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The World Health Organization (WHO) recentlypublished a global overview of oral health, a statementthat described the WHO Oral Health Programme'sapproach to promotion of further improvement in oral healthduring the 21st Century.1 The report emphasized that despitegreat improvements in the oral health status of populationsacross the world, problems still persist. This is particularly soamong underprivileged groups in both developed anddeveloping communities. Oral diseases and conditions,including oral cancer, oral manifestations of HIV/AIDS, dentaltrauma, craniofacial anomalies, and noma (cancrum oris), allhave broad impacts on health and well-being.

Dental caries and periodontal diseases have historicallybeen considered the most important global oral diseaseburden. At present, the distribution and severity of dentalcaries vary in different parts of the world and within thesame country or region (Figure 1 and Figure 2). Thesignificant role of socio-behavioural and environmentalfactors in oral disease and health is demonstrated in a largenumber of epidemiological surveys.2 Dental caries is still amajor public health problem in most industrializedcountries, affecting 6090% of schoolchildren and the vastmajority of adults. It is also a most prevalent oral disease inseveral Asian and Latin American countries, while it appearsto be less common and less severe in most Africancountries. However, it is expected that the incidence ofdental caries will increase in the near future in manydeveloping countries of Africa, particularly as a result ofgrowing consumption of sugars and inadequate exposure tofluorides (Figure 3). The current pattern of dental cariesreflects primarily distinct risk profiles across countries (i.e. living conditions, lifestyles and environmental factors) and the outcome of implementation of preventiveoral health systems.

While in some industrialized countries there has been apositive trend of reduction in tooth loss among adults inrecent years, the proportion of edentulous persons amongstthe elderly is still high in some countries (Figure 4).3 Inmost developing countries, access to oral health services islimited and teeth are often left untreated or are extractedbecause of pain or discomfort. Tooth loss and impaired oralfunction are therefore expected to grow as a public healthproblem in many developing countries. Meanwhile, toothloss in adult life may also be due to poor periodontal

health. Severe periodontitis which may result in tooth loss isfound in 515% of most populations.1 In industrializedcountries, studies show that tobacco use is a major riskfactor for adult periodontal disease.4 With the growingconsumption of tobacco in many developing countries therisk of periodontal disease and tooth loss, therefore, mayincrease. Periodontal disease and tooth loss are also relatedto general chronic diseases such as diabetes mellitus.5 Thegrowing incidence of diabetes may further impact negativelyon the oral health of people in several developing countries.Oral cancer is highly related to use of tobacco and excessiveconsumption of alcohol. The incidence of oral cancer isparticularly high among men, the eighth most commoncancer worldwide (Figure 5).6 In south-central Asia,consumption of tobacco in various forms is particularly highand cancer of the oral cavity ranks amongst the three mostcommon types of cancer. The variation in oral cancerincidence rate across the world primarily reflects different riskprofiles and access and availability to health services.

In several industrialized Western countries, oral health careis made available to the population, comprises preventiveand curative services and is based on either private or publicsystems. Meanwhile, people in deprived communities,certain ethnic minorities, homebound or disabled individualsand older people are not sufficiently covered by oral healthcare. Many developing countries have a shortage of oralhealth personnel, services are mostly offered from regional orcentral hospitals of urban centres and little importance isgiven to preventive or restorative dental care.

Research for oral healthEssentially, we have sufficient knowledge about the causes ofmost oral diseases for public health action, yet ourknowledge about causal factors related to certain diseasessuch as cleft lip and palate and noma is incomplete. Themajor priority for new research is on prevention policy,translation of science and evaluation of programmeeffectiveness. Clinical and public health research has shownthat a number of individual, professional and communitypreventive measures are effective in preventing most oraldiseases.7 However, optimal intervention in relation to oraldisease is not universally available or affordable because ofescalating costs and limited resources in many countries.This, together with insufficient emphasis on primary

Article by Poul Erik Petersen

Global research challengesfor oral health

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prevention of oral diseases, poses a considerable challengefor several countries, particularly developing countries andcountries with economies and health systems in transition.

