Understanding Measurement of Dental Diseases and Research Participation in Practice Set-Up

A general understanding of the measurement of dental diseases can help practitioners in the process of assessing the patient’s future risk of disease. More importantly, as clinical studies shift from the traditional academic setting to practice-based networks, practitioners might play a more significant role in research. An important issue in oral health disease management in the future will be the standardization of clinical criteria and the development of alternative mechanisms of data collection for epidemiologic purposes.

Determination of disease status requires precise judgment. The process of disease determination, referred to as “diagnosis” , requires a sound and up-to-date understanding of the nature of the disease that is being measured. As our scientific understanding of the various disease processes increase, clearer definitions, precise diagnostic criteria, appropriate therapeutic rationale, and more effective treatment options are conceived and operationalized. Clinicians make diagnostic judgments and treatment decisions based on the consideration of a predefined set of signs and symptoms, and usually one or more diagnostic tests based on scientific evidence and experience. After diagnoses are made and clear-cut treatment options prescribed, treatment options may need to be modified or selected from several alternative options based on factors not directly related to the disease, such as including sociodemographic characteristics of the patient, societal consensus, and available resources, as well as the severity and prevalence of the disease in the community. As much as this decision should be based on scientific evidence, it may also be subjective and vary by individual cases. Measuring a disease level in a population such as in epidemiologic studies, on the other hand, requires a more objective and standardized criteria, so the results can be compared over time, place, and between different populations.

Understanding of oral diseases has increased vastly over the past 150 years. During this period, significant technical advances have been made and substantial changes in disease distribution have been observed . These changes need to be incorporated in measurement of the disease and include new disease definitions, new diagnostic criteria, adoption of new technology, and determination of disease activity . This article describes the measurement issues pertaining to three important dental diseases—dental caries, periodontal disease, and dental fluorosis—and expounds the available resources for oral health data and how practicing clinicians can contribute to research using newly developing networks.

Measuring dental caries

Dental caries is the destruction of the dental hard tissue resulting from localized acidic by-products from bacterial fermentation of dietary carbohydrates . For a long time, the term dental caries has been used synonymously with frank cavities, despite early precavitated carious lesions on enamel being recognized in the late nineteenth century . Currently, dental caries is understood to involve a continuum of disease states, ranging from initial subclinical, subsurface changes to later stages of clinically detectable lesions manifesting as small cavities that may have significant dentinal involvement at still later stages .

Caries measurement criteria and clinical implication

In 2004, the International Consensus Workshop on Caries Clinical Trials (ICW-CCT) clarified the meaning of caries diagnosis (which implies a human professional summation of all available data), and further differentiated it to lesion detection (which implies some objective method of determining whether or not disease is present) and lesion assessment (which aims to characterize or monitor a lesion once it has been detected) . From here on, this article will follow the ICW-CCT terminology.

Dental clinicians have been trained to diagnose, detect, and treat “cavities” with the focus of stopping further progression of disease and restoring damaged hard tissue and functionality at the postcavitated phase. Similarly, epidemiologic studies have also measured and reported prevalence of dental caries in population groups using presence of “cavity” as a measurement . This basis of clinical dental care, starting in the early and mid twentieth century, was initiated and sustained in industrialized countries that experienced very high levels of prevalence and incidence of dental caries. This seemed a reasonable approach, considering the ubiquity of severe disease (cavities) and the relatively fast progression of a caries lesion to form a cavity and finally involve the pulp tissue (as is the situation in developing countries, and also in high-risk groups in developed countries today).

With the introduction of preventive measures, mainly water fluoridation, most industrialized countries have experienced substantial declines in caries prevalence and severity . With low prevalence and slow progression of caries, it is seen that precavitated caries (reversible condition) lesions are more prevalent than cavitated lesions (irreversible condition) in these countries today . Therefore, it seems appropriate to also develop criteria to identify caries at earlier stages (precavitated), compared with the traditional overt and irreversible lesion only . Current consensus is to detect dental caries at the precavitated stages . The stage at which caries is measured significantly affects epidemiologic assessments of disease prevalence and treatment need in a population, as well as dental clinicians’ practice decisions .

