The document discusses various caries activity tests that assess caries susceptibility and manage restorative procedures. It details specific tests such as lactobacillus colony count test, calorimetric Snyder test, and salivary buffer capacity test among others, explaining their procedures, advantages, and disadvantages. Additionally, it outlines the clinical and research applications of these tests in caries management and prevention.

2. Introduction
 Caries activity: refers to increments of active
caries lesions over a stated period of time.
 Caries susceptibility: refers to inherent tendency
of host, target tissue & tooth to be afflicted by
carious process.
 Caries activity tests: measure the degree to
which the local environment challenge favors
the probability of carious lesions.

3.  Determine the need & extent of personalized
preventive measures.
 Serve as an index of the success of therapeutic
measures.
 Motivate & monitor the effectiveness.
 Manage the progress of restorative procedures.
 To identify high risk individuals.

4. Tests.
 Lactobacillus col0ony count
test
 Synder test
 Swab test.
 S mutans level in saliva
 Dip slide method for S
mutans
 Salivary buffer capacity test.
 Enamel solubility test
 Salivary reductase test
 Alban test
 S mutans screening test
 Fosdick calcium
dissolution test
 Dewar test

5. Lactobacillus colony count test.
 Estimates the number of acidogenic & aciduric
bacteria in patients saliva by counting the
colonies appearing on tomato agar plate after
inoculation with a sample of saliva.
 A selective media favouring the growth of
aciduric lactobacilli is the basis of test.

6. Procedure.
 Colllect the stimulated saliva & shake it.
 Saliva sample is diluted to 1: 10 dilution by pipetting
1ml saliva into 9ml saline solution.
 1: 100 dilution is made by pipetting 1ml of 1:10
dilution into another 9ml tube of saline solution.
 0.4ml of each dilution is spread on the surface of
agar plates.
 Plates are incubated for 3 – 4days at 37 C .
 Colonies are counted
 The number of lactobacilli/mm saliva is calculated by
multiplying the number of colonies on plate by the
dilution factor of its inoculums.

7. L bacilli counts i.r.t caries susceptibility
No of
organisms/c.c
Symbolic
designation
Degree of caries
activity
suggested
0 - 1000 +/- Little/ none
1000 - 5000 + Slight
5000 - 10000 ++ Moderate
More than 10000 +++ Marked

8. Advantage & disadvantages.
 Usefull for monitoring the
effectiveness of restorative
care
 Simple to carry out.
 Used as a screening test
for caries activity I n large
groups.
 Inacurate in predicting the
onset of caries.
 does not completely
exclude the growth of other
aciduric org.
 Counting is tedious process.
 Counts involving single
individuals are not reliable.

9. Calorimetric Snyder test.
 Measures the ability of salivary microorganisms to
form organic acids from a carbohydreate medium.
 Medium contains an indicator dye, Bromocresol
green.
 Colour changes from green to yellow in the range of
pH 5.4 – 3.8.
 Test also measures acidogenic & aciduric bacteria.

10. Procedure.
 0.2 ml stimulated saliva is collected & mised with 10
ml melted agar containing medium in test tube cooled
to 50C, allowed to solidify & then incubated at 37C.
 Amount of acid produced is indicated by changes in
pH indicator & is compared to an uninoculated control
tube after 24, 48, 72 hours.
 Rate of colour change from green to yellow is
indicative of degree of caries activity.

11. Colour observations in Snyder test
24 hr 48 hr 72 hr
If yellow
Marked caries
susceptibility
If yellow
Definite caries
susceptibility
If yellow
limited caries
susceptibility.
If green
continue to
incubate &
observe at 48 hr.
if green
continue to
incubate &
observe at 72 hr.
if green caries
inactive.

12. Advantages & disadvantages
 Simple to carry out.
 Test are of value in
assessing the oral
environment mental
cariogenic challenge.
 No dilutions are
required.
 Time consumed is more
 Sometimes colour
changes are not clear.

13. Swab test
 Based on same principle like Snyder test.
 Oral flora is sampled by swabbing the buccal
surfaces of teeth with cotton applicator, which is
subsequently incubated in the medium.
 Change in pH following a 48 hour incubation is read
on pH meter/ colour change is read by use of colour
comparator.

14. Interpretation
 pH 4.1 & < 4.1 = marked caries activity
 pH 4.2 – 4.4 = active
 pH 4.5 – 4.6 = slightly active.
 pH 4.6 & above = caries active.

15. Advantages
 Test is of value in predicting caries increments,
particularly in children with low or no previous
caries experience.
 No saliva collection.

16. S mutans level in saliva.
 Test measures the number of S mutans CFU/ unit
volume of saliva & culturing of plaque samples from
discrete sites, such as occlusal surface, preximal area
is used for detecting & quantitating S mutans.
 Incubation is done on Mitis salivarius agar selective
medium with addition of high concentrated of
sucrose 20% & 0.2 bacterium/ ml supress the growth
of mutans colonies.

17. Procedure.
 Sample is collected by tongue blades which are
then pressed against S mutans selective MSB
against petri dishes.
 Plates are incubated at 37C for 48 hours in 95%
at 5% Co2 gas mixture.