The major challenges of the future will be to translateknowledge and experiences of disease prevention into actionprogrammes. Advances in oral health science andknowledge have not yet benefited developing countries tothe fullest extent possible. Clear disparities in economicstrength, political will, scientific resources and capabilities,and the ability to access global information networks have, in fact, widened the knowledge gap between rich andpoor countries.

Building an international research agendafor oral healthThe need to re-examine an existing research agenda forinternational collaborative researchhas been stimulated by recent oralhealth sessions held at the annualForums of the Global Forum forHealth Research in 2002 inTanzania, in Geneva in 2003 andmost recently in Mexico City in2004:

a) The 5th Forum session focusedon developing internationalcollaborative research that activelyinvolves research centres indeveloping countries. Significantexperiences have been gained by theWHO Collaborating Centre forDental, Oral and CraniofacialResearch at the National Institutes ofHealth, Bethesda, Maryland, theUnited States.

b) The 6th Forum session con-

sidered examples of internationalcollaborative research that spansdeveloping and developed countriesand focuses on the measurement ofsocio-dental outcomes for thepurpose of planning and evaluatingoral health services.

c) The 7th Forum session discussedthe development of an internationalcollaborative research agenda thatwould be relevant to the MillenniumDevelopment Goals (MDGs) andincluded discussants from the WHO,the International Association forDental Research (IADR) and some ofthe WHO collaborating centres sitedin the Americas. The sessionfocused on building research teamsthat address questions of globalimportance. Such research includesoral disease-systemic disease inter-

relationships, HIV/AIDS related oral disease, cranio-facialanomalies, oral cancer, health outcomes measurement suchas quality of life indicators, and health promotion. It is considered highly relevant to ensure integration of oralhealth research into other health research projects at acommunity level that should enable efficient linkages of oralhealth measures with biological, social and environmentalhealth determinants.

WHO and oral health researchIn the future, more emphasis should be devoted to certainareas of research:Modifiable common risk factors to oral health and chronic

disease, particularly the role of diet, nutrition and tobacco.Oral health-general health interrelationships.Psychosocial implications of oral health/illness and

quality of life

Figure 1: Levels of dental caries experience in 12-year-olds as measured by the Decayed,Missing due to Caries, Filled Teeth (DMFT) index 1

Figure 2: Levels of dental caries experience in 3544-year-olds as measured by the DMFT index1

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Inequity in oral health and disease.Diagnostics and cost-effective intervention strategies

in relation to certain conditions such as noma andcraniofacial birth defects.

Identification of the most indicative oral manifestations of HIV/AIDS.

Population studies of oral mucosal lesions, includingepidemiological surveys of HIV/AIDS related oral disease in developing countries.8

The burden of oro-dental trauma, particularly indeveloping countries, and related risk factors.

Evidence in oral health care: clinical care and publichealth practice.9

Operational research oneffectiveness of alternativecommunity oral healthprogrammes, including researchon optimal levels of fluoride frommultiple sources.

Health systems research onreorientation of oral healthservices towards prevention andhealth promotion.

Time-series data for oral healthsurveillance in developingcountries.The WHO Oral Health Programme

has prioritized oral health researchas part of the global strategy forbetter health.1 The Programmestimulates oral health research for,with and by developing countries inseveral ways:Supporting initiatives that will

strengthen research capability indeveloping countries so that research isrecognized as the foundation of oralhealth policy. Increased involvement of WHOCollaborating Centres on Oral Health inhigh-priority areas of research withinnational, regional or interregionalcentres. Encourage oral health researchtraining programmes at local level orbased on inter-university collaborativesandwich programmesProvide universities and researchinstitutes in developing countries witheasy access to the scientific literaturewithin oral health and online access toscientific articles and reportsFacilitate the use of the CochraneLibrary that provides systematic

reviews about the evidence for public health action.In addition to WHO Collaborating Centres on Oral Health,

the WHO Oral Health Programme supports research indeveloping countries in joint projects with non-governmentalorganizations such as the IADR and the World DentalFederation. Reducing the 10/90 gap in oral health researchcannot take place in an isolated way, but may effectivelytake place through work within the framework of the GlobalForum for Health Research. This forum provides support to priority-setting methodologies, sound measurement, and dissemination of results in order to break the viciouscircle of ill health and poverty.