For example, if only cavitated lesions are counted, and prevalence of precavitated lesions is high, then the reported total prevalence (and incidence) of caries would be low and any preventive policy based on such estimates will ignore preventing precavitated lesions from transforming to the cavitated stages. Alternatively, if both precavitated and cavitated lesions are counted, a correct prevalence and incidence estimate will be obtained for “total caries burden,” and a policy based on this estimate will presumably address the issue better. However, because preventive measures (primary, secondary, and tertiary) for precavitated and cavitated lesions are substantially different in conceptualization, planning, resource allocation, resource use, and measurement techniques, clear diagnostic criteria distinguishing these two formats of disease should be applied, and total caries burden should also be categorized by precavitated and cavitated lesion category.

An important issue in caries measurement is the lack of coherent and standardized criteria applicable universally. This leads to miscommunications among clinicians, educators, and researchers, and difficulties in interpretability of data from different studies manifesting as apparently conflicting results from studies and reports. A recent review identified 29 different caries assessment criteria-systems being used and found substantial variability in disease processes measured and ambiguity of disease descriptions . One recent development that addresses this issue is a new caries detection system: the International Caries Detection and Assessment System (ICDAS) . The ICDAS classifies the caries process in fives stages, ranging from first visible signs of caries in enamel to extensive cavity with visible dentin, that reflect different steps in the development of dental caries in tooth surfaces and the different levels of care that would be required, ranging from preventive to operative care. The ICDAS aims to provide a flexible yet consistent platform in caries measurement for clinicians and researchers to choose the stage of caries process and other features that fit the needs of their research or practice. This new system has been field tested for validity and reliability .

Accuracy of caries measurement

One important source of potential error in measuring precavitated and cavitated lesion is diagnostic (or detection) accuracy. When caries are measured simply as “cavity” versus “no cavity,” diagnostic accuracy of visual examination was estimated in a systematic review as having a sensitivity of 63% and specificity of 89% . Use of a sharp explorer did not seem to add substantial accuracy in diagnosis of caries , while visual-tactile examination has a sensitivity of 92% . Accuracy of detecting caries at an early stage (eg, precavitated or early or late cavitated) reportedly has a level of sensitivity (66%) similar to that of determining “cavity,” but a specificity of only 69% .

The level of specificity indicates the level of false positive diagnoses: for example, 95% specificity means 5% false positive. Given same levels of sensitivity and specificity, positive and negative predictive values change depending on the prevalence of disease in a population . As the prevalence of disease declines, a level of false positive diagnoses translates to a lower level of positive predictive value; in other words, a smaller proportion of individuals who are diagnosed as diseased may actually have the disease, which may result in over-treatments and unnecessary anxiety experienced by the patient ( Table 1 ). This has a direct bearing on how caries is defined and measured in epidemiologic studies (as mentioned above), and research data should be interpreted keeping this source of variation in mind.

Table 1
Illustration of disease prevalence on PPV of a diagnostic test (Sensitivity = 66%, Specificity = 95%)
Prevalence PPV NPV
1% 12% >99%
5% 41% 98%
10% 59% 96%
20% 81% 89%
50% 93% 74%

Abbreviations: PPV, positive predictive value, or the probability that a person who has a positive test result actually has the disease; NPV, negative predictive value, or the probability that a person who has a negative test result actually is healthy (no disease).

Caries measurement and decayed-missing-filled index

The presence of dental caries is summarized as the decayed-missing-filled (DMF) index at an individual or at a group of individuals, such as a community, state, and country. The DMF index is, by definition, a count that can range from 0 up to 32 when applied at the tooth level (ie, DMFT) or from 0 up to 128 when applied to the tooth surface level (ie, DMFS). Since its first introduction in 1938 , the DMF index has been used universally as a dental caries summary measure. Details of the DMF index, especially its limitations, are well summarized by Burt and Eklund . As caries measurement moves toward detection of precavitated or early lesions, there arise two important additional issues with the DMF index: (1) it may not be easily usable to determine restorative or preventive treatment need, and (2) DMF indices from different studies may not be comparable unless detection criteria and examination methods (eg, use of an explorer) are clearly described .

The DMF index score indicates a total caries experience of an individual and it gives equal weight to decayed, missing because of caries, filled tooth, or tooth surface. Hence, it does not differentiate untreated decay from a well-restored tooth . Also, applying DMF scores to DMFS has raised concerns of overestimation of the number of tooth surfaces missing because of caries. However, using only DF scores underestimates the disease status . Analytical methods to adjust overestimation of disease by the M-component have been proposed . Despite the criticism of its limitations, the DMF index will continue to be used until the criteria for dental caries status is defined more clearly. These limitations underscore the need for a more agreed upon description of caries measurement criteria and examination methods .

