Is the prevalence of periodontitis in the USA in decline?
Authors: Charles M. Cobb, Karen B. Williams, Mary M. Gerkovitch
Journal: Periodontology 2000 (2009)

Two recent reports have suggested that the prevalence of periodontitis in the USA is in dramatic decline (13, 69). Prevalence refers to the frequency of a given condition or disease in a designated population at a given point (39). At the very least, this is an interesting observation with significant public health implications in terms of allocation of financial resources, personnel, treatment emphasis and public health policy. Additionally, if accurate, this observation certainly has implications for dental education curricula as regards course content emphasis, allocation of instructional time and faculty budget lines in departments of periodontics and dental hygiene, and need for and size of residency programs. Lastly, referral patterns to private practice periodontists may be impacted, which, in turn, may produce changes in the delivery of patient-care services (e.g. less time devoted to treatment of chronic periodontitis and more time devoted to esthetic surgical procedures and dental implant site development and placement). One would think that an objective assessment of the stated decline in prevalence of a major oral disease, such as chronic periodontitis, would be relatively straightforward. However, this is not the case. Accurate assessment of the prevalence of periodontitis is complicated by multiple factors such as different operational definitions of clinical periodontitis (25, 34, 69, 81); characteristics of the study populations, such as age, ethnicity and race, geographic location and risk factors (1, 10, 12, 14–18, 43, 52, 62, 76, 80); measurement of clinical parameters (e.g. probing depth, clinical attachment loss, bleeding on probing, radiographic bone loss, presence of dental calculus or plaque, etc.); and choice of partial vs. whole-mouth examination (5, 9, 22, 29, 31, 46, 47, 59, 60, 73–75, 87). Moreover, most prevalence data are either estimates obtained from relatively small observational (cross-sectional) studies, or are derived from larger epidemiological studies that do not permit an in-depth diagnostic assessment of subjects. Consequently, determining whether there is a real decline in the actual prevalence in periodontitis in the USA may not be possible, but analysis of trends may provide insight in this regard. The reader is admonished to not mistake this article as being a systematic or in-depth review of the literature. Over the past decade, several outstanding articles and in-depth reviews of the literature have been published that address the prevalence of periodontitis in the USA and other geographic locations worldwide (2, 4, 5, 11, 21, 25, 35, 67, 69, 70). The science of epidemiology is complex and steeped in design and statistical methodology, and, to some extent, sociologic considerations. Simply put, the intent of this paper is to present an abbreviated and uncomplicated review in a manner that may have relevance to the practicing clinician, educators and policy makers alike. Periodontitis has been described as an irreversible, cumulative condition, initiated by bacteria but propagated by host factors (58). Susceptibility to development of periodontitis may increase owing to the interaction of environmental, acquired and genetic risk factors that modify the host response to the putative pathogenic microbes (68). Traditionally, the presence and severity of periodontitis have been determined by pocket probing depth, clinical attachment loss and bleeding on probing measurements and by evidence of radiographic alveolar bone loss. These data are collectively interpreted contextually for each patient in order to establish a diagnosis of periodontitis that includes both the extent and severity of disease. A major problem associated with interpreting the meaning of these clinical parameters in epidemiologic studies is the lack of consensus on a standard case definition of periodontitis. For example, how much pocket depth, clinical attachment loss and radiographic bone loss equates to slight, moderate or severe periodontitis? In addition, various studies have used different measures of periodontal disease. Lastly, there is significant variation in the threshold levels used in defining a periodontitis case, regardless of the clinical parameters used for measurement. Simply put, before prevalence of periodontitis can be accurately assessed there must be agreement on what constitutes a case of periodontitis. The first national US survey to determine the prevalence of periodontal diseases was conducted in 1960–62 as part of the National Health Examination Survey. Subsequent surveys were conducted in 1971–74 by the National Health and Nutrition Examination Survey or