Guidelines on the use of fluoride for caries prevention in children: an updated EAPD policy document

Babies and children under the age of 4 years are considered to be at risk of dental fluorosis of permanent incisors and first molars, because the calcification and maturation of these teeth occur during this period of life. The longitudinal Iowa study found that exposure to fluoride during the first 3 years of life were most important for fluorosis development on the permanent maxillary incisors, but other individual periods were also important (Hong et al. 2006). It is during this period when the use of fluorides must be carefully monitored and balanced with the need to prevent the occurrence of early childhood caries. Special attention should be given to the use of topically applied fluorides during this period of life, because of the inadequate control of the swallowing reflex.

The posterior teeth (premolars and second molars) are calcifying and maturing during this period and at risk of dental fluorosis. Nevertheless, when this occurs, it represents less of an aesthetic problem, which needs to be weighed against the marked benefit of caries prevention brought about by the use of fluoride.

Silver diamine fluoride (SDF) at a concentration of 38% (44,800 ppmF) has been rarely used in Europe to arrest or prevent dental caries, whereas in the Americas, Australasia and Asia, it has been frequently used to arrest dental caries in children (Gao et al. 2019; Tiripathi et al. 2019). The American Academy of Pediatric Dentistry (AAPD) produced guidelines (Crystal et al. 2017) on the use of SDF for the management of dental caries in children based on a systematic review of Gao et al. (2016). Per GRADE, this is a CONDITIONAL recommendation based on low-quality evidence. Interest in the use of SDF in Europe is now growing.

Apart from the basic caries prevention by the use of fluoridated toothpaste, other topical fluorides can be used especially in children assessed as being at increased risk for caries development, including children with special oral health care needs or under orthodontic treatment and in risk periods such as tooth eruption. The evidence for the caries-preventive effect of gels, rinses and varnishes is greater in quality and quantity for permanent than primary teeth (Marinho et al. 2013, 2015, 2016; Twetman and Keller 2016). Especially in preschool children, the risk of ingestion and subsequent dental fluorosis should be weighed against the potential caries-preventive benefits. Additionally, the cost effectiveness has to be considered for groups with low caries prevalence (Schwendicke et al. 2018). This is also true for the mode of application, e.g., with gels, where in-office application offers greater control, but also higher costs, compared with settings such as schools or home application with lower costs, but also possibly reduced compliance.

Milk fluoridation has been reported to be successful in dental caries prevention, particularly among children, and schemes have been developed in countries around the globe based on integration with school health and nutrition programmes (Jürgensen and Petersen 2013). Fluoridated milk is only ingested by children on school days and therefore not at weekends and school holidays. As no effort is required from the individual for ingesting fluoridated water, salt or milk, these methods have been designated as automatic systems for dental caries prevention. The use of milk as a vehicle for providing additional fluoride in dental public health programmes was evaluated in two recent systematic reviews (Cagetti et al. 2013; Yeung et al. 2015). Cagetti et al. (2013) searched literature from 01.01.1966 to 03.31.2011 and found nine papers of which only two papers fulfilled their inclusion criteria (Bian et al. 2003; Stecksén-Blicks et al. 2009). Both these studies investigated the caries-prevention effect of milk fluoridation on primary teeth. In the first study, the GRADE recommendation strength is CONDITIONAL (Bian et al. 2003), each participant consumed 200 ml of fluoridated milk (concentration 2.5 mg F-per litre) a day for 21 months. At the end of the experimental period, the mean net caries increment was 0.4 dmft for the test group and 1.3 dmft for the control group (t test, p < 0.001). The second study (Stecksén-Blicks et al. 2009) evaluated the effect of fluoridated milk on caries development in preschool children. Children in the intervention group received 150 ml of milk supplemented with 2.5 mg of fluoride per litre for lunch, while the control group received standard milk for 21 months. The authors concluded that daily consumption of milk containing fluoride reduced caries in preschool children, with a prevented fraction of 75%. The GRADE strength of recommendation for this study was also CONDITIONAL. Of the other five studies, only one study (Ketley et al. 2003) failed to demonstrate the caries-preventive effect of milk fluoridation. Four studies suggested that fluoridated milk had a beneficial effect, reducing caries incidence in both the primary and permanent dentitions. Cagetti et al. (2013) concluded that the consumption of fluoridated milk was an effective measure to prevent caries in primary teeth but that there was low evidence that the use of milk fluoridation was effective in reducing the caries increment.