Measuring periodontal disease

The term “periodontal disease” has been historically used to describe diseases of gingiva and periodontal ligament. Gingivitis is an inflammation of the gingival tissues where the junctional epithelium, although affected by the disease, remains attached to the tooth at its original level. Periodontitis is also an inflammatory process characterized by clinical attachment loss, alveolar bone loss, and periodontal pockets with or without gingival inflammation . Periodontitis may or may not result as a progression of gingivitis, but not all sites affected by gingivitis transition to periodontitis. Periodontal disease is highly prevalent in older adults in the United States, affecting 34% of Americans 30 years or older , and remains to be a major cause of tooth loss in adults both in the United States and throughout the world .

Gingival disease measurement

Introduced in the 1963, the Gingival Index (GI) of Löe and Silness is still used. The GI scores the gingiva on an ordinal scale of 0 to 3 by probing on the mesial, distal, lingual, and buccal surfaces of the teeth. The GI does not take into consideration profound changes in the periodontal tissues and is sensitive enough to capture differences between groups with incipient and severe gingivitis. However, in the mid ranges of gingivitis, its validity is questionable.

Bleeding after probing has become a standard measure of gingivitis in studies, because visual evaluations of inflammation are subjective and conducive to bias. However, the validity of the probing has also been questioned as the pressure applied by different examiners during probing can vary drastically, ranging from 3 g to 130 g depending on the examiner . Gingival probing is not recommended for screenings, surveys, or surveillance because these programs do not require this level of sensitivity, there are concerns about infection control, and bleeding indexes have vague discriminatory power in field studies .

Periodontal disease measurement

Initial epidemiologic studies of periodontal diseases used radiographic assessments of alveolar bone loss . However, the use of radiographs requires strict standardization of radiographic techniques across clinics and research centers for appropriate comparison of resultant data. Such standardization is difficult to achieve and concerns were raised over ethical issues of exposing participants with radiation. These issues led to the development of more convenient indexes. In the 1960s, the Periodontal Index (PI) introduced by Russell was perceived as an ideal field index and used in epidemiologic studies. The United States Public Health Service agencies measured periodontal disease status in their surveillance activities using the PI until the 1980s. Current understanding of periodontal disease has led to identification of certain deficiencies of the PI. For example, the PI did not include an assessment of clinical attachment loss and graded all pockets of 3 mm or larger equally, combining both gingivitis and periodontitis on the same scale. During the late 1970s there was consensus among many researchers that accurate disease surveillance should include a site-specific measuring as well as clinical attachment loss to represent periodontal disease properly.

The Community Periodontal Index of Treatment Needs (CPITN), introduced by the World Health Organization (WHO) in 1983 , included periodontal probing on 10 index teeth. The CPITN has been used as a mechanism to assess treatment needs in most countries throughout the world . Methodologic and theoretic issues have been raised against the CPITN. For example, the CPITN treats gingivitis and periodontitis in the same scale following the paradigm that periodontitis is merely an extension of gingivitis. As a result, the CPITN is not indicated as a tool to assess prevalence of periodontal disease .

Carlos and colleagues introduced the Extent and Severity Index (ESI) in 1986 , attempting to summarize both the extent and the average severity of disease within the group being studied. The ESI uses estimates of attachment level from probing measurements of 14 sites in a quadrant in the maxillary arch and 14 in the contralateral mandibular arch. The ESI is not really an index but a method of summarizing data that permits comparisons among different epidemiologic studies.

A contentious issue that has dogged periodontal disease measurement has been which teeth should be measured for obtaining a true disease burden estimate by maximizing examination efficiency. The ideal solution would be to measure the entire periodontium, checking every available periodontal tissue point. However, it was recognized very early that such an exercise would be very inefficient and consume enormous time and resources, making the examination prohibitively expensive to conduct. Therefore, interest has always been keen to find a way to measure periodontal disease accurately with a resource-conserving paradigm.

