Etiology and Pathogenesis of Periodontal Disease Flashcards
What is the etiologic factor of Periodontal Disease?
PLAQUE
Define gingivitis?
An inflammatory process confined to the gingival tissues
Is gingivitis reversible?
Yes, usually.
Define periodontitis?
Inflammation not confined to the gingiva, but involves the attachment apparatus (cementum, periodontal ligament, alveolar bone, and soft tissue)
Where does periodontal disease stem from?
Microbial plaque
Genetics/Host Factors
Acquired/Environmental Factors
What are Koch’s postulates?
1) Microbe must be present in all cases
2) Microbe must then be isolated and grown
3) Microbe must cause same disease in another animal
4) Microbe must be reisolated and prove to be the original microbe
Based off the Danish study, how long does it take to develop gingivitis?
10-21 days
Based off the Danish study, how long did it take for people who had gingivitis to recover with oral hygiene?
1 week
Based off the Danish study, the appearance of gram negative flora preceded detectable gingivitis by how many days?
3-10 days
In what layers do bacteria grow?
aerobic -> facultative -> anaerobic
What hypothesis is believed to be the etiology of periodontal disease?
Specific plaque hypothesis combined with a susceptible host.
1) Bacterial infections
2) Risk factors
3) Systemic effects
What bacterial enzymes are known to cause tissue destruction?
Collagenase Proteases Nueraminidase Ribonuclease Deoxyribonuclease Hyaluronidase Chondroitin sulfatase
What bacterial cytotoxic agents cause cell death?
Exotoxin of actinobacillus Endotoxin (gram negative) Mucopeptides (gram positive) Ammonia Hydrogen Sulfide Toxic amines Organic acids
What did the sri lanka data?
Not all individuals get periodontitis
What microbes make up microbial plaque?
Bacteria Fungus Protozoa Virus Mycoplasm
What are innate risk factors that lead to periodontal disease?
Race Sex Genetic factors/inheritance Congenital immunodeficiencies Phagocytic dysfunction Down syndrome Papillon-Lefevre/Ehlers-Dantos syndrome
What are two places calculus attaches to?
Supragingival calculus
Subgingival calculus
Basic properties of biofilms?
Cooperating community
Microcolonies connected with channels
Microcolonies protected with protective matrix
Quorum Sensing
Resistance to antibiotics, immune system, antimicrobials
What types of colonizers are there that attach to the pellicle?
Early Colononizers
Late Colonizers
Which type of colonizers are most likely to cause periodontal diseases?
1) Red Complex
- P. gingivalis
- T. forsythensis
- T. denticola
- Aggregatibacter actinomycetemcomitans
2) Orange complex
- Campylobacter: gracili, rectus, showae
- Eubacterium: nodatum
- Fusobacterium: nucleatum, polymorphum
- Prevotella: intermedia, nigrescens
- Peptostreptococcus: micros
- Streptococcus: constellatus
What do many of the main late colonizers have in common?
gram neg
non-motile
What does the fluid gradient in the mouth do to help a biofilm?
moves nutrients around
allows bacteria to communicate
How can biofilms resist antibiotics?
antibiotic penetrates too slowly or incompletely
What initiates and progresses periodontal disease?
Initiation: non specific plaque accumulation
progression: G- bacteria and susceptible host.
Where is plaque most likely to accrue?
Distally, on the buccal posterior teeth
T/F Not all gingivitis progresses to periodontitis but all periodontitis is preceded by gingivitis.
T
Virulence or pathogenicity factors that enable bacteria to cause disease?
1) fimbrae, pili: allow attachment and prevent phagocytosis
2) Capsule: allows protection, attachment, prevents phagocytosis
3) Endotoxin: activation of inflammatory response, cytokine production, bone resorption
T/F The ability for bacteria to adhere is a virulence factor?
T
How are bacteria displace if they do not attach to the pellicle?
Due to gingival crevicular fluid
What is the formula that adds up to periodontal disease?
Pathogenic flora + Lack of beneficial bacteria + susceptible host
What is larger player with a big name known to be a periodontal pathogen?
Aggregatibacter actinomycetemcomitans
What are beneficial bacteria in the periodontium?
Actinomyces spp. Strep. mitis Strep. sanguis Capnocytophaga spp. V. parvula
What are factors that could lead to a susceptible host?
Impaired neutrophils Inadequate immune response LPS responsiveness AIDS Diabetes Smoking Drugs
What are the types of dental plaque?
