MFD21

Question 1

What anatomical sites are there of caries?

Answer 1

Pits and fissures, smooth surfaces (enamel caries or root caries, which starts on exposed cementum/dentin).

Question 2

What is residual caries?

Answer 2

the decayed material left in a prepared cavity and over which a restoration is placed

Question 3

What term is used to describe disease caries that occurs on the tooth after the filling has been used for a period of time?
2) What is it the opposite to? What does that term mean?

Answer 3

1) secondary/ residual caries
2) primmary caries
3) the lesion constitutes the initial attack of the tooth surface

Question 4

what are the opposites of the following:

a) cavitated caries
b) active caries

Answer 4

• Cavitated vs non-cavitated.

* Active vs inactive (arrested)

Question 5

What is early childhood caries?

Answer 5

the presence of one or more decayed (non-cavitated or cavitated lesions), missing (due to caries) or filled tooth surfaces in any primary tooth in a preschool-age child between birth and 71 months of age

Question 6

Who is mostly affected by root caries?

2) Why?

Answer 6

1) elderly

2) Gum tissue recedes and cementum isn’t as strong as enamel

Question 7

Why is caries so prevalent? + a bit of scientific evidence

Answer 7

Probably due to our diet, in the medieval times caries affect surfaces was very low.

Question 8

What is the most common global disease?

2) What is the 10th most common disease?

Answer 8

1) Untreated caries in permanent teeth is the most common global disease (2.4 bn affected)
2) Untreated caries in deciduous teeth is 10th most common disease (621 m affected)

Question 9

Caries is the result of microbial sugar fermentation – or is it?
What are the other theory plx list:

Answer 9

1. chymical theory
2. parasitic or septic theory
3. chemico-parasitic theory
4. proteolytic theory
5. proteolysis-chelation theory

Question 10

What was the chymical theory?

Answer 10

) Food putrefaction released unidentifed chemical (chymical) agent which dissolved teeth

Question 11

What was the Parasitic or Septic Theory ?

Answer 11

Erdl (1843) described a filamentous parasite in plaque which he thought responsible

Question 12

What was the Chemico-parasitic theory ?

Answer 12

2 stages • Stage 1 – decalcification of enamel • Stage 2 – dissolution of the soft residue

Question 13

What was the Proteolytic Theory ?

Answer 13

Microbes invade enamel lamellae and initiate caries by proteolysis • Pincus (1950) proposes it’s proteolysis of the cuticle (Proteolysis probably plays a role in root caries, but not what starts the disease)

Question 14

Proteolysis-chelation theory ?

Answer 14

Schatz (1955) - argued that there was too much emphasis on protons and Miller was misunderstood • Microbial proteolytic destruction of the organic matrix • Calcium is removed by chelation (organic acids). By binding out the calcium you force the equilibrium to dissolution.

Question 15

What are the 2 possible hypothesises of the role of microorganism in caries?

Answer 15

1. Ecological plaque hypothesis (disease is an imbalance)

2. Specific plaque hyporthesis (caries aetiology)

Question 16

What microorganisms are associated with dental caries?

Answer 16

Mutans streptococci
• Lactobacillus spp. 
• Actinomyces spp. 
• Bifidobacterium spp. and related 
• Scardovia wiggsiae

Question 17

What is the basis fo the link between microorganisms associated with dental caries? (2)

Answer 17

1) • Elevated at sites of caries (sometimes)

2) • Virulence factors

Question 18

Give e.g.s of virulence factors of microorganisms in caries:

Answer 18

• Acid production from sugars (acidogenicity)
• Acid tolerance (aciduricity)
• Adhesions and others: intracellular storage granules, extracellular polysaccharides,

Question 19

Which of the 7 species of mutans streptococci are found in humans?

Answer 19

S.mutans and S.sobrinus

Question 20

Mutans Streptococci:

1) gram- or +
2) catalase - 0r +
3) saccharolytic or asaccharolytic
4) aerobe, anaerobe ro something else…
5) What structures do many form?
6) When is it acquired

Answer 20

1) +
2) -
3) saccharolytic
4) facultative anaerobe
5) chains
6) infancy

Question 21

S.mutans

1) is it acidogenic
2) is it aciduric
3) What does it form from sucrose?

Answer 21

1) yes
2) yes
3) glucans

Question 22

S.sobrinus and S.mutans

1) Which is carried by more people
2) which is more acidogenic ?

Answer 22

1) S.mutans (around 96%, while S.Sobrinus (6-35%)

2) S.sobrinus

Question 23

What features does Scardovia has which is characteristic of cariogenic organism?

2) is it gram + or -
3) WHat did it used to be called?
4) describe shape

Answer 23

1) anaerobic, Saccharolytic – produce acetic and lactic acid
2) +
3) bifidobacterium
4) pleymorphic (alters shape and size in response to environmental conditions ) bacilli (rod shaped)

Question 24

What groups of caries-associated streptococci are there?

