7 Etiology of Periodontal Disease

7/31/2019 7 Etiology of Periodontal Disease

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Etiology of PeriodontalDisease

Dr. Marcel Hallare


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Periodontal disease is a pathologic processthat affects the periodontium

The vast majority of inflammatory diseasesof the periodontium results from bacterial

infection The dominating causative agents of

periodontal disease are microorganisms thatcolonize the tooth surface (bacterial plaque

and products) No systemic disorder is known to be the

initiating cause of periodontitis in theabsence of bacterial plaque


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TOOTH-ACCUMULATED MATERIALS

1. Bacterial plaque2. Acquired pellicle

3. Calculus

4.

Food debris5. Materia alba


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Bacterial plaque

Two types of plaque that are closelyassociated with periodontal disease:

1. Consists of a mat of densely packed,colonized, and colonizing microorganismsthat grow on and attach to the tooth

2. Free floating or loosely attached betweenthe soft tissue and teeth


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Acquired pellicle

Primarily a protein film that forms onerupted teeth and can be removed byabrasives

Quickly reforms after being removed

Not removed by forceful rinsing


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Calculus

Calcified plaque that is usually coveredby a soft layer of bacterial plaque


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Food debris

Food matter that is retained in the mouth


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Materia alba

(literally, white matter)A soft mixture of salivary proteins, some

bacteria, many desquamated epithelialcells, and occasional disintegrating

leukocytes Usually flushed off with forceful water

spray


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BACTERIAL FACTORS INPERIODONTAL DISEASE


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Morphology of BacterialPlaque

Under light and SEM, supragingivalplaque and subgingival plaque havedistinct morphological differences


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Supragingival Plaque

Bacterial cells appear to be denselypacked on the tooth surface and thedeposits may be thick (0.5mm or more)

Composition of the microbial deposits

includes coccoid and relatively numerousfilamentous bacteria


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Some filamentous bacteria are coveredwith coccal organisms, which appear as

corncob formations

Flagellated forms and spirochetes areobserved apically and on the outer

surface


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Subgingival Plaque

Subgingival plaque in periodontitispatient is composed of an inner and anouter layer

The inner layer is tightly adherent

bacteria is continuous with, but is thinnerand less organized than supragingivalplaque


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Outside this tightly adherent layer, andadjacent to the soft tissue of the pocket,is a loosely adherent layer ofmicroorganisms

This layer consists of numerousspirochetes, gram-negative bacteria, and

bacteria grouped into bottle-brush ortest-tube brush formations


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Microorganisms of Plaque

Young plaque (1-2 days) consistsprimarily of gram-positive and somegram-negative cocci and rods

From 2-4 days of growth, undisturbed

plaque changes in the numbers and thetypes of organisms present


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The number or gram-negative cocci androds increase and fusiform bacilli and

filamentous organisms becomeestablished

From 4-9 days, this ecologically complexpopulation of microorganisms is further

complicated by the presence of theincreasing number of motile bacteria,namely, spirilla and spirochetes


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1. Epithelial cells2. White Blood cells

3. Erythrocytes

4. Protozoa

5. Food particles

6. Miscellaneous components

Other Constituents of Plaque


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Mechanism of Bacterial Action

1. Invasion2. Cytotoxic agent

3. Enzymes

4. Immunopathologic mechanism

5. Combined action


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Invasion

Bacterial invasion is not necessary forgingival inflammation to occur

All that is required id that enoughbacteria (and possibly specific pathogenic

bacteria) be fixed to the tooth, near thegingiva, for sufficient length of time tochallenge the tissue with their toxicproducts


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Cytotoxic agent

Endotoxins, which are lipopolysaccharideconstituents of the cell wall of gram-negative bacteria, can be a direct causeof tissue necrosis, as well as initiator of

inflammation by triggering animmunologic response and activation ofthe complement system


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Enzymes

Collagenasedepolymerizes collagen

fibers and fibrils, the major formedelements in the gingiva and periodontalligament

Proteases, a family of enzymes,contribute to breakdown of non-collagenous proteins and increasecapillary permeability


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Hyaluronidasehydrolyzes hyaluronic acid,an important tissue cementingpolysaccharide, and can act as a

spreading factor to increase tissuepermeability

Chondroitinasehydrolyzes chondroitin

sulfate, another tissue-cementingpolysaccharide


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Immunopathologic mechanism

The role of the immunologic response inperiodontal disease is not completelyunderstood; however, the potential tocause tissue destruction is apparent


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Combined action

It is possible that more than onemechanism may be involved in theinitiation and progression of inflammatoryperiodontal disease


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SYSTEMIC FACTORS ANDPERIODONTAL DISEASE

Any condition that might reduce theresistance of periodontium to toxic insultshould be expected to contribute to theinitiation of the inflammation and to

influence the rapidity and severity of thedisease process


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LOCAL CONTRIBUTING FACTORSAND PERIODONTAL DISEASE

1. Anatomic factors2. Iatrogenic factors

3. Calculus formation

4. Traumatic factors

5. Chemical injury

6. Excessive occlusal force


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Anatomic factors

Root morphology Position of tooth in arch

Root proximity


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Iatrogenic factors

Operative procedures Restorative materials and restorations

Removable partial dentures

Fixed partial denture Exodontics

Orthodontics


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Calculus formation

Important in the progression of disease Serves as a coral reef within which

microorganisms can multiply and releasetheir toxic products

The rough surface of calculus makes itdifficult if not impossible, for the patientto remove associated bacterial plaque


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Traumatic factors

Toothbrush abrasion Factitious disease

Food impaction


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Chemical injury

Indiscriminate use of topically appliedaspirin tablets, strong mouthwashes, andvarious escharotic drugs may result inulceration of the gingival tissue


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Excessive occlusal force


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Neoplasms


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Renewal of GingivalEpithelium

The oral epithelium undergoescontinuous renewal

Its thickness is maintained by a balancebetween new cell formation in the basal

and spinous layers and the shedding ofold cells at the surface


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Mitotic activity exhibits a 24-hourperiodicity, with highest and lowest ratesoccurring in the morning and eveningrespectively

Mitotic rate is highest in nonkeratinizedareas and is increased in gingivitis,without significant gender differences


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Turnover times of tissue:

palate, tongue, cheek 5-6 days

gingiva 10-12 days

junctional epithelium 1-6 days


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The End

7 Etiology of Periodontal Disease

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