Infectious agents causing periodontal diseases

Periodontal DiseasePeriodontal Disease DefinitionDefinitionAn inflammatory disease of the An inflammatory disease of the

supporting tissues of the teeth supporting tissues of the teeth caused by specific microorganism, caused by specific microorganism, resulting in progressive destruction resulting in progressive destruction of the periodontal ligament and of the periodontal ligament and alveolar bone with pocket formation, alveolar bone with pocket formation, recession or both.recession or both.

Periodontal StructuresPeriodontal Structures Attachment Attachment

Apparatus:Apparatus:

CementumCementum BoneBone PPeriodontal eriodontal

ligamentligament

Periodontal MicrobiologyPeriodontal Microbiology 1960’s1960’sSpirochete Spirochete might be the cause of acute might be the cause of acute

necrotizing ulcerative gingivitis necrotizing ulcerative gingivitis (ANUG)(ANUG)

Actinobacillus actinomycetemcomitans Actinobacillus actinomycetemcomitans (A.A.) possible pathogen in localized (A.A.) possible pathogen in localized aggressive periodontitisaggressive periodontitis

Porphyromonas Gingivalis Porphyromonas Gingivalis suggested to suggested to be important in chronic periodontitis. be important in chronic periodontitis.

Periodontal MicrobiologyPeriodontal Microbiology

Complexity of the Complexity of the problemproblem

Technical difficultiesTechnical difficulties

Taking of the plaque samplesTaking of the plaque samples

Uncontaminated samples Uncontaminated samples Laboratory diagnosisLaboratory diagnosis CultivationCultivation

Inadequate understanding of Inadequate understanding of Disease PathogenesisDisease Pathogenesis

Misclassification of the disease type and statusMisclassification of the disease type and status

Disease due to different species at different sitesDisease due to different species at different sites

SuccesiveSuccesive episodes of disease due to different episodes of disease due to different speciesspecies

MistakenMistaken conclusion of samples taken from sites conclusion of samples taken from sites in remissionin remission

Pathogens may result from the disease Pathogens may result from the disease rather than the causerather than the cause

Two or more species act together and cause Two or more species act together and cause diseasedisease

The carrier state of disease can represent a The carrier state of disease can represent a

long lag phase prior to detection of diseaselong lag phase prior to detection of disease

Differences in clonal typesDifferences in clonal types

Complexity of the Complexity of the ProblemProblem

Approach to Determining Approach to Determining Etiologic AgentsEtiologic Agents

Koch’s Postulates:Koch’s Postulates:

1) 1) The agent must be The agent must be routinely isolatedroutinely isolated from diseased from diseased individualsindividuals and and recovered from cases of recovered from cases of other forms of other forms of diseasedisease or or healthy individualshealthy individuals

2) 2) The agent mustThe agent must be isolated as a be isolated as a pure culturepure culture

3) 3) Produce a similar diseaseProduce a similar disease when inoculated into when inoculated into susceptible laboratory animalssusceptible laboratory animals

4) 4) The agent must beThe agent must be re-re-isolatedisolated from infected animal from infected animal

Approach to Determining Approach to Determining Etiologic AgentsEtiologic Agents

In recent years, periodontal researchers In recent years, periodontal researchers have extended Koch’s postulates including:have extended Koch’s postulates including:

AssociationAssociation Requires that suspected pathogenic species be more Requires that suspected pathogenic species be more

frequently detected and at higher level in cases than in frequently detected and at higher level in cases than in the controlsthe controls

EliminationElimination Successful therapy will diminish the level of a pathogen Successful therapy will diminish the level of a pathogen

and and stopstop disease progression disease progression Host responseHost response

the organism must have high levels of serum, salivary the organism must have high levels of serum, salivary and gingival fluid antibody against it in periodontally and gingival fluid antibody against it in periodontally diseased subjectsdiseased subjects

Approach to Determining Approach to Determining Etiologic AgentsEtiologic Agents

Virulence factorsVirulence factors the organism must be found to produce the organism must be found to produce

virulence factors in vitro which can be virulence factors in vitro which can be correlated with clinical histopathologycorrelated with clinical histopathology

Animal PathogenicityAnimal Pathogenicity the organism must mimic similar pathogenic the organism must mimic similar pathogenic

properties in an appropriate animal modelproperties in an appropriate animal model

Evolving ConceptsEvolving Concepts

Active Disease

Absence of Beneficial Species

Presence of Pathogens

Susceptible Host

Destructive Periodontal Disease

Evolving ConceptsEvolving ConceptsSusceptible HostSusceptible Host

Impaired NeutrophilsImpaired Neutrophils Inadequate or unregulated Inadequate or unregulated

immunological responseimmunological response LPS ResponsivenessLPS Responsiveness AIDSAIDS DiabetesDiabetes SmokingSmoking DrugsDrugs

