Microbiology of caries

Question 1

what are dental biofilms?

Answer 1

natural and beneficial

Question 2

how many species are present in a Biofilm?

Answer 2

700+

Question 3

what is the biofilm composed of?

Answer 3

bacteria
viruses
fungi

Question 4

what does the biome help with?

Answer 4

with key functions
helps to regulate the immune system
and helps with host defences

Question 5

what is desquamination

Answer 5

the shedding of epithelial cells- reduces the bacterial load

Question 6

examples of non shedding surfaces

Answer 6

teeth
dentures
implants

Question 7

what is the bacterial load like on non shedding surfaces

Answer 7

it is high unless you remove the load by eg brushing

Question 8

how can we tell which bacteria are beneficial or harmful

Answer 8

by traditional culture such as
grow the organism

Question 9

what are the issues with traditional culture

Answer 9

laborious
expensive
only half the species in the mouth grow on blood agar
very time consuming- need to do multiple tests and isolate the species

Question 10

what are the issues with microscopy

Answer 10

only will tell you the shape of the species( cell morphology)

Question 11

what does FISH stand for

Answer 11

fluorescent in situ hybridisation- can help recognise a few species

Question 12

what are the molecular approaches to identify the species in the microbiome

Answer 12

HOMIM (human oral microbiome identification microarray )
DNA-DNA hybridisation
PCR
high throughput whole genome sequencing

Question 13

what is the gold standard to see what species an organism is

Answer 13

high throughput whole genome sequencing- and put into the database and you can see which organism is present

Question 14

what is metagenomics

Answer 14

complex clinical sample such as plaque
extract DNA
cut DNA
sequence and then the short fragments will make a long sequence
tested across a database and we can see which species are present

Question 15

what does metatranscriptonomics look at

Answer 15

RNA to see which proteins are transcribed

Question 16

what is HOMD

Answer 16

human oral microbiome database

Question 17

how is the bacteria in the dental biofilm organised

Answer 17

structurally organised
functionally organised

Question 18

why are bacteria in the biofilm functionally organised

Answer 18

so that the aerobic organisms are nearer the surface for O2
and anaerobic at the base

Question 19

what are the features of the dental biofilms

Answer 19

concerted and collaborative metabolism
food chains
environment modification
matrix formation
cell-cell signalling
complex interactions- balance

Question 20

why are dental biofilms helpful

Answer 20

they help get rid of harmful organisms in the mouth due to pathogen exclusion

Question 21

how can the load of helpful bacteria in the dental biofilm be reduced

Answer 21

due to long term antibiotic therapy

Question 22

what can be the result of long term antibiotic therapy

Answer 22

overgrowth of yeasts

Question 23

bacteria from which organ can cause a inflammatory reaction

Answer 23

gut and the mouth but rare
eg Crohns disease in the gut

Question 24

why do we rarely see inflammatory reaction in the mouth

Answer 24

because the bacteria communicate between one another and the host

Question 25

what is the entero salivary nitrate circulating system

Answer 25

where nitrate from green vegetables is reabsorbed from the gut/ intestines and appears in saliva and the beneficial bacteria can break it down to nitrite which modifies blood pressure . and nitrite that is swallowed becomes acidified nitric oxide which is antibacterial and stimulates mucus

Question 26

where does the body get nitrate from

Answer 26

from green veggies we eat

Question 27

what does the nitrate get converted to

Answer 27

get converted into nitrite by beneficial bacteria in the oral cavity

Question 28

why is nitrite good

Answer 28

it can reduce blood pressure

Question 29

what does XS nitrite that is swallowed get converted into

Answer 29

acidified nitric oxide

Question 30

where is the XS nitrite converted

Answer 30

in the stomach

Question 31

why is acidified nitric oxide good

Answer 31

due to the fact it stimulates mucus production which protects the stomach lining and it is antibacterial

Question 32

examples of bacteria seen in carious lesions

Answer 32

strep oralis/mitis fusobacterium nucleatum actinomycetes spp haemophillus spp neisseria spp

Question 33

why is caries multifactorial

Answer 33

various factors can contribute to the disease

Question 34

what factors are included in environmental factors

Answer 34

cariogenic diet, poor oral hygiene, low saliva flow

Question 35

what are the confounding factors?

Answer 35

fluoride availability, diversity of microbiota, non specific virulence traits

Question 36

what evidence do we have for the role of microbes in causing caries?

Answer 36

gnotobiotic animal studies, human epidemiology studies and vaccination

Question 37

what is a gnotobiotic animal study?

