3- etiology 1

What are periodontal diseases?

Inflammatory diseases of infectious origin

What 2 things should the diagnosis and treatment of perio diseases be based on?

Understand plaque and its formation

Also interactions with host

What should the objective of periodontal treatment be based on?

Altering and eliminating plaque to prevent formation of bacterial complexes that can cause tissue destruction

What does plaque do?

Accumulates after 1-2 days, follows a predictable pattern determined by ecological factors- inflammatory response

What are the 3 types of hypotheses that have been proposed to explain the pathogens is of plaque?

Non specific- more microorganisms, more risk, not all gingivitis evolves to periodontitis

Specific (Loesche)- only certain plaque is pathogenic depends on few microorganisms

Ecological- environmental changes produce xs growth

Why can’t periodontitis be considered an infectious disease? (Koch’s postulates 1884)

Be routinely isolated from diseased individuals

Be grown in pure culture in the lab

When introduced in animals, produce similar disease

Same agent recovered from lab animal lesions

Most periodontal pathogens can be found…

In small quantities in healthy oral flora

Opportunistic pathogens so must control ecological conditions to regulate bacterial growth

Why are there differences in the composition of supra and subgingival plaque? (4)

Available blood products

Pocket depth

Redox potential

Conc of dissolved o2

Phase 1- What is acquired film composed of?

Organic material- peptides, proteins, glycoproteins, receptors for bacteria

Forms upon immersion of solid substrate into oral cavity fluid

Phase 2- Colonisation- what occurs once the acquired pellicle is formed?

Alters charge and free energy of surface- more efficient adhesion

During first 4-8hrs- most streptococcus

What occurs in phase 3 of plaque formation- multiplication?

Coadhesion- primary colonising bacteria attached to film acts as receptors to bind to other bacteria

Forms microcolony

What occurs in phase 4 of plaque formation- maturation?

Heterogeneity increases with time

Diffusion of o2 and nutrients becomes more difficult

Bacteria which colonise perio pockets release hydrolytic enzymes which break down tissues

Why are nutrients and o2 important ecological determinants?

Dietary products dissolved in saliva are needed for bacteria causing supragingival plaque

Bacteria vary their ability to grow at diff levels of o2

What is a biofilm and what are the advantages of the structure?

structured communities of bacteria embedded in a glycocalyx matrix fixed to a surface

Mechanical and chemical protection

Facilitates intake of nutrients

Cross nutrition- other species use products of the other

Appropriate physio chemical environment

What are exopolysaccharides? (In biofilm)

maintain biofilm integrity, prevent drying, and protect against harmful agents

What 5 factors effect supragingival plaque formation?

Topography- faster in lower jaw, interdental spaces, vestibular surfaces

Surface roughness- rougher

Individual variables

Gingiva inflammation and saliva

Age- more inflammation in old people

What 2 types of hypothesis explain mineralisation

Mineral precipitation- rise in saturation of calcium and phosphate ions

Sending agents induce calcification

Why is plaque considered a secondary etiologic factor?

Mineralised plaque covered by non mineralised so not in direct contact with tissues

What the difference between infection and infalmmatiom?

The invasion and multiplication of pathogens vs protective response to that invasion

What are signs of inflammation vs infection?

Redness, swelling, heat, pain

Fever, pus

There are some periodontal pathogens that are rare in healthy people. They are called…

Exogenous pathogens

The mere presences needs intervention