bacterial etiology of caries
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Factors influencing hydroxyapapite solubility
- ionic strength of solvent (enamel partially dissolves in pure H2O)
- Ca2+ and PO4- concentration (both in saliva)
Hydroxyapatite crystals are stable
at physiological pH of ____
though small amounts of demineralizationÛremineralization can
Can caries heal?
no bu t you can retore it
How did animal studies help the study of caries?
- 1960 hamster model shows caries infections are transmissible
- Germ & caries free animals acquire
- caries upon microbe exposure
- Gnotobiotic rodent studies indicated importance
- of species of the Streptococcus genus for producing caries
- Animal studies confirmed sugar relationship with caries germ free rodents did not develop caries in presence of sucrose
- - if exposed to bacteria at later time in presence of sucrose®caries
What are the human studies on caries
- Sognnaes study: sugar rationing resulted in decrease caries in children
- Vipeholm: sucros high diets increased caries incidence. sticky and adhesive form for food increase it too
- Australian orphanage sugar0free diet offered protection but not long
How does children between 6-30 months become infected with bacteria?
Exchange in the family unit
MS can be trasnsmitted from mother to ____.
CHildren's caries patterns more closely to mothers or fathers caries experience?
MS can colonize the mouths of whom?
the 2nd window for MS to affect children is when?
6 years old
biofilm is consists of what 3 things?
liquid + bacteria + surface
what is the 3 stages in biofilm life cycle?
- 1. attachment
- 2. growth
- 3. dispersal
Dental plaque forms naturally on teeth and, indeed,
forms part of the host’s defenses by helping to prevent colonization by what?
exogenous (and often pathogenic) microorganisms.
How many different species are there in the flora of the oral cavity?
200: anaerobic and facultative aerobic
many bacteria can not adhere to pellicle coated teeth yet can adhere to ______ and other bacterial species
_______ are the major pathogens of human dental caries.
Mutans Streptococci (MS)
What does MS produce and grow in?
- Produces acid : acidogenic
- grows in acid: acidouric
Streptococci species are __________ and _____ shaped.
- facultative aerobes
- cocci shaped
T or F. low-pH non- MS can also have a big part in caries.
Enamel caries initially irreversible. T or F
F it is reversible
If bacteria enter lesion, _____________ of bacteria is required.
what are the host factors in saliva that prevent caries?
- 1. lysozyme: hydrolyzes peptidoglycan of bacterial cell wall
- 2. Lactoferrin: binds iron essential for bacterial growth. Iron required for function of many bacterial proteins. This protein has otehr anti-microbial properties.
- 3. Lactoperoxidase: produces hypothiocyanate ion. Ion reacts with bacterial enzyme sulfhydral groups, inhibiting enzyme
- 4. Immunoglobins: IgA, IgG, IgM
How does saliva help prevent caries?
- -helps clear mouth of food, cellular and bacterial
- debris; this helps reduce nutrients for plaque growth
- -buffers pH
- -lots of calcium, phosphate-this promotes enamel remineralization
Why can't caries vaccine be feasible?
- 1. complex flora associated with caries
- 2. ability of bacteria to rapidly mutate
- 3. S. mutans contains antigens similar to heart muscle
What are the most cariogenic species for enamel caries? (2)
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