Epidemiology

Although significant caries prevalence has been noted since the time of pre-Neolithic humans (10,000 bc ) with reported caries prevalence between 1.4% and 12.1% carious teeth, it was not until the fourteenth and fifteenth century when a sharp increase in caries prevalence was noted. This increase is often ascribed to a sucrose-civilization-caries trinity, with caries prevalence rising above 25%. The sucrose-civilization-caries trinity fails to describe the entire picture. At the same time as sucrose consumption increased, so did life expectancy. These observations hold true today as the world’s population continues to grow older, retaining teeth longer. Worldwide caries prevalence varies widely. Caries prevalence is generally reported as decayed-missing-filled teeth (DMFT) or decayed-missing-filled surfaces (DMFS). Caries prevalence estimates have been most frequently based on caries visibly (or occasionally also using radiographs) penetrating to the dento-enamel junction (the so-called D ₃ MF, dentinal caries diagnostic threshold). Dental caries and tooth loss were among the most common causes for rejection from service in the American Civil War and both World Wars. With the introduction of fluoride, both in the public water supply and toothpaste, a change in the worldwide ubiquitous nature of dental caries occurred. Nations and individuals with the financial resources available to invest in oral health have seen steep improvements in both DMFS and DMFT during the latter half of the twentieth century. As examples, mean DMFT in all age groups in the United States has decreased from 38.30 DMFS to 27.86 DMFS during the interval 1971 to 2005 with the most significant improvements in children younger than 12 years. Socio-economic status and level of education are key factors, both at the individual and national levels. A study in Scotland on 5-year-old children demonstrated a direct relationship between the number of untreated decayed surfaces and filled teeth with social deprivation. An analysis of data in the United States reveals that adults are 4 times more likely to be edentulous if they have not graduated from high school or live below the federal poverty level. Industrialized countries with high gross domestic product (GDP) have recognized a significant reduction in DMFT while countries with medium GDP per capita have the highest DMFT. Countries with the lowest GDP actually have the lowest DMFT in 12-year-olds, which may reflect a financial inability of families to purchase large amounts of processed sucrose-containing foods. Socio-economic conditions affect caries rates throughout the world but are not the only determinant of caries prevalence, as demonstrated by the prevalence of caries in 5- to 7-year-old children throughout Europe. Children’s caries prevalence ranged from less than 1 decayed and filled tooth in Ireland (east) to 5.5 decayed and filled teeth in Poland.

Epidemiologic study of caries distribution also reflects the change in population demographics. For instance, a 2005 report on caries in the United States revealed that 31% of adults older than 60 years had root caries (treated and restored) whereas the presence of root caries was less than 9% in those younger than 40. Although the number of adults older than 60 years had increased since 1988, so also did the number of adults older than 60 who retained their teeth. Significant progress has been achieved in preventing caries in the younger population but disease trends internationally indicate that the prevalence of caries in later adulthood remains significant, with 91% of dentate adults older than 20 years having caries experience. In addition to increases in root caries seen with aging, as populations have seen decreases in caries from the introduction of fluoride, the decrease in caries has not been evenly distributed over all surfaces of the teeth. Significant reductions in smooth-surface caries have been noted with the introduction of fluoride in both public water supply and toothpaste, but commensurate reductions in occlusal caries have not been seen as the result from fluoride. Additional preventive strategies are required.

All of the above trends and research reflect a bias toward surgical dental care where surgical intervention is required when caries reaches the dento-enamel junction. As subsequent articles describe, the dental caries process starts long before the cavitation is noted. Further, new criteria for detection (as discussed later) and new mechanisms of treatment mandate a “new” definition of caries. This “new” definition, reflected in all the articles of this issue, leads to the determination that the prevalence of caries disease may be much greater because the detection criteria were so crude in looking for signs of cavitation rather than the earlier signs of demineralization, which may be reversible and preventable with the current therapies. As stated by Pitts and colleagues in 2003, “where data are collected and reported at the D ₃ (caries into dentin only) threshold, the proportion of the population classified as ‘caries free’ conveys the mistaken impression that there is no disease at all present….” Internationally, epidemiologic assessments of caries prevalence are increasingly being undertaken at the D ₁ (caries into enamel and/or dentin threshold) to capture more of the true caries burden.