In 1951, Ramfjord proposed the Periodontal Disease Index (PDI), which was perhaps a more sensitive version of the PI . Because the PDI is a composite index, it had the same weaknesses as the PI. As a result, the PDI is not longer used. However, Ramfjord’s legacy includes the indirect method of measuring clinical attachment loss he described and the partial mouth recording or “Ramfjord teeth,” a set of six teeth presumed to the represent the entire mouth during examination (teeth numbers: 3, 9, 12, 19, 25, and 28). Whether the assumption of representation of the dentition for measuring periodontitis is valid or not is being assessed by several studies.

A truer and more exemplative representation of periodontal disease burden in the mouth seems to be obtained through random sampling of measurable sites in the mouth rather than through a fixed set of teeth. A recent study evaluated the bias and precision of probing depth and clinical attachment level estimates of fixed partial examination methods (for example, Ramfjord teeth) and randomly selected sites in the mouth, compared with full-mouth examinations . Among the fixed site methods, Ramfjord’s method had the least bias and best representation of periodontal disease in the mouth. However, compared with a method of selecting 36 sites in the mouth randomly, Ramfjord’s teeth method had greater bias and relative error. Thus, randomly selected sites provide a better picture of the true burden of periodontal disease in the mouth compared with any fixed site-based measurement method. However, the study noted that both methods underestimated prevalence of periodontal disease; still, random site selection methods were less likely to underestimate prevalence than fixed site based methods. Because of these promising results in favor of random site selection methods, further development of these methods can be expected in the future.

Periodontal disease surveillance

National estimates of periodontal disease prevalence in the United States were calculated for the first time based on the information from the National Health Examination Survey, which included an assessment of periodontal status using the PI . The National Health Examination Survey, which was later renamed as the National Health and Nutrition Examination Survey (NHANES), did not include an oral examination during NHANES II (1976–1980). Instead, the National Center for Health Statistics conducted a periodontal assessment of a subgroup of the Hispanic Population. The Hispanic Health and Nutrition Examination Survey (1982 and 1984) assessed the periodontal status of the Hispanic population using the PI. At this point the use of the PI to measure periodontal status in national surveys was discontinued. NHANES III (1988–1994) assessed periodontal status by recording probing depths, loss of attachment, and presence of calculus and bleeding in a partial mouth examination.

Surveillance of periodontal status in the United States ceased in the National Health Interview Survey because of the extensive resources required for conducting the clinical examinations. Data collected in NHANES have been used to gain a better understanding of the association between periodontal disease and systemic conditions, including tobacco, heart attack, and cardiovascular disease. Despite the clinical value of the data generated, the surveillance as conducted had limitations. The use of partial mouth evaluations might have led to misrepresentation of the true prevalence of periodontal disease . Partial versus full-mouth assessment and fixed site versus randomly selected sites for periodontal disease assessment have been discussed above. The clinical examination process for conducting periodontal assessment in NHANES and other surveys was a very resource-intensive process. In 2005 with a funding reduction in place, the clinical periodontal assessment was eliminated in NHANES . As a result, surveillance for periodontal diseases is almost nonexistent at state, county, or local levels in the United States .

A potential alternative to overcome these problems is the use of self-reported periodontal disease status assessment in population surveys. In 2003, the Centers for Disease Control and Prevention (CDC), in conjunction with the American Academy of Periodontology convened a conference, where the importance of periodontal disease surveillance and its potential association with systemic diseases were discussed. A panel of experts was formed to make recommendations for alternative mechanisms to assess periodontal disease that could be integrated into existing surveillance. In particular, the panel was to determine whether self-reported measures could be valid to predict the prevalence of periodontal disease and to develop and test questions to be used to survey the United States population .

The inexpensiveness and convenience of self-reports measures are appealing for health surveillance and forecasting health outcomes. For example, since 1984 the CDC has used self-reported questions to track chronic diseases and risk behaviors among the United States populations as part of the Behavioral Risk Factor Surveillance System, with compelling evidence for high reliability and validity . However, using self-reported measures to estimate the prevalence of periodontal disease presents several challenges . For example, because periodontal disease is in many cases an asymptomatic process, individuals affected by periodontal disease may be unaware of the condition . Therefore, disease prevalence may be underestimated because asymptomatic individuals are unaware of their disease status. Individuals learn about their disease once they are informed by their dentist .

