Epidemiology of Periodontal Disease
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This handout is provided by the CLR.
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
 Identify characteristics but cannot asses prevalence or
incidence
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
 Can be quantified, tabulated and used in comparisons
 Predict disease patterns, progression and trends
- 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
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This handout is provided by the CLR.
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)
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This handout is provided by the CLR.
Contains endotoxins that release upon cell lysis and directly affect
host tissues or activate a host response
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
- P. gingivalis
- T. forsynthensis
- F. nucleatum
- A. actinomycetemcomitans
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
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This handout is provided by the CLR.
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
- First molars and sometimes incisors
- A. actinomycetemcomitans is main agent
- Familial pattern of defective PMN’s
- Less GR – than periodontitis
HIV Associate Periodontitis Conditions
- Differ than other infections because of reduced host response and
ability to fight infection