Community Dental Health (2016) 33, 66–68 © BASCD 2016 doi:10.1922/CDH_Petersen03

Prevention of dental caries through the use of fl uoride – the WHO approach Poul Erik Petersen and Hiroshi Ogawa

Dental caries continues to pose an important public health problem across the world. The World Health Or-ganization (WHO) emphasizes that the disease affects about 60–90% of schoolchildren, the vast majority of adults and that dental caries contributes to an extensive loss of natural teeth in older people globally (Petersen, 2008a; WHO, 2016). Meanwhile, in most westernized high income countries, an improvement in dental health has taken place over the past three decades in parallel with the introduction of prevention-oriented oral health systems. A decline in the prevalence and the severity of dental caries is particularly observed in countries having established public health programmes using fl uoride for dental caries prevention, coupled with changing living conditions, healthier lifestyles, and improved self-care practices. In Eastern Europe and Central Asia dental car-ies levels are high and with health systems in transition the exposure of the population to fl uoride for disease prevention has diminished dramatically. In low and mid-dle income countries of Africa, Asia, and Latin America the lack of preventive programmes is further complicated by the fact that these countries have a shortage of oral health personnel and the capacity of health systems is mostly limited to treatment of symptoms or emergency care. In children and adults suffering from severe tooth decay, teeth are often left untreated or they are extracted to relieve oral pain or discomfort. In the future, tooth loss and impaired quality of life are therefore expected to increase as a public health problem in many develop-ing countries.

The current global and regional patterns of dental car-ies largely refl ect distinct risk profi les of countries which relate to structure of society, living conditions, lifestyles, and the existence of preventive oral health systems (Kwan and Petersen, 2010). The socio-behavioural risk factors in dental caries are found universally and they play sig-nifi cant roles in children, adults and older people. The disease level is relatively high among underprivileged population groups, i.e. people with low education back-ground, poor living conditions, people with poor dietary habits and high consumption of sugars, and people with limited tradition of dental care. Unless serious efforts are made to tackle the social inequity by modifying risk factors and by establishing effective caries prevention

Correspondance to: Dr Poul Erik Petersen, ppe@euro.who.int, and Dr Hiroshi Ogawa, ogawah@who.int, WHO Oral Health Programme, 20 Avenue Appia, CH-1211 Geneva, Switzerland.

Editorial

programmes, the level of dental caries in disadvantaged populations and countries will unduly increase (Kwan and Petersen, 2010). Evidently, substantial population groups in low and middle income countries have not yet obtained the health benefi t from fl uoride in community prevention programmes. The reasons for not having been able to implement prevention programmes varies in nature ranging from lack of national policy for oral health to low awareness of the importance of oral health.

Fluoride and prevention of dental caries

The major reasons for the burden of dental caries in countries relate to the high consumption of sugars and inadequate exposure to fl uoride (WHO, 2010; 2015). The use of fl uoride is a major breakthrough in public health. Controlled addition of fl uoride to drinking water supplies in communities where fl uoride concentration is below optimal levels to have a cariostatic effect began in the 1940s and since then extensive research has confi rmed the successful reduction in dental caries in many countries. Industrial production of fl uoridated salt started in Switzerland in 1955 and its use expanded to several countries in various parts of the world with similar success as water fl uoridation. Milk fl uoridation has also 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). As no effort is required from the individual for ingesting fl uoridated water, salt or milk these methods have been designated as auto-matic systems for dental caries prevention. Fluoride in toothpaste has also been available for decades and it is considered a main contributor to the decline in dental caries observed among people of industrialized countries; unfortunately, toothpastes are not universally used due to the cost factor which inhibits poor population groups from accessing such preventive measure. Finally, fl uoride has been made available in products for professional application, including gels, varnishes and restorative materials. Fluoride mouth rinses incorporated in school health programmes have also been available for decades with various degrees of success in caries prevention.

