Dental Caries

Dental caries develops by the localized dissolution of the tooth hard tissues, caused by acids that are produced by bacteria in the biofilms (dental plaque) on the teeth and eventually lead to "cavities." The biofilm consists of microorganisms, including the highly cariogenic mutans streptococci, and a matrix made up mainly of extracellular polysaccharides. The destructive acids are produced when fermentable carbohydrates (sugars) reach these biofilms, each episode resulting in tooth damage (attack). If this process does not occur frequently, then the natural capacity of the body (through saliva) to remineralize will prevent formation of a cavity. Thus, the main risk factors include presence of cariogenic biofilms and frequent consumption of fermentable carbohydrates. Exposure to fluorides in optimum concentrations reduces the risk, and normal saliva flow and saliva protective systems are also important to counteract the cariogenic factors.

Untreated caries can give rise to infection of the tooth pulp, which can spread to the supporting tissues and the jaws, culminating in advanced disease conditions that are often painful. For example, in Thailand, recent surveys of a sample of 12-year-old children revealed that 53 percent had suffered from pain or discomfort from teeth over the past year (Petersen and others 2001). The corresponding figures in China were 34 percent for 12-year-olds (Peng, Petersen, Fan, and others 1997) and 74 percent for adults (Petersen, Peng, and Tai 1997).

Tooth decay is a public health problem worldwide. According to the U.S. Surgeon General's report (U.S. Public Health Service 2000), dental caries is the single most common chronic childhood disease in the United States. Epidemiological data for almost 200 countries are available in the World Health Organization (WHO) Country/Area Profile Programme (CAPP) oral health database (http://www.whocollab.od.mah.se/index.html) (see table 38.1 for examples). Caries prevalence of permanent teeth is expressed by the decayed, missing, and filled teeth (DMFT) index (calculated by counting the number of DMFT of individuals and taking the mean for the group examined). One indicator age group used for international comparisons is 12-year-old children. The WHO oral health goal was to achieve three DMFT or fewer among 12-year-olds by 2000. According to the CAPP database, 70 percent of the countries had achieved three DMFT or fewer by 2001, representing 85 percent of the world population. Several developing economies, however, have reported a trend toward higher levels of dental caries.

Table 38.1

Mean DMFT and SiC Index of 12-Year-Olds for Some Countries, by Ascending Order of DMFT.

A detailed analysis of caries data for many countries, both industrial and developing, shows skewed distributions of the disease—that is, a proportion of a population of children showing a high or very high number of caries and the rest showing a low number of caries or none. Expressing caries prevalence as mean DMFT may, therefore, not accurately describe the disease level in populations with skewed distribution. The Significant Caries (SiC) Index was proposed to bring attention to those hidden high caries groups (Bratthall 2000). The SiC Index is calculated by simply taking the mean DMFT of the one-third of the group having the highest DMFT in a population (figure 38.1). Table 38.1 shows several countries having fewer than three mean DMFT but high SiC Index values, thus illustrating the hidden caries burden for children (Nishi and others 2002).

Figure 38.1

DMFT for 331 12-Year-Olds, West Kalimantan, Indonesia

Dental caries is found not only in children and young adults but also in all age groups. The elderly, in particular those with exposed tooth root surfaces, constitute a special risk population (Barmes 2000). A Swedish study reported DMFT values of 21.4 and 24.4 for 50- and 70-year-olds, respectively, indicating that nearly all teeth were affected in these age groups (Hugoson and others 1995). Thomson (2004), reviewing longitudinal studies of older adults (age 50+), found an incidence of root surface caries varying from 29 to 59 percent and concluded that older people are a caries-active group, experiencing new caries at a rate comparable to that of adolescents. With increasing numbers of people becoming 50 years of age or older in some developing countries, root surface caries may become a significant problem.

