Advances in Dental Research

Despite impressive worldwide improvements in oral health, inequalities in oral health status among and within countries remain a daunting public health challenge. Oral health inequalities arise from a complex web of health determinants, including social, behavioral, economic, genetic, environmental, and health system factors. Eliminating these inequalities cannot be accomplished in isolation of oral health from overall health, or without recognizing that oral health is influenced at multiple individual, family, community, and health systems levels. For several reasons, this is an opportune time for global efforts targeted at reducing oral health inequalities. Global health is increasingly viewed not just as a humanitarian obligation, but also as a vehicle for health diplomacy and part of the broader mission to reduce poverty, build stronger economies, and strengthen global security. Despite the global economic recession, there are trends that portend well for support of global health efforts: increased globalization of research and development, growing investment from private philanthropy, an absolute growth of spending in research and innovation, and an enhanced interest in global health among young people. More systematic and far-reaching efforts will be required to address oral health inequalities through the engagement of oral health funders and sponsors of research, with partners from multiple public and private sectors. The oral health community must be “at the table” with other health disciplines and create opportunities for eliminating inequalities through collaborations that can harness both the intellectual and financial resources of multiple sectors and institutions.

The IADR Global Oral Health Inequalities Task Group on Dental Caries has synthesized current evidence and opinion to identify a five-year implementation and research agenda which should lead to improvements in global oral health, with particular reference to the implementation of current best evidence as well as integrated action to reduce caries and health inequalities between and within countries. The Group determined that research should: integrate health and oral health wherever possible, using common risk factors; be able to respond to and influence international developments in health, healthcare, and health payment systems as well as dental prevention and materials; and exploit the potential for novel funding partnerships with industry and foundations. More effective communication between and among the basic science, clinical science, and health promotion/public health research communities is needed. Translation of research into policy and practice should be a priority for all. Both community and individual interventions need tailoring to achieve a more equal and person-centered preventive focus and reduce any social gradient in health. Recommendations are made for both clinical and public health implementation of existing research and for caries-related research agendas in clinical science, health promotion/public health, and basic science.

Periodontal diseases constitute one of the major global oral health burdens, and periodontitis remains a major cause of tooth loss in adults worldwide. The World Health Organization recently reported that severe periodontitis exists in 5-20% of adult populations, and most children and adolescents exhibit signs of gingivitis. Likely reasons to account for these prevalent diseases include genetic, epigenetic, and environmental risk factors, as well as individual and socio-economic determinants. Currently, there are fundamental gaps in knowledge of such fundamental issues as the mechanisms of initiation and progression of periodontal diseases, which are undefined; inability to identify high-risk forms of gingivitis that progress to periodontitis; lack of evidence on how to prevent the diseases effectively; inability to detect disease activity and predict treatment efficacy; and limited information on the effects of integration of periodontal health as a part of the health care program designed to promote general health and prevent chronic diseases. In the present report, 12 basic, translational, and applied research areas have been proposed to address the issue of global periodontal health inequality. We believe that the oral health burden caused by periodontal diseases could be relieved significantly in the near future through an effective global collaboration.

Four oral mucosal infections were identified as Global Oral Health Priorities: (a) HIV and associated viral, bacterial, and fungal infections; (b) tuberculosis; (c) NOMA; and (d) sexually transmitted diseases. Huge global inequalities exist in all four. HIV-associated infections constitute the major challenge. Oral manifestations of AIDS can be specifically diagnostic, indicating a significant role for dentists within health teams. The World Workshops in Oral Health & Disease in AIDS have identified a research program, elements of which are being implemented. Data on oral mucosal involvement in tuberculosis, syphilis, and gonorrhea are incomplete in developed countries and virtually non-existent in low- and middle-income countries, indicating the need for further epidemiological studies. Oral manifestations of tuberculosis and sexually transmitted diseases are largely associated with general health, so action programs should be integrated with agencies treating the systemic diseases. NOMA is very much in the oral health domain. It is a preventable disease associated with malnutrition and unidentified bacterial factors. Prevalence is probably grossly overestimated at present; but nevertheless it constitutes a challenge to the profession, especially in the NOMA belt. Current treatment is surgical, but plans for its eradication should be achievable. The global oral health community, especially the IADR, has a major role to play.

The mouth and oropharynx are among the ten most common sites affected by cancer worldwide, but global incidence varies widely. Five-year survival rates exceed 50% in only the best treatment centers. Causes are predominantly lifestyle-related: Tobacco, areca nut, alcohol, poor diet, viral infections, and pollution are all important etiological factors. Oral cancer is a disease of the poor and dispossessed, and reducing social inequalities requires national policies co-ordinated with wider health and social initiatives – the common risk factor approach: control of the environment; safe water; adequate food; public and professional education about early signs and symptoms; early diagnosis and intervention; evidence-based treatments appropriate to available resources; and thoughtful rehabilitation and palliative care. Reductions in inequalities, both within and between countries, are more likely to accrue from the application of existing knowledge in a whole-of-society approach. Basic research aimed at determining individual predisposition and acquired genetic determinants of carcinogenesis and tumor progression, thus allowing for targeted therapies, should be pursued opportunistically.

The birth prevalence of orofacial clefts, one of the most common congenital anomalies, is approximately one in 700 live births, but varies with geography, ethnicity, and socio-economic status. There is a variation in infant mortality and access to care both between and within countries, so some clefts remain unrepaired into adulthood. Quality of care also varies, and even among repaired clefts there is residual deformity and morbidity that significantly affects some children. The two major issues in attempts to address these inequalities are (a) etiology/possibilities for prevention and (b) management and quality of care. For prevention, collaborative research efforts are required in developing countries, in line with the WHO approach to implement the recommendations of the 2008 Millennium Development Goals (www.un.org/millenniumgoals). This includes the “common risk factor” approach, which analyzes biological and social determinants of health alongside other chronic health problems such as diabetes and obesity, as outlined in the Marmot Health inequalities review (2008) (www.ucl.ac.uk/gheg/marmotreview). Simultaneously, orofacial cleft research should involve clinical researchers to identify inequalities in access to treatment and identify the best interventions for minimizing mortality and residual deformity. The future research agenda also requires engagement with implementation science to get research findings into practice.

This paper reviews the shortcomings of present approaches to reduce oral diseases and inequalities, details the importance of social determinants, and links that to research needs and policies on implementation of strategies to reduce oral health inequalities. Inequalities in health are not narrowing. Attention is therefore being directed at determinants of major health conditions and the extent to which those common determinants vary within, between, and among groups, because if inequalities in health vary across groups, then so must underlying causes. Tackling inequalities in health requires strategies tailored to determinants and needs of each group along the social gradient. Approaches focusing mainly on downstream lifestyle and behavioral factors have limited success in reducing health inequalities. They fail to address social determinants, for changing people’s behaviors requires changing their environment. There is a dearth of oral health research on social determinants that cause health-compromising behaviors and on risk factors common to some chronic diseases. The gap between what is known and implemented by other health disciplines and the dental fraternity needs addressing. To re-orient oral health research, practice, and policy toward a ‘social determinants’ model, a closer collaboration between and integration of dental and general health research is needed. Here, we suggest a research agenda that should lead to reductions in global inequalities in oral health.