Answer 37

controlled research environments where no microbes are present or at least present are known and are controlled vigoruously eg. gnotobiotic animals such as rats must be completely devoid of microbes in their bodies

Question 38

what does the gnotobiotic rat study show us about caries

Answer 38

when they were infected with just strep much and sugars they showed caries therefore shows; 1) some bacteria are more cariogenic than others 2) diet and particular fermentable sugars 3) transmission from animal to animal 4) antimicrobial agents

Question 39

what does human epidemiology studies show us about caries? what are the 3 methods we use to investigate?

Answer 39

1) cross sectional study= cheaper but only show us associations 2) longitudinal study= shows cause and effect relationships between microbe and disease 3) vaccination= carried out by rodent and primates

Question 40

what serotype is found of strep mutans

Answer 40

c e and f

Question 41

what stereotypes found in s. sobrinus

Answer 41

d and g

Question 41

what stereotypes found in s. sobrinus

Answer 41

d and g

Question 41

what stereotypes found in s. sobrinus

Answer 41

d and g

Question 41

what stereotypes found in s. sobrinus

Answer 41

d and g

Question 41

what stereotypes found in s. sobrinus

Answer 41

d and g

Question 42

describe strep mut

Answer 42

* Gram positive cocci/short rods * Found on hard non-shedding surfaces * Implicated in initiation of caries

Question 43

give eg of actinomyces

Answer 43

o A. naeslundii o A. odontolyticus o A. israelii or A. gerencseriae

Question 44

give eg of actinomyces

Answer 44

o A. naeslundii o A. odontolyticus o A. israelii or A. gerencseriae

Question 44

give eg of actinomyces

Answer 44

o A. naeslundii o A. odontolyticus o A. israelii or A. gerencseriae

Question 45

describe Lactobacillus

Answer 45

Lactobacillus – gram positive rod, implicated in advanced dental caries

Question 46

describe bifidobacterium

Answer 46

Bifidobacterium – gram positive rod, branched cells, recently implicated in caries

Question 47

name a species of candida

Answer 47

c. albicans

Question 48

what are the difficulties with trying to associate microorganisms with dental caries

Answer 48

1) disease occur at sites with natural, diverse microbiota 2) pathogens found at "healthy" sites often as minor component of multi- species biofilms 3) difficult to correlate microbiota to enamel status= once lesions appear they can be remineralised 4) pathogenic traits are non specific and many factors contributing to caries

Question 49

what bacteria is found at caries sites according to cross sectional studies

Answer 49

s. mutans

Question 50

according to cross section studies which bacterias have an inverse relationship

Answer 50

MS and s. sanguinis

Question 51

what are the most caries prone sites

Answer 51

fissures and fissures that had Mutan Streptococci indicated carious fissures.

Question 52

what % of caries had more than 10% MS

Answer 52

71% therefore 30% caries fissures had lower or no MS

Question 53

what percentage of caries free fissures had no detectable MS

Answer 53

70%

Question 54

when can MS occur

Answer 54

first signs of demineralisation

Question 55

can caries also occur if MS is not present and what does this show

Answer 55

yes that other species have a role in caries progression eg. ;lactobacilli in advanced lesions

Question 56

examples of acidogenic bacteria

Answer 56

s. mitis and s.oralis

Question 57

give examples of lactate utilising bacteria

Answer 57

Veillonella utilises lactic acid in plaque and converts it into a weaker acid, reducing demineralisation.

Question 58

give eg of base producing species

Answer 58

Streptococcus salivarius, A. naeslundii and s. sanguinis

Question 59

what can s. salivarius and A. naeslundii hydrolyse urea into?

Answer 59

ammonia and co2

Question 60

what is the role of s. sanguinis

Answer 60

utilises the arginine deaminase system

Question 61

what bacteria is associated with childhood caries/nursing bottle caries

Answer 61

MS and lactobacillus

Question 62

which bacteria is associated with root surface caries in early studies

Answer 62

actinomyces spp

Question 63

which bacterias are associated with root surface caries in later studies

Answer 63

MS and lactobacilli

Question 64

which bacterias are associated with root surface caries in recent studies

Answer 64

diverse microbiota actinomyces spp MS gram negative rods

Question 65

what molecular changes do you find in infected dentine

Answer 65

31 new taxa data suggests combinations of acidogenic bacteria combined with proteolytic and collagenolytic anaerobes

Question 66

what bacteria do you find in infected dentine

Answer 66

MS Lactobacilli actinomycetes spp (a. israelii A. gerencseriae gram negative anaerobic rods