Abstract
Continued ageing of the global population is expected to pose significant challenges to maintaining optimum lifelong health in individuals and populations. Oral health is an essential element of general health and quality of life throughout an individual's life course, yet it is often neglected in integrated approaches to general health promotion. Surveillance and monitoring systems are essential for developing oral health policy and strategy at both national and community levels. As major oral diseases, dental caries and periodontal diseases are core indicators for surveillance at every stage of life. In addition, oral mucosal lesions and masticatory function are essential indicators, especially in an ageing population. The assessment of risk factors such as tobacco use, alcohol consumption or dietary habits (e.g., sugar intake) is also important for oral disease prevention. Although surveillance is conducted through clinical examinations (normative assessments), this method is becoming more difficult to use because of high costs and human resource shortages, even in high-income countries. Alternative and less resource-demanding approaches, such as self-reported protocols, are therefore needed at the global level. The World Health Organization's (WHO) oral health surveillance and monitoring activities have evolved into the Oral Health STEPwise approach, which includes questionnaire surveys (Step 1) and clinical examinations (Step 2). Collaboration between international organisations such as the World Dental Federation (FDI), WHO and the International Association for Dental Research (IADR) is now needed to coordinate global oral health surveillance and monitoring systems.
Key words: Surveillance, monitoring, self-reported questionnaire, oral health examination, common risk factor, elderly people
Introduction
Oral health is an essential element of general health. It affects quality of life (QOL) throughout life, yet it is often neglected in integrated approaches to general health promotion1. Private and public clinicians and government personnel aim to reduce major oral diseases such as dental caries and periodontal diseases to improve and maintain QOL across communities. In the late twentieth century, modest reductions in the prevalence of dental caries were achieved globally in children. At the same time, efforts to extend the oral healthcare system for the elderly were uncommon. Continued ageing of the global population ageing throughout the twenty-first century is expected to pose significant challenges to maintaining optimum lifelong health both in individuals and populations.
This paper describes the FDI Oral Health for an Ageing Population Task Team's proposal of ‘Four Steps for Achieving Oral Health in an Ageing Society’. The four steps comprise needs assessment and monitoring (Step 1), determining the appropriate healthcare system and provisions (Step 2), reducing the global burden of oral diseases and disability based on human rights (Step 3) and contributing to and achieving a healthy ageing society (Step 4)2. In the ‘Surveillance and Monitoring’ section, we discuss core oral health indicators and related risk factors in relation to data collection and dissemination within appropriate oral healthcare monitoring systems.
Surveillance and monitoring
Oral health/disease surveillance is an ongoing activity involving the collection, analysis and interpretation of data to generate information for the prevention and control of oral diseases. As defined by U.S. Centers for Disease Control and Prevention, surveillance data are obtained not for research, but rather for action. That is, the collated information can be used in various ways to (i) evaluate the effectiveness of preventive and control interventions, (ii) monitor changes in health conditions, (iii) support oral health planning and the allocation of appropriate resources within the healthcare system, (iv) identify high-risk populations or areas to target interventions and (v) provide a valuable archive of disease activity for future reference3. To be effective, the collection of surveillance data must be standardised on a global basis and be relevant and available at local, regional and national levels.
Nationwide data on missing teeth, which is an important key indicator of oral health status in the elderly, have been reported from several countries around the world. The mean number of missing teeth varied between 9.4 (U.S., 1999–2004) and 26.6 (Malaysia, 2010) among persons aged 75 years or older over the past four decades. Before the year 2000, the mean number of missing teeth was 18 or more (Japan: 19.6–23.8, 1975–1987; U.S.: 19.0, 1988–1991; Norway: 18.1, 1996–1999)4, whereas after the year 2000, the mean number was slightly lower except in the case of Malaysia (U.S. 9.4, 1999–2004; Switzerland: 15.8, 2002; Japan: 14.0–18.2, 2005–2011; New Zealand: 13.7, 2009; UK: 14.9, 2009; Malaysia: 26.6, 2010; Germany: 16.6, 2014)4. Information about changes in the number of missing teeth among the elderly is scarce. The mean number of missing teeth decreased to about 10 both in the U.S. during the 16-year period from 1988 to 1991 and in Japan (Figure 1)5., 6., 7., 8., 9., 10., 11., 12. during the 23-year period from 1987 to 2012.
Figure 1.
Change in mean number of missing teeth (
) in persons aged ≥75 years (1975–1987) and 75–84 years (1993–2011) and percentage of persons with 20 or more teeth (
) in Japan's national oral health surveillances between 1975 and 2011, alongside oral health policy and actions during that period.
