Transcript Infectious agents causing periodontal diseases
Infectious agents causing periodontal diseases
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.
Periodontal Structures
Attachment Apparatus: Cementum Bone Periodontal ligament
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.
Periodontal Microbiology
Complexity of the problem
Technical difficulties Taking of the plaque samples Uncontaminated samples Laboratory diagnosis Cultivation
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
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
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 animals when inoculated into susceptible laboratory 4) The agent must be re-isolated from infected animal
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
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
Active Disease
Evolving Concepts
Susceptible Host Presence of Pathogens Absence of Beneficial Species Destructive Periodontal Disease
Evolving Concepts
Susceptible Host Impaired Neutrophils Inadequate or unregulated immunological response LPS Responsiveness AIDS Diabetes Smoking Drugs
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
Evolving Concepts
Absence of Beneficial species Actinomyces sp Capnocytophaga ochracea [] C. ochracea; [] P. gingivalis Diminished attachment loss S. mitis S. mitis produces H 2 O 2 Kills A. a.
Streptococcus sanguis Veillonella parvula
Veillonella parvula Actinomyces odontolyticus S. mitis S. oralis S. sanguis S. gordonii S. intermedius Capnocytophaga spp.
Eikinella corrodens A. actinomycetemcomitans Camp yl obacter rectus Campylobacter. showae Eubacterium nodatum Fusobacterium nucleatum Prevotella intermedia Peptostreptococcus micros Prevotella nigrescens Porphyromonas gingivalis Treponema denticola Tannerella forsythensis (Bacteroides forsythus )
Microbial Complexes in Subgingival Plaque
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
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
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
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
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