When we consider the global epidemiology of dental caries, the main patterns seem to be the following:

• Countries with low mean sugar consumption (less than 10 to 15 kilograms of sugar per person per year) generally have low mean caries prevalence.
• Countries with high mean sugar consumption (more than 20 to 25 kilograms of sugar per person per year) and without effective preventive programs generally have high mean caries prevalence.
• Countries with high mean sugar consumption (more than 20 to 25 kilograms of sugar per person per year) using effective preventive programs have been able to reduce the caries prevalence.

If we consider the prevalence of caries within a population, the main patterns seem to be as follows:

• Disadvantaged or poor population groups have higher dental caries experience than advantaged groups.
• Individuals with poor oral hygiene and frequent sugar intake are at increased risk.
• Individuals not exposed to fluorides—for example, from fluoridated water or toothpastes—are at increased risk of caries.
• Persons with individual risk factors, such as reduced saliva flow or exposed tooth root surfaces, or with certain general diseases are also at increased risk of caries.

Effectiveness of the Oral Health Programs

In countries with systematic national oral disease prevention programs, the total cumulative effect of these programs is reflected in the epidemiological figures demonstrating caries decline (table 38.2) and in the growing proportions of caries-free individuals. However, singling out the effects of specific activities or methods of programs is difficult because several program components often operate simultaneously. For example, in industrial countries, practically all individuals use fluoridated toothpaste, and removing this preventive measure from a group of individuals just to evaluate the effect of another fluoride program would be unethical. In addition, other factors affect caries reduction, such as changing lifestyles, changing patterns of sugar consumption, and improving living conditions.

Table 38.2

Declining Caries Experience in Some Countries.

The current trend in clinical health care and public health is to base recommendations on evidence derived from systematic reviews of the literature and critical assessment of the quality of results (U.S. Public Health Service 2000). The office of the U.S. Surgeon General (U.S. Public Health Service 2000) and the Swedish Council on Technology Assessment in Health Care (SBU 2002) are examples of entities that have attempted to determine the effectiveness in public health of evidence-based approaches and technologies.

Oral Health in America, the U.S. Surgeon General's report (U.S. Public Health Service 2000), reviewed experiences from the administration of fluorides. Primarily based on U.S. studies, the report had these conclusions:

• Strong evidence exists supporting the effectiveness of water fluoridation in preventing crown and root caries in children and adults.
• Strong evidence exists of the effectiveness of the school-based fluoride supplement (tablets) program. The program, with motivated supervising personnel, such as teachers, is recommended for children at high risk for caries.
• Evidence supports the effectiveness of school-based fluoride (0.2 percent sodium fluoride) mouth-rinsing programs conducted before 1985 (before the introduction of fluoride toothpastes) in preventing caries in children. The cost-effectiveness of this intervention is reduced with the current decline in prevalence of caries. It is recommended for use in high-risk children consistently over a period of time.

• Strong evidence supports the effectiveness of sealants in preventing pits and fissure caries. The report recommends that the programs be limited to high-risk children and high-risk teeth.
• Fluoride varnishes were not approved for use in the United States until 1994; hence, investigations are ongoing of the effectiveness of this intervention.

The Swedish Council on Technology Assessment in Health Care (SBU 2002) applied strict criteria of evidence of effectiveness; that is, the study had to be randomized and have a sample representing the total population. For permanent teeth, a three-year follow-up was necessary. The number of studies meeting all the criteria was not very high. Here are some conclusions of this review:

• Daily use of fluoridated toothpaste is an effective method to reduce caries in permanent teeth among children and adolescents. Daily, weekly, or biweekly fluoride mouth rinsing can reduce caries, but together with daily fluoride toothpaste use, the additional effects are not strong.
• Daily fluoride mouth rinsing can reduce root surface caries in the elderly, and professional application of fluoride varnish twice a year has a caries-reducing effect in permanent teeth among youth, as does the use of fluoridated toothpaste.
• Fissure sealants have a caries-reducing effect.

