#3 The Microbiology of Dental Caries

Question 1

In optimum oral health, why is demin/remineralization of tooth structure in dynamic balance?

Answer 1

Lactic acid produced by bacteria dissolves mineral from enamel and minerals in the saliva are deposited in the enamel- no net change occurs

Question 2

Bacteria in biofilms on the surface of the tooth produce _____ acid from glycolysis of sugars.

Answer 2

lactic

Question 3

Is it possible for the outermost enamel to be structurally sound but the subsurface to be demineralized? Why or why not?

Answer 3

It is possible. In fact it happens regularly. Salivary pellicle proteins stabilize the tooth surface, so initial demineralization is subsurface. This leaves an enamel shell over the lesion

Question 4

T/F remineralization and “healing” of the lesion is possible as long as the surface is retained?

Answer 4

True- once cavitation occurs you can’t remineralize

Question 5

Why is remineralized enamel stronger than normal enamel?

Answer 5

Because of the incorporation of fluoride

Question 6

There are a few properties of caries-causing bacteria. I shall list them for you on the reverse of this card. They all make logical sense, so no need to memorize, just read the list.
What bacteria really characterizes everything that a caries causing pathogen should be? In the land of caries production, who is king?

Answer 6

They attach to the tooth and form a biofilm
They produce acid (acidogenic)
They survive the acidic environment (aciduric)
They survive the “famine” in between meals
They use multiple fermentable sugars at low concentrations
They accumulate storage polysaccharides
S. mutans possesses all of these qualities. He is king!

Question 7

T/F the species of bacteria in the mouth vary based on location/niche?

Answer 7

True

Question 8

Caries is initiated by which species of bacteria?

Answer 8

Strep mutans

Other streps

Question 9

Caries progression is propagated by which bacteria?

Answer 9

Strep mutans

Lactobacillus fermentum

Question 10

T/F strep are the most common supra gingival organisms?

Answer 10

True

Question 11

S. mutans is the primary caries pathogen. It is a gram- ______ cocci. In biofilm it attaches to ____________.

Answer 11

positive

S. sanguinis

Question 12

In this lecture she goes over 10 separate species of bacteria and their respective attributes- I have included only a couple of them that she spend the most time on.

Answer 12

Good to know.

Question 13

S. sanguinis is a good _____ colonizer.

Answer 13

primary

Question 14

Veillonella metabolizes lactic acid. What effect does this have?

Answer 14

It actually raises the pH. This could have the effect of protecting against acid and helping the acidogenic community of bacteria survive.

Question 15

S. sanguinis binds to the pellicle via what?

S. mutans binds to S sanguinis via what?

Answer 15

specific adhesins

specific adhesins

Question 16

S. mutans uses what to elaborate the extracellular matrix? How does S. mutans bind to this?

Answer 16

Glucan

S. mutans binds to gulan via gulan binding proteins

Question 17

Out of S. sanguinis and S. mutans, which bacteria ferments sugars better and low pH. Which one ferments sugar better at higher pH?

Answer 17

At lower pH, S. mutans wins.

At higher pH S. sanguinis is better at fermenting sugars.

Question 18

T/F healthy bacteria grow and make acid at high pH and the stop making acid at low pH?

Answer 18

True

Question 19

What is the short term effect of sugar consumption?

What is the long term effect?

Answer 19

Short term- drop in pH
Long term- you can select for S. mutans in the plaque. Resting plaque can be as much as 1 pH unit lower because of this. As you can imagine, this leads to great demineralization.

Question 20

T/F children can get S. mutans from caregivers? What are we doing about this?

Answer 20

Truth.

We’re thinking we can protect the children by decreasing S. mutans in the caregiver.

Question 21

We’re trying to get rid of S. mutans. What are some ways that we’re trying to do that?

Answer 21

Vaccines to S mutans.
Mucosal vaccination for active immunity
Passive immunity through antibodies in tobacco plants and immunized cows milk
Replacement therapy with S mutans that doesn’t produce lactate
STAMPs- specifically targeted antimicrobial peptides that kill targeted species only.