Supragingival: coronal, marginal
Subgingival: Attached plaque (tooth, epithelium, CT) Unattached
What characteristic do unattached plaque usually have?
G-
Motile
Inbetween attached plaque and sulcular epithelium
In contact with junctional and sulcular epithelium
Steps of plaque formation?
1) Pellicle formation
2) Attachment
3) Young supra-gingival plaque (G+ mainly)
4) Aged supra-gingival plaque (G- increase)
5) Sub-gingival plaque (attached, unattached)
What main difference exist between supra and sub gingival plaque?
Supra: G+ mostly, non-motile mainly, aerobic unless thick, metabolizes carbs
Sub: G- mostly, motile, anaerobic, metabolizes proteins
What main differences exist between tooth and epithelium associated subgingival plaque?
Tooth-associated: G+, does not extend to JE, may penetrate cementum, calculus & root caries
Epithelium-associated: G+ & G-, Extends to JE, may penetrate epithelium/CT, gingivitis and periodontitis
Bacteria with a very strong association to Periodontal diseases?
A.a.
P. Gingivalis
T. Forsythia
Bacteria with a strong association to Periodontal diseases?
P. intermedia E. nodatum Treponema sp. Eubacterium sp. C. rectus
Bacteria with a moderate association to Periodontal diseases?
S. intermedius
F. nucleatum
E. corrodens
P. Micros
Chronic periodontitis commonly involves what bacteria?
P. gingivalis P. intermedia F. nucleatum A.a. C. recta T. forsythia
What does LAP stand for?
Localized agressive periodontitis
- A.a.
- P. intermedia
- P. gingivalis
Refractory disease is commonly caused by what bacterium?
T. forysthia
P. gingivalis
P. intermedia
C. recta
What does NUG stand for?
Necrotizing Ulcerating Gingivitis
- caused by P. intermedia (intermediate sized spirochetes)
What are HIV associated bacteria that cause gingivitis?
Candida albicans (yeast) P. gingivalis P. intermedia F. nucleatum A.a. C. recta
Describe attributes of Aggregatibacter actinomycetemcomitans?
Small, non-motile G- Facultative anaerobe Saccharolytic Coccobacillus Prevelance 90% in LAP Prevelance 30-50% in chronic periodontitis
What unique ability does Aggregatibacter actinomycetemcomitans to cause serious damage?
- * has the ability to invade host epithelial cells**
* *** releases exotoxin called a LEUKOTOXIN
What is an endotoxin?
Found in G- bacteria. LPS layer has the ability to release virulent factors into surrounding environment either by cell degradation or by budding off pieces of LPS.
This has cytotoxic effects. Leads to bone resorption.
Describe attributes of P. gingivalis?
G- anaerobic non-motile Bacillus Fimbriae forms dark brown-black colonies
Describe unique attributes of P. gingivalis?
- * has the ability to invade host epithelial cells**
- *** able to grow at low pH
- *** has a thick capsule to resist phagocytosis
- *** has proteinases - include collagenase
- *** stimulates cytokine production in monocytes and macrophages
Describe attributes of T. forsythia
G-
anerobic
grows best with F. nucleatum
** invades epithelial cells
Describe attributes of P. intermedia
Black pigmented bacteroides
G-
anaerobic
Elevated in ANUG
Describe attributes of F. nucleatum
G-
anaerobic
Spindle shaped rod
** most common isolate from sub-gingival samples
Describe attributes of C. rectus
G-
anaerobic
Motile
*** produces leukotoxin
Describe attributes of P. micros
G+ (only one in lecture discussed)
anaerobic
small coccus
Describe attributes of spirochetes
G-
anaerobic
helical shaped
related to NUG
What is considered an active site?
A site that shows attachment loss greater than 2-2.5mm in 2 months.
What occurs with initial (2-4 day) lesion?
Histologically: Vasculitis, exudation of fluid from sulcus, inc. in leukocytes into j.e. and sulcus, serum proteins released extrvascularly *fibrin
Clinically: appears healthy
What occurs with early lesion (4-7) days?
Histologically: accumulation of lymphoid cells into j.e., fibroblast activation, loss of collagen network of marginal gingiva, proliferation of basal cells of j.e.
Clinically: gingivitis, w/ no change in pp depth or bone loss
What occurs with an established lesion (2-3) weeks?
Histologically: acute inflammation, plasma cells present w/o bone loss, immunoglobulins extravascular in CT and j.e., continuation of tissue loss, early pocket formation
Clinically: gingivitis, change in gingiva color, no periodontal pocket or bone loss
What occurs with an advance lesion (>3 weeks)?