According to the SBU report, it was difficult to interpret the effect of programs aimed at reducing the intake of sugars or the effect of so-called sugar substitutes. Systematic evaluation of community preventive programs should be carried out in the future, particularly to help identify appropriate alternatives for developing countries.

Aspects of Treatment of Cavities and of Caries Disease

One has to differentiate between treatment of cavities and treatment of the disease process resulting in cavities. The normal treatment of a tooth with a cavity is a filling or, if the cavity is large, a crown. Large cavities may involve "root-fillings" or even extraction of the tooth. A variety of materials are used globally: composites, amalgam, gold, porcelain, and others. Options for replacing extracted teeth include removable prostheses, fixed bridges, or implants. The more complex treatments are costly, and no country has been able to afford to introduce systems in which all dental costs are covered by public funds. Moreover, a filling does not affect the disease process causing the cavities. Treatment must be directed against the causative factors (described earlier). For the individual case, several options are available in addition to the various fluoride programs mentioned: dietary counseling, sugar substitutes, antimicrobial agents to reduce plaque and specific bacteria, and the use of saliva-stimulating products.

In many developing countries, the lack of dental manpower means that carious teeth remain untreated. The ratio of dentists to population is particularly unfavorable in the African region compared with Western European countries. For instance, according to CAPP, the ratio is 1 to 1.2 million in Ethiopia, 1 to 225,000 in Mali, and 1 to 166,000 in Zambia, against about 1 to 1,000 in Scandinavian countries and 1 to 2,100 in the United Kingdom (see http://www.whocollab.od.mah.se/index.html). In India, the ratio is 1 to 27,000 in the urban areas but 1 to 300,000 in the rural areas (Shah 2001). Such ratios mean that neither dental caries disease nor the cavities will receive proper attention.

After taking into consideration the high costs for dental treatment and the lack of dentists, atraumatic restorative treatment (ART) was introduced. This approach requires only hand instruments rather than sophisticated electric dental drills, and trained dental auxiliaries can deliver ART. The public dental health services in South Africa adopted the approach as an appropriate and economic means of providing basic restorative care in certain communities. A randomized clinical trial conducted in Tanzania showed no statistically significant differences between the retention of occlusal amalgam (74 percent) and ART occlusal restorations (67 percent) after a six-year follow-up (1992–98) (Mandari, Frencken, and Van't Hof 2003). A potentially affordable treatment procedure that could prevent untreated carious teeth from being extracted, ART may have relevance to some middle-income countries, although the method is not realistic for most low-income countries, where sustainability of such programs would be low.

Periodontal Diseases: Chronic Gingivitis and Chronic Periodontitis

Gingivitis, the inflammation of gum tissue caused by bacteria accumulating in the plaque along the gingival margin, precedes chronic periodontitis. The more destructive form of periodontal disease, which breaks down the supporting tissues of the teeth, progressively leading to loosening of teeth and tooth loss, affects 10 to 15 percent of most adult populations (Papapanou 1999). Cigarette smoking and diabetes mellitus (with poorly controlled diabetes) are two major risk factors associated with periodontal disease and appear markedly to affect the initiation and progression of the disease (Genco 1996; Papapanou 1999).

In recent years there has been a growing awareness of the association between some systemic diseases and oral disease, especially periodontal diseases. For example, a national study in the United States found that the prevalence of diabetes mellitus in patients with periodontitis was significantly greater (twofold) than in nonperiodontal patients (Soskolne and Klinger 2001). Periodontal disease may be considered one of the complications of diabetes. Effective control of periodontal infection in diabetics appears to reduce the levels of advanced glycogen end-products in the serum.

Proper oral hygiene practices can prevent both gingivitis and advanced periodontal disease. All intervention programs leading to improved oral hygiene are instrumental in the control of periodontal disease and will reduce risk of future tooth loss. The school-based oral health educational programs previously discussed are effective in preventing gingivitis, but no community-based intervention program addresses periodontal disease, especially among adults. Tobacco cessation programs are also important in the prevention of periodontal diseases. Treatment of periodontal diseases consists of plaque removal, scaling, and sometimes surgery, plus motivation and instruction in oral hygiene. Dental hygienists can perform parts of the treatment program.