Most recently, the WHO published the World Report onKnowledge for Better Health.10 The report provides a

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1980 1981 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998

Developed countries All countries Developing countries

DMFT

Figure 3: Changing dental caries experience index (mean number) of 12-year-olds indeveloping and developed countries as measured by the DMFT index1

Figure 4: Percentage of edentulous persons aged 6574 years in selected countries1

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compass to reorient health research so that it may respondmore effectively to public health challenges on a national andglobal level. This re-orientation requires a strengthening ofthe health research sector, an environment that is moreconducive to research-informed policy and practice, andmore focus on key priorities for research to improve healthsystems. The analysis and recommendations of the reportapply to continuous oral health systems development andadjustment as well as to oral health research. o

Acknowledgement

The author is grateful for the valuable comments made to a previous

version of the paper by Dr Lois KCohen, PhD, Director of theWHO Collaborating Centre forInternational Collaboration in Dental and CraniofacialResearch, NIH, Bethesda,Maryland, the United States. TheWHO Collaborating Centre hasprovided significant support tothe development of an agenda forglobal oral health research andDr Cohen played an importantrole in leading Forum sessions onoral health research at theannual meetings of the GlobalForum for Health Research,beginning in Tanzania, 2002.

Poul Erik Petersen is Chief of the Oral Health Programme at theWHO in Geneva. Prior to 2002, he was Professor in CommunityDentistry at the University of Copenhagen. He was elected Dean ofthe School of Dentistry, and was also Vice-Director of the School

of Public Health. His academic background encompassesdentistry, public health and sociology, combined with broad

international experience. Dr Petersen has worked in communityoral health research, enhancement of public health in universitiesworldwide, health systems development and in planning andimplementation of community health projects in an extensivenumber of industrialized countries, countries with economies intransition and in developing countries.

References1. Petersen PE. The World Oral Health Report 2003: Continuous

improvement of oral health in the 21st century the approach of theWHO Global Oral Health Programme. Community Dent Oral Epidemiol,2003, 31(Suppl 1):324

2. Petersen PE. Sociobehavioural risk factors in dental caries internationalperspectives. Community Dent Oral Epidemiol, 2005, 33 (In press)

3. Petersen PE, Yamamoto T. Improving the oral health of older people: theapproach of the WHO Global Oral Health Programme. Community DentOral Epidemiol, 2005, 33:8192

4. Tomar SL, Asma S. Smoking attributable periodontitis in the UnitedStates: findings from NHANES III. J Periodontol, 2000, 71:74351

5. Petersen PE, Ogawa H. Strengthening the prevention of periodontaldisease the WHO approach. J Periodontol, 2005, 76 (In press)

6. Stewart BW, Weihues P. World Cancer Report. Lyon: WHO InternationalAgency for Research on Cancer, 2003

7. Cohen L, Gift HC (Eds). Disease prevention and health promotion: Socio-dental sciences in action. Copenhagen: Munksgaard,1995

8. Petersen PE. Strengthening the prevention of HIV/AIDS related oraldisease. Community Dent Oral Epidemiol, 2004, 32:399401

9. Petersen PE, Kwan S. Evaluation of community-based oral healthpromotion and oral disease prevention WHO recommendations forimproved evidence in public health practices. Community Dent Health,2004, 21(Suppl 1): 31920

10. World Health Organization. World Report on Knowledge for BetterHealth. Geneva: WHO, 2004

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