Show Menu
Cheatography

Theories of Oral Infection Cheat Sheet by

Robert Koch's Germ Theory:

All subjects must present with the same symptoms
Causative organism must be isolated in pure culture
When inoculated into a 2nd host, it must produce the same symptoms
Identical pure culture must be obtained from second host
Modi­fic­ation of Koch’s postulates for oral opport­unistic infect­ions:
> Should be present in sufficient numbers to cause disease
> Should have access to the affected tissues
> Should be in an enviro­nment that permits its survival and multip­lic­ation
> Inhibitory organisms should be absent or not affect it
> The host must be suscep­tible

Diffic­ult­ies­:Koch's Postulate in Oral Infect­ions:

> No overt pathogen - mostly mixed infections
> More than 700 identified oral species
> Not all members of biofilm community are cultivable
> Presence may be as a result rather than cause of disease
> Sites don't appear to be actively progre­ssing at all times
> Different sites in mouth may break down as a result of different species
> Strains of putative pathogens may vary in virulence
> Some strains may harbour bateri­ophages or plasmids that confer virulence properties

Non-sp­ecific Plaque Hypothesis

Overgrowth of indigenous microbiota
Same organisms observed in health and disease
Shifts in microbial propor­tions rather than specific pathogens
Any plaque biofilm can cause disease
Problems with NSPH:
- Focus is on quanti­tative changes only
- Disease in animals not the same as in humans
- Imprac­tical to compare virulence in different host species
- Doesn't explain why indivi­duals with: 1) longst­anding plaque don't develop disease and 2) minimal plaque have lower resistance to disease

Specific Plaque Hypothesis

More sophis­ticated studies demons­trated:
> Improved cultural and sampling methods
> Compos­ition of plaque biofilm differs both inter-­orally and intra-­orally
> Increase at a sight of infection
> Decrease in health or following treatment
> Qualit­ative changes in plaque biofilm
 

Exogenous Theory:

Exogenous pathogens and not endogenous microb­iota caused disease
Fails to explain:
> Mode of transm­ission
 
> Acquis­ition
 
> Means of coloni­zation
 
> Effect of treatment on indigenous species
Cont­rai­ndi­cat­ions:
- Over simpli­fic­ation
- Overlaps often occurred (Negated SPH and NSPH)
- Eradic­ation of exogenous pathogens (Incor­porated both SPH and NSPH)

Ecological Plaque Hypoth­esis:

Opport­unistic endogenous infection
Ecological shift from predom­inatly G+ cocci to G- rods/c­occ­i-b­acilli
Any bacterial species may be pathogenic
Ecological changes in enviro­nment dictate virulence mechanisms
Disease prevented by elimin­ation or interr­uption of ecological succession

Role of Biofilms in Infection:

Most common:
1. Dental caries (supra­gin­gival plaque)
2. Period­ontal disease (subgi­ngival plaque)

Dental Caries Theories

1) Tooth worm:
5000BC, 1803 - Diagrams and 1825- Case histories
2) Humoral Theory:
Blood, phlegm, black bile, yellow bile - Imbal­ance= disease
3) Chemical Theory:
Fermen­tation of food remains
4) Parasitic Theory:
Decomp­osition resulting from action of organisms in the mouth
 

Millers (1882) Chemo-­par­asitic Theory:

2 stage process:
i) decalc­ifi­cation of enamel resulting in destru­ction of dentin
ii) dissol­ution of softened residue of enamel and dentin
Dietary carboh­ydrates -> convert into acid -> calcium and phosphate diffuse out of enamel -> a caries lesion

Proteo­lytic Theory (Gotliebb 1946)

Invasion of enamel by m/o's -> proteo­lytic activity -> alteration of pH -> resulting in liquid­ifi­cation of organic matrix of enamel -> inorganic salts dissolved by acidogenic bacteria

The proteo­lyt­ic-­che­lation Theory

Schutz and Martin (1955)
Simult­aneous attack on organic and inorganic compounds of tooth
Kaerat­ino­lytic bacteria attack enamel ->

Breakdown of protein and other organic components of enamel (keratin) ->

Formation of complexes with calcium from plaque which chelates with mineral component of the tooth ->

Increased solubi­lity, decalc­ifi­cation of enamel ay neutral or alkaline pH

Current Concepts in Caries Etiology

Keyes Triad & Newbeun's Tetrad

 

Comments

No comments yet. Add yours below!

Add a Comment

Your Comment

Please enter your name.

    Please enter your email address

      Please enter your Comment.

          Related Cheat Sheets

          More Cheat Sheets by Carmilaa

          Osteology of Maxilla and Mandible Cheat Sheet