Oral Precancer and Cancer

The most frequent form of oral precancerous lesion, leukoplakia, appears as a white patch that cannot be rubbed off, typically in the buccal mucosa, lateral borders of the tongue, and floor of the mouth. The prevalence of leukoplakia among those 15 years old and above ranged from 1.1 percent in Cambodia, to 1.7 percent in Myanmar, to 3.6 percent in Sweden (Axell 1976; Ikeda and others 1995). Malignant transformation varies in different populations; nearly 5 percent of lesions are found to be malignant at first biopsy, and 5 percent develop into malignancy at a later stage. Erythroplakias appear as red patches and are less common but have a higher tendency (90 percent or more) than leukoplakias to transform into malignancies (Sudbo and Reith 2003).

Oral cancers affect about 300,000 people worldwide annually (Ferlay and others 2001) and often develop from oral precancerous lesions (Sudbo and Reith 2003). Early detection of oral precancerous lesions, notably oral leukoplakia and erythroplakia, could easily prevent the development of the disfiguring disease oral cancer and premature death.

Tobacco use in any form (smoking or chewing) and excessive alcohol consumption remain the primary risk factors in the development of these precancerous lesions ("Early Diagnosis and Prevention of Oral Cancer and Precancer" 1995; Reichart 2001). Factors such as local irritation, Candida albicans infection, and nutritional deficiencies are also associated with the presence of leukoplakia.

Screening populations and routine examination in dental and medical clinics for oral precancer and early cancer lesions would reduce the mortality, morbidity, and cost of treatment associated with oral cancers. Not all oral premalignancies show malignant transformation, and detection of these oral lesions by biopsies are straightforward, not requiring sophisticated equipment. Tobacco cessation programs aimed at younger and older age groups and control of excessive alcohol intake are definitely beneficial in the prevention of oral cancer.

Oral Manifestations of HIV/AIDS

The scarce epidemiological data available on oral manifestations of HIV in developing countries are difficult to interpret because these studies are not standardized (Holmes and Stephan 2002). In the study groups, the prevalence of oral lesions in Africa ranged from 15 percent to more than 90 percent of infected individuals; in India the prevalence was 72 percent; and in Thailand it was 82 percent. Reviews are available on the different studies performed on oral manifestations of HIV and AIDS (Naidoo and Chikte 1999; Patton and others 2002).

Candida infections, oral hairy leukoplakia, oral ulcers, and Kaposi's sarcoma are some of the common oral manifestations of HIV and AIDS. Notably, Kaposi's sarcomas were never detected in the Asian populations studied in India, Singapore, and Thailand but were seen in South African, Zambian, and Zimbabwean studies (Arendorf and others 1998; Hodgson 1997; Holmes and Stephan 2002; Lim and others 2001; Nittayananta and Chungpanich 1997; Ranganathan and others 2000). The presence of oral candidiasis and hairy leukoplakia alone or at the same time in an apparently healthy individual could be an early indicator of the undetected HIV infection progressing to AIDS. Those signs may be used as indicators during clinical examinations in developing countries where technology for laboratory tests is not available or is too expensive (Greenspan and Greenspan 2002; Holmes and Stephan 2002).

Noma (Cancrum oris)

Noma usually begins as a small ulcer of the gingiva and develops into a rapidly spreading gangrenous condition of the oral and facial tissues. Seen mainly in debilitated and malnourished children, it is disfiguring and deadly. The condition is reported in developing countries in several regions of the world, particularly in Sub-Saharan Africa (Enwonwu, Falkler, and Idigbe 2000; Naidoo and Chikte 2000; Petersen 2003). Noma disappeared from the industrial world in the 20th century except during World War II. In contrast, risk factors such as poverty, poor hygiene, and malnutrition, eventually in combination with infectious diseases such as HIV and AIDS, may have recently increased the prevalence of this disease in Sub-Saharan Africa (Enwonwu 1995; Naidoo and Chikte 2000). Most important, 90 percent of infected children die without having received any care.