NHANES I, in 1981 by the Health Resources and Services Administration/US Public Health Service, in 1985–86 by the National Institute of Dental Research (currently known as the National Institute of Dental and Craniofacial Research) and in 1988–94 (by the National Health and Nutrition Examination Survey III), followed by National Health and Nutrition Examination Survey III data-collection cycles in 1999–2000 and 2002–2004 (69). It should be noted that since 2005, surveillance of periodontal status in the USA, as part of the National Health and Nutrition Examination Survey, has ceased. Even amongst these national surveys, inconsistencies in methodology, operational definition of periodontitis and selection of disease parameters for measurement influence the findings and severely limit valid comparisons between the different surveys (60). Dye & Thornton-Evans (35) and Page & Eke (69) have recently published in-depth reviews that chronicle the histories of national surveillance efforts for periodontal disease in the USA, the evolution of case definitions for periodontitis and the prevalence estimates from various surveys. As noted by these authors, the early epidemiologic surveys focused on gingival inflammation and used the Russell Periodontal Index as the instrument for measurement (74). Russell’s index employs a weighted, six-category ‘severity’ ranking scale that requires radiographic interpretation to assign values associated with the three highest ranked values. Additionally, an inherent problem with this scale is the lack of specificity in category attributes and the lack of mutually exclusive severity categories in interpretation. The Russell Periodontal Index was subsequently modified as the Ramfjord Periodontal Disease Index, and applied the Russell Periodontal Index schema to six index teeth, based on the assumption that the six teeth were representative of the entire dentition (73). Both the Russell Periodontal Index and the Ramfjord Periodontal Disease Index yield scores that represent the severity of periodontal disease, and both methods assume that gingivitis is an early stage of periodontitis (Table 1). However, both indices were developed for the rapid screening of large numbers of subjects and do not utilize specific clinical parameters (pocket depth, clinical attachment loss, bleeding on probing or radiographic bone loss) to assess the extent of disease or conform to standard characteristics for measurement categories that are mutually exclusive and collectively exhaustive. Additionally, partial-mouth examinations tend to underestimate the prevalence, extent and severity of disease (6, 36, 37, 49, 59). Notably, the Russell Periodontal Index was used for assessing periodontal prevalence in both the 1960–62 National Health Examination Survey and the 1971–74 National Health and Nutrition Examination Survey I. The National Health and Nutrition Examination Survey II, conducted in 1976–80, did not procure oral health data. Consequently, almost a decade elapsed before the Health Resources and Services Administration/US Public Health Service conducted the 1981 national survey on prevalence, severity and extent of periodontal disease (19). This survey used a modified Russell Periodontal Index that assessed gingivitis and periodontal pocket depth separately. Thus, this survey became the first to incorporate the periodontal pocket depth into the examination methodology. Periodontitis was defined as having one or more pockets ≥4 mm; moderate disease being one or more pockets of 4–6 mm; and severe disease being one or more pockets with pocket depth >6 mm. The greatest criticism of this assessment was that pocket depth was measured only on the mesial of each available permanent tooth. Thus, survey results concerning pocket depth were based on what was essentially a biased (by site) partial-mouth examination. A second national survey was conducted by the National Institute of Dental Research (currently the National Institute of Dental and Craniofacial Research) in 1985–86 (20). The survey was the first to measure gingival recession and clinical attachment loss in addition to pocket depth and gingivitis. The survey was also distinctive in that teeth in two randomly selected quadrants (one maxillary and one mandibular) were evaluated, again representing a partial-mouth examination. Each available tooth (exclusive of third molars) in the selected quadrants was probed at the mid-buccal and mesio-buccal surfaces, again potentially biasing findings by site. Case definition of periodontitis was not applicable in this study as data were presented based on progressive disease severity (Table 1). The National Health and Nutrition Examination Survey III study of 1988–94 (5, 22), similar to the National Institute of Dental Research/National Institute of Dental