Periodontics. Fernando Suarez

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СКАЧАТЬ 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 periodontics^10–17

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 considered the most common form of periodontal disease.^21–23

      Aggressive periodontitis

      It is estimated that the prevalence of aggressive periodontitis among US schoolchildren is around 0.4% for 13- to 15-year-olds and 0.8% for 16- to 19-year-olds.²⁴ Löe and Brown²⁵ in 1991 as well as Albandar et al²⁴ in 1997 found that the prevalence of aggressive periodontitis is highest among African Americans (2.64% and 2.6%), followed by Hispanic Americans (1.08% and 0.5%), whereas White Americans had the lowest prevalence (0.17% and 0.06%). In most populations, the prevalence of aggressive periodontitis is similar in males and females.²⁶

      Tooth loss

      The main reason for tooth extraction in the ages up to 40 to 45 years is dental caries. On the other hand, periodontal disease is the major cause of tooth loss in older adults. In fact, extractions for periodontal reasons increase with age and account for over two-thirds of all extractions in adults over 50 years of age.²⁷ Second molars and mandibular incisors are the teeth most frequently extracted for periodontal reasons.²⁸

      Dental Biofilm

      The human oral microbiome is an exceptional habitat for many different species of bacteria. Data from molecular and culture studies with the support of the United States National Institute of Health and the Human Microbiome Project have shown that approximately 700 distinct bacterial phyla may be able to live in the oral cavity.²⁹ Nevertheless, not all of them will be present simultaneously in a particular individual. It has been estimated that an individual subject may harbor about 100 to 200 taxa in the mouth.³⁰ In addition, some species are site specific, while other species are subject specific.³¹

      Oral bacteria will produce various polysaccharides and glycoproteins that have the ability to adhere to other suspended or planktonic microorganisms (coaggregation) or to other already-adhering microorganisms or surfaces (coadhesion). Additionally, salivary glycoproteins and antibodies will form the acquired pellicle on the tooth surface, which facilitates bacterial adhesion.

      In 1998, Socransky et al³² were able to use the checkerboard DNA-DNA hybridization technique to identify different groups of bacteria that often exist together in subgingival plaque. Five bacterial clusters were identified and classified into different colors: red, orange, purple, yellow, and green (Fig 3-1).³² Additionally, a relationship between those bacterial clusters was identified, categorizing them in different stages and severity of periodontal disease. Actinomyces (purple complex), Streptococcus (yellow complex), and Capnocytophaga (green complex) species are considered early colonizers because these will be the first microorganisms colonizing the tooth surface. Usually the early or primary colonizers are facultative anaerobic gram-positive cocci. Later, secondary colonizers like Fusobacterium nucleatum or Prevotella intermedia (orange complex) will interact with the early colonizers, and the shift to gram-negative anaerobic bacterial flora will begin. Finally, the late colonizers, red complex bacteria such as Porphyromonas gingivalis, Treponema denticola, or Tannerella forsythia, will coaggregate with the secondary colonizers, resulting in a more pathogenic microbiota (Fig 3-2).^33,34

      Fig 3-1 Microbial complexes. (Adapted from Socransky et al.³²)

      Fig 3-2 Spatiotemporal model of oral bacteria colonizing a tooth surface. Early colonizers will attach to specific receptors on molecules of the acquired pellicle. Coadhesion of secondary colonizers, and specifically of F nucleatum, will play a role of “bridging” species from early and late colonizers because it has the ability to coaggregate with multiple bacteria. (Adapted with permission from DÜzgÜnes.³⁴)

      These bacteria associations are regulated by quorum sensing, which is the ability to detect and respond to cell density and thereby coordinate cell behavior. As such, bacteria secrete and detect autoinducer molecules, which accumulate in a cell density–dependent manner and regulate the expression of specific genes.³⁵ A major advantage for bacteria grouped in the biofilm is the protection it provides against environmental factors such as host-defense mechanisms and toxic substances in the environment, such as antimicrobials. Along with providing protection, biofilms also facilitate the uptake of nutrients and water, as well as the removal of metabolic waste products.³⁶ As a result, it has been estimated that organisms in biofilms could be up to 1,000 times more resistant to antibiotics as compared with their planktonic state.³⁷

      Dental calculus usually represents СКАЧАТЬ