The issue with nomenclature

One of the recurring themes of this review is the need for recording of caries lesion severity and activity in our clinical charts as a starting point to risk assessment and monitoring of the impact of management strategies aiming to control the caries disease process and arrest or remineralize caries lesions. Thus, it would seem logical that the discussion should begin with a critical review of nomenclature and its importance in driving diagnostic and management strategies, including a definition of dental caries and a glossary of commonly used terms in cariology. As simple as this task seems to be, it is evident that one of the major barriers in the translation of caries detection, assessment, diagnosis, risk assessment, and management findings from the research domain to everyday clinical practice has been the confusion around the variety of terms clinical dentistry, education, and research choose to use when referring to dental caries. Warren wrote a very provocative editorial in the Journal of Operative Dentistry (1998) called “Coming to Terms with Terminology.” In it, he suggested that “accuracy of definition and use of terms is essential to clear thinking and communication.” In fact, the way we choose to communicate may reflect what we believe or understand regarding the caries process and hence, how we eventually choose to act. As stated so elegantly by the International Caries Detection and Assessment System (ICDAS) Coordinating Committee ( www.ICDAS.org ), “the future of research, practice, and education in cariology requires the development of an integrated definition of dental caries and uniform systems for measuring the caries process.” This is important not only for communications between clinicians to accurately take place, but it is also essential for accurate communication with patients. Several consensus development conferences, committees, and dental organizations have addressed this problem in recent years by debating and developing definitions which reflect up-to-date evidence in relation to various specific key aspects of caries. Our goal will be merely to highlight some of those, adding to them when necessary, to fuel this constructive discussion and clarification process. At the end of this article we have included a glossary of terms in cariology, with references to appropriate sources, starting with the most current glossary published by Longbottom and colleagues in 2009, which included representatives of the ICDAS, the European Organization for Caries Research (ORCA), the European Association of Dental Public Health (EADPH), and the American Dental Education Association (ADEA) Cariology Special Interest Group (SIG, now Section). This glossary has also been distributed internationally as an early part of the FDI World Dental Federation’s Global Caries Initiative, in response to the expressed need from the launch event for a common language to discuss modern cariology and preventive caries care. We also include, when appropriate, a discussion of terms commonly used in practice in North America that have in some instances hampered, and in other instances complicated the translation of best evidence into best practice.

Dental caries is the localized destruction of susceptible dental hard tissue by acidic by-products from bacterial fermentation of dietary carbohydrates. If allowed to progress the disease will result in the development of detectable changes in the tooth structure, or caries lesions, which initially are noncavitated (ie, macroscopically intact), but which eventually might progress to cavitation. Dental caries is not the “cavity” in the tooth, therefore, we cannot “remove all the caries.” The “medical model,” where the etiologic disease-driving agents are balanced against protective factors, in combination with risk assessment, offers the possibility of patient-centered disease prevention and management before there is irreversible damage done to the teeth. In 2001, the NIH Consensus Development Conference on Diagnosis and Management of Dental Caries Throughout Life identified the need to use new strategies “to provide enhanced access for those who suffer disproportionately from the disease; to provide improved detection, risk assessment, and diagnosis; and to create—and enhance use of—improved methods to arrest or reverse the noncavitated lesion while improving surgical management of the cavitated lesion.” If one does not start by differentiating between the caries disease process and the caries lesion, and focus only on the cavity, the need for disease management and remineralization is de-emphasized.

Furthermore, in dentistry the terms caries diagnosis and caries detection are very often used incorrectly and interchangeably. This usage is possibly due to the fact that the earlier stages of the disease process are virtually symptom-free, giving the perception by many, in the restorative dominated strategies of the past, that a diagnostic step is not needed, and that caries assessment becomes ultimately a question of detection, that is, whether caries lesions are present or not. Furthermore, the detection of frank cavitations in teeth requiring restoration is still considered by many as the main focus of caries treatment plans. By contrast, modern dental caries management should focus on the detection of earlier stages of the disease process (eg, noncavitated caries lesions) and the practitioner’s ability to diagnose whether those lesions are active, in addition to the identification and assessment of more severe lesions. An International Consensus Workshop on Caries Clinical Trials (ICW-CCT) was held in 2002 involving 95 participants from 23 countries. The final Consensus Statements represent international agreement on where the evidence leads in caries clinical trials, and in it important definitions of caries detection, assessment, and diagnosis were provided. To “diagnose” dental caries implies not only an objective determination of whether lesion(s) or disease is present at one point in time (ie, detection), and a characterization of how severe it is once it has been detected (ie, caries assessment) but, most importantly, assimilation by a human professional of all available data to decide if it is active or arrested. This diagnosis should be one of the guiding factors for caries risk assessment (risk of developing new lesions in the future ) and management (encompassing surgical and nonsurgical care and prevention), and decision making.