Evolving ConceptsEvolving ConceptsPresence of PathogensPresence of Pathogens

AActinobacillusctinobacillus actinomycetemcomitans actinomycetemcomitans T. forsythusT. forsythus EEikenellaikenella corrodens corrodens FFusobacteriumusobacterium nucleatum nucleatum PPeptostreptococcuseptostreptococcus micros micros PPorphyromonasorphyromonas gingivalis gingivalis PPrevotellarevotella intermedia intermedia CCampylobacterampylobacter rectus rectus Selenomonas sp.Selenomonas sp. Eubacterium sp.Eubacterium sp. SpirochetesSpirochetes

Evolving ConceptsEvolving ConceptsAbsence of Beneficial speciesAbsence of Beneficial species

Actinomyces sp Actinomyces sp CCapnocytophagaapnocytophaga ochracea ochracea

[] C. ochracea; [] C. ochracea; [] P. gingivalis [] P. gingivalis Diminished attachment lossDiminished attachment loss

S. mitisS. mitis S. mitis produces HS. mitis produces H22OO22

Kills A. a.Kills A. a. SStreptococcustreptococcus sanguis sanguis VVeillonellaeillonella parvula parvula

Porphyromonas gingivalis

Treponema denticola

Tannerella forsythensis

(Bacteroides forsythus )

Campylobacter rectusCampylobacter. showaeEubacterium nodatumFusobacterium nucleatumPrevotella intermediaPeptostreptococcus microsPrevotella nigrescens

Capnocytophaga spp.

Eikinella corrodens

A. actinomycetemcomitans

Veillonella parvula

Actinomyces odontolyticusS. mitis

S. oralisS. sanguisS. gordoniiS. intermedius

Microbial Complexes in Subgingival PlaqueMicrobial Complexes in Subgingival Plaque

Role of Disease Role of Disease SusceptibilitySusceptibility

Microbial species unevenly distributed from Microbial species unevenly distributed from subject to subject and from site to sitesubject to subject and from site to site

Subjects with widespread disease had more Subjects with widespread disease had more sites showing new attachment loss than sites showing new attachment loss than subjects with fewer affected sites at baselinesubjects with fewer affected sites at baseline

Percentages of suspected pathogens is highest Percentages of suspected pathogens is highest in subjects with localized destruction and in subjects with localized destruction and lowest in widespread disease subjectslowest in widespread disease subjects

Subjects with widespread disease and high Subjects with widespread disease and high levels of suspected pathogens had a greater levels of suspected pathogens had a greater number of active sites than subjects in other number of active sites than subjects in other groupsgroups

Bacterial interactions Bacterial interactions Different types of microorganisms Different types of microorganisms

existing in periodontal pockets may existing in periodontal pockets may act synergistically to induce disease act synergistically to induce disease progressionprogression

Bacterial interactions may be Bacterial interactions may be beneficial to the hostbeneficial to the host

Virulent Clonal Types of Virulent Clonal Types of PathogensPathogens

Multiple clonal types within a Multiple clonal types within a pathogenic speciespathogenic species

Clonal types differ in pathogenicity Clonal types differ in pathogenicity (A.a.)(A.a.)

Some clonal types are associated Some clonal types are associated with health and others with diseasewith health and others with disease

Regulation by the Local Regulation by the Local EnvironmentEnvironment

Strains of many species may turn Strains of many species may turn virulence factors “on/off”, depending on virulence factors “on/off”, depending on the nature of their environment:the nature of their environment: TemperatureTemperature

subgingival subgingival new attachment loss (appears) new attachment loss (appears)

Iron [ ]Iron [ ] CalciumCalcium MagnesiumMagnesium Osmolarity Osmolarity

ConclusionsConclusions For a disease to result from a pathogen:For a disease to result from a pathogen:

Be a virulent clonal typeBe a virulent clonal type Must possess chromosomal/extrachromosomal Must possess chromosomal/extrachromosomal

genetic factors to initiate diseasegenetic factors to initiate disease Host must be susceptible to pathogensHost must be susceptible to pathogens Pathogen must be in numbers sufficient to exceed Pathogen must be in numbers sufficient to exceed

threshold for the hostthreshold for the host Must be located in the right placeMust be located in the right place Other bacterial species must foster or at least not to Other bacterial species must foster or at least not to

inhibit the processinhibit the process Local environment must be favorable to disease Local environment must be favorable to disease

expressionexpression