67

WHO policy on use of fl uoride for prevention of dental cariesThe use of fl uoride for population based prevention of dental caries has been endorsed offi cially by WHO since the late 1960s. The policy on automatic administration of fl uoride is emphasized by several World Health As-sembly (WHA) Resolutions, i.e. WHA22.30 (1969) and WHA28.64 (1975) on fl uoridation and dental health, and WHA31.50 (1978) on fl uoride for prevention of dental caries. These previous statements particularly focused on the public health importance of water fl uoridation. The most recent WHA resolution (WHA60.17, 2007) confi rms the current WHO policy for promoting oral health and the approach of WHO Oral Health Programmes at global and regional levels. It emphasizes that oral disease inter-vention is a signifi cant component of non-communicable disease prevention. The Resolution “Oral Health: Action Plan for Promotion and Integrated Disease Prevention” (Petersen, 2008b) urges Member States to ensure that populations benefi t from appropriate use of fl uoride. The item reads as follows:

(4) for those countries without access to optimal levels of fl uoride, and which have not yet established systematic fl uoridation programmes, to consider the development and implementation of fluoridation programmes, giving priority to equitable strategies such as the automatic administration of fl uoride, for example, in drinking-water, salt or milk, and to the provision of affordable fl uoride toothpaste.

Various countries are in the process of developing fl uoridation programmes while other countries are adjust-ing existing programmes. At global and regional levels the WHO provides advice and technical support on request to Member States for planning appropriate fl uoridation schemes in agreement with socio-cultural conditions. Subsequent to the WHA60.17, WHO published in 2010 a document entitled “Inadequate or excess fl uoride: a major public health concern” which describes the use of fl uoride in a public health environment (WHO, 2010). Fluoride is most effective in dental caries prevention when a low level of fl uoride is constantly maintained in the oral cavity. Meanwhile, there are some undesirable side-effects of excessive fl uoride exposure. Experience has shown that it may not be possible to achieve ef-fective fl uoride-based caries prevention without some degree of mild enamel fl uorosis, regardless of which methods are chosen to maintain a low level fl uoride in the mouth. Public health administrators must therefore seek to maximize caries reduction while minimizing enamel fl uorosis. It is important that fl uoride exposure be known and health administrators be made aware of exposure before the introduction of any fl uoridation or supplementation programmes for prevention and dental caries (WHO, 2014).

The Technical Report Series 846 (TRS846) on “Fluorides and Oral Health” (WHO, 1994) is the existing authoritative WHO publication offering advice and technical support to countries. The TRS846 has been widely used as a manual in planning of fl uoride programmes by public health authorities and administrators of oral health programmes. In addition,

the manual is used extensively by academic institutions, researchers, and oral health professionals. The TRS846 was published in 1994. Over the past two decades the emphasis on an evidence-based approach has grown signifi cantly to advance policy and to apply sound interventions for public health. This initiative also applies to the request of updating the evidence on use of fl uoride.

Evidence-based public healthThe Randomized Controlled Trial (RCT) is considered essential for clinical research; although such a design is inadequate for evaluating the effi cacy of public health interventions (Rychetnik et al., 2002). The RCT design may have relevance in measuring the effect of clinical interventions as the causal chain between the agent and the outcome is relatively short and simple. The causal chains in public health interventions are more complex, making RCT results inappropriate for systematic assessment of the performance and the impact of large-scale interventions. Community trials involve population groups under normal conditions in fi eld settings and quasi-experimental designs, observational studies, and time-series evaluations are often the only feasible options; therefore such alternative ap-proaches may well yield valid and generalizable evidence. Systematic reviews are essential tools for health care workers, researchers, consumers and policy makers who want to keep up with the evidence that is accumulating in their fi eld. Consequently, such reviews are important to the validation of the benefi t of the use of fl uoride.

