Oral Micro Final Flashcards by Tim Agee

Caries is a disease caused by microorganisms feeding on what?

Fermentable carbohydrates

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T/F

Remineralization can occur in the early stages of Caries.

True

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What are the 4 factors contributing to caries?

Microorganisms

Metabolic Substrates

Teeth and their environment

Time

*quality/quantity with each

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What is the Main and 2 Minor ingredients to the Organic Matrix of teeth?

Protein (like collagen)

mucopolysaccharides, chondroitin sulfate

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Ca10(PO4)6(OH)2

Hydroxyapatite

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Name 5 positive ions and 2 negative Secondary ions that can make up teeth.

Lead, zinc, strontium, silver, nickel, iron

carbonate, fluoride

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Enamel is ___% mineral and dentine is ____% mineral.

95%

70%

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Describe hydroxyapatite crystal.

OH center

Phosphate and Calcium star of david

6 Calcium

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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

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What is the critical pH for net loss and demineralization of the tooth?

* above net gain, below net loss

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What is more resistant to acid than optimally fluoridated human teeth?

Beaver enamel - lots of Iron instead of Calcium

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T/F

Hydroxyapatite is covalently linked

False

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With enamel maturation, the regularity of the hydroxyapatite crystals tend to increase ______

Spontaneously

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Why can free ions diffuse into the mineral lattice of enamel?

Porous

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T/F

Hydroxyapatite is essentially insoluble at neutral pH

True

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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

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Limited access for saliva, plaque retention, pits/fissures are all caries-suceptible.

True

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The occlusal surfaces of Molars and Premolars most are susceptible to caries where?

Pits and fissures

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______ of molars and _______ of maxillary incisors are susceptible to caries.

Buccal Pits

Palatal Pits

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What approximal surface site is susceptible to caries?

Cervical to contact

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T/F

The cervical margin just coronal to the gingival margin is susceptible to caries

True

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In patients with gingival recession ________ surfaces area susceptible to caries.

Exposed root surfaces

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T/F

Margins of deficient restorations, and tooth surfaces adjacent to dentures and bridges are susceptible to caries

True

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Limited saliva access favors what?

Plaque retention

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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