Although the specific etiologic factors for noma are not known, poverty has been identified as the single most important risk indicator. Accordingly, improving the overall socioeconomic conditions can prevent noma. Public health approaches such as providing a high-protein diet, clean water, and sanitation and preventing communicable diseases such as diphtheria, dysentery, and tuberculosis would be needed for effective prevention of noma in Africa. Prognosis of noma is considerably better with timely administration of antibiotics.

Developmental Disorders

Developmental disorders involve teeth and the craniofacial structures. A few of these disorders are congenital diseases of the enamel or dentin; problems related to the number, size, or shape of teeth; and craniofacial birth defects, such as cleft lip and palate (CL/P). Among the most common congenital malformations seen in humans, cardiovascular malformation is ranked as the first and CL/P as the second. Unilateral CL/P occurs six times more frequently than the bilateral form. Females are more prone to get cleft palates, whereas cleft lip or CL/P is most common in males (U.S. Public Health Service 2000).

The incidence of CL/P differs from 0.18 to 3.74 per 1,000 live births, the highest incidence being seen in Native Americans at 3.74 per 1,000, closely followed by the Japanese at 3.36 per 1,000 live births. A fairly uniform incidence of 1 per 600 to 700 live births is reported among Europeans. Overall, the incidence rates appear high among Asians (0.82 to 3.36 per 1,000 live births), intermediate in Caucasians (0.9 to 2.69 per 1,000 live births), and often very low in black Africans (0.18 to 1.67 per 1,000 live births) (Hewson and McNamara 2000; Vanderas 1987; Wantia and Rettinger 2002).

The causes of CL/P are complex, involving multiple genetic and environmental risk factors. Not all cases of CL/P are inherited. A number of risk factors, such as folic acid deficiencies, maternal smoking, and maternal age, have been implicated in the formation of clefts (Wantia and Rettinger 2002).

Advanced surgery, specific prosthetic appliances, and orthodontic treatment can improve the quality of life for those born with clefts. However, such treatment is not accessible to children of several developing countries. Tobacco cessation programs aimed at pregnant mothers are essential in the prevention of CL/P.

Fluorosis of Teeth

Fluorosis of teeth develops during formation of teeth when children are young. Drinking water having more than 1.5 ppm of fluoride can give rise to enamel defects and discoloration of teeth, leading to endemic fluorosis in the population. These effects may vary from mild to severe. For example, in the Great Rift Valley area of East Africa, the ground water has high levels of fluoride, leading to high rates of dental fluorosis—nearly 90 percent in some parts of Kenya (Chibole 1987). Some individuals in developed countries can acquire fluorosis of teeth as a result of the widespread use of different forms of fluorides in the prevention of caries, though the degree of fluorosis often is mild compared with endemic fluorosis.

Defluoridation of the central water supplies is possible when naturally occurring fluoride is excessive in the drinking water. However, most developing countries do not have central water distribution systems, and the cost of defluoridation equipment and its maintenance can be high. WHO encourages effective and inexpensive methods that are useful for individual households or community defluoridation of drinking water (WHO 1994). Such methods exist, but a number of operational problems have been identified, requiring further initiatives in this field (Kloos and Haimanot 1999).