Answer 24

1. S.Mutans
2. S.Sobrinus
3. “non mutans low-pH streptococci”( atypical ones within group e.g. some strains of S.sanguinis)

Question 25

What specific adhesions, a virulence factor of mutans streptococci, have?

Answer 25

oAntigen I/II protein
oGlucosyltransferases (GTFs)
oGlucan binding proteins (allows them to attach to polyglycans in matrix)

Question 26

What specific way is acid produced, a virulence factor of mutans streptococci, have?

Answer 26

o F-ATPase (kicks protein out the cell)

Question 27

How is mutans streptococci resistant to acid a virulence factor of mutans streptococci, have? (2)

Answer 27

oDNA repair proteins

oProtective membrane proteins

Question 28

Name 2 Health-promoting factors ( in the mouth)?

Answer 28

1. adhesions of commensal bacteria

2. Alkali production

Question 29

Adhesions of commensal bacteria :

Answer 29

antigen 1/2 protein

Question 30

1) How is both glucose and sucrose used by bacteria?
2) How is sucrose only used?
3) what is the significance of ans 2?
4) What is this in spite of?

Answer 30

1) to make acid and intracellular storage polymer
2) to make exopolysaccharides
3) sucrose is more cariogenic than glucose
3) glucose is more easily converted to acid

Question 31

What do we need to know about sugar uptake in S.mutans?

Answer 31

1, polysaccharides can be digested

2. many different mon/disaccharides can be imported
3. Xylitol import leads to a “futile” cycle (this results in energy loss, therefore being added to chewing gum to try and reduce caries)

Question 32

what about S.mutans metabolic reactions are regulated?

2) What is not?

Answer 32

1. transporters

2. glucose uptake transporters

Question 33

What are the effects of transporter (other than glucose) regulation of fermentation in S.mutans have on the products in:
high sugar environments

Answer 33

o lactate is the major product (homofermentation), and glycolysis is accelerated
o Intracellular polysaccharides (IPS) are made

Question 34

What are the effects of transporter (other than glucose) regulation in S.mutans have on the products in:
low sugar environments

Answer 34

o Mixed acid fermentation (heterofermentation) - lactate dehydrogenase is inhibited
o IPS are degraded

Question 35

1) when is intracellular polysaccharides made by S.mutans?
2) from what molecule?
3) what is the intracellular polysaccharide called?
3) When is it broken down? what is the name of this series of reactions?
4) How may it be involved in caries?

Answer 35

1) when carbohydrate is in excess
2) Produced via glucose-1- phosphate
3) Glycogen-type glucan
4) Broken down and used for glycolysis during starvation
5) uncertain, but may extend period of time bacteria produce acid after glucose source is removed.

Question 36

What is the role of S.mutans in the food? what is it’s symbiotic relationship?

Answer 36

• End products of metabolism can be recycled by other bacteria
• Several different bacteria can utilize lactate; in the case of Veillonella spp. it is an essential nutrient

Question 37

aciduricity is what type of response?

2) How do studies support this?

Answer 37

adaptive

2) Pre-acidification results in greater acid tolerance, particularly in bacteria that are relatively acid sensitive.

Question 38

What mechanisms of acid adaptation are there?

Answer 38

• Reduced permeability of cell membrane to H+ .
• Induction of H+ -translocating ATPase (expels protons from cells).
• Induction of alkali production systems (arginine deiminase or urease).
• Induction of stress proteins that protect enzymes and nucleic acids from denaturation.

Question 39

What enzymes do Strep. Gordonii and
Strep. sanguinis have for alkali production? in order of there use in the pathway
B) which steps produce NH3, what is the total no. produced?

Answer 39

A) 1. arginine deiminase
2. Ornithine transcarbamylase
3. carbamate kinase
B) step 1 and 3, total =2 NH3

Question 40

state the reactions in alkali production in order for Strep. Gordonii and
Strep. sanguinis:

Answer 40

1. Arginase = citruilline +NH3
2. Citrulline = carbamoyl phosphate
3. carbamoyl phosphate +ADP = CO2 + NH3 +ATP

Question 41

What enzymes do Strep. salivarius and
Actinomyces johnsonii have for alkali production? in order of there use in the pathway
B) which steps produce NH3, what is the total no. produced?

Answer 41

A) 1.arginase
2. Urease
B) step 2 only, total 2

Question 42

state the reactions in alkali production in order for Strep. salivarius and
Actinomyces johnsonii

Answer 42

1. Arginine to Urea

2. Urea +ADP= ATP + CO2 + 2NH3

Question 43

Does the composition of the oral flora change in relation to the nutrients in the environment?

Answer 43

yes

Question 44

A) At pH neutral,
State a bacteria group present at:
1. low sugar level
2. high sugar level.
B) at low pH, and high sugar:

Answer 44

1. asaccharolytic bacteria e.g. P.gingivalis
2. oral streptococci
   B) strep. mutans and lactovacillus spp.