and Craniofacial Research survey of 1985–86, used a partial-mouth examination consisting of measurements obtained from all available teeth (exclusive of third molars) in two randomly selected quadrants. The methodology was similar to the 1985–86 survey where pocket depth was measured at mid-buccal and mesio-buccal sites. A significant improvement to the methods was added in that clinical attachment loss was determined at these sites and the extent of furcation involvement was noted. Periodontitis was defined as active destruction of the supporting tissues at one or more sites, characterized by pocket depth ≥3.0 mm and clinical attachment loss ≥3.0 mm at the same site. The survey subdivided severity of disease into mild periodontitis (one or more teeth with pocket depth ≥3.0 mm or one or more posterior teeth with Class I furcation involvement); moderate periodontitis [one or more teeth with pocket depth ≥5.0 mm or two or more teeth (or 30% of teeth examined) with pocket depth ≥4 mm, or one or more posterior teeth with a Class I furcation involvement]; and severe periodontitis [two or more teeth (or 30% of teeth examined) with pocket depth ≥5 mm, or four or more teeth (or 60% of teeth examined) with pocket depth ≥4 mm, or one or more posterior teeth with a Class II furcation involvement]. Data from the National Health and Nutrition Examination Survey III of 1999–2000 and the 2002–2004 data-collection cycle were based on the following case definition of periodontitis: at least three sites with clinical attachment loss ≥4 mm and at least two sites with pocket depth ≥3 mm. Unlike the previous National Health and Nutrition Examination Survey studies, these clinical parameters did not have to occur at the same site or involve the same tooth (13) and thus probably produced findings that are not directly comparable. Lastly, in 2003 a standardized case definition of periodontitis for population-based studies was jointly devised by the Centers for Disease Control and Prevention and the American Academy of Periodontology. Moderate periodontitis was defined as two or more interproximal sites with >4 mm clinical attachment loss, not on the same tooth, or two or more interproximal sites with pocket depth >5 mm, not on the same tooth. Severe periodontitis was defined as two or more interproximal sites with clinical attachment loss ≥6 mm, not on the same tooth, and one or more interproximal sites with pocket depth ≥5 mm (69). It is apparent that the operational definition of periodontitis has evolved over time, becoming more refined in keeping both with the progression in knowledge of periodontal disease pathogenesis and the need for accurate surveillance data upon which to base public health policy. Paradoxically, the continued evolution of the case definition compromises meaningful comparisons of the obtained data over time. Despite the challenge presented by the lack of continuity in design and case definition between surveys, one can still identify trends in the prevalence of periodontitis. In 1950, Neal W. Chilton (27) noted that there was ‘very little information of statistically reliable nature on the epidemiologic characteristics of periodontal disease.’ His opinion was echoed 5 years later by Marshall-Day et al. (64), who noted that much of the information concerning prevalence and incidence of the periodontal diseases was based on clinical impression that was unsupported by reliable statistical data. The authors proceeded to conduct a cross-sectional study of adolescents and adults in the Boston, Massachusetts, area. The sample of 1,279 individuals comprised adults participating in a ‘multiphasic health protection program’, and high school and college students, yielding an age range of 13–65+ years. The examination consisted of a 20-film radiographic survey, measurement of pocket depth, determination of the presence of supragingival and/or subgingival calculus, evaluation of gingival inflammation based on visual parameters (e.g. color, contour, consistency, recession and suppuration) and occlusal analysis using study models. The results showed that 87.4% of the population 19–65+ years of age exhibited ‘chronic destructive periodontal disease’. Additionally, 98–100% of those in the 35–65+ years age-group suffered from the disease as manifested by radiographic bone loss that averaged 2.77 mm with a range of 2.16–3.32 mm. Destructive periodontitis was rarely noted before age 18 years, but the incidence increased rapidly from 14 to 69% between the ages of 19 and 26 years, with a steady increase thereafter until at age 45 years the incidence was 100%. By age 40 years, the authors noted that 90% of the population exhibited periodontal disease consisting of either overt gingivitis or increased pocket depth with bone loss. The study did not establish a case definition