Common-Risk-Factor Intervention Programs

New research is pointing to associations between chronic oral infections—particularly periodontitis—and heart and lung diseases, stroke, osteoporosis, low birthweight, and premature births in addition to diabetes. Such findings strengthen WHO health promotion strategies that are based on the common-risk-factor approach, which controls essential risk factors that contribute to a large number of chronic diseases (Petersen 2003). Risk behaviors such as smoking; alcohol; diets rich in fats and sugars and low in fiber, fruit, and vegetables; stress; poor hygiene; and sedentary lifestyle are factors leading to such major chronic diseases as cardiovascular diseases, cancers, diabetes, obesity, osteoporosis, dental caries, and periodontal disease. These principal risk factors for major chronic diseases are often seen to cluster in the same individuals.

The WHO Global Oral Health Programme recommends the common-risk-factors approach (Petersen 2003), which implies development of integral activities in health promotion and disease prevention, involving health education, community empowerment, and legislative policy development. For example, such programs could aim at reducing the caries levels among preschool children and simultaneously improving general health. Promoting the reduction of sugar consumption would improve not only oral health but also general health through better quality of children's diet. Some prevention strategies for oral health, suitable for developing countries are outlined in table 38.3.

Table 38.3

Prevention Strategies for Oral Health.

Research and Future Actions

Several promising actions against factors causing the two major oral diseases, caries and periodontal disease, are ongoing: attempts to control the formation of the biofilm with its microflora are of high priority. One research line is to identify pathogenic bacteria and try to replace them with genetically modified, less pathogenic bacteria or to eradicate them by antibiotics or antiseptics. Preventing dental caries by a vaccine is not a new idea, and efforts continue. Among other ideas is the use of plantibodies (plant-derived therapeutic antibodies) or genetically modified bacteria, releasing components targeting pathogens. Functional foods, which include various elements in food, may be another future option to control oral diseases. Although pilot or small-scale studies seem promising, it will be several years before such methods can possibly be of use in populations because large clinical trials have not even started.

Saliva is believed to be usable as a diagnostic tool, providing noninvasive assessment of a number of oral and systemic diseases. Devices are being designed to identify in saliva various bacteria and their virulence factors, drugs, metabolic products, hormones, biomarkers for oral cancer, inflammatory mediators, and more. Future developments may result in other affordable and effective devices.

Continuous attempts are being made to assess the sociobehavioral factors in oral health and the information on risk factors. Caries risk assessment models are tested also for the individual cases. Through present knowledge, individuals in need of targeted actions can be identified. Another strong trend is to use evidence-based reviews. This type of research is, of course, not restricted to oral health. Several reviews have already been done, and a frequent conclusion is that the number of randomized clinical trials is limited, in particular for common clinical procedures. This trend will change as the quality of future oral health research improves, but not all research problems can be solved by such studies. Community-based participatory research is another approach that may be used to improve oral health studies (O'Fallon and Dearry 2002).

Within the management of dental diseases—in particular, caries—is the "minimally invasive dentistry" approach, which promotes the concept that large restorations (crowns, bridges) are not as necessary as believed. Risk assessment, preventive measures, and improved dental materials with good adhesion capacity are some of the several components in this approach.

Research in transfer of knowledge using the Internet or other electronic media is another strongly expanding area, from which developing countries should be able to benefit.

Cost-Effectiveness of Oral Health Care

Using the evidence available, the U.S. Surgeon General's report (U.S. Public Health Service 2000) and the report of the Swedish Council on Technology Assessment in Health Care (SBU 2002; see also Kallestal and others 2003) have attempted to determine the cost-effectiveness of oral health intervention programs from developed countries.

Among the findings in the U.S. report were the following:

• Water fluoridation costs about a dollar per person per year for water serving most individuals in the United States. Community water fluoridation is believed to be an effective and cost-effective caries preventive method.
• Economic analyses of community dental sealant programs suggest that they are cost-effective and may even provide cost savings when used in high-risk populations.

The Swedish report (SBU 2002), reviewing original studies on economic evaluation of caries prevention (a total of 17 selected from 1966 to 2003 MEDLINE and manual Internet searches), commented that no conclusion could be drawn owing to the low evidence values and contradictory results. This comment prompted the group to present its own calculation for cost-effectiveness based on Swedish caries prevalence and charges used in Swedish dental care. The group found that the cost-effectiveness for fluoridated toothpaste is extremely good (cost per prevented DMFT very low), which, of course, is not surprising, given the significant caries-reducing results in combination with low cost for society.