Fluoride and Oral HealthThe present issue of Community Dental Health provides an important update of the scientifi c evidence on use of fl uoride for prevention of dental caries. It examines the effect of fl uoride from biological, clinical and public health perspectives. The document focuses on the pres-ence of fl uoride in the environment; fl uoride metabolism and excretion; fl uoride in teeth and bone; biomarkers of fl uoride exposure; dental caries prevention and enamel fl uorosis; fl uoridated drinking water, salt and milk; topi-cal use of fl uoride, and fl uoride-containing toothpaste. Based on the modern conception of evidence for public health the report emphasizes the effectiveness and ap-propriateness of different fl uoride administration forms in communities and specifi es the practical impact of implementation of combined administration of fl uoride. This publication aims at summarizing the experiences from use of fl uoride around the globe. Such update information is highly relevant to countries which are in process of introducing fl uoride programmes or to those countries engaged in adjustment of programmes.

References

Jürgensen, N. and Petersen, P.E. (2013): Promoting oral health of children through schools: Results from a WHO global survey 2012. Community Dental Health 30, 204–218.

Kwan, S. and Petersen, P.E. (2010): Oral health: equity and social determinants (pp159-176). In: Blas, E. and Kurup, A.S. Equity, social determinants and public health programmes. Geneva: WHO.

Community Dental Health (2016) 33, 66–68 © BASCD 2016 doi:10.1922/CDH_Petersen03

Prevention of dental caries through the use of fl uoride – the WHO approach Poul Erik Petersen and Hiroshi Ogawa

Dental caries continues to pose an important public health problem across the world. The World Health Or-ganization (WHO) emphasizes that the disease affects about 60–90% of schoolchildren, the vast majority of adults and that dental caries contributes to an extensive loss of natural teeth in older people globally (Petersen, 2008a; WHO, 2016). Meanwhile, in most westernized high income countries, an improvement in dental health has taken place over the past three decades in parallel with the introduction of prevention-oriented oral health systems. A decline in the prevalence and the severity of dental caries is particularly observed in countries having established public health programmes using fl uoride for dental caries prevention, coupled with changing living conditions, healthier lifestyles, and improved self-care practices. In Eastern Europe and Central Asia dental car-ies levels are high and with health systems in transition the exposure of the population to fl uoride for disease prevention has diminished dramatically. In low and mid-dle income countries of Africa, Asia, and Latin America the lack of preventive programmes is further complicated by the fact that these countries have a shortage of oral health personnel and the capacity of health systems is mostly limited to treatment of symptoms or emergency care. In children and adults suffering from severe tooth decay, teeth are often left untreated or they are extracted to relieve oral pain or discomfort. In the future, tooth loss and impaired quality of life are therefore expected to increase as a public health problem in many develop-ing countries.

The current global and regional patterns of dental car-ies largely refl ect distinct risk profi les of countries which relate to structure of society, living conditions, lifestyles, and the existence of preventive oral health systems (Kwan and Petersen, 2010). The socio-behavioural risk factors in dental caries are found universally and they play sig-nifi cant roles in children, adults and older people. The disease level is relatively high among underprivileged population groups, i.e. people with low education back-ground, poor living conditions, people with poor dietary habits and high consumption of sugars, and people with limited tradition of dental care. Unless serious efforts are made to tackle the social inequity by modifying risk factors and by establishing effective caries prevention

Correspondance to: Dr Poul Erik Petersen, ppe@euro.who.int, and Dr Hiroshi Ogawa, ogawah@who.int, WHO Oral Health Programme, 20 Avenue Appia, CH-1211 Geneva, Switzerland.

Editorial

programmes, the level of dental caries in disadvantaged populations and countries will unduly increase (Kwan and Petersen, 2010). Evidently, substantial population groups in low and middle income countries have not yet obtained the health benefi t from fl uoride in community prevention programmes. The reasons for not having been able to implement prevention programmes varies in nature ranging from lack of national policy for oral health to low awareness of the importance of oral health.

