W4 Biofilm Flashcards
What are the characteristics of bacteria?
Fimbriae: hair like structures
Capsule: protection against phagocytosis
Peptides: Induce inflamation.
Exotoxins: damage host immune cells
Enzymes: damage host protein acquisition of nutrients
How do you classify bacteria?
Gram staining: Positive and negative Positive, purple, thick peptidoglycan Negative, red, thin layer of peptidoglycan on the
Cell morphology: cocci, bacilli, spirilla
Motile vs non-motile
Relationship with Oxygen to sustain life, will affect sub/supra
What are the stages of biofilm formation?
Acquired pellicle Associated/Adhesion: Coaggregation/Multiplycation Microcolony Formation Maturation & Dispersal
Describe Association
Within a few hours after pellicle formation, bacterial associate loosely with the acquired pellicle , fibriae.
Describe Adhesion
Some bacteria have surface molecules called adhesions that bind to pellicle receptors that aid in stronger attachment. Early colonisers
What is the acquire pellicle?
Made from saliva that consists of glycoproteins & antibodies. It can facilitate adhesion of platonic bacteria
Describe Coaggregation
Secondary colonizers: not random, bacteria have specific coaggregation partners, important in biofilm development
Describe multiplication
Multiplication of attached micro-organisms
Describe Microcolony Formation
Attachment of Fusobacterium Nucleatum coaggregates with initial, early and late colonizers, acts at the bridge. → Coaggregation of Late Colonizers Gram negative species (rods, cocci, spirochetes) pathogenic species
Describe Maturation and Dispersal
Bacteria proliferate and begin to grow away from the tooth surface in mushroom-shaped microcolonies. Allows coaggregation of Periodontal pathogens
What bacteria cause caries?
Streptococci Mutans: S.mutans and S. sobrinus - which are faculative anaerobe and gram positive
Lactobacilli - facultative anaerobe, gram positive. Both are acidogenic and produce lactic acid. Thrive in low pH
What causes periodontal pathogens?
Porphyromonas gingivalis: obligate anaerobes promotes inflammatory response in phagocytic cells.
Fusbacterium Nucleatum: Anaerobe, activates inflammatory pathway in epithelial cells,
Tannerella Forsythia: most significant risk factor
Spirochetes Aggregatibacter: strongly associated with aggressive tissue destruction characteristic of disease
- Prevotella Intermedia*
- Treponema denticola*
What Socranskys colours are related to health?
Yellow and green
What Socranskys colours are associated with periodontal disease?
Orange and red
What are the benefits for bacteria living in a plaque biofilm?
Protection and resistance from the host defence mechanism Protection and resistance from anti microbial agents
What are the benefits of the Supragingival Environment?
Avaliable nutrients (dietry carbs) Salivary glycoproteins pH (aerobic initially)
What are the benefits of Subgingival environment?
Available nutrients comes from gingival crevicular fluid Little to no saliva Periopocket depth
What is the enamel caries zone?
4 zones,
- Translucent zone (porosity 1%)
- Dark zone (porosity 2-4%)
- Body of lesion (porosity 25%)
- Surface zone (relatively unaffected)
What is the first zone to be affected by enamel caries?
Surface Zone - not always present the superficial, relatively unaffected
What is reactionary/reparative dentine?
Bacterial by products reaching tubules triggers its synthesis
What is sclerotic dentine?
Sclerotic dentine shows occluded tubules wih a thich peritubular layer and a calcified tubular lumen that contains minerals
What are dead tracts?
Due to tubular occlusion within the sckerotic zone and retraction of the odontoblastic cellular processes, the dentinal tubules in the dead-tract zone appear empty and cut off from the living odontoblast
Define the zone of demineralization
AFFECTED:Clinically referred to as affected dentine. It is caused by the diffusion of bacterial acids into dentine, contains less mineral that sclerotic dentine, becomes stained and progressively more stained (darkbron) leather and hard in texture
Define the zone of demineralization
AFFECTED:Clinically referred to as affected dentine. It is caused by the diffusion of bacterial acids into dentine, becomes stained and progressively more stained (darkbrown) leather and hard in texture
Define the Zone of penetration
INFECTED:Referred to clinically as infected dentine. Occurs after cavitation permits direct bacterial invasion; appears clinically soft, yellow-brown mass of cheesy texture.
What is pulpal inflammation?
The progressing carious lesion triggers an inflammatory pulpal reaction due to the permeability of dentine ti soluble products of bacteria. Lymphocytes, macrophages and plasma cell early response. It may be reversible. Odontoblasts stimulated to synthesis tertiary dentine.
What happens once caries lesion has progressed to secondary dentine or pulp cavity’?
Large inflammatory response will take place and production of acute inflammatory cells mostly neutrophils in the tissue beneath the lesion. Lysosomal enzymes discharged by the neutrophils result in wide spread tissue damage and suppuration
What are the stages of disease pathogenesis?
Kiane and Lindhe.
- Clinical healthy
- Normal healthy gingiva
- Early gingivitis
- Established gingivitis
- Periodontitis
What should normal healthy gingiva look like?
Histological inflammation signs appear within 4 days of plaque accumulation, it is not clinically visible.
Sucular and Junctional are immunologically active sensors of plaque biofilm, epithelium has receptors that recognise pathogens and release chemical mediators to initiate immune response.
Tight epithelial cell junctions act as a physical barrier to bacterial invasion.
What are the signs of early gingivitis?
Approx after 7 days of plaque accumulation an inflammatory infiltrate of leukocytes develops at sight of initial lesion.
Cytokines result in destruction of collagen. Biochemical mediators are released - clinical signs of redness and swelling
What are the signs of established gingivitis?
After 2-3 weeks of plaque accumulation the early lesion evolves into an established lesion.
↑ size of affected area lots of plasma cells and lymphocytes. Macrophages and lymphocytes are most numerous in CT, Neutrophil infiltration into the sulcus. Gingival sulcus deepens, ↑ probing depth redness and swelling
What are the signs of periodontitis?
Plaque biofilm grows along the root surfac, changes marked by T-cell to B-cell predominance, accompanied by destruction of CT, apical migration of epithelial attachment.
Clinical sings include periodontal pocket formation, surface ulceration suppuration, destruction of alveolar bone, tooth mobility, drifting and tooth loss
On a cellular level what is periodontitis?
Chronic inflammation results in sustained overproduction of pro-inflammatory biochemical mediators
Cytokines: recruit cells to the infection site
Matrix metalloproteinases: over production break down CT and collagen
Prostoglandins: trigger osteoclasts to destroy crest of alveolar bone
