Oral Micro Final Flashcards
Caries is a disease caused by microorganisms feeding on what?
Fermentable carbohydrates
T/F
Remineralization can occur in the early stages of Caries.
True
What are the 4 factors contributing to caries?
Microorganisms
Metabolic Substrates
Teeth and their environment
Time
*quality/quantity with each
What is the Main and 2 Minor ingredients to the Organic Matrix of teeth?
Protein (like collagen)
mucopolysaccharides, chondroitin sulfate
Ca10(PO4)6(OH)2
Hydroxyapatite
Name 5 positive ions and 2 negative Secondary ions that can make up teeth.
Lead, zinc, strontium, silver, nickel, iron
carbonate, fluoride
Enamel is ___% mineral and dentine is ____% mineral.
95%
70%
Describe hydroxyapatite crystal.
OH center
Phosphate and Calcium star of david
6 Calcium
In Hydroxyapatite, what can substitute OH?
What substitutes Phosphate?
What 5 substitutes for Calcium?
Fluoride for OH
Carbonate for Phosphate
Lead, strontium, radium, Iron, Magnesium for Calcium
What is the critical pH for net loss and demineralization of the tooth?
- 5
* above net gain, below net loss
What is more resistant to acid than optimally fluoridated human teeth?
Beaver enamel - lots of Iron instead of Calcium
T/F
Hydroxyapatite is covalently linked
False
With enamel maturation, the regularity of the hydroxyapatite crystals tend to increase ______
Spontaneously
Why can free ions diffuse into the mineral lattice of enamel?
Porous
T/F
Hydroxyapatite is essentially insoluble at neutral pH
True
What 2 ions are essentially in a saturated state (ready to precipitate) in the body?
Calcium
Phosphate
- rxn goes to right, dissolution, left, remineralization
- *pH dependent
Limited access for saliva, plaque retention, pits/fissures are all caries-suceptible.
True
The occlusal surfaces of Molars and Premolars most are susceptible to caries where?
Pits and fissures
______ of molars and _______ of maxillary incisors are susceptible to caries.
Buccal Pits
Palatal Pits
What approximal surface site is susceptible to caries?
Cervical to contact
T/F
The cervical margin just coronal to the gingival margin is susceptible to caries
True
In patients with gingival recession ________ surfaces area susceptible to caries.
Exposed root surfaces
T/F
Margins of deficient restorations, and tooth surfaces adjacent to dentures and bridges are susceptible to caries
True
Limited saliva access favors what?
Plaque retention
What is the sequence of plaque development?
Salivary proteins > Pellicle > Plaque bioflim > calculus
What is the acellular, homogenous, organic film that forms on enamel by selectively adsorbing glycoproteins and salivary proteins?
Pellicle
Are bacteria necessary for the formation of Pellicle?
no
*forms spontaneously
If the Pellicle is removed by meticulous cleaning, it takes how long to re-form?
Minutes to hours
T/F
The pellicle serves to protect the tooth
False
*maybe, but not proven
T/F
The plaque biofilm is soft and non-mineralized
True
What are the 3 layers making up the Plaque Biofilm?
Pellicle (plaque-tooth interface)
Microbial layers/colonies
Insoluble Intercellular matrix
What 2 things make up the Insoluble intercellular matrix of the plaque biofilm?
Carbohydrates (glucans, fructans, other polysaccharides)
Protein
*CHO produced by the bacteria
The metabolic fermenting process of bacteria on teeth of CHO produces what? (2 things)
H+
Extracellular Polymers
*some plaque bacteria produce these 2
Once inorganic deposits are present in plaque biofilm, what has formed?
What does this greatly increase risk for?
Calculus
Periodontitis
T/F
Germ free animals do not develop caries even when fed a cariogenic diet
True
What is the term for known oral flora used in testing?
What are the experiments called?
Gnotobiotic
Add-back
Testing using gnotobiotic animals in add-back experiments have implicated what 3 species of bacteria in caries?
S. mutans
Lactobacillus spp.
Actinomyces spp.
T/F
Caries is an infectious disease
True
Would bubble boy have dental caries?
I think so.
Still has a microbiome, just prone to infectious disease.
Name 3 byproducts of bacterial CHO metabolism
sachrolytic bacteria
EtOH
Acid
Lactic Acid
What is a homolactic acid producer?
Heterolactic?
Produces only lactic acid
other acid (or ethanol), lactic acid
What are the 2 major Streptococci implicated in caries?
S. mutans
S. sobrinus
Mutans streptococcus attaches to Oral Biofilm, is a good CHO transporter at low pH, and is a _______ fermenter.
Homolactic
- so all Lactic Acid
- *Acidogenic
What is Mutans preferred pH?
Acidophilic - likes low pH
What insoluble product does Mutans produce?
Glucan (aka Mutan aka Dextran)
- glc polymers
- *decreases buffer availability, increases acid conc.
What are the 2 types of “snacks” Mutans makes itself?
Intracellular polysaccharide
Extracellular Levan (frc polymer)
T/F
Most oral bacteria have excellent sugar transport at low pH
False
*Mutans does
Tolerating a high acidity environment is ______
Preferring acidic environment is ______
Aciduric
Acidophilic
What do Mutans do with extra glucose?
Extra fructose?
Make insoluble glucans
Extracellular levans
What is the small molecule that S. mutans uses to kill their competitors?
