the 1999 classification. J Periodontol 2018;89(suppl 1):S1–S8.
39. Armitage GC. Development of a classification system for periodontal diseases and conditions. Ann Periodontol 1999;4:1–6.
40. Tonetti MS, Greenwell H, Kornman KS. Staging and grading of periodontitis: Framework and proposal of a new classification and case definition. J Periodontol 2018;89(suppl 1):S159–S172.
Fernando Suárez López del Amo, DDS, MS
DEFINITIONS AND TERMINOLOGY
Aggressive periodontitis: A diverse group of highly destructive forms of periodontitis affecting primarily young individuals, including conditions formerly classified as “early-onset periodontitis” and “rapidly progressing periodontitis.”1
Chronic periodontitis: Forms of destructive periodontal disease that are generally characterized by slow progression.1
Epidemiology: The study of the distribution of disease or a physiologic condition in human populations and of the factors that influence this distribution.2
Gingivitis: Site-specific inflammatory condition initiated by dental biofilm accumulation and characterized by gingival redness and edema and the absence of periodontal attachment loss.3
Incidence: The frequency in which some event, such as a disease or trait, appears in a particular population or area.
Necrotizing ulcerative gingivitis: An infection characterized by gingival necrosis presenting as “punched out” papillae, with gingival bleeding and pain. Halitosis and pseudomembrane formation may be secondary diagnostic features. Fusiform bacteria, Prevotella intermedia, and spirochetes have been associated with the lesion. Predisposing factors may include stress, poor diet, smoking, and HIV infection.4
Necrotizing ulcerative periodontitis: An infection characterized by necrosis of gingival tissues, periodontal ligament, and alveolar bone. These lesions are most commonly observed in individuals with systemic conditions, including but not limited to HIV infection, malnutrition, and immunosuppression.4
Periodontal health: State free of inflammatory periodontal disease.5
Periodontitis: Chronic multifactorial inflammatory disease associated with dysbiotic plaque biofilms and characterized by progressive destruction of the tooth-supporting apparatus.1
Prevalence: The proportion of a population that has a specific characteristic at a given time.
Periodontal diseases are the result of a complex interaction between bacterial plaque, the host’s immune response, and modifying factors that may impact the course of the disease. Periodontitis in particular represents a chronic inflammatory disease typically resulting in the apical migration of the junctional epithelium along with destruction of connective tissue attachment and alveolar bone. While microbial plaque and its byproducts are the main etiologic factors initiating the disease, it is the host’s response to bacterial challenge that accounts for most of the periodontal destruction. Modifying factors such as diabetes, smoking, obesity, and genetic predisposition, among others, may exacerbate the progression of periodontal disease. Also, many of the features of periodontal disease are derived from the unique anatomy of the periodontium, in which a hard nonshedding structure (ie, a tooth) is partially embedded within the maxillary and mandibular processes.
This chapter focuses on the epidemiology, etiology, and pathogenesis, as well as the characteristics of the different forms of periodontal disease. It is important to mention that, while acknowledging the latest classification in periodontal diseases and conditions from the 2017 World Workshop (see chapter 2), several terms pertinent to previous classifications, including chronic periodontitis and aggressive periodontitis, have been used for clarification purposes.
Epidemiology
Epidemiologic studies must be conducted in humans, comprising a control or comparison group, and should consider all clinically relevant endpoints. These studies must provide data on the prevalence of periodontal diseases in different populations, as well as the severity of the cases. Additionally, the studies should clarify aspects of the etiology and risk factors and should provide information regarding the effectiveness of preventive and therapeutic measures on the population. Information on epidemiologic studies is gathered by clinical and radiographic assessment of the periodontal status. On the other hand, an index is a numeric value that is often used to describe the relative status of the population on a scale with definite upper and lower limits.6 Since the 1950s, different clinical, laboratory, and radiologic recording systems and indices have been used to measure the prevalence, extent, and severity of periodontal diseases at individual and population levels. Indices require validity, reliability, clarity, simplicity, objectivity, quantifiability, sensitivity, and acceptability by both the examiner and the subject.7–9 Some of the most commonly used in periodontology indices are shown in Box 3-1.10–17
BOX 3-1 Commonly employed indices in periodontics10–17
| Assessment of periodontal inflammationGingival Index10Gingival Bleeding Index11Assessment of plaquePlaque Index12Hygiene Analysis Index13Assessment of loss of periodontal supportRussell’s Periodontal Index14Periodontal Disease Index15Radiographic assessment of radiographic bone lossSchei’s ruler16Percent of bone lossAssessment of periodontal treatment needsCommunity Periodontal Index of Treatment Needs17 |
PREVALENCE
One of the major challenges in assessing the prevalence of periodontal diseases relies on the great heterogeneity of indices used, the variations within population, the measurement errors, and the subjectivity of the examiners. However, recent epidemiologic studies have attempted to identify and overcome these issues.
Periodontitis
Between 2009 and 2014, the National Health and Nutrition Examination Survey (NHANES) conducted a survey on the prevalence of periodontitis among adults in the United States.18 The findings were as follows:
42.2% of adults 30 years or older have periodontitis7.8% have severe periodontitis34.4% have mild or moderate periodontitis
59.8% of adults 65 years or older have periodontitis
Gingivitis
It is estimated that more than 82% of adolescents in the United States have signs of gingival bleeding and therefore gingivitis.19 Additionally, more than 75% of the adults in the United States have signs of gingivitis.20 Consequently, gingivitis is prevalent at all ages and is