However, the resource conservative nature is a strong argument in favor of using periodontal disease status self-report as a method to estimate periodontal disease prevalence for surveillance purpose, and is currently being field tested by the CDC. The initial step of the CDC Periodontal Disease Surveillance Project consisted of a thorough review of the literature of previous studies that measured the validity of self-reported measures to predict the prevalence of periodontal disease . Based on the results of this review, the workgroup focused on exploring the use of combined self-reported measures (gum disease, bone loss, history of treatment of gum disease, history of loose teeth, use of mouth wash or dental rinse, and cleaning between teeth) and known risk factors (age, smoking, and diabetes) to predict the prevalence of periodontitis among the population . As a set of promising self-reported questions that showed evidence of being valid predictors of periodontal disease prevalence within populations were derived from a range of existing datasets analyzed by the panel experts. The validity of six periodontal screening questions were assessed as part of the Australian National Survey of Adult Oral Health, a population based survey in Australia that has interview and clinical protocols similar to NHANES.

The Australian study concluded that the questions could be used in large population surveys, attaining useful levels of validity in predicting the prevalence of clinically evaluated periodontal disease . After testing for comprehension in the United States the workgroup made slight modifications to the language and format and a set eight questions were adopted for further testing in a pilot study ( Box 1 ) . The National Center for Health Statistics is conducting the study using NHANES protocols for interviews and clinical examinations, including a full-mouth examination. If the pilot study proves to be successful, the valid questions will be incorporated into NHANES 2009–2010 .

Box 1

Gum disease is a common problem with the mouth. People with gum disease might have swollen gums, receding gums, sore or infected gums, or loose teeth.

  • PB1: Do you think you might have gum disease?

  • 1 = Yes

  • 2 = No

  • 7 = Refused

  • 9 = Don’t Know

  • PB2: Overall, how would you rate the health of your teeth and gums?

  • 1 = Excellent

  • 2 = Very good

  • 3 = Good

  • 4 = Fair

  • 5 = Poor

  • 7 = Refused

  • 9 = Don’t Know

  • PB3: Have you ever had treatment for gum disease, such as scaling and root planning, sometimes called “deep cleaning”?

  • 1 = Yes

  • 2 = No

  • 7 = Refused

  • 9 = Don’t Know

  • PB4: Have you ever had any teeth become loose on their own, without an injury?

  • 1 = Yes

  • 2 = No

  • 7 = Refused

  • 9 = Don’t Know

  • PB5: Have you ever been told by a dental professional that you lost bone around your teeth?

  • 1 = Yes

  • 2 = No

  • 7 = Refused

  • 9 = Don’t Know

  • PB6: During the past 3 months, have you noticed a tooth that doesn’t look right?

  • 1 = Yes

  • 2 = No

  • 7 = Refused

  • 9 = Don’t Know

  • PB7: Aside from brushing your teeth with a toothbrush, in the last 7 days, how many times did you use dental floss or any other device to clean between your teeth?

  • ___: Number of days

  • 77 = Refused

  • PB8: Aside from brushing your teeth with a toothbrush, in the last 7 days, how many times did you use mouthwash or other dental rinse product that you use to treat dental disease or dental problems?

  • ___: Number of days

  • 77 = Refused

Personal Communication, Dr Bruce Dye. Centers for Disease Control and Prevention, National Center for Health Statistics.

Self-report questions to the prevalence of periodontal disease in the United States population to be used in the 2009–2010 NHANES

Measuring periodontal disease

The term “periodontal disease” has been historically used to describe diseases of gingiva and periodontal ligament. Gingivitis is an inflammation of the gingival tissues where the junctional epithelium, although affected by the disease, remains attached to the tooth at its original level. Periodontitis is also an inflammatory process characterized by clinical attachment loss, alveolar bone loss, and periodontal pockets with or without gingival inflammation . Periodontitis may or may not result as a progression of gingivitis, but not all sites affected by gingivitis transition to periodontitis. Periodontal disease is highly prevalent in older adults in the United States, affecting 34% of Americans 30 years or older , and remains to be a major cause of tooth loss in adults both in the United States and throughout the world .

Gingival disease measurement

Introduced in the 1963, the Gingival Index (GI) of Löe and Silness is still used. The GI scores the gingiva on an ordinal scale of 0 to 3 by probing on the mesial, distal, lingual, and buccal surfaces of the teeth. The GI does not take into consideration profound changes in the periodontal tissues and is sensitive enough to capture differences between groups with incipient and severe gingivitis. However, in the mid ranges of gingivitis, its validity is questionable.

