Microbiology of Dental caries

Describe relationship between plaque and oral diseases
Describe role of plaque in development of caries
Define Dental Caries
Describe the aetiology and the role different factors play in ini4a4on and progression of the disease
Describe the role played by different microorganisms

1. Dr. Ali Yaldrum
SEGi UC, KD
Dental!Caries
Microbiology

3. Learning!Outcomes
At!the!end!of!this!session!students!should!be!

! Describe!rela4onship!between!plaque!and!oral!diseases
! Describe!role!of!plaque!in!development!of!caries
! Define!Dental!Caries
! Describe!the!ae4ology!and!the!role!different!factors!
play!in!ini4a4on!and!progression!of!the!disease
! Describe!the!role!played!by!different!microorganisms

4. Plaque bacteria to Caries
Relationship of

5. Plaque & Caries
Historically!for!any!microbe!to!be!considered!responsible!
for!a!given!condi4on,!Koch`s postulate was!applied

6. Koch`s Postulate
1. The!microbes!should!be!found!in!all!cases!of!the!disease!with!a!
distribu4on!corresponding!to!the!observed!lesions
2. The!microbes!should!be!grown!on!laboratory!media!for!several!
subcultures
3. A!pure!subculture!should!produce!the!disease!in!the!suscep4ble!
animal
4. A!high!an4body!4ter!to!the!microbe!should!be!detected!during!
infec4on;!this!may!provide!protec4on!on!subsequent!reinfec4on

7. Koch`s Postulate
1. A!microbe!should!be!present!in!sufficient!numbers!to!ini4ate!
disease
2. The!microbe!should!generate!high!levels!of!specific!an4bodies
3. The!microbe!should!produce!relevant!virulence!factors
4. The!microbes!should!cause!disease!in!an!appropriate!animal!
model
5. Elimina4on!of!!the!microbe!should!result!in!clinical!improvement

8. Role!of!Plaque
! The!bSpecific!Plaque!Hypothesis`(fig.1)
! The!bNonPSpecific!Plaque!Hypothesis`!(fig.2)
! The!bEcological!Plaque!Hypothesis`(fig.3)

9. Specific Plaque Hypothesis
Plaque
Disease
( )
X problem disease can still occur in absence of these
organisms
few species out of diverse resident
flora are actively involved in disease {
fig.1

10. Non-Specific Plaque Hypothesis
Plaque
Disease
( )
problem plaque mediated diseases are polymicrobial but one
specific organism predominate
out come of the overall activity of
the total plaque microflora {
fig.2

11. Ecological Plaque Hypothesis
Plaque
Disease ( )
disease only initiates as a result of shift in
the balance of resident microflora
organisms associated with disease
are already present on teeth but very
low to detect {
fig.3

12. Dental Caries

13. Dental Caries

! It!is!bacterial!disease!of!calcified!4ssue!of!the!teeth!characterized!
by!demineraliza4on!of!the!inorganic!and!destruc4on!of!the!
organic!substance!of!the!tooth.

bDental Caries is known as disease of civilization`

14. The Early theories
!  The legend of Worms
!  Endogenous Theory
!  Chemical Theory
!  Parasitic Theory
! Chemoparasitic Theory
Dental Caries

15. !  Chemoparasitic theory
Miller!in!1890!suggested!that!oral!bacteria!converted!dietary!
carbohydrates!into!acid!which!solubilized!the!calcium!phosphate!of!
enamel!to!produce!a!caries!lesion
Dental Caries

16. Aetiology of Dental Caries

17. Saliva
Saliva
Saliva
Saliva
Time
Plaque
Bacteria
Susceptible Surface
Sugar
Caries
aetiology of caries fig.4

18. Role of Saliva

19. Saliva!plays!a!vital!role!in!the!maintenance!of!oral!health!
and!the!integrity!of!oral!4ssues
Saliva!contains:
• exfoliated!epithelial!cells
• oral!microorganisms
• food!residues!(carbohydrates)
• an4microbial!factors
• minerals
Role of Saliva

20. ! Mechanical!washing!ac4on!of!saliva!is!very!effec4ve!for!
cleaning!of!teeth
! high!buffering!capacity!neutralizes!acid
! supersaturated!with!Calcium!and!phosphorus!helps!in!
remineraliza4on
Salivary!flow!rate:!0.8!mm!/min!on!upper!labial!surface
!!!!!!!!!!!!!!!!!!!!!!!5.0!P!8.0!mm/min!on!lower!lingual!surface
Role of Saliva

21. Susceptible Surface

22. Susceptible Surface
Some!areas!of!the!tooth!are!more!suscep4ble!to!developing!caries!
than!others,!known!as!bsusceptible areas`

Suscep4bility!is!related!to!several!factors
! Mineral!&!Fluoride!Content
! Structure!of!that!par4cular!area

23. Susceptible Surface
Susceptible tooth surfaces includes

! Pits!&!Fissures!(fig.5)
! Approximal!Enamel!cervical!to!contact!point!(fig.6)
! Exposed!root!surface!(fig.7 & 8)
! Margins!of!Restora4on!(fig.6!&!9)
! Cervical!margins!of!tooth!(fig.10)

24. pits & fissures caries
fig.5

25. Approximal Caries Caries under restoration
fig.6

26. Root surface Caries
fig.7

27. fig.8
Root Surface Caries

28. Caries under restoration
Amalgam restoration
fig.9

29. white spot lesions
fig.9

30. white spot lesion Cavitation
From white spot to cavity formation
earliest clinical evidence (reversible) Later clinical stage (irreversible)

