Host defences against microbial plaque Flashcards
The balance between what 4 things prevents the formation of periodontal diseases?
- Presence of pathogen
- Absence of beneficial species
- Host response
- Conducive environment around the oral cavity
What are the functions of the host defences?
- To keep bacteria out out of the periodontium
2. Destroy any foreign microbes which succeeded in entering the system
What does plaque accumulation begin with?
Begins with pioneer species attach to the pellicle of a clean tooth surface
What are the stages of plaque formation
- Pioneer species attach to the pellicle surface of a clean tooth
- These multiply to form micro colonies
- Resulting in confluent growth of biofilm
- This increases species diversity
Name the 5 things that help defend us from plaque
- Saliva
- Gingival epithelium
- Inflammation
- Immune system
- Mediators
What are the functions of saliva?
It has a washing effect
It is a vehicle for swallowing bacteria
It also has an antimicrobial effect
Approx how many bacteria do we swallow?
10^8 bacteria in every mL of saliva we swallow
Name some antimicrobial substances in saliva
- Peroxidase/ Hypothiocyanate
- Lysozyme/ Lactoferrin
- Antibodies (IgA)
What occurs if there is a lack of saliva?
Xerostomia
What are some factors that may cause Xerostomia?
- Patients who are out breathers
- Drugs/ alcohol
- Radiotherapy
- Patients who have had their salivary glands removed surgically
What are people with xerostomia more susceptible?
Gingivitis
Cervical caries
What is the gingival epithelium comprised of?
The oral gingival epithelium
The oral sulcular epithelium
The junctional epithelium
Describe how the gingival epithelium provides a mechanical barrier
- Seals against bacterial
- Has keratinocytes
- Has langerhans cells
What is the junctional epithelium permeable to?
- Bacterial products that need to go in
- Crevicular fluid and neutrophils that need to go out
- It becomes more permeable in disease
Describe the junctional epithelium in periodontal health
Has an intact junctional epithelium
Describe east happens to the junctional epithelium as periodontal health deteriorates
Junctional epithelium migrates apically
This eventually forms a pocket between the junctional epithelium and root surface
What is associated with the formation of a pocket between the junctional epithelium and root surface
Loss of connective periodontal attachment and loss of alveolar bone
What is inflammation?
It is a response of living tissue to injury and provides a rapid first line of defence
What are the 2 types of inflammation?
- Acute
2. Chronic
What is acute inflammation?
It is non specific and has both fluid and cellular components
Describe chronic inflammation
It is slower to establish than acute inflammation §
What are the functions of the inflammatory response?
- To dilute by increasing crevicular fluid
- To wall off the inflammatory cells
- Destroy the inflammatory cells and the damaging pathogens
Describe the sources of the fluid response of inflammation
- Vasodilation
- Increased permeability of endothelial cells
- Fluid and plasma proteins are release into the tissues and through GCF
What is the inflammatory exudate
plasma proteins like antibodies and compliment that are released into the tissues and through GCF
How many proteins are involved in the compliment system?
9
Why does the compliment system play an important role in the fluid response of inflammation?
- It is responsible fro mass cells producing histamine
- Chemotaxis for neutrophils
- Responsible for lysis and inhibition of a few species off bacteria
- Can lead to opsonisation for phagocytosis
What do we expect to see as the fluid response of inflammation is occurring ?
- Increased crevicular fluid flow
- Gingival erythema
- Oedema and selling of the gingiva
Name the key components of the cellular response of inflammation
- Neutrophils
2. Macrophages
Why are neutrophils important?
- They form the first line of defence
- They can prevent bacteria from entering the gingival crevice
- They form a layer on the surface of plaque
Describe the function of neutrophils in response to UNATTACHED bacteria
- They recognise and bind to bacteria
- They perform phagocytosis
- They produce antibacterial agents
- They digest micro organisms
- They expel remnants
- Contributes to bystander damage
What can bystander damage cause?
A little bit of damage to the surrounding tissues
Describe the function of neutrophils in response to bacteria in the plaque matrix
- Neutrophils attach to the plaque matrix
- They secrete antibacterial enzymes
- They kill bacteria
- They dissolve the plaque matrix
- Contributes to bystander damage
Name some antibacterial enzymes neutrophils secrete
- Hydrogen peroxide
2. Hypochlorous acid
What is a recognised side effect to the host defence system?
Bystander damage
Where do macrophages develop?
They develop from monocytes in the blood
What do macrophages play an important role in?
Both immunity and inflammation
Where do macrophages emigrate too?
They emigrate to inflamed gingival tissue
Few of them enter the gingival crevice
What role do macrophages have in inflammation?
- Phagocytosis
- Secrete tissue degrading enzymes
- They secrete compliment components
- They secrete mediators