Bleeding after probing has become a standard measure of gingivitis in studies, because visual evaluations of inflammation are subjective and conducive to bias. However, the validity of the probing has also been questioned as the pressure applied by different examiners during probing can vary drastically, ranging from 3 g to 130 g depending on the examiner . Gingival probing is not recommended for screenings, surveys, or surveillance because these programs do not require this level of sensitivity, there are concerns about infection control, and bleeding indexes have vague discriminatory power in field studies .

Periodontal disease measurement

Initial epidemiologic studies of periodontal diseases used radiographic assessments of alveolar bone loss . However, the use of radiographs requires strict standardization of radiographic techniques across clinics and research centers for appropriate comparison of resultant data. Such standardization is difficult to achieve and concerns were raised over ethical issues of exposing participants with radiation. These issues led to the development of more convenient indexes. In the 1960s, the Periodontal Index (PI) introduced by Russell was perceived as an ideal field index and used in epidemiologic studies. The United States Public Health Service agencies measured periodontal disease status in their surveillance activities using the PI until the 1980s. Current understanding of periodontal disease has led to identification of certain deficiencies of the PI. For example, the PI did not include an assessment of clinical attachment loss and graded all pockets of 3 mm or larger equally, combining both gingivitis and periodontitis on the same scale. During the late 1970s there was consensus among many researchers that accurate disease surveillance should include a site-specific measuring as well as clinical attachment loss to represent periodontal disease properly.

The Community Periodontal Index of Treatment Needs (CPITN), introduced by the World Health Organization (WHO) in 1983 , included periodontal probing on 10 index teeth. The CPITN has been used as a mechanism to assess treatment needs in most countries throughout the world . Methodologic and theoretic issues have been raised against the CPITN. For example, the CPITN treats gingivitis and periodontitis in the same scale following the paradigm that periodontitis is merely an extension of gingivitis. As a result, the CPITN is not indicated as a tool to assess prevalence of periodontal disease .

Carlos and colleagues introduced the Extent and Severity Index (ESI) in 1986 , attempting to summarize both the extent and the average severity of disease within the group being studied. The ESI uses estimates of attachment level from probing measurements of 14 sites in a quadrant in the maxillary arch and 14 in the contralateral mandibular arch. The ESI is not really an index but a method of summarizing data that permits comparisons among different epidemiologic studies.

A contentious issue that has dogged periodontal disease measurement has been which teeth should be measured for obtaining a true disease burden estimate by maximizing examination efficiency. The ideal solution would be to measure the entire periodontium, checking every available periodontal tissue point. However, it was recognized very early that such an exercise would be very inefficient and consume enormous time and resources, making the examination prohibitively expensive to conduct. Therefore, interest has always been keen to find a way to measure periodontal disease accurately with a resource-conserving paradigm.

In 1951, Ramfjord proposed the Periodontal Disease Index (PDI), which was perhaps a more sensitive version of the PI . Because the PDI is a composite index, it had the same weaknesses as the PI. As a result, the PDI is not longer used. However, Ramfjord’s legacy includes the indirect method of measuring clinical attachment loss he described and the partial mouth recording or “Ramfjord teeth,” a set of six teeth presumed to the represent the entire mouth during examination (teeth numbers: 3, 9, 12, 19, 25, and 28). Whether the assumption of representation of the dentition for measuring periodontitis is valid or not is being assessed by several studies.

A truer and more exemplative representation of periodontal disease burden in the mouth seems to be obtained through random sampling of measurable sites in the mouth rather than through a fixed set of teeth. A recent study evaluated the bias and precision of probing depth and clinical attachment level estimates of fixed partial examination methods (for example, Ramfjord teeth) and randomly selected sites in the mouth, compared with full-mouth examinations . Among the fixed site methods, Ramfjord’s method had the least bias and best representation of periodontal disease in the mouth. However, compared with a method of selecting 36 sites in the mouth randomly, Ramfjord’s teeth method had greater bias and relative error. Thus, randomly selected sites provide a better picture of the true burden of periodontal disease in the mouth compared with any fixed site-based measurement method. However, the study noted that both methods underestimated prevalence of periodontal disease; still, random site selection methods were less likely to underestimate prevalence than fixed site based methods. Because of these promising results in favor of random site selection methods, further development of these methods can be expected in the future.