Japan follows a clear model of oral health surveillance, which is followed by development of oral health strategy with monitoring and evaluation of outcomes. Japan's National Oral Health Survey has been conducted every 6 years since 19575., 6., 7., 8., 9., 10., 11., 12.. Figure 1 shows that the percentage of people aged 75 years and older who had 20 or more teeth between 1975 and 2011 gradually increased from 6.3% in 1975 to 9.3% in 1993, with the oral health policies and actions carried out in that period also shown. In 1989, a national campaign, the 8020 Movement, was started by the Ministry of Health and Welfare, the Japan Dental Association and dental faculties/universities. The ‘8020’ refers to retaining at least 20 natural teeth by the age of 80. After this campaign was introduced, the percentage significantly increased from 15.5% in 1999 to 38.3% in 2011. Over the last two decades, public health leaders in Japan have integrated oral health goals into four legislative actions, the Health Promotion Law (2002), New Health Frontier Strategy (2007), Oral Health Promotion Bylaw (Prefecture basis) and Oral Health Promotion Law (2011), allowing access to governmental resources to address the oral health needs of the elderly.
Definitions of indicators
Indicators are quantifiable outcomes measured by surveillance activities that are used to monitor the morbidity and mortality of diseases in the population, as well as their risk factors and burden on populations. Oral cancer has a mortality indicator because it and its sequelae can be fatal. Other oral diseases, such as dental caries and periodontal diseases, have morbidity indicators, representing the frequency, severity and extent of disease. Common risk factors including tobacco use, alcohol consumption, lack of physical activity, quality of diet and nutrition and other risky behaviours are obtainable through national and local systems.
Oral examinations
More than 130 health administrations have conducted oral health surveys following the basic methods described by WHO since the first edition of the manual on oral health surveys was published in 1971. The following paragraphs describe the potential data elements and their justifications for surveillance in the elderly.
Number of teeth
The number of retained teeth has a significant association with the intake of several nutrients and vitamins as well as vegetables, fish and shellfish, and their consumption is significantly lower among subjects with fewer teeth13. Associations between the number of teeth and systemic diseases14 or mortality15 are also reported. Furthermore, according to many studies, elderly people with 20 or more teeth can maintain good physical and mental health and high QOL16.
Dental caries
Dental caries is the most prevalent chronic disease, and its monitoring reflects access to preventive and curative approaches in populations. In addition, treatment and other therapeutic strategies for dental caries affect the quantity and quality of saliva, and this further increases the risk of dental caries. Furthermore, there are social expectations to keep one's natural teeth and the physiological or pathological migration of epithelium on root surfaces from periodontal attachment loss that can occur with ageing carries a higher risk of dental caries, because cementum-covered root surfaces have a much higher potential for decalcification than enamel-covered tooth crowns.
The presence of natural teeth and prosthodontic replacements should be essential elements of the WHO Oral Health Survey Basic Methods 5th edition as applied for adults and seniors17.
Periodontal conditions
Many systematic reviews and consensus panels have addressed the relationships between periodontal infections and various systemic diseases18., 19.. Periodontitis imparts an increased risk of atherosclerotic cardiovascular disease (ACVD)19 and could be a risk factor for reduced kidney function in the elderly, although future studies should evaluate the contribution of periodontal therapy to reducing susceptibility to the development or progression of kidney disease20. Periodontitis could potentially exacerbate diabetes-induced hyperlipidemia, immune cell alterations and hinder tissue repair. A body of evidence supports various degrees of association between periodontitis and inflammatory responses, but there is insufficient evidence to label this association as causal, or to recommend interventions to reduce periodontal infections with the goal of preventing systemic diseases19.
Clinical periodontal assessments include bleeding on probing (BOP), pocket probing depth (PPD) and clinical attachment level (CAL). BOP is a surrogate for the presence of inflammation and is recorded by tooth site. PPD and CAL measure disease sequelae expressed as cumulative loss of supporting tissue around the tooth. The current edition of the WHO Oral Health Survey Basic Methods includes separate assessments of BOP and PPD for all teeth in the mouth17.