31. Sugar Substrate
Time &

32. ! Direct!rela4onship!between!intake!of!Carbohydrates!
(sugar)!&!Caries
! Glucose,!Fructose!&!Sucrose!are!cariogenic!
!Sucrose!is!the!most!cariogenic!sugar
• !fermentable
• easily!penetrates!plaque
Sugar Substrate

33. There!is!a!direct!rela4onship!between!caries!and:
! Frequency!of!sucrose!consump4on
! s4ckiness!of!the!sucrose

Both!affects!the!amount!of!4me!sugar!stays!into!contact!
with!the!teeth!surface
Time & Sugar Substrate

34. Plaque Bacteria

35. Dental!Caries!does!not!occur!in vivo!if!microorganisms!in!
the!form!of!dental!plaque!are!absent;!making!it!clear!that!
dental!caries!is!a!plaque!mediated!disease
Plaque Bacteria
b
b

36. ! Streptococcus!mutans
! Lactobacillus!species
! Ac4nomyces!Species
! Veillonella!species
Plaque Bacteria

37. The!term!mutans!streptococci!refers!to!a!group!of!7!
different!species,!but!two!species!are!most!commonly!
found!in!humans
! S.!mutans!(serotypes!c/e/f)
! S.!sobrinus!(serotypes!d/g)
Streptococcus species

38. Factors related to Cariogenicity of S. mutans
!S.mutans!counts!in!saliva!and!at!site!of!lesion
! Isolated!from!site!before!the!development!of!caries
! Efficient!sugar!metabolism!&!transport!capability
!Acidogenic!&!acidouric
! Liele!effect!of!pH!on!growth!and!metabolism
! Produc4on!of!EPS!&!IPS
Streptococcus species

39. S.!mutans!been!implicated!in!
! Pits!&!fissure!caries!(strong!evidence)
! Root!surface!caries
! All!forms!of!caries
! Some!strains!are!more!pathogenic!than!others
Streptococcus species

40. ! S.!Sobrinus!role!is!uncertain
! Frequently!isolated!from!plaque!but!in!lesser!numbers
! Shares!the!same!cariogenic!proper4es!as!S.mutans

Streptococcus species

41. Lactobacilli!can!be!divided!into!two!groups
! Homofermenta4ve!species
! Heterofermenta4ve!species

Lactobacillus species

42. Homofermentative species
! L.!acidophilus!&!L.!casei
! Mainly!produce!lac4c!acid!from!glucose!fermenta4on
Heterofermentative species
! L.!fermentum
! Produce!lac4c!acid!and!significant!amounts!of!acetate

Lactobacillus species

43. Most!commonly!isolated!species!from!oral!cavity!are
! L.!casei
! L.!fermentum
! L.!acidophilus

Lactobacillus species

44. Factors related to Cariogenicity of Lactobacillus
species
! Increased!number!in!carious!cavi4es!affec4ng!enamel!&!
root!surface
! Number!in!saliva!reflect!caries!ac4vity
!Acidogenic!and!acidouric
! Few!strains!can!produce!EPS

Lactobacillus species

45. ! Have!a!low!affinity!for!tooth!surface
! Low!in!numbers!at!healthy!site
! Implicated!in!progression!of!caries!deeper!into!den4ne!
rather!than!ini4a4on
! Implicated!in!ae4ology!of!root!surface!caries

Lactobacillus species

46. Ac8nomyces!spp.!form!a!major!and!complex!part!of!the
oral!microflora,!par4cularly!at!the!approximal!site!and
gingival!crevice

Actinomyces species

47. !Ac8nomyces!odontoly8cus!been!associated!with!!very!
early!stages!of!tooth!demineraliza4on
!Ac8nomyces!naeslundii!been!associated!with!
development!of!root!surface!caries

Actinomyces species

48. CariesVaccination

49. In!rats!,!experimental!dental!caries!have!been!reduced!by!
immunizing! with! cellPwall! associated! an4gens! or!
glucosyltransferase!from!S.mutans

Caries Vaccination

50. The!following!mechanism!have!been!suggested

!Inhib4on!by!secretory!IgA!of!bacterial!coloniza4on!of!
teeth
! Interference!with!bacterial!metabolism
! Enhancement!of!phagocy4c!ac4vity!in!gingival!crevices


Caries Vaccination

51. ! Dental!Caries!is!a!mul4factorial!disease,!strongly!
associated!with!the!dental!plaque
! Ecological!Plaque!Hypothesis!caries!forms!as!a!result!of!
disturbance!in!the!normal!balance!of!Oral!Biota
! The!main!factors!involved!are!suscep4ble!tooth!surfaces,!
4me,!sugar!substrate!and!plaque!bacteria
! Pits!&!fissure!are!the!most!suscep4ble!areas
! Frequency!of!sugar!intake!is!more!decisive!than!total!
consump4on

Summary

52. ! Sucrose!is!the!most!cariogenic!sugar
!Mutans!streptococci!are!implicated!in!ini4a4on!of!pits!&!
fissure!and!root!caries
! Lactobacillus!spp!are!associated!with!progression!of!
caries

Summary

53. ! Philip!D.!Marsh,!Michael!V!Mar4n,!lPlaque!mediated!
diseasesP!Dental!Caries!and!Periodontal!diseasesz!in!Oral!
Microbiology,!5
th
!Edi4on,!Churchil!Livingstone,!2009,!pp!
104P117
! J.!Bagg,!T.!W.!Macfarlane,!I.!R.!Poxton!and!A.!J.!Smith,!
lDental!Cariesz!in!Essen4als!of!Microbiology!for!Dental!
Students,!2
nd
!Edi4on,!Oxford!University!Press,!2006!
pp238P248

References