Micro of Dental Caires Flashcards
where do caries occur most
pits and fissures- most often in patients with low caries rate
where are smooth surface and proximal caries often found
patients with high caries rate and often diet related
root caries
found in pts with exposed root surfaces
secondary caries
found at restorative margins
explain the balance of demineralization and remineralization in health
lactic acid produced by bacteria dissolves enamel and salivary minerals are deposited in enamel causing no net change
when does tooth structure loss occur
when body’s remineralization cant keep pace with acid production
when do bacteria produce lactic acid
from glycolysis of sugars
what does lactic acid do
drops pH and dissolves tooth minerals
what happens to tooth surface at initial demineralization
tooth surface is stabilized by salivary pellicle proteins but demineralization occurs subsurface leaving a thin enamel shell
when does cavitation occur
when subsurface demin becomes too severe and thin enamel shell is broken
once cavitation occurs what is no longer possible
biologic repair is no longer possible once enamel shell is broken
what is stronger and why? remineralized tooth structure or virgin enamel
remineralized tooth structure is stronger bc it has F incorporated in HA
name 5 properties of caries causing bacteria
attach and form biofilm produce acid (acidogenic) tolerate acid (aciduric) continue to produce acid at low pH survive famine between meals by using fermentable sugars and storing polysaccharides
is biofilm organization important to cause caries?
YES biofilm holds a diverse set of species that work together to produce conditions that are caries causing
what are the 3 species that initiate caries
S mutans (as well as other streps).
Veillonella
and AA
what species are responsible for caries progression
S mutans, L casei, rhamnosus, gassera, fermentum
bifido and scardovia
what are the most common supra gingival organisms
strep! difficult to distinguish between the different streps
describe the 3 important points of S mutans
primary caries pathogen
gram + cocci facultative
ferments carbs
describe biofilm behavior of S mutans
attaches to S sanguinis
make ECM polysaccharide
what is S mutants protected by
self protect by excretion of lactate well adapted for feast or famine
what make S mutans a good scavenger during famine
good storage mechs, can maintain energy and low pH
what does fluoride do to S mutants
F interferes with transport and intracellular processes of S mutans
how are S mutans good for the host
S mutants protect against B hemolytic or other pathogenic streps and produces lactate and bacteriocins
What is S sobrinus called and who is it related to
S sobrinus termed MS, related to S mutans
Is S sobrinus associated with caries?
S sobrinus is strongly associated with caries but found at lower numbers than S mutans
What is the earliest acquired bacteria that is not cariogenic and what is it bound by
S mitis= earliest acquired oral bacteria bound by salivary amylase and NOT cariogenic
Where is S sanguinis found and describe it
S sanguine found in healthy plaque its gram + cocci facultative
Describe S Sanguinis action with biofilm
S sanguinis is a good initial colonizer of pellicle coated tooth surfaces attaching via adhesins
describe the metabolic and acid ways of S sanguinis
S sanguinis ferments carbs and proteins producing lactic acid at high pH can survive without sugar using the arginine hydrolase pathway raising pH
what is often a cause of infective endocarditis (IE)?
S sanguinis
Describe the bio of S salivarius
S salivarius has tongue and tooth niches associated with carries, in saliva but DOES NOT grow there
Describe bio of AA
saccharolytic, acidogenic, filamentous, gram +
anaerobic or facultative
what may contribute to root caries
AA
what may be important in early stages of enamel caries
AA
Describe bio of Veilonella
DOES NOT ferment carbs
ferments lactate!! raises pH
gram - anaerobic
How does Veilonella contribute to caries?
Veilonella ferments lactate produce by streps which raises the pH thus helping pathogenic organisms survive and continue producing acid
what is important in established and deep caries
Lactobacilli
describe bio of lactobacilli
Lactobacilli is gram + rod
anaerobic, saccharolytic, acidogenic
what may be important in deep caries that is a gram + rod that is anaerobic saccharolytic and acidogenic
Bifidobacterium and scardovia
S sanguinis binds to pellicle via what
via specific adhesins
S mutans binds to S sanguinis via what
via specific adhesins
S mutan elaborates ECM from what
ECM from polysaccharide= glucan
how does S mutans bind to glucan
via glucan binding proteins
aciduric means what
bacteria can survive low pH so acid TOLERANT
acidogenic means what
bacteria can lower pH
SO ACID PRODUCING!
who can ferment sugars at low pH S sanguinis or S mutans
S mutans ferments sugars better at low pH than S sanguinis does
what do healthy bacteria do
grow and make acid at high pH stops at LOW pH
what do caries bacteria do
grow and make acid at LOW pH
what do S mutans do in response to environmental exposure changes
S mutans will change gene expression thus making them more resistant to O2, higher pH and UV, enhances glycolysis causes S mutans to be more acid tolerant and produce more acid
what is more important to caries short or long term sugar exposure
LONG term is more carious
Low pH plaque due to inc sugar and carbs consumption does what
more favorable for S mutans than S sanguinis thus removing protective check from alkali generating organism like S sanguinis causing more acid to be produced thus lowering pH more thus demineralizing more thus deselecting for healthy bacteria more
Describe the acquisition of S mutans
S mutans are usually acquired around 26 months (window of infectivity) from caregivers or others
Caries vaccines to S mutans target what
glucosyl transferase and binding proteins
what passive immunity approaches are under way for caries vaccines
ABs in tobacco plants, in immunized cows,
Active immunity vaccines for carries include
mucosal vaccination for active immunity adjuvants required to elicit much response
what is replacement therapy
replacement of carious wild type S mutans with genetically engineered non lactate producing strain
what are stamps
Stamps are pheromone or AB guided antimicrobials that kill only targeted species