Oral mucosal lesions including oral cancer/precancer
Oral and pharyngeal cancers commonly occur in middle-aged and older individuals, although a larger than expected number of these malignancies located in the oropharynx have been reported in younger adults in recent years21. Because of relatively low prevalence and seriousness, the surveillance of oral and pharyngeal cancers requires a complex system of diagnostics, reporting and follow-up by tumour registries and cancer surveillance programs, such as those of the International Agency for Cancer Research, and not population surveys. Moreover, the detection of oral mucosal lesions [i.e., changes of the lesion to white, red (ulcers) or growths (tumours)], and referrals for follow-up have always been a focus in the WHO Oral Health Survey Basic Methods17. In addition, the surveillance of common risk factors with other noncommunicable diseases (NCDs) such as tobacco, alcohol and sexual risk behaviours are part of the WHO NCD approach. These and other behaviours can be introduced as items in self-reported questionnaires as recommended by the WHO Oral Health Survey Basic Methods.
Masticatory function
Deterioration of occlusal and masticatory functions affects nutrition. Measures of the number and type of occlusal contacts could be introduced into surveillance along with their impact on daily living and performances22., 23.. Another tool is the Eichner Index (EI)24 based on existing natural tooth contacts between the maxilla and mandible in the bilateral premolar and molar regions (tooth contact is defined as the presence of a natural tooth on the maxilla and corresponding mandible, including wisdom teeth, but excluding remaining roots or root caps). Four zones are recorded as follows: right molar region, right premolar region, left premolar region and left molar region. Class A represents contact in all four support zones, while Class B represents contact in one to three zones or the frontal region only. Class C represents complete absence of tooth contact. Physical fitness including lower extremity dynamic strength, agility and balance significantly correlates with occlusal supports measured by the EI in elderly people25. Moreover, the ability to perform daily living activities independently may be reduced26. Posterior occluding pairs score (i.e., the number of contacts between upper and lower paired teeth) is another option for measuring occlusal supports and is used for analyses between oral health condition, QOL and dietary/nutritional status27., 28.. Further epidemiological, biological and intervention studies are needed to explore the mechanism that starts with a decline in masticatory function and leads to sarcopenia. There may be a combination of several factors involved in the relationship between oral health and bone metabolism (osteopenia/osteoporosis)29 including depression30, cognitive decline31., 32., social factors and nutritional status in elderly people.
Denture status assesses a denture wearer's recovery of mastication ability. The assessment of denture status is easy to standardise, making it available for all dental clinicians in low-, middle- and high-income countries.
A 27-year follow-up study assessed the effects of missing teeth and highlighted the concept of shortened dental arches (SDAs). Thus, immediate replacement of missing teeth may not be necessary, especially in individuals with a free-end removable denture prosthesis (RDP), because RDPs are associated with a less favourable clinical course and long-term outcome33. Liang et al.34 concluded that subjects with extreme SDAs had reduced masticatory performance by around 30–40%, and distal-extension RDP compensated for this reduction only partially, by around 50%.
Self-assessment by questionnaire
The WHO Oral Health Surveys Basic Methods states that questionnaires should be used to collect data on health behaviours (e.g., frequency of dental visits), oral health behaviours (e.g., oral hygiene habits), dietary habits (e.g., sugar consumption and frequency of sugar intake), smoking and drinking17. Systematic information on the prevalence of risk factors is important in the planning of community-oriented oral disease prevention and oral health promotion programs. By merging clinical oral health and risk factor data into a common database, the oral health effects of socio-behavioural factors could be estimated and lead to the design of relevant intervention strategies. Consequently, oral health programs could be planned more effectively to meet the needs of specific populations. The collection of self-assessment data is less time-consuming and less costly and can enable health information to be collected in large-scale surveys even in developing countries17.
Self-reported assessments to obtain population characteristics, risk factors and diseases are acceptable tools for surveillance. Among the oral diseases, we can obtain information about behaviours, knowledge and attitudes via questionnaires. The U.S. Centers for Disease Control and Prevention and the American Academy of Periodontology have developed, tested and validated self-reported measures as a proxy measure of periodontal diseases. The questionnaire includes eight items, and it was concluded that the self-reported measures performed well in identifying adults with periodontitis in the US. In areas where the preferred clinical-based measures are unattainable, locally adapted variations of these self-reported measures may be an alternative for the surveillance of periodontitis35., 36., 37..
Another possibility for using self-assessment methods is to assess the self-reported number of remaining teeth; for example, the Behavior Risk Factors Surveillance System, which is a phone-based system, is used in the U.S.38. Self-reported number of remaining teeth provides reasonably valid data on the actual number of teeth within a population group39, and this method has been used in epidemiological studies40., 41..
Common risk factors
There are supporting and nonsupporting published articles on the association between periodontal diseases and diabetes mellitus19, kidney disease20 or bone metabolism29 and between tooth loss and insufficient nutritional intake13, physical fitness25., 26., cognitive function31., 32., depression30 and mortality15. The underlying link in these associations may be common risk factors such as tobacco use, diet, excessive alcohol consumption, stress and poor hygiene practices.