To apply these concepts we must start by deciding what we need to record in our clinical settings and what we should call each element. Based on current thinking, certainly a continuous measure of lesion severity and activity is required to help guide the diagnostic and monitoring steps. We further propose that we set as a goal the elimination in our daily lexicon of terms that are not diagnostic (eg, that the patient is “caries free” when a full examination of clean dry teeth with the benefit of lesion detection aids has not been performed, or “the patient has a decalcification”) or terms that merely reflect uncertainty in the diagnosis (eg, this is a “watch”). Without undertaking a diagnostic decision as to whether a lesion is active, be it progressing slowly or rapidly, or arrested, a logical clinical treatment decision cannot be made. Of utmost importance is to clearly define lesion thresholds and clinical conditions that separate surgical from nonsurgical interventions, as these have immediate treatment consequences. As an example, an international effort has created a new set of harmonized criteria building on best evidence, ICDAS ( www.ICDAS.org ), designed to be a unifying, predominantly visual set of criteria codes based on the characteristics of clean, dry teeth at both the enamel and dentin caries levels, which is capable of assessing both caries severity and activity, and has supporting histologic validation. For clarity, the shared aim of the ICDAS initiative, which drives the focus on agreed definitions for the “stages” of caries, are that ICDAS is: (a) a clinical visual caries scoring system for use in clinical practice, dental education, research, and epidemiology, (b) designed to lead to better-quality information to inform decisions about appropriate diagnosis, prognosis, and clinical management at both the individual and public health levels, and (c) the provider of a framework to support and enable personalized comprehensive caries management for improved long-term health outcomes.

The issue with nomenclature

One of the recurring themes of this review is the need for recording of caries lesion severity and activity in our clinical charts as a starting point to risk assessment and monitoring of the impact of management strategies aiming to control the caries disease process and arrest or remineralize caries lesions. Thus, it would seem logical that the discussion should begin with a critical review of nomenclature and its importance in driving diagnostic and management strategies, including a definition of dental caries and a glossary of commonly used terms in cariology. As simple as this task seems to be, it is evident that one of the major barriers in the translation of caries detection, assessment, diagnosis, risk assessment, and management findings from the research domain to everyday clinical practice has been the confusion around the variety of terms clinical dentistry, education, and research choose to use when referring to dental caries. Warren wrote a very provocative editorial in the Journal of Operative Dentistry (1998) called “Coming to Terms with Terminology.” In it, he suggested that “accuracy of definition and use of terms is essential to clear thinking and communication.” In fact, the way we choose to communicate may reflect what we believe or understand regarding the caries process and hence, how we eventually choose to act. As stated so elegantly by the International Caries Detection and Assessment System (ICDAS) Coordinating Committee ( www.ICDAS.org ), “the future of research, practice, and education in cariology requires the development of an integrated definition of dental caries and uniform systems for measuring the caries process.” This is important not only for communications between clinicians to accurately take place, but it is also essential for accurate communication with patients. Several consensus development conferences, committees, and dental organizations have addressed this problem in recent years by debating and developing definitions which reflect up-to-date evidence in relation to various specific key aspects of caries. Our goal will be merely to highlight some of those, adding to them when necessary, to fuel this constructive discussion and clarification process. At the end of this article we have included a glossary of terms in cariology, with references to appropriate sources, starting with the most current glossary published by Longbottom and colleagues in 2009, which included representatives of the ICDAS, the European Organization for Caries Research (ORCA), the European Association of Dental Public Health (EADPH), and the American Dental Education Association (ADEA) Cariology Special Interest Group (SIG, now Section). This glossary has also been distributed internationally as an early part of the FDI World Dental Federation’s Global Caries Initiative, in response to the expressed need from the launch event for a common language to discuss modern cariology and preventive caries care. We also include, when appropriate, a discussion of terms commonly used in practice in North America that have in some instances hampered, and in other instances complicated the translation of best evidence into best practice.

Dental caries is the localized destruction of susceptible dental hard tissue by acidic by-products from bacterial fermentation of dietary carbohydrates. If allowed to progress the disease will result in the development of detectable changes in the tooth structure, or caries lesions, which initially are noncavitated (ie, macroscopically intact), but which eventually might progress to cavitation. Dental caries is not the “cavity” in the tooth, therefore, we cannot “remove all the caries.” The “medical model,” where the etiologic disease-driving agents are balanced against protective factors, in combination with risk assessment, offers the possibility of patient-centered disease prevention and management before there is irreversible damage done to the teeth. In 2001, the NIH Consensus Development Conference on Diagnosis and Management of Dental Caries Throughout Life identified the need to use new strategies “to provide enhanced access for those who suffer disproportionately from the disease; to provide improved detection, risk assessment, and diagnosis; and to create—and enhance use of—improved methods to arrest or reverse the noncavitated lesion while improving surgical management of the cavitated lesion.” If one does not start by differentiating between the caries disease process and the caries lesion, and focus only on the cavity, the need for disease management and remineralization is de-emphasized.