Yeung et al. (2015) included in a Cochrane review only one unpublished RCT and concluded that there was low-quality evidence to suggest that fluoridated milk may be beneficial to schoolchildren, contributing to a substantial reduction in dental caries in primary teeth. Due to the low quality of the evidence, further research is likely to have an important impact on our confidence in the estimate of effect. Furthermore, there was no information about the potential adverse effects of the intervention. Additional RCTs of high quality are needed before we can draw definitive conclusions about the benefits of milk fluoridation (Yeung et al. 2015).

Traditionally, the fluoridation of salt has been considered as an effective method for reducing caries, especially in areas where water fluoridation cannot be implemented. Two systematic reviews have been published on the clinical effectiveness of salt fluoridation (Yengopal et al. 2010; Cagetti et al. 2013). In one of these (Cagetti et al. 2013), no paper related to the use of salt fluoridation in caries prevention fulfilled the inclusion criteria, and the other one (Yengopal et al. 2010) concluded that the contribution of fluoridated salt to the decrease in the prevalence of caries could not be quantified, and further high-quality studies are needed. Wennhall et al. (2014) observed that domestic salt in low caries communities with vulnerable groups of schoolchildren did not seem to reduce the number of new caries lesions or slow down the progression rate. But, it should be taken into account that several confounders and bias were identified in this study.

Fabruccini et al. (2016) concluded that in a cross-sectional oral health survey, fluoridated water appeared to provide a better protective effect against caries than fluoridated salt among schoolchildren from developing countries. However, Jordan et al. (2017) observed that the use of fluoridated salt in a community feeding programme in an environment with negligible availability of fluoride from other sources resulted in a considerable caries-preventive effect.

Salt fluoridation is suggested (Pollick 2013; O’Mullane et al. 2016) when water fluoridation cannot be implemented, but one concern is that promotion of salt consumption for oral health benefits would be contradictory to the desired reduction of consumption of salt to decrease the risk of hypertension, and the drawbacks related to variation in ingestion resulted in difficulties in maintaining an ideal concentration.

Fluoride tablets/lozenges and drops were first introduced to provide systemic fluoride in areas where water fluoridation was not available. At the time of introduction, the effectiveness of fluoride toothpaste was not yet firmly established. Since the mid 1970s, effective fluoride toothpastes became widely available. In these years, it was also accepted that the post-eruptive effects of fluorides were sufficiently strong to keep one’s teeth healthy when properly used (Fejerskov et al. 1981; Fejerskov 2004). These findings rated fluoride tablets/lozenges and drops as less meaningful caries-preventive measures. Additionally, when using them, care should be taken that the products have sufficient substantivity in the oral cavity to also exert a topical effect.

In 2009, the EAPD concluded that at that time there was a lack of evidence to make good recommendations (Swedish Council on Technology Assessment in Health Care 2002; Espelid 2008). The EAPD also advised to monitor the total daily amount of fluoride ingested which should not exceed 0.07 mg/kg bodyweight daily (Fejerskov et al. 1977).

Since the previous position paper of the EAPD et al. (2009), no new RCTs examining the effect of fluoride tablets/lozenges or drops have been published. Two systematic reviews concluded that there might be an effect for permanent dentition, but that there was no clarity on the effect on primary dentition (Tubert-Jeanin et al. 2011; Tomasin et al. 2015). It has to be noted that both reviews examined older studies, conducted at a time when topical fluorides were not widely used and that were also available when the previous position paper of the EAPD (2009) was compiled.

One Cochrane review examining whether it was beneficial for pregnant women to use fluoride supplements to prevent future dental caries in their offspring found no evidence to support this (Takahashi et al. 2017).

Fluoridated milk and fluoridated salt could be part of community health programmes in target groups with high caries prevalence and low compliance for tooth brushing with fluoridated toothpaste in areas without water fluoridation (GRADE of recommendation: CONDITIONAL). Fluoride tablets/lozenges and drops could be considered on an individual basis for children at high risk for caries (GRADE of recommendation: CONDITIONAL), but improving the quality of tooth brushing or using a higher concentration of fluoridated toothpaste would be the first option.