for periodontitis or thresholds for the various clinical parameters. Based on US Bureau of Census data, the US population in the year 1955 was 161,497,000, of which 106,373,000 comprised the age group 19–65+ years (84). Thus, a prevalence rate of 87.4% translates to 92,970,000 individuals afflicted with ‘chronic destructive periodontal disease’ (Table 2). Having made such an extrapolation, it must be noted that it is highly questionable that a cross-sectional survey of periodontal disease in a population from greater Boston, Massachusetts, can be generalized to that of the population of the total USA. The 1960–62 National Health Examination Survey examined a sample of 6653 randomly selected individuals between the ages of 18 and 79 years (54) from the target population of approximately 90 million adults. As noted previously, the National Health Examination Survey was the first attempt to generate a national estimate of periodontal disease prevalence in the USA. Using the Russell Periodontal Index as the instrument for measuring existence and severity of chronic periodontitis, it was determined that only 27.8% of those examined were free of periodontal disease, while 25% exhibited periodontitis. Although the sample statistically represented 90 million adults, examination of the US Bureau of Census data for the years 1960, 1961 and 1962 indicate that, in general there were 115,200,000 adults in the 18–79 years age-group (77). Thus, given a 25% prevalence rate, one can extrapolate that approximately 28,800,000 individuals were afflicted with periodontal disease (Table 2). The National Health and Nutrition Examination Survey I, conducted from 1971 to 1974 on a target population of subjects 18–74 years of age, again used the Russell Periodontal Index for assessment of periodontal disease (57). The authors reported disease severity by identifying those with one to three periodontal pockets and those with four or more periodontal pockets. Using this stratification, the authors were able to show a positive correlation between disease severity and age. For example, 39.7% of Americans aged 65–74 years had four or more pockets compared with 10.3% of those aged 18–44 years. The overall prevalence of periodontitis for the population aged 18–74 years was 25.5%. The average number of individuals in this age group from 1971 to 1974 was approximately 132,387,000 (77). Given the 25.5% prevalence rate, about 34,233,262 individuals could have been afflicted with chronic or aggressive periodontitis (Table 2). The National Health and Nutrition Examination Survey II was conducted from 1976 to 1980 but did not include oral health data from which to estimate the prevalence of periodontitis. However, during the years 1982–1984, the National Center for Health Statistics conducted the Hispanic Health and Nutrition Examination Survey that focused on three population subgroups of Hispanics aged 18–74 years [i.e. Mexican-Americans (n = 5983), Cuban Americans (n = 1192) and Puerto Ricans (n = 2226)]. Here again, the Russell Periodontal Index was used to assess for periodontal disease. Of the dentate examinees, the authors reported that 40.6% of Puerto Ricans, 36.9% of Mexican-Americans and 22.8% of Cuban-Americans exhibited periodontitis. Paradoxically, although Cuban-Americans had the lowest prevalence of periodontitis, as a group they had the greatest prevalence (6.1%) of total tooth loss (52, 53). A 1981 survey of a US population, ≥19 years of age, sponsored by the Health Resources and Services Administration/US Public Health Service, addressed the prevalence and severity of periodontal disease and its role in tooth loss (19). As pocket depth was measured only at the mesial of all available permanent teeth, this methodology probably underestimated disease prevalence. Pocket depth ≥4 mm affected 36% of the study population, with 8% exhibiting at least one site ≥6 mm. Only 15% of the survey population was considered free of periodontal disease. Using the US Bureau of Census estimated population of 230,990,000 for the year 1980, there were 163,088,740 individuals ≥19 years of age (83). Thus, using a 36% prevalence rate, one can extrapolate that approximately 58,712,000 individuals were affected by periodontitis (Table 2). A 1985–86 survey, sponsored by the National Institute of Dental Research/National Institute of Dental and Craniofacial Research, reported a periodontal disease prevalence of 14% involving those in the 18–64 years age-group, using pocket depth as the determinant of disease. When using clinical attachment loss of ≥3 mm as the determinant of disease, the prevalence rate is 47.2% for the same age-group (20). Extrapolation of disease severity to the estimated US population for the years 1985–86, as based on Bureau of Census data, indicates that approximately 