Furthermore, in dentistry the terms caries diagnosis and caries detection are very often used incorrectly and interchangeably. This usage is possibly due to the fact that the earlier stages of the disease process are virtually symptom-free, giving the perception by many, in the restorative dominated strategies of the past, that a diagnostic step is not needed, and that caries assessment becomes ultimately a question of detection, that is, whether caries lesions are present or not. Furthermore, the detection of frank cavitations in teeth requiring restoration is still considered by many as the main focus of caries treatment plans. By contrast, modern dental caries management should focus on the detection of earlier stages of the disease process (eg, noncavitated caries lesions) and the practitioner’s ability to diagnose whether those lesions are active, in addition to the identification and assessment of more severe lesions. An International Consensus Workshop on Caries Clinical Trials (ICW-CCT) was held in 2002 involving 95 participants from 23 countries. The final Consensus Statements represent international agreement on where the evidence leads in caries clinical trials, and in it important definitions of caries detection, assessment, and diagnosis were provided. To “diagnose” dental caries implies not only an objective determination of whether lesion(s) or disease is present at one point in time (ie, detection), and a characterization of how severe it is once it has been detected (ie, caries assessment) but, most importantly, assimilation by a human professional of all available data to decide if it is active or arrested. This diagnosis should be one of the guiding factors for caries risk assessment (risk of developing new lesions in the future ) and management (encompassing surgical and nonsurgical care and prevention), and decision making.

To apply these concepts we must start by deciding what we need to record in our clinical settings and what we should call each element. Based on current thinking, certainly a continuous measure of lesion severity and activity is required to help guide the diagnostic and monitoring steps. We further propose that we set as a goal the elimination in our daily lexicon of terms that are not diagnostic (eg, that the patient is “caries free” when a full examination of clean dry teeth with the benefit of lesion detection aids has not been performed, or “the patient has a decalcification”) or terms that merely reflect uncertainty in the diagnosis (eg, this is a “watch”). Without undertaking a diagnostic decision as to whether a lesion is active, be it progressing slowly or rapidly, or arrested, a logical clinical treatment decision cannot be made. Of utmost importance is to clearly define lesion thresholds and clinical conditions that separate surgical from nonsurgical interventions, as these have immediate treatment consequences. As an example, an international effort has created a new set of harmonized criteria building on best evidence, ICDAS ( www.ICDAS.org ), designed to be a unifying, predominantly visual set of criteria codes based on the characteristics of clean, dry teeth at both the enamel and dentin caries levels, which is capable of assessing both caries severity and activity, and has supporting histologic validation. For clarity, the shared aim of the ICDAS initiative, which drives the focus on agreed definitions for the “stages” of caries, are that ICDAS is: (a) a clinical visual caries scoring system for use in clinical practice, dental education, research, and epidemiology, (b) designed to lead to better-quality information to inform decisions about appropriate diagnosis, prognosis, and clinical management at both the individual and public health levels, and (c) the provider of a framework to support and enable personalized comprehensive caries management for improved long-term health outcomes.

How about evidence-based dentistry and caries management?

The more traditional methods used for treating dental caries in practice today remain largely focused on the use of surgical tooth restoration alone (ie, restorative treatment), without consistent and individualized consideration of the underlying disease process for each patient. However, there is limited evidence that restorative care is effective in preventing or managing the dental caries disease process in the longer term. Clinical trials that provide clear evidence regarding the effectiveness of various interventions are, as yet, insufficient to permit the formulation of definitive guidelines for all cases. Thus, the clinician is left with two choices: (1) to continue using the outdated traditional restorative-only approach based on irreversible procedures, or (2) to use nondestructive risk-based caries management strategies using the best scientific evidence available. The latter choice is the one that the scientific and best practice clinical community has been encouraging the profession to embrace on a national and international level. Apart from fluorides and sealants, highest-quality evidence for other therapeutic caries management strategies is limited and contentious, and so dentists are encouraged not to incorporate these strategies as a replacement of higher-evidence strategies, but rather as supplements to them, if so desired. It is clear that the search for more effective and practical therapeutic approaches for the management of patients at risk of dental caries needs to continue, as does the search for stronger evidence for available treatment strategies/choices. As new evidence appears and is assessed, caries management strategies need to be able to evolve without decades of delay or the impairment of remuneration systems. In summary, the goal of ideal evidence-based patient care is to always select the therapeutic option that is supported by the highest level of evidence, and is practicable, feasible, and acceptable to the particular dentist-patient team. As we move forward in caries detection, assessment, and preventive management, we should continue to be guided by an evidence-based dentistry philosophy to plan care that results in doing the right thing , done right , at the right time for the right person. For this reason there is an increasing focus on patient-centered, personalized treatment plans, rather than a traditional mechanistic focus in which very different patients with different states of disease activity, caries risk, behaviors, and needs end up with very similar “automatic” care plans.