Diet and smoking are common causes of dental caries and periodontal disease, as well as many NCDs. Furthermore, the use of tobacco, excessive alcohol consumption and unprotected sexual contact are common factors shared by many cancers. The prevalence of human papillomavirus (HPV) infection could be contributing to the growing number of cases of HPV-positive oral squamous cell carcinoma. Oral HPV infection can be transmitted between people, with oral sex and open-mouthed kissing as probable routes for oral HPV infection42. Thus, a core group of modifiable risk factors is common to many chronic diseases and oral diseases (Figure 2)43., 44.. The greatest burden among all diseases is carried by disadvantaged and socially marginalised people.
Figure 2.
Common risk factors and noncommunicable diseases (Petersen PE, WHO).
Discussion
Some high-income countries such as the U.S. have developed their own surveillance systems adjusted for their populations45., 46.. However, oral health surveillance and monitoring systems at a global level require additional protocol adjustments and refinements to fulfil the primary mission of monitoring disease levels and trends, while also allowing meaningful and valid comparisons between countries and regions. Clinical examinations in surveys must be simple and standardised to ensure reliable data, and self-reported data should be objective, valid and reliable. WHO oral health survey methodology has a long history, and findings are reported to and are tabulated by the WHO Collaborating Center, Malmo University4. The protocol serves as a framework for defining protocols to assess the oral health status of adults and seniors as explained in their paper. Protocols should answer five basic questions: (i) what needs to be measured, (ii) in which populations, (iii) how frequently, (iv) using which instruments and (v) by whom.
In this study, we have proposed key elements for addressing the first question on what should be measured: (i) number of teeth, (ii) occlusal contacts, (iii) dental caries and (iv) periodontal status. In addition, based on the population of interest, it seems appropriate to insert measures of general health status, medical diagnosis and the use of drugs as part of these epidemiological evaluations.
Table 1 shows the core, expanded and optional indicators of oral health surveillance for the elderly according to the WHO STEPwise approach to chronic disease surveillance17. At step 1, the core indicators support the acquisition of information on the self-assessment of oral conditions, risk factors (tobacco use and alcohol consumption) and oral behaviour (oral health practices, measurements of diet, self-reported oral health and QOL and social position), all of which are based on standard WHO definitions17. The core indicators may be targeted as a minimum requirement for global (low-, middle- and high-income countries) use. The expanded indicators in Step 1 include number of teeth, occlusal supports and periodontal disease. An optional module could include self-reported medical history. Core indicators for Step 2 consist of clinical data collection17. Clinical data in addition to those obtained in Step 1 are relevant to most countries. Expanded indicators are more complex or time-consuming procedures that high- and middle-income countries may adopt depending on the situation. Step 3 comprises information obtained from biochemical analysis, such as measurement of Streptococcus mutans levels17, or any salivary or serum markers related to periodontal diseases. However, WHO does not recommend advanced oral health measurements for countries with limited resources17.
Table 1.
Core, expanded and optional indicators of oral health for elderly populations according to the WHO STEPwise approach to chronic disease surveillance
| Global use | High-, middle-income countries use | High-income countries use | |
|---|---|---|---|
|
Step 1 Self-reported |
Core
|
Expanded
|
Optional
|
|
Step 2 Clinical examinations |
|
|
|
|
Step 3 Biological measurements |
|
Defining useful approaches to monitor the oral health status of adults and seniors would require the concerted efforts of international agencies such as WHO and its regional offices, FDI and surveillance efforts at the country level. WHO has accumulated experience for the collection of oral health data at the country level to develop global oral health policies and strategies. Figure 3 shows a tentative scheme of the collaboration. ‘Clinical Examinations’ and/or ‘Self-reported Survey’, according to the WHO Oral Health STEPwise approach, are now recognised and conducted around the world.
Figure 3.
Tentative scheme of the oral health surveillance and monitoring system.
Conclusion
Oral health policies and strategies for the global ageing population are rare at both national and community levels. Surveillance and monitoring systems are essential for their development. We recommend adopting modified oral health indicators and risk/behavioural factors according to the WHO Oral Health STEPwise approach for surveillance of the elderly.
Acknowledgements
This article was made possible through an unrestricted grant from GC International AG. FDI World Dental Federation thanks GC International AG for their generous support and commitment towards the promotion of oral health for an ageing population.
Conflict of interest
The authors declare no conflict of interest.
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