Fluoride and prevention of dental caries

The major reasons for the burden of dental caries in countries relate to the high consumption of sugars and inadequate exposure to fl uoride (WHO, 2010; 2015). The use of fl uoride is a major breakthrough in public health. Controlled addition of fl uoride to drinking water supplies in communities where fl uoride concentration is below optimal levels to have a cariostatic effect began in the 1940s and since then extensive research has confi rmed the successful reduction in dental caries in many countries. Industrial production of fl uoridated salt started in Switzerland in 1955 and its use expanded to several countries in various parts of the world with similar success as water fl uoridation. Milk fl uoridation has also 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). As no effort is required from the individual for ingesting fl uoridated water, salt or milk these methods have been designated as auto-matic systems for dental caries prevention. Fluoride in toothpaste has also been available for decades and it is considered a main contributor to the decline in dental caries observed among people of industrialized countries; unfortunately, toothpastes are not universally used due to the cost factor which inhibits poor population groups from accessing such preventive measure. Finally, fl uoride has been made available in products for professional application, including gels, varnishes and restorative materials. Fluoride mouth rinses incorporated in school health programmes have also been available for decades with various degrees of success in caries prevention.

67

WHO policy on use of fl uoride for prevention of dental cariesThe use of fl uoride for population based prevention of dental caries has been endorsed offi cially by WHO since the late 1960s. The policy on automatic administration of fl uoride is emphasized by several World Health As-sembly (WHA) Resolutions, i.e. WHA22.30 (1969) and WHA28.64 (1975) on fl uoridation and dental health, and WHA31.50 (1978) on fl uoride for prevention of dental caries. These previous statements particularly focused on the public health importance of water fl uoridation. The most recent WHA resolution (WHA60.17, 2007) confi rms the current WHO policy for promoting oral health and the approach of WHO Oral Health Programmes at global and regional levels. It emphasizes that oral disease inter-vention is a signifi cant component of non-communicable disease prevention. The Resolution “Oral Health: Action Plan for Promotion and Integrated Disease Prevention” (Petersen, 2008b) urges Member States to ensure that populations benefi t from appropriate use of fl uoride. The item reads as follows:

(4) for those countries without access to optimal levels of fl uoride, and which have not yet established systematic fl uoridation programmes, to consider the development and implementation of fluoridation programmes, giving priority to equitable strategies such as the automatic administration of fl uoride, for example, in drinking-water, salt or milk, and to the provision of affordable fl uoride toothpaste.

Various countries are in the process of developing fl uoridation programmes while other countries are adjust-ing existing programmes. At global and regional levels the WHO provides advice and technical support on request to Member States for planning appropriate fl uoridation schemes in agreement with socio-cultural conditions. Subsequent to the WHA60.17, WHO published in 2010 a document entitled “Inadequate or excess fl uoride: a major public health concern” which describes the use of fl uoride in a public health environment (WHO, 2010). Fluoride is most effective in dental caries prevention when a low level of fl uoride is constantly maintained in the oral cavity. Meanwhile, there are some undesirable side-effects of excessive fl uoride exposure. Experience has shown that it may not be possible to achieve ef-fective fl uoride-based caries prevention without some degree of mild enamel fl uorosis, regardless of which methods are chosen to maintain a low level fl uoride in the mouth. Public health administrators must therefore seek to maximize caries reduction while minimizing enamel fl uorosis. It is important that fl uoride exposure be known and health administrators be made aware of exposure before the introduction of any fl uoridation or supplementation programmes for prevention and dental caries (WHO, 2014).

The Technical Report Series 846 (TRS846) on “Fluorides and Oral Health” (WHO, 1994) is the existing authoritative WHO publication offering advice and technical support to countries. The TRS846 has been widely used as a manual in planning of fl uoride programmes by public health authorities and administrators of oral health programmes. In addition,

the manual is used extensively by academic institutions, researchers, and oral health professionals. The TRS846 was published in 1994. Over the past two decades the emphasis on an evidence-based approach has grown signifi cantly to advance policy and to apply sound interventions for public health. This initiative also applies to the request of updating the evidence on use of fl uoride.