An overview and update of the caries disease process: prelude to the articles that follow

The etiology of caries disease is certainly multifactorial; however, the presence of an acidogenic bacterial biofilm is an absolute requirement for bacterial acid generation. We now know that dental caries disease is a transmissible infection that can be treated and even prevented before damage to dental hard tissue occurs. Recent research has challenged the concept of mutans streptococci and lactobacilli as the only important bacteria in caries disease. Article by Philip D. Marsh elsewhere in this issue examines the complexities of oral biofilms, where multiple bacterial species interact in a dynamic environment. In this environment, pH fluctuations result in large ecological changes, with an acidic environment driving selection of a cariogenic biofilm. However, an acidogenic biofilm is not the only factor that determines caries disease activity; environmental factors such as saliva, pellicle, diet, and hard tissue ultrastructure all are critical. Article by Hara and Zero elsewhere in this issue examines the role of each environmental factor in relation to caries disease. However, remineralization and demineralization of dental hard tissues depends on the dynamic chemistry within the oral cavity. This dynamic process of demineralization and remineralization occurs often throughout the day. As long as there is not a net mineral loss, there will be no permanent changes to the tooth and the process is considered to be in a healthy balanced state; this is reviewed in detail in the article by Carlos González-Cabezas elsewhere in this issue. However, when there is a net mineral loss from the tooth then a caries lesion will develop or an existing lesion will progress. Detecting and diagnosing caries lesions at the earliest possible stage are the key to chemically arresting and reversing the demineralization process, and are discussed in the article by Braga and colleagues elsewhere in this issue. If demineralization and remineralization occurs on all individuals, why do some people get caries lesions while others do not? This question is answered in the article by Young and Featherstone elsewhere in this issue by the caries balance/imbalance concept whereby pathologic caries risk factors and disease indicators are balanced against the protective factors. By evaluating the current caries risk of a patient, a clinician can determine what behaviors are increasing a patient’s risk for disease and disease progression, and take corrective action. These strategies lead to the development of evidence-based questionnaires or caries risk assessment forms to help determine caries risk and to suggest effective treatment options based on that risk. Using this new protocol it has become possible to develop a treatment plan designed to arrest dental caries by stopping demineralization, or reverse the caries disease process via remineralization, therefore reducing the chance of cavitation. This process has been called caries management by risk assessment (CAMBRA).

Article by Mathilde C. Peters elsewhere in this issue reviews suggestions for noninvasive repair of demineralized, precavitated (no-cavitated) lesions. The art of CAMBRA comes into play when the clinician must find ways to educate and motivate patients to change the pathologic behaviors identified by the caries risk assessment. While reading the article by Mathilde C. Peters elsewhere in this issue, keep in mind that there are many ways (rather than one correct way) and increasing numbers of products to assist in rebalancing the patient’s oral health. Article by Mathilde C. Peters elsewhere in this issue reviews what strategies are available for noninvasive demineralized tissue repair, while the article by Svante Twetman elsewhere in this issue reviews existing treatment protocols for the management of the disease process. Article by Edwina A.M. Kidd elsewhere in this issue reviews guidelines on when to restore surgically (compared with chemical remineralization). The evidence to support thresholds for partial or complete caries removal is presented. When continued removal of the remaining infected dentin is very likely to lead to pulp exposure on an asymptomatic vital tooth, the concept of sealing in active demineralization is discussed. In addition, the research demonstrating that stain does not correlate to bacterial invasion of the dentin is reviewed and the practice of removing all stain challenged. Article by Hien Ngo elsewhere in this issue presents practical clinical guidelines on how to do minimally invasive dentistry by taking advantage of bioactive restorative materials. In this article research showing internal remineralization underneath conventional glass ionomer suggests that this material constitutes a good method of treating the caries lesion chemically at the time of restoration. Article by Wang and Lussi elsewhere in this issue discusses the increasing problem of dental erosion (loss of tooth mineral from the surface due to acid sources other than bacteria). In contrast to caries disease, where the initial acid attack affects the enamel subsurface, in dental erosion stronger nonbacterial acids affect the surface layer directly.