19. Advantages & Disadvantages.
 The count is used as
an adjacent in caries
management.
 Difficulty of distinguishing
between a carrier state &
cariogenic infection.
 S mutans may constitute
less than 1% of total flora
of plaque.
 Mutans tend to be located
at specific sites only.

20. Dip slide method for S mutans count.
 Method is devised for the estimation of S mutans
level in saliva.
 Undiluted stimulated saliva is poured on special
plastic slide coated with MSA containing 20%
sucrose.
 Two discs containing 5 mg of bacitracin are placed
on agar 20 mm apart.
 Slide is tightly screwed & incubated at 37C for 48
hours in sealed candle jar.

21. Evaluation.
 Score 1 = low: the colonies are discrete & could be
readily counted at 15x magnification with the total
count of CFU inside less than 200.
 Score 2 = Medium: the colonies are discrete & the
number in the zone of inhibition is more than 200 &
32x magnification.
 Score 3 = High: colonies are tiny & almost completely
cover the inhibition zone with colonies
uncontrollable even with 32x magnification.

22. Salivary buffer capacity test.
 Test measures the no of ml of acid required to
lower the pH of saliva through an arbitrary pH
interval, such as from pH 7 – 6 or the amount of
acid or base necessary to bring colour indicators
to their end point.
 Buffer capacity is quantified using pH meter or
colour indicators.

23. Procedure.
 10 ml of stimulated saliva is collected under oil at least 1
hr after eating; 5ml of this is measured into beaker.
 After correcting the pH meter to room temp, pH of saliva
is adjusted to 7 by adding lactic acid or base.
 Level of lactic acid is then added to sample until a pH of
6 is reached.
 The number of ml of lactic acid needed to reduce pH
from 7 – 6 is measure of buffer capacity.

24. Evaluation.
 Test gives inverse relationship between
buffering capacity of saliva and caries activity.
 The saliva of individuals whose mouth contain a
considerable number of carious lesions
frequently has low buffer capacity.

25.  Advantage :
 simple to carry out.
 Disadvantage :
 do not correlate adequately with caries activity.

26. Enamel solubility test.
 It is based on the fact that when glucose is added to
saliva containing powdered enamel, organic acids are
formed.
 Decalcify the enamel, resulting in an increase in amount
of soluble calcium in the saliva – glucose - enamel
mixture.
 The extent of increased calcium is direct measure of
degree of caries susceptibility.

27. Disadvantage
 Not suitable for office procedures.
 Complex equipments are required
 High cost
 Need personnel training.

28. Salivary reductase test.
 Measures the activity of reductase enzyme
present in salivary bacteria.
 Saliva is collected in plastic container & the
sample is mixed with dye diazoresorcinol.
 Colour changes & caries conduciveness reading
is taken after 15 min.

29. Colour Time Score Caries
activity
Blue 15 min 1 Non
conducive
Orchid 15 Min 2 Slightly
conducive
Red 15 mins 3 Moderately
conducive
Red Immediately 4 Highly
conducive
Pink/ white immediately 5 Extremely
conducive.

30. Advantages & disadvantages
 Quick results
 No incubation
required
 Test results vary with
time after food intake
& brushing.

31. S mutans screening test : Plaque/ tooth pick
method.
 Test involves a simple screening of dilute plaque
sample streaked on selctive culture media.
 Plaque samples are collected from gingival third of
buccal tooth surfaces from each quarant & placed in
Ringers solution.
 Sample is shaken till homogenized.
 Plaque suspension is stretched across MSA plates.
 Incubated at 37C for 72 hours & colonies in 10 fields
are recorded.

32. Plaque tooth pick

Grade Colonies/ 10 fields.
1 None
2 < 8
3 8

33. Saliva/ tongue blade method.
 Test estimates the number of S. mutans in mixed
stimulated saliva when cultured in MSB agar.
 Subjects chew paraffin for 1 min to displace plaque
microorganisms.
 Subjects are given sterile tongue blade, which they
rotate in mouth for 10 mins, so that both the sides
are thoroughly inoculated by flora.
 Flora pressed on to MSB agar & incubated at 37 c for
48 hours.

34. Fosdick calcium dissolution test.
 Test measures mgs of powdered enamel dissolved
in 4 hours by acid formed when patients saliva is
mixed with glucose & powdered enamel.
 25 ml of stimulated saliva is collected & part of it
is analysed for calcium content.
 Rest of saliva is placed in tube with about 0.1 mg
of powdered enamel.
 Tube is sealed & shaken for 4 hours at body temp,
after which it is again analysed for calcium
content.

35.  Chewing of gum to stimulate the saliva produces
sugar; if paraffin is used, a concentration of
about 5% glucose is added.
 Amount of dissolution increases as the caries
activity increases.

36. Dewar test.
 Similar to Fosdick test , only difference is that the
final pH after 4 hours is measured instead of
amount of calcium dissolved.

37. Uses for clinician
 Determine the need for caries control measures.
 Indicator of patient co – operation.
 Acts as an aid in timing of recall appointments.
 Aid in determining prognosis.
 Precautionary signal to orthodontist in placing
bands.

38. Uses for research worker.
 As an aid in selecting patients for caries studies.
 To help in screening of potential therapeutic
agents.
 Serve as an indicator of periods of exacerbation
& remission.

39. Thank you