Etiology of periodontal diseases4)6-4...Etiology of periodontal diseases •The clinical...

Etiology of periodontal

diseases 6/4/2020 9سيميستر

Etiology of periodontal diseases

• The clinical manifestations of periodontal disease

result from a complex interplay between the etiologic

agents, specific bacteria found in dental plaque, and

the host tissues.

Etiology of Periodontal Diseases

Initiating factors Predisposing factors

(modifying)

Dental plaque

Local Systemic


• Bacteria of oral cavity can be classified according to:

Morphotypes : cocci (spherical), rods(bacilli),

spirochetes (spiral).

Cell wall staining: gram +ve , gram –ve.

Oxygen requirement for growth: Aerobics,

Anaerobic, facultative anaerobic.

Bacterial metabolism: saccharolytic, Asaccharolytic

Dental plaque

• It is defined clinically as a structured, soft

yellow-grayish substance that adheres

tenaciously (firmly) to teeth surfaces and

other intraoral hard surfaces including

removable and fixed restorations.


• Composition of dental plaque:


• This matrix consists of organic and inorganic

materials derived from saliva, gingival crevicular

fluid, and bacterial products:

Classification of dental plaque ( based on its position )

Supragingival Subgingival

At or above gingival margin below gingival margin

The different regions of plaque are significant

to different processes associated with diseases:


• Formation of dental plaque


1. Formation dental of pellicle:


2. Initial adhesion and colonization of bacteria


3. Secondary Colonization and Plaque

Maturation.


• Coaggregation:


• interactions of secondary colonizers with early

colonizers include the coaggregation of:

F. nucleatum with S. sanguis,

P. loescheii with A. viscosus,

Capnocytophaga ochracea with A. viscosus.


Microscopic Structure and Plaque as a

biofilm:


II. Subgingival plaque:

- Less oxygen tension ( anaerobic)

- Need more motile


• The tooth-associated (attached) plaque


• tissue-associated plaque


• Physical properties and Significance of the

Plaque Biofilm Environment:


• The host also functions as an important source of

nutrients. For example,

1. the bacterial enzymes that degrade host proteins

result in the release of ammonia, which may be used

by bacteria as a nitrogen source

2. Hemin iron from the breakdown of host hemoglobin

may be important in the metabolism of P. gingivalis


3. Increases in steroid hormones are associated with

significant increases in the proportions of P.

intermedia found in subgingival plaque (pregnancy)


• Significance of the Biofilm

- The bacteria within the biofilm are well protected

from host response as well as antimicrobial agents.

- So periodontal therapy depend mainly on elimination

and physical destruction of the biofilm (scaling &

root planning )


ASSOCIATION OF PLAQUE MICROORGANISMS

WITH PERIODONTAL DISEASES:


Nonspecific Plaque Hypothesis


Specific Plaque Hypothesis


• criteria of periodontal pathogen:


• Microorganisms Associated with Specific

Periodontal Diseases:


Gingivitis:


Chronic Periodontitis:


Localized Aggressive Periodontitis:


Necrotizing Periodontal Diseases:


Abscesses of the Periodontium.

Etiology of periodontal diseases4)6-4...Etiology of periodontal diseases •The clinical...

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