Periodontal disease surveillance

National estimates of periodontal disease prevalence in the United States were calculated for the first time based on the information from the National Health Examination Survey, which included an assessment of periodontal status using the PI . The National Health Examination Survey, which was later renamed as the National Health and Nutrition Examination Survey (NHANES), did not include an oral examination during NHANES II (1976–1980). Instead, the National Center for Health Statistics conducted a periodontal assessment of a subgroup of the Hispanic Population. The Hispanic Health and Nutrition Examination Survey (1982 and 1984) assessed the periodontal status of the Hispanic population using the PI. At this point the use of the PI to measure periodontal status in national surveys was discontinued. NHANES III (1988–1994) assessed periodontal status by recording probing depths, loss of attachment, and presence of calculus and bleeding in a partial mouth examination.

Surveillance of periodontal status in the United States ceased in the National Health Interview Survey because of the extensive resources required for conducting the clinical examinations. Data collected in NHANES have been used to gain a better understanding of the association between periodontal disease and systemic conditions, including tobacco, heart attack, and cardiovascular disease. Despite the clinical value of the data generated, the surveillance as conducted had limitations. The use of partial mouth evaluations might have led to misrepresentation of the true prevalence of periodontal disease . Partial versus full-mouth assessment and fixed site versus randomly selected sites for periodontal disease assessment have been discussed above. The clinical examination process for conducting periodontal assessment in NHANES and other surveys was a very resource-intensive process. In 2005 with a funding reduction in place, the clinical periodontal assessment was eliminated in NHANES . As a result, surveillance for periodontal diseases is almost nonexistent at state, county, or local levels in the United States .

A potential alternative to overcome these problems is the use of self-reported periodontal disease status assessment in population surveys. In 2003, the Centers for Disease Control and Prevention (CDC), in conjunction with the American Academy of Periodontology convened a conference, where the importance of periodontal disease surveillance and its potential association with systemic diseases were discussed. A panel of experts was formed to make recommendations for alternative mechanisms to assess periodontal disease that could be integrated into existing surveillance. In particular, the panel was to determine whether self-reported measures could be valid to predict the prevalence of periodontal disease and to develop and test questions to be used to survey the United States population .

The inexpensiveness and convenience of self-reports measures are appealing for health surveillance and forecasting health outcomes. For example, since 1984 the CDC has used self-reported questions to track chronic diseases and risk behaviors among the United States populations as part of the Behavioral Risk Factor Surveillance System, with compelling evidence for high reliability and validity . However, using self-reported measures to estimate the prevalence of periodontal disease presents several challenges . For example, because periodontal disease is in many cases an asymptomatic process, individuals affected by periodontal disease may be unaware of the condition . Therefore, disease prevalence may be underestimated because asymptomatic individuals are unaware of their disease status. Individuals learn about their disease once they are informed by their dentist .

However, the resource conservative nature is a strong argument in favor of using periodontal disease status self-report as a method to estimate periodontal disease prevalence for surveillance purpose, and is currently being field tested by the CDC. The initial step of the CDC Periodontal Disease Surveillance Project consisted of a thorough review of the literature of previous studies that measured the validity of self-reported measures to predict the prevalence of periodontal disease . Based on the results of this review, the workgroup focused on exploring the use of combined self-reported measures (gum disease, bone loss, history of treatment of gum disease, history of loose teeth, use of mouth wash or dental rinse, and cleaning between teeth) and known risk factors (age, smoking, and diabetes) to predict the prevalence of periodontitis among the population . As a set of promising self-reported questions that showed evidence of being valid predictors of periodontal disease prevalence within populations were derived from a range of existing datasets analyzed by the panel experts. The validity of six periodontal screening questions were assessed as part of the Australian National Survey of Adult Oral Health, a population based survey in Australia that has interview and clinical protocols similar to NHANES.

The Australian study concluded that the questions could be used in large population surveys, attaining useful levels of validity in predicting the prevalence of clinically evaluated periodontal disease . After testing for comprehension in the United States the workgroup made slight modifications to the language and format and a set eight questions were adopted for further testing in a pilot study ( Box 1 ) . The National Center for Health Statistics is conducting the study using NHANES protocols for interviews and clinical examinations, including a full-mouth examination. If the pilot study proves to be successful, the valid questions will be incorporated into NHANES 2009–2010 .

Oct 29, 2016 | Posted by in General Dentistry | Comments Off on Understanding Measurement of Dental Diseases and Research Participation in Practice Set-Up
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