Evidence-based public healthThe Randomized Controlled Trial (RCT) is considered essential for clinical research; although such a design is inadequate for evaluating the effi cacy of public health interventions (Rychetnik et al., 2002). The RCT design may have relevance in measuring the effect of clinical interventions as the causal chain between the agent and the outcome is relatively short and simple. The causal chains in public health interventions are more complex, making RCT results inappropriate for systematic assessment of the performance and the impact of large-scale interventions. Community trials involve population groups under normal conditions in fi eld settings and quasi-experimental designs, observational studies, and time-series evaluations are often the only feasible options; therefore such alternative ap-proaches may well yield valid and generalizable evidence. Systematic reviews are essential tools for health care workers, researchers, consumers and policy makers who want to keep up with the evidence that is accumulating in their fi eld. Consequently, such reviews are important to the validation of the benefi t of the use of fl uoride.

Fluoride and Oral HealthThe present issue of Community Dental Health provides an important update of the scientifi c evidence on use of fl uoride for prevention of dental caries. It examines the effect of fl uoride from biological, clinical and public health perspectives. The document focuses on the pres-ence of fl uoride in the environment; fl uoride metabolism and excretion; fl uoride in teeth and bone; biomarkers of fl uoride exposure; dental caries prevention and enamel fl uorosis; fl uoridated drinking water, salt and milk; topi-cal use of fl uoride, and fl uoride-containing toothpaste. Based on the modern conception of evidence for public health the report emphasizes the effectiveness and ap-propriateness of different fl uoride administration forms in communities and specifi es the practical impact of implementation of combined administration of fl uoride. This publication aims at summarizing the experiences from use of fl uoride around the globe. Such update information is highly relevant to countries which are in process of introducing fl uoride programmes or to those countries engaged in adjustment of programmes.

References

Jürgensen, N. and Petersen, P.E. (2013): Promoting oral health of children through schools: Results from a WHO global survey 2012. Community Dental Health 30, 204–218.

Kwan, S. and Petersen, P.E. (2010): Oral health: equity and social determinants (pp159-176). In: Blas, E. and Kurup, A.S. Equity, social determinants and public health programmes. Geneva: WHO.

68

Petersen, P.E. (2003): The World Oral Health Report 2003: continuous improvement of oral health in the 21st century - the approach of the WHO Global Oral Health Programme. Community Dentistry and Oral Epidemiology 31, suppl. 1, 3-24.

Petersen, P.E. (2008a): Oral Health. In: Heggenhougen, K. and Quah, S. eds. International Encyclopedia of Public Health 4, 677-685.

Petersen, P.E. (2008b): World Health Organization global policy for improvement of oral health - World Health Assembly 2007. International Dental Journal 58, 115-121.

Rychetnik L., Frommer, M., Hawe P., and Schiell, A. (2002): Criteria for evaluating evidence on public health interventions. Journal of Epidemiology and Community Health 56, 119-127

World Health Organization (1994): Fluorides and Oral Health. Technical Report Series No. 846. Geneva: WHO.

World Health Organization (2010): Inadequate or excess fl uoride: a major public health concern. Geneva: WHO.

World Health Organization (2014): Basic methods for assessment of renal fl uoride excretion in community prevention programmes for oral health. Geneva: WHO.

World Health Organization (2015): Guideline: Sugars intake for adults and children. Geneva: WHO.

World Health Organization (2016): Global Oral Health Data Bank. Geneva: WHO. http://www.mah.se/CAPP/Country-Oral-He alth-Profi les

Community Dental Health (2016) 33, 69–99 © BASCD 2016Received 8 July 2015; Accepted 11 January 2016 doi:10.1922/CDH_3707O’Mullane31

Fluoride and Oral HealthD.M. O’Mullane1, R.J. Baez2, S. Jones3, M.A. Lennon4, P.E. Petersen5, A.J. Rugg-Gunn6, H. Whelton7 and G.M. Whitford8

1Oral Health Services Research Centre, University College Cork, Ireland; 2University of Texas Health Science Center at San Antonio School of Dentistry, USA; 3Research and Information Offi ce, British Fluoridation Society, UK; 4University of Sheffi eld, UK; 5WHO Collaborating Centre, University of Copenhagen, Denmark; 6Newcastle University, UK; 7Leeds Dental Institute, Clarendon Way, Leeds, UK 8Georgia Regents University, Augusta, GA, USA

