Epidemiology of Periodontal Disease



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Epidemiology of Periodontal Disease


  • Epidemiology- the study of health and disease in human populations and associated factors

    • Prevalence » number of cases

    • Incidence » rate of occurrence

    • Severity » level of disease

    • Risk Factors

      • Local » environmental (bad dentistry, overhangs)

      • Systemic » medical conditions

      • Host » influences of ones own body

      • Determinants » risk factors one can not change

  • Periodontal disease is a complex interaction of bacterial infection, host response, and patient behavior

  • Types of Experimental Designs

    • Cross-Sectional » presence or absence of disease at a particular point in time

      • Entire population or a subset

      • Determines the prevalence of disease

    • Cohort » examines a population over time

      • Generally disease free at start and monitored for the onset of disease

      • Asses the incidence of disease and risk factors

    • Case Control » compares those with and without disease

  • Indices- measurement systems used for collecting the necessary data

    • Periodontal disease

      • Plaque

      • Calculus

      • Gingival inflammation

      • Periodontal attachment level

      • Bleeding

      • Mobility

    • Index- tool which collects objective data, numerical expressions

    • Plaque- the major etiologic agent in the initiation and progression of inflammatory periodontal disease

      • Plaque Index of Silness and Loe

        • 0-3 (no plaque at margin to heavy plaque at margin)

      • Must be present for disease, but not all plaque causes disease

        • Amount, virulence, bacteria and host response/defense matters

    • Gingival Bleeding

      • Gingival Index of Loe and Silness (GI)

        • Measure inflammation and bleeding

        • 0-3

      • Sulcus Bleeding Index (SBI)

        • 0-5

        • Differentiates more severe signs of inflammation » significant swelling and color change

    • Gingival Crevicular Fluid

      • Identifies early inflammation

      • As inflammation increases » so does gingival fluid flow

      • First measurable change in the inflammatory process of the periodontium

      • Periotron calibrates filter strips

    • Mobility

      • Miller Index of Tooth Mobility

      • 0-3 ( no movement to >1mm in any direction, or tooth is depressible or can be rotated in its socket)

      • not all movement is pathologic

    • Calculus- not an etiologic agent

      • Irritant to gingival tissues which causes inflammation

      • Can cause progression of disease

      • Calculus Index (of Simplified Oral Hygiene Index)

        • Amount of calculus covering what portion of the tooth

        • 0-3 (no calculus to covering more than 2/3)

  • Plaque is a dense, nonmineralized, complex mass of bacterial colonies living in a gel-like intermicrobial matrix

    • Readily adheres to the surface

  • Material Alba is a loosely adherent mass of bacteria and cellular debris

    • Can be removed by a strong water spray

  • Key difference: strength of adherence

  • Accumulation of bacteria is not random

    • Specific, complex

    • Based on bacterial characteristics

  • Five criteria make species or groups of bacteria important in the etiology of perio disease

    • High numbers in advancing lesions or sites » low numbers in healthy or nonprogressing sites

    • Clinical healing occurs upon removal

    • Present prior to evident clinical changes

    • Create a tissue reaction

    • Produce disease in experimental animals or humans

  • Gram positive have a thick glycocalax capsule (slime layer) and a thin peptidoglycan layer

    • Lysozyme can split these units and cause lysis

  • Gram negative have a thin capsule and a lipopolysacharides(LPS) (outer membrane)

  • Fimbriae or pili- small protein aqueous projections that mediate adhesion

  • Flagella- long fine wavy structure used for motility

  • Aerobes- require oxygen

  • Faculative anaerobes- can use oxygen but use anaerobic fermentation when not present

  • Aerotolerant anaerobes- can not use oxygen but can tolerate

  • Obligate anaerobes- cannot survive in the presence of oxygen

  • Fermentative or saccharolytic- obtain energy by breaking down complex organic compounds (carbs) such a sugars, to smaller products (lactic acid)

  • Nonfermentative or asaccharolytic- use amino acids, simple petides and proteins for energy

  • Bacteria Important to Periodontal Disease

  • Stage 1:Pellicle Formation

    • Pellicle formation; membranous film that serves a nutrient source for bacteria

      • Polishing removes

      • Forms within minutes after cleaning teeth

      • Forms from glycoproteins in saliva

    • Supragingival plaque has a salivary based nutrition, it is very organized and has the ability to adhere to the pellicle

    • GR + bacteria, mainly cocci

  • Stage 2: Initial Adherence and Colonization

    • Hours afters pellicle formation GR –bacteria begin to proliferate

    • GR + rods and numerous filaments

    • Only bacteria with specific binding sites for pellicle constituents, and occurring in sufficient numbers can bind

      • Lectins are adhesions that allow

      • Secretory IGa can prevent attachment of bacteria

      • Saliva plays a facilitative and inhibitory role in plaque formation

  • Stage 3: Growth and Maturation

    • Shifts to predominately GR –

    • Can take anywhere from 4-7 to 7-14 days

    • Plaque mass accomplished by the adhesion of bacteria to one another

    • Bacterial coaggregation- direct interaction between surface components of different bacteria

    • Filaments at the salivary or external plaque become coated with cocci » corncob appearance

    • Bacteria can bridge for bacteria that cannot interact

    • Shifts from predominantly aerobic to mostly anaerobic

      • Facultative organisms use all the oxygen so “healthy” GR + die

      • GR – obligate anaerobes takeover due to lack of oxygen

    • Mature plaque has the ability to invade the gingival space

      • Supragingival cause inflammation » gingival less tight so bacteria invades crevice

      • Subgingival plaque is more anaerobic, more GR – ad more motile and more asaccharolytic than supragingival plaque

  • Gingival Health vs. Disease

    • Health

      • Sparse bacterial flora

      • Mostly GR + cocci, facultatively anaerobic

      • Some GR + rods such has Actinomyces

    • Gingivitis

      • Plaque accumulation for 10-21 days

      • Initial flora of GR + cocci and rods and GR – cocci becomes more complex

      • Increase in anaerobic GR – rods

      • F. nucleatum, P, intermedia, and an increase in Actinomyces

    • Periodontitis

      • Domination by GR – rods

      • P. gingivalis most important

      • P. intermedia, T. forsynthensis, F. nucleatum

  • Localized Juvenile Periodontitis

  • HIV Associate Periodontitis Conditions

    • Differ than other infections because of reduced host response and ability to fight infection





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