In the 21st century, dental caries remains a global health problem. It is estimated that 573 million children worldwide have untreated dental caries in their primary teeth, while untreated caries in permanent teeth affects 2.5 billion people (Kassebaum et al. 2017). Community water fluoridation (CWF) is the process of adjusting the amount of fluoride found in water to achieve optimal prevention of dental caries (Centers for Disease Control and Prevention 2016). The fluoride concentration of water in CWF programmes typically ranges from 0.5 to 1.1 mg/L.

CWF was introduced over 70 years ago as a public health measure to prevent and control caries at a population level, and in many countries throughout the world, CWF remains a core component of oral health policy. In 2012, the worldwide total of people supplied with artificially fluoridated water was estimated at approximately 370 million (British Fluoridation Society 2012).

The great advantage of CWF is that it benefits all residents in a community, regardless of age, socio-economic status, education, oral hygiene practices, employment or access to routine dental care, making it a truly equitable public health practice (Buzalaf et al. 2011; Public Health Agency of Canada 2016). CWF is also a cost-effective method of delivering caries prevention to a large population, and the larger the community served is, the greater the cost saving will be (Ran and Chattopadhyay 2016).

The effectiveness of CWF at preventing dental caries has been extensively and regularly investigated since the middle of the 20th century. A recent Cochrane review estimated that the initiation of CWF reduced caries levels by 35% in the primary dentition and 26% in the permanent dentition of children. The review also found that CWF led to a 15% increase in the percentage of children with caries-free primary teeth and a 14% increase in the percentage of children with caries-free permanent dentitions, compared to children without water fluoridation (Iheozor-Ejiofor et al. 2015). The reviewers questioned the applicability of these results to current lifestyles, as most of the included studies were conducted before the widespread use of fluoride toothpaste. The inclusion criteria of the Cochrane review, which focused on the initiation of CWF, meant that the large body of contemporary data on CWF was excluded. Contemporary studies of the effectiveness of water CWF are primarily cross-sectional surveillance surveys in populations with established CWF programmes, where the use of fluoride toothpaste is ubiquitous. Reviews of such contemporary studies have reported substantial caries reductions in both children and adults who reside in fluoridated areas, compared to those in non-fluoridated areas (Griffin et al. 2007; Rugg-Gunn and Do 2012). A Cochrane review of the effectiveness of fluoride toothpaste also found an additional caries-preventive benefit when F toothpaste was used in areas with fluoridated water (Marinho et al. 2003).

Since its introduction in the mid-20th century, concerns have been expressed about the possible health effects of CWF. Several recent comprehensive reviews on the impact of fluoridated water on human health have been published (Scientific Committee on Health and Environmental Risks (SCHER) 2011; Royal Society of New Zealand & Office of the Prime Minister’s Chief Scientific Advisor 2014; Sutton et al. 2015; National Health and Medical Research Council (NHMRC 2016)). No reliable evidence for any adverse health effects associated with the use of fluoridated water at the low levels used in CWF were found by any of these reviews. One review also considered the environmental impact of artificially fluoridated water and concluded that exposure of environmental organisms to the levels of fluoride used for fluoridation of drinking water was not expected to lead to unacceptable risks to the environment (Scientific Committee on Health and Environmental Risks (SCHER) 2011).

Dental fluorosis at the lower levels (Dean’s Index) is the only unwanted effect that is definitively associated with CWF. The Cochrane review of water fluoridation estimated a prevalence of 12% for fluorosis of aesthetic concern at water fluoride levels of 0.7 mg/L (Iheozor-Ejiofor et al. 2015).

Bottled drinking water is extensively used in many countries, including those with CWF, where it may displace the consumption of fluoridated tap water. Bottled water, if optimally fluoridated, could offer an additional option for population caries prevention. However, further research on the role of fluoride-containing bottled waters, dental caries and fluorosis is needed.

The EAPD reaffirms its support for the use of community water fluoridation as a safe, effective, relevant and cost-saving public health measure for the prevention and control of dental caries. The Academy recognises that CWF alone is not a panacea but should be seen as an important element in a multi-faceted approach to caries prevention and control, which includes oral health promotion and access to affordable care.

The Academy recognises the need for ongoing population surveillance of the dental and health effects of fluoridated water to assure its continued safety, effectiveness and relevance.