Sections:1. Introduction ................................................................. 692. Presence of fl uoride in the environment ................... 703. Fluoride metabolism and excretion ............................ 724. Fluoride in teeth and bone ......................................... 735. Biomarkers of fl uoride exposure ................................ 756. Caries prevention and enamel fl uorosis ..................... 777. Fluoride in drinking-water .......................................... 788. Fluoridated salt ............................................................ 819. Fluoridated milk. ......................................................... 8310. Fluoride supplements (tablets and drops) .................. 84

11. Fluoride toothpastes ..................................................... 8512. Topical fl uorides (other than toothpaste) .................... 8813. Multiple fl uoride exposure .......................................... 9014. Fluorides and adult dental health ................................ 9015. Recommendations ........................................................ 91Annexe 1. Worldwide totals for populations with artifi cially and naturally fl uoridated water ....... 92Annexe 2. Worldwide use of fl uoridated salt ................... 94Annexe 3. Worldwide use of fl uoridated milk ................. 95Acknowledgments ............................................................... 95References ........................................................................... 95

Key words: fl uorides, drinking water, salt, milk, supplements, toothpastes, varnishes and gels

1. Introduction

At the 2007 WHO World Health Assembly, a resolution was passed that universal access to fl uoride for caries prevention was to be part of the basic right to human health (Petersen, 2008). There are three basic fl uoride delivery methods for caries prevention; community based (fl uoridated water, salt and milk), profession-ally administered (fl uoride gels, varnishes) and self-administered (toothpastes and mouth-rinses). Whilst the effectiveness of these different methods is considered separately in this publication, it is important to note that combinations of different methods are in use in many communities throughout the world. For example, in the recent review of fl uoride use in twenty Asian countries

Correspondence to: Denis O’Mullane, Emeritus Professor and Consultant, Oral Health Services Research Centre, University College Cork, Ireland. Email: d.omullane@ucc.ie.

this diversity of approach was evident (Petersen and Phantumvanit, 2012).

In revising the 1994 edition of “Fluorides and Oral Health” the increasing emphasis on an evidence-based approach is fully taken into account. In this respect the fi ndings of published systematic reviews underpin the evidence to support the conclusions reached. In addition, account is taken of the fact that many complex public health programmes and interventions are not amenable to measurement using the classical randomised control clinical trial design; the fi ndings of observational stud-ies are also relevant in assessing the value of these interventions (Downer, 2007; O’Mullane et al., 2012; Rugg-Gunn et al, 2016; von Elm et al., 2008).

The discovery during the fi rst half of the 20th century of the link between natural fl uoride, adjusted fl uoride levels in drinking water and reduced dental caries prevalence proved to be a stimulus for worldwide on-going research into the role of fl uoride in improving oral health. Epidemiological studies of fl uoridation programmes have confi rmed their safety and their effectiveness in controlling dental caries. Major advances in our knowledge of how fl uoride impacts the caries process have led to the development, assessment of effectiveness and promotion of other fl uoride vehicles including salt, milk, tablets, toothpaste, gels and varnishes. In 1993, the World Health Organization convened an Expert Committee to provide authoritative information on the role of fl uorides in the promotion of oral health throughout the world (WHO TRS 846, 1994). This present publication is a revision of the original 1994 document, again using the expertise of researchers from the extensive fi elds of knowledge required to successfully implement complex interventions such as the use of fl uorides to improve dental and oral health. Financial support for research into the development of these new fl uoride strategies has come from many sources including government health departments as well as international and national grant agencies. In addition, the unique role which industry has played in the development, formulation, assessment of effectiveness and promotion of the various fl uoride vehicles and strategies is noteworthy. This updated version of ‘Fluoride and Oral Health’ has adopted an evidence-based approach to its commentary on the different fl uoride vehicles and strategies and also to its recommendations. In this regard, full account is taken of the many recent systematic reviews published in peer reviewed literature.