association. DO'Yard is a member of the Irish Skilful Body on Fluorides and Wellness. PPS is the President, Ontario Association of Public Wellness Dentistry. WMT was a member of the panel which produced the Royal Society of New Zealand report on community water fluoridation. SMW works for The Borrow Foundation. SPZ is Chief Dental Officer with Israeli Ministry of Health. The other authors declare no interests.

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Rugg-Gunn, A., Spencer, A., Whelton, H. et al. Critique of the review of 'Water fluoridation for the prevention of dental caries' published past the Cochrane Collaboration in 2015. Br Dent J 220, 335–340 (2016). https://doi.org/10.1038/sj.bdj.2016.257

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• Accepted: xix February 2016

• Published: 08 Apr 2016

• Upshot Appointment: 08 April 2016

• DOI : https://doi.org/10.1038/sj.bdj.2016.257

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