No clear correlation appears to exist between caries experience and health care investment for individual countries. Some countries with the lowest health care expenditures have values for caries experience (DMFT) that are similar to or even lower than those countries having the highest expenditures on health (figure 38.2). Those low-income countries often have low per capita sugar consumption and, therefore, do not need to install expensive measures for treatment or prevention.

Figure 38.2

DMFT as Related to Health Care Expenditure per Capita for 12-Year-Olds in 149 Countries

It may seem surprising that so few studies are available regarding the cost-effectiveness of caries prevention, or of any other oral disease. In a critical review article, Schwarz (1998) analyzed the issue. He wrote, "Several decades after considerable improvements in the oral disease situation were documented in Scandinavia, doubts are still expressed about whether preventive measures are cost-effective." In addition, he recommended that four elements be considered when a preventive effect was evaluated: the definition of prevention, the practical perception of effective prevention, the appropriateness of traditional cost-effectiveness analysis, and the time factor. He pointed out that "caries prevention is not uniformly defined by the profession, that dental research is casting doubt on the effectiveness of traditionally accepted preventive measures, that political pressures on health care are motivated by economic pressures." Finally, he stated that traditional cost-benefit and cost-effectiveness analyses have not been able to help the decision makers choose wisely and that the time perspective for the real effects of prevention lies beyond the interests of decision makers.

However, without proper prevention, the alternative strategy is restorative dentistry—that is, to make fillings, crowns, and dentures. Is this a feasible alternative for developing countries? Yee and Sheiham (2003) give some examples: In Nepal, a simple amalgam filling would cost about US$4, which does not include the many additional expenses for impoverished rural families, who may have to travel by bus or walk for a day or two to get to the clinic. The total expenses incurred, including dental fees, meals, and lodging but not including lost wages, would amount to US$12, an enormous sum considering the average Nepalese's earning of US$0.75 per day, and it is enough to buy food for a month. Yee and Sheiham conclude that treating caries with the traditional method of restorative dentistry is beyond the financial capabilities of most low-income nations because three-quarters of these countries do not even have sufficient resources to finance an essential package of health care services for their children. Yee and Sheiham (2003) estimate that treating dental caries by the traditional amalgam restorative dentistry in the permanent dentition of the child population would cost about US$2,000 for 1,000 children of mixed ages from 6 to 18 years, which would require financial resources beyond the capabilities of low-income nations. Hence, they propose a public health and health promotion approach to reduce caries burden instead of the restorative approach.

Although several studies evaluating the effectiveness of intervention and oral health promotion programs in developing countries are becoming available (Estupinan-Day and others 2001; Pakhomov and others 1995; Petersen and others 2004), a definite need exists for further cost-effectiveness analysis on such programs, which should be addressed in the future. It would also be useful if studies were commenced on intervention programs using the common-risk approach suggested by WHO (Petersen 2003).

Conclusions

Dental caries and periodontal diseases are the most known oral diseases, but other conditions can strongly and negatively influence the quality of life. Effective programs to reduce the burden of oral diseases—in particular, caries—are available in principle, but to run these programs in developing countries, new approaches are needed. The WHO strategy of identifying common risk factors seems promising for health promotion. In broad terms, the most important challenges for oral health in the 21st century relate to the transfer of knowledge and experiences in preventive oral care to the poor and disadvantaged population groups in both developing and developed countries.

Acknowledgments

We acknowledge with great appreciation comments and suggestions from Dr. Lois Cohen, Dr. Kevin Hardwick, Dr. Jeanne C. Sinkford, and Thomas Wall. Sir George Alleyne, our editor, is to be congratulated for his constructive ideas and patience.

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