64,620,550 individuals between the ages of 18 and 64 years were afflicted with periodontitis (Table 2). Comparison of pocket depth and clinical attachment loss data from the 1981 Health Resources and Services Administration/US Public Health Service, 1985–86 National Institute of Dental Research and 1988–94 National Health and Nutrition Examination Survey III surveys shows the prevalence of periodontitis to vary only slightly between the years of 1981 and 1994 (Table 3). However, the most dramatic findings regarding periodontitis prevalence are presented in the 1988–94, 1999–00 and 2002–04 National Health and Nutrition Examination Survey III reports, using slightly different case definitions for periodontitis. When viewed collectively, findings from the three National Health and Nutrition Examination Survey III reports show a progressive decrease in the prevalence of periodontitis between the years 1988 and 2004. For example, the first of these three data-collecting cycles reported a prevalence rate of 35% for individuals aged 30–90 years. Based on US Census data for the years 1988–94 (78), this translates to approximately 49 million US individuals afflicted with periodontitis (Table 2). The second and third data-collecting cycles reported a prevalence of 7.3 and 4.2%, respectively, for individuals ≥18 years – translating to 15,313,247 and 9,255,104 people with periodontitis, respectively (Table 2). All large epidemiologic studies of periodontal disease in the US population have employed partial-mouth examinations. As noted previously, the partial-mouth examination is likely to produce biased estimates of disease prevalence (6, 36, 49, 59). Thus, consideration of one relatively small study that used full-mouth circumferential probing combined with radiographic evaluation of alveolar bone levels to determine prevalence of periodontitis makes an interesting comparison. In 1990, Horning et al. (46) examined 1788 active duty and 125 retired military personnel and 25 military dependents for a total survey population of 1984 individuals. The mean age of the population was 30.3 with a range of 13–84 years. Periodontitis was defined as: ‘early periodontitis’, consisting of bleeding on probing and pocket depth of 3–5 mm; ‘moderate periodontitis’, consisting of bleeding on probing, pocket depth of 5–7 mm, radiographic bone loss up to one-third of the root length and Class I furcation involvement; and ‘advanced periodontitis’, consisting of bleeding on probing, pocket depth >7 mm, radiographic bone loss greater than one-third of the root length and Class II or Class III furcation involvement. Given the disease categories and definitions, the authors reported prevalence rates of 33% for early periodontitis, 14% for moderate periodontitis and 15% for advanced periodontitis. Additionally, 0.5% exhibited aggressive periodontitis (juvenile periodontitis) and 0.5% presented with necrotizing ulcerative gingivitis. The overall prevalence rate for periodontitis for the survey population was 63%. If one considers only moderate and advanced periodontitis (plus aggressive periodontitis) the prevalence rate becomes 29.5%. The results of this survey were similar to those of Marshall-Day et al. (64) who reported on a similar sized population (n = 1279). However, the 63% prevalence rate in the study of Horning et al. (46) is obviously higher than that of the 1981 Health Resources and Services Administration/US Public Health Service, the 1985–86 National Institute of Dental Research and the 1988–94 National Health and Nutrition Examination Survey III surveys, which reported overall prevalence rates of 36, 43.8 and 35%, respectively (5, 19, 20). These comparative results appear to justify some degree of skepticism concerning the reliability of partial-mouth examination vs. that of full-mouth circumferential probing when combined with radiographic evaluation of bone loss. Indeed, Eaton et al. (36) has reported that the prevalence of clinical attachment loss of ≥2 and ≥3 mm when using partial-mouth vs. full-mouth examination was underestimated by 22 and 36%, respectively. Querna et al. (72), Covington et al. (29) and Diefenderfer et al. (31) examined smaller groups of active duty military personnel (n = 500–1107) using the Periodontal Screening and Recording system or a modification thereof. They reported 47.6, 17.6 and 23.8% prevalence rates of periodontitis, respectively. Again, the prevalence rates reported in these three studies are considerably greater than those reported in the comparable 1988–94 National Health and Nutrition Examination Survey III and the 1999–00 and 2003–04 data-collection cycles which were 35, 7.3 and 4.2%, respectively. Burt (25) made the pertinent observation that ‘Any prevalence data need the reference markers of the relevant case definition and the age group to which they apply.’ As an example, when periodontitis is operationalized as one or more sites with clinical attachment loss of ≥2 mm, the conclusion is reached that nearly 80% of adults are affected. Furthermore, given that definition, approximately 90% of those in the 55–64-years age-group are afflicted with periodontitis (25). However, if one defines periodontitis as one or more sites with clinical attachment loss of ≥4 mm or clinical attachment loss of ≥6 mm, the prevalence in individuals 55–64 years of age decreases to about 50% or <20%, respectively (25). Clearly, age and case definition impact conclusions made about periodontitis prevalence. Past interpretation of such data led to the assumption that periodontitis was a disease of aging, that is, age of and by itself was a risk factor for developing the disease. However, the relationship between age and periodontitis is deceiving. For example, Albandar (2, 3) notes that the effect of age appears to be different for pocket depth and clinical attachment loss, with the latter increasing with increased age. In the case of pocket depth, age appears to have minimal impact. Indeed, several studies have shown that clinical attachment loss increases with age but without significant loss of function in affected teeth (33, 38, 40, 50). Furthermore, good oral hygiene and periodontal health equate to long-term tooth retention, regardless of age (1, 26). Lastly, it appears that periodontitis may begin in adolescence and/or early adulthood (23, 24). This suggests that susceptibility to periodontal disease may be more important than age (5, 88). Consequently, current paradigms view increasing clinical attachment loss as resulting from a lifetime of disease exposure rather than an age-specific disease (25, 71). As noted previously, Hispanic populations 18–74 years of age and living in the USA, were the subject of a 1982–84 National Center for Health Statistics sponsored periodontal health survey. The population subgroup exhibiting the highest prevalence of periodontitis were the Puerto Ricans (40.6%), followed in order by Mexican-Americans (36.9%) and Cuban-Americans (22.8%) (52). With the exception of the Puerto Rican subgroup, the prevalence of periodontitis in the Hispanic community, for this time period, was very similar to the prevalence rate of 36% reported for the overall US population in the 1981 Health Resources and Services Administration/US Public Health Service survey (19). The National Health and Nutrition Examination Survey III of 1988–94 reported a higher prevalence of periodontitis in non-Hispanic blacks and Mexican-Americans compared with non-Hispanic whites (5). Comparison of pocket depth, clinical attachment loss and furcation involvement, regardless of age, showed the prevalence of adverse clinical parameters to be consistently greater for non-Hispanic blacks and Mexican-Americans than for non-Hispanic whites (Table 4). The pattern of non-Hispanic blacks (African-Americans) exhibiting a higher prevalence of periodontitis followed by Mexican-Americans and non-Hispanic whites appears consistent, regardless of case definition (7, 17, 29, 51). However, as with age, the relationship of race/ethnicity with the prevalence of periodontitis comes with several caveats. As Williams (89, 90) and Borrell & Papapanou (11) have suggested, race and ethnicity are social constructs that can strongly influence socioeconomic status, access to health care (e.g. geographic location and availability of insurance), educational levels and frequency of dental visits. Furthermore, Kaufman et al. (56) and Borrell et al. (15) maintain the importance of recognizing the interaction of socioeconomic status and health status as a function of social, political and historical consequences. As an example, Borrell et al. (15) reported that high-income African-Americans exhibit a higher prevalence of periodontitis than do low-income African-Americans or high-income Caucasians. Indeed, it may be that periodontal disease status may have little association with the use of dental services among low-income patients because those exhibiting the greatest incidence of clinical attachment loss may be those least likely to seek dental care (41, 42, 79). Interestingly, using multivariate analyses based on data derived from the 1985–86 National Institute of Dental Research survey, Oliver et al. (67) determined an odds ratio of 79:1 for development of periodontitis for an individual with a high-risk profile consisting of age >34 years, less than 12 years of education, presence of subgingival calculus and bleeding on probing, and had not seen a dentist for ≥3 years. It should be noted, however, that the odds ratio was not supported by a confidence interval and thus may represent an unreliable estimate. Hujoel et al. (48) have estimated