Bacterioeins
What acts as a selective killer for mutans?
Xylitol
What is the Xylitol mechanism in Mutans?
Ingests, phosphorylates, then kicks out
*all uses ATP
What are the 3 sucrose enzymes on the surface of S. mutans?
Functions?
Glucosyl Transferase (makes Insoluble matrix)
Invertase (splits into frc/glc and send inside cell)
Fructosyl Transferase (makes Levanase)
Why wouldn’t HFCS end up as a structural component?
What is the metabolic consequence?
Glucosyl Transferase and Fructosyl Transferase both need Sucrose
Makes more Lactic Acid
What is more cariogenic, sucrose or HFCS?
Sucrose, because the Extracellular Dome is more important in caries formation than Acid.
Levan is made from chains of…
Levan is broken down by what?
Fructose
Levanase
The insoluble ECM made by mutans is made from chains of…
Glucose
What 2 bacterial species have Fructosyl Transferase and can therefore make Levan?
S. mutans
S. salivarius
What S. mutans enzyme has the highest affinity for Sucrose?
Invertase
*snacks, ECM only produced in abundance.
What does Fluoride inhibit in bacterial metabolism?
Enolase
which creates phosphoenol pyruvate > PEP > Pyruvate > lactate
What are the 3 major ways F- lowers the risk of caries?
Most electronegative element, so holds hydroxyapatite more tightly
Decreases Carbonate (by binding tightly)
Poisons key metabolic enzymes (enolase) to Lower Acid Production
Anti-caries mechanisms fall into what 2 very general mechanisms?
Which is more important?
Systemic (developmental)
Topical (after eruption)
Topical most important
A diet high in sugar selects for what?
Aciduric bacteria (able to tolerate lots of acid)
What 2 species are found in very low numbers in “healthy” plaque?
S. mutans
Lactobacillus spp.
(mutans and L. casei increase after sugar increase)
Aciduric bacteria increase most when _____ is excluded
buffer
What is the term for pH affecting the type of bacteria that can grow?
Bacterial succession
What 3 bacteria are in much higher percentage at caries sites?
S. mutans
Actinomyces spp.
Lactobacillus spp.
Why does Mutans compete so well at low pH?
Even though produces less acid, produces more than most even at low pH
What are the 4 major locations of caries formation?
Pits/fissures
Smooth surfaces
Dentin
Root caries
What is the major cause of caries in Pits/Fissures?
S. mutans
What is the major cause of caries on Smooth Surfaces?
S. mutans
What is the major cause of caries in Dentin?
What other pathology mirrors this?
S. mutans, Actinomyces spp., Lactobacillus spp.
Root caries
*mutans does the drilling
What infections are generally a mixture of various G- anaerobes?
What are cause Primarily by G- anaerobes (and facultative)?
Endodontic pulp infections
Gingivitis/Periodontitis
Are caries vaccines theoretically possible?
Yes
T/F
Caries can arise even without sugar
False
What are the 2 most acidic byproducts of bacterial metabolism of Pyruvate in the mouth?
Formic acid - 3.7
Lactic acid - 3.8
**for some reason, Lactic acid is considered to by the most “powerful” of these acids
Name 7 byproducts of bacterial metabolism in the mouth.
Popionic acid
Formic acid
Lactic acid
Succinic acid
Acetic acid
EtOH
CO2
What graphical representation demonstrates the rapid and sustained drop in pH upon ingestion of CHO?
Stephan Curve
T/F
Plaque can have a lower “resting” pH, and that plaque leads to rampant caries
True
T/F
Brushing teeth lowers the amount of acid produced
True
What 2 factors determine how well a CHO can be cariogenic?
Metabolizability
Diffusion ability
Plaque bacteria use what kind of CHO most effectively?
Simple sugars
What is more important than the amount of CHO consumed?
Frequency
What regulates salivary secretion?
Autonomic
parasympathetic - good flow, watery
sympathetic - low flow, thick
What is the salivary flow rate?
1-2 mL/min
between meals - small. Sleep - small
What 2 ingredients does Saliva contain that helps tooth remineralization?
Why can they precipitate on teeth?
Ca and PO4
saturated
What are 2 antimicrobials contained in Saliva?
Lysozym and Antibody
T/F
Saliva acts as a buffer and maintains mouth pH near 7 through bicarb and recycles topical fluoride
True
T/F
Caries incidence has increased recently
True
When should fluoride gel be given?
early age
There has been some headway in using engineered antibody to bind attachment fibers of cariogenic bacteria
True
*this would be a vaccine
Why does a broad spectrum prevention seem to be counterproductive?
Often bad strains survive
What is STAMP?
Specifically targeted anti-microbial peptides
**reduced S. mutans by 50%
GMO germs and probiotics are possible prevention avenues
True
The probiotic theory of prevention relies on what mechanism?
Competitive exclusion
What is the main Ab that activates the complement cascade?
IgG
Probiotics lower Neonatal Necrotizing Enterocolitis by how much?
15-20%
T/F
There have been modest to good results in probiotic treatment for gingivitis, halitosis, dental caries, and periodontal disease.
True
*periodontal hardest to carry out, in vivo animal exp’s promising
What is a common probiotic species influential of a healthy mouth (or lack of caries)?
Lactobacillus acidophilus
T/F
Oral administration of Lactobacillus acidophilus in the 1st year of life reduced caries 9 years later by half.
True