Histologically: Extension into alveolar bone and PDL, Collagen loss in pocket epithelium continued, periodontal pockets present, quiescence and exacerbation, bone marrow converted into fibrous connective tissue, widespread inflammation
Clinically: Periodontitis, change in color, Periodontal Pocket, Alveolar bone loss on radiographs
How does the body heal from periodontal disease?
Bacteria and bacterial products removed by phagocytes
Cytokines aid in repair of tissue and epithelium.
What is the bodies immune response to plaque accumulation and initiation of gingivitis?
Mast cells
acute phase proteins
PMNs
Antibodies
Events of the inflammatory process?
1) tissue injury –> chemical mediators released to increase permeability of adjacent small blood vessels
2) Blood vessel dilation and inc. permeability –> Tissues swell, Elevated temp, Redness, Pain from pressure in tissues
3) WBC adhere to walls of blood vessels –> chemotaxis of WBC, phagocytosis induced, and Antibody production intiated
What do mast cells release during inflammation?
Histamine
Chemotactic factors: eosinophils and PMN can come in
Interleukins
TNF alpha: recruitment of granulocytes –> fever
Leukotrienes: dilation of blood vessels
Protaglandins: inc. vascular permeability
Describe acute phase proteins.
Plasma proteins increased due to microbial infection Examples: C-reactive protein Fibrinogen Complement Mannose-binding protein Metal-binding proteins
What is a complement system?
20 different protein molecules always found in the blood. There are no cells in the system. With an infection, this system of molecules is activated, leading to a sequence of events on the surface of the pathogen that helps destroy the pathogen and eliminate the infection.
The complement system can be activated in two main ways. The first means of activation is part of the innate (natural) immune response. (i.e.; neither antibodies nor T cell receptors are involved.) For example, certain polysaccharides found on the surface of bacteria can activate the system. This can occur immediately and does not require prior exposure to the molecules.
The second and most potent means occurs in a adaptive immune response when antibodies (IgG or IgM) binds to antigen at the surface of a cell. This exposes the Fc region of the antibody in a way that allows the first complement protein (C1) to bind.
What happens as a result of the activation of a complement system?
A cascade of events follows, in which each step leads to the next. At the center of the cascade are steps in which the proteolysis of a complement protein leads to a smaller protein and a peptides. The smaller protein remains bound to the complex at the surface of the microorganism, while the peptide diffuses away.
Complement C3 is cleaved into C3b and C3a. C3b remains bound to the complex at the surface of the microorganism. This not only activates the next step, but also C3b is a good opsonin. The small peptide, C3a diffuses away and acts as a chemotactic factor and an inflammatory paracrine.
Next, complement protein C5 is cleaved into C5b and C5a. The C5b remains bound to complex on the surface of the cell while the C5a diffuses away and acts much like C3a.
Then the complement proteins C6, C7, and C8 bind successively to the growing complex. Finally, a number of C9 complement proteins bind to the complex. These C9 proteins are elongated molecules that form a circle with a large hole in the middle. This structure, which is called a membrane attack complex (MAC), pierces the membrane of the cell. This initiates a sequence of event leading to lysis (of a microbe) or apoptosis (of a cell of the body in pathologies and tissue transplants).
A complement response system aids in carrying out what parts of an immune response?
opsonization (labeling pathogen)
chemotaxis
inflammation
lysis, apoptosis
What does a MAC do?
Membrane attack complex: creates a hole in the membrane of the pathogens cell wall.
What types of leukocytes are there?
Granulocytes: Neutrophils (aka PMN, most common of all cells), Eosinophils, Basophils
Mononuclear phagocytes: –> monocytes, machrophages, dendritic cells
Lymphocytes: NK cells, T cells, B cells
What are characteristic of PMNs?
Terminal cell with short half life
Roll around on endothelium (diapedesis, chemotaxis)
Adhere to target, phagocytize, lyse or apoptose
*****Kill with oxidative or nonoxidative means
What stimulates the entrance of PMNs into infected tissue?
Bacterial LPS layers triggers selectins to be released on endothelium
Additionally monocyte releases IL-1 or TNF-alpha which causes selectins to be released on endothelium
Then Integrins are expressed on endothelium and PMN enters
What is the most common bacterial protein that the body detects to initiate an immune response?
F-met peptides
What are common everyday host risk factors can modify neutrophils ability to be effective?
Diabetes
Smoking