a 31% decrease in the prevalence of periodontitis between the years 1955 and 2000. Furthermore, these authors estimate an additional 8% decrease by the year 2020. They attributed the decrease to changes in tobacco smoking habits. There is a well-established and documented relationship between smoking and development and/or severity of periodontitis (55, 61, 62, 80). In spite of actual and projected decreases in smoking habits (66), a better understanding of the pathogenesis of periodontitis, and more refined and goal-directed therapies, there is still evidence that dentistry is not consistently achieving a timely diagnosis and appropriate and timely treatment of existing periodontitis (28, 32). Although not well researched, there is evidence that the use of a probe for diagnosing and recording periodontal status in treatment records in the general dental practice has yet to achieve the level of a routine and consistent habit (8, 30, 44, 65). In fact, McFall et al. (65), in a study of 36 general dental practices, noted that except for radiographs, the records of most patients contained insufficient diagnostic information to describe their periodontal status. Tugnait et al. (82) used a self-report questionnaire to determine the rate of periodontal examination by 800 general practitioners. Given the problems of validity inherent to data obtained by self-report, the authors found that 44% of the general practitioners claimed to assess probing depths on all new patients. Obviously, at least 56% evidently did not! In this regard, it is interesting to note that at least one study has reported the existence of a disconnect between dentists’ perception of treatment rendered and actual treatment as recorded in patient records (45). Somewhat more encouraging is the study by Heins et al. (44), who reported that 62% of practices performed and recorded full-mouth periodontal probing on all new patients. Although ‘recall’ patients received similar scrutiny in 57% of practices, the mean frequency between periodontal probing was 12.7 months. Cobb et al. (28) compared the pattern of referral of periodontitis patients in 1980 vs. 2000 using patient record data from three geographically diverse private periodontal practices. Results of the record audit revealed the following trends occurring over the 20-year time span: decreased use of tobacco; increase in the percentage of patients exhibiting advanced chronic periodontitis with a concomitant decrease in the percentage of patients with mild-to-moderate disease; increase in the average number of missing teeth per patient; and increase in the average number of teeth scheduled for extraction per patient. Docktor et al. (32) used data from patient records from three private periodontal practices located within a major metropolitan area to determine the level of care delivered in the general practice office prior to referral. Conclusions from this study support those reported by Cobb et al. (28). In addition, the authors noted that 74% of the patients referred were considered to have advanced periodontitis, and that of those 74%, 30% were treatment planned for extraction of two or more teeth. In addition, periodontal treatment provided by the general dental office did not vary because of disease severity. Lastly, the average number of periodontal maintenance visits/patient/year in the general dental office were lower than the standard of care according to severity of disease, for example, 68% of patients with advanced periodontitis reported between none and two periodontal maintenance visits per year rather than the recommended every 3 months. This latter point is rather poignant as Lanning et al. (63) reported that 86% of general dentists surveyed reported providing periodontal maintenance in their practices. Viewed in aggregate, the trends reported by Cobb et al. (28) and Docktor et al. (32) support the contention that timely diagnosis and appropriate and timely treatment of chronic periodontitis have not significantly improved over time. The prevalence of periodontitis in a given US population is dependent upon case definition, age and race/ethnicity. Even given these variables, comparison of data from various US periodontal health surveys are suggestive of a progressive decrease in the prevalence of moderate-to-advanced periodontitis. Furthermore, one may conclude that epidemiology has demonstrated that the majority of the US adult population exhibits, to some extent, a mild, chronic periodontitis. Indeed, it appears that mild attachment loss of 2 mm is compatible with long-term function of the dentition (25). However, regardless of prevalence, for those individuals afflicted with more severe disease (clinical attachment loss ≥3 mm or pocket depth ≥5 mm), periodontitis remains a significant social and economic concern.