1. Infectious agents causing periodontal
diseases

2. Periodontal Disease Definition
An inflammatory disease of the supporting tissues of the teeth caused by specific microorganism, resulting in progressive destruction of the periodontal ligament and alveolar bone with pocket formation, recession or both.

3. Periodontal Structures
Attachment Apparatus:
Cementum
Bone
Periodontal ligament

4. Periodontal Microbiology
1960’s
Spirochete might be the cause of acute necrotizing ulcerative gingivitis (ANUG)
Actinobacillus actinomycetemcomitans (A.A.) possible pathogen in localized aggressive periodontitis
Porphyromonas Gingivalis suggested to be important in chronic periodontitis.
1960 they observed large numbers of this organisms in sections of lesions of this disease. Returned of the specificity as a fundamental concept of the etiology of periodontal disease

5. Periodontal Microbiology

6. Complexity of the problem
Technical difficulties
Taking of the plaque samples
Uncontaminated samples
Laboratory diagnosis
Cultivation
Technical difficulties and the inadequate understanding of the biology of destructive peridontitis, uncontaminated samples from the correct location

7. Inadequate understanding of Disease Pathogenesis
Misclassification of the disease type and status
Disease due to different species at different sites
Succesive episodes of disease due to different species
Mistaken conclusion of samples taken from sites in remission
Interprating them as if th ey from sites undergoing active destruction

8. Complexity of the Problem
Pathogens may result from the disease rather than the cause
Two or more species act together and cause disease
The carrier state of disease can represent a long lag phase prior to detection of disease
Differences in clonal types

9. Approach to Determining Etiologic Agents
Koch’s Postulates:
1) The agent must be routinely isolated from diseased individuals and recovered from cases of other forms of disease or healthy individuals
2) The agent must be isolated as a pure culture
3) Produce a similar disease when inoculated into susceptible laboratory animals
4) The agent must be re-isolated from infected animal
Third criteria was abandoned by kocks in 1884

10. Approach to Determining Etiologic Agents
In recent years, periodontal researchers have extended Koch’s postulates including:
Association
Requires that suspected pathogenic species be more frequently detected and at higher level in cases than in the controls
Elimination
Successful therapy will diminish the level of a pathogen and stop disease progression
Host response
the organism must have high levels of serum, salivary and gingival fluid antibody against it in periodontally diseased subjects

11. Approach to Determining Etiologic Agents
Virulence factors
the organism must be found to produce virulence factors in vitro which can be correlated with clinical histopathology
Animal Pathogenicity
the organism must mimic similar pathogenic properties in an appropriate animal model

14. Plus associated with the bacteria

15. Evolving Concepts Susceptible Host Active Disease
Presence of Pathogens
S sanguis
Absence of Beneficial Species
Destructive Periodontal Disease

16. Evolving Concepts Susceptible Host Impaired Neutrophils
Inadequate or unregulated immunological response
LPS Responsiveness
AIDS
Diabetes
Smoking
Drugs
Lps some patient il1react very high to and have high responsivenes to lipopolisacharides,inmmunological response like in papillon lefre

17. Evolving Concepts Presence of Pathogens
Actinobacillus actinomycetemcomitans
T. forsythus
Eikenella corrodens
Fusobacterium nucleatum
Peptostreptococcus micros
Porphyromonas gingivalis
Prevotella intermedia
Campylobacter rectus
Selenomonas sp.
Eubacterium sp.
Spirochetes

18. Evolving Concepts Absence of Beneficial species Actinomyces sp
Capnocytophaga ochracea
 [] C. ochracea;  [] P. gingivalis
Diminished attachment loss
S. mitis
S. mitis produces H2O2
Kills A. a.
Streptococcus sanguis
Veillonella parvula

19. (Bacteroides forsythus )
Veillonella parvula
Actinomyces odontolyticus
S. mitis
S. oralis
S. sanguis
S. gordonii
S. intermedius
Campylobacter rectus
Campylobacter. showae
Eubacterium nodatum
Fusobacterium nucleatum
Prevotella intermedia
Peptostreptococcus micros
Prevotella nigrescens
Porphyromonas gingivalis
Treponema denticola
Tannerella forsythensis
(Bacteroides forsythus )
Capnocytophaga spp.
Eikinella corrodens
A. actinomycetemcomitans
Red complexes is associated with periodontitis
Microbial Complexes in Subgingival Plaque

20. Role of Disease Susceptibility
Microbial species unevenly distributed from subject to subject and from site to site
Subjects with widespread disease had more sites showing new attachment loss than subjects with fewer affected sites at baseline
Percentages of suspected pathogens is highest in subjects with localized destruction and lowest in widespread disease subjects
Subjects with widespread disease and high levels of suspected pathogens had a greater number of active sites than subjects in other groups

21. Bacterial interactions
Different types of microorganisms existing in periodontal pockets may act synergistically to induce disease progression
Bacterial interactions may be beneficial to the host

22. Virulent Clonal Types of Pathogens
Multiple clonal types within a pathogenic species
Clonal types differ in pathogenicity (A.a.)
Some clonal types are associated with health and others with disease

23. Regulation by the Local Environment
Strains of many species may turn virulence factors “on/off”, depending on the nature of their environment:
Temperature
 subgingival
 new attachment loss (appears)
Iron [ ]
Calcium
Magnesium
Osmolarity

24. Conclusions For a disease to result from a pathogen:
Be a virulent clonal type
Must possess chromosomal/extrachromosomal genetic factors to initiate disease
Host must be susceptible to pathogens
Pathogen must be in numbers sufficient to exceed threshold for the host
Must be located in the right place
Other bacterial species must foster or at least not to inhibit the process
Local environment must be favorable to disease expression