caries activity tests in pediatric dentistry

1. CARIES ACTIVITY TESTS
Presented by
SAFNA AMEEN

2. CARIES??????
Dental caries is an irreversible progressive disease of multifactorial
in nature affecting the calcified tissues of the teeth characterized by
demineralization of inorganic portion and destruction of organic
portion.
CARIES ACTIVITY
It refers to the increment of active lesions over a stated period of
time.
Caries activity is the measure of the speed of progression of a
carious lesion.

3. CARIES ACTIVITY TEST..??
It measures the degree to which the local environmental challenge
(eg. Dietary effect on microbial growth and metabolism) favours
the probability of occurrence of carious lesions.
CARIES SUSCEPTIBILITY
It refers to the inherent tendency of the host and target tissue, the
tooth to be affected by the caries process.
This is the susceptibility of a tooth to a caries producing
environment.

4. PURPOSE OF CARIES ACTIVITY TEST..
• Identify high risk groups and individuals
• Need for personalized preventive measure and motivate the
individual
• Monitor the effectiveness of oral health
• Ensure a low level of caries activity before starting any extensive
restorative procedure
• Index help to reduce S. mutans and lactobacilli

5. IDEAL REQUISITES OF A CARIES ACTIVITY
TEST
• Test should be reproducible and valid
• There should be good correlation between the caries activity
scores and actual caries development
• Should be simple
• Results should be obtained rapidly, within hours or few days
• Should have measurement of mechanisms involved in caries
process
• Should be inexpensive, non-invasive and applicable to any
clinical setting

6. ACTIVITY AND
SUSCEPTIBILITY
TESTS

7. CAT
Count method
Evaluation of
virulence
• Snyder’s colorimetric
test
• Enamel solubility test
• Fosdick calcium
dissolution test
• Salivary reductase test
• Lactobacillus colony
count test
• Streptococcus mutans
level in saliva
• Alban’s test
• Swab test
• Salivary buffer capacity
test

8. LACTOBACILLUS COLONY COUNT TEST
PRINCIPLE
This test estimates the number of acidogenic and aciduric micro-
organisms in a patient’s saliva by counting the number of
colonies by culturing the bacteria on peptone agar plates after
inoculation with a sample.
Selective media favouring the growth of aciduric lactobsacilli is
the basis for the test.

9. EQUIPEMENTS
• Saliva collecting bottles
• Paraffin
• 29 ml tubes of saline
• 2 agar plates
• 2 bent rods
• Incubator
• Qubec counter
• Pipettes
• PROCEDURE
saliva is collected by chewing paraffin before breakfast
• The specimen is vigorously shaken and after that 0.1 cc of the
sample is withdrawn
• Dilute and undiluted samples are then spread evenly over a
rogosa SL agar plate
• The plate is incubated for 4 days and the number of lactobacilli
colonies that developed are counted

10. NUMBER OF
LACTOBACILLI/ML
CARIES ACTIVITY
0-1000 Little or no activity
1000-5000 Slight activity
5000-10,000 Moderate activity
>10,000 Marked activity
INTERPRETATION

11. DISADVANTAGES
• Inaccurate for predicting the onset of caries
• It does not completely exclude the growth of other relative
aciduric organisms
• Requires relatively complex equipments
• It only takes a few minutes to do the test , result takes several
days

12. COLOMETRIC SNYDER TEST
PRINCIPLE INVOLVED
• It measures the ability of salivary micro-organism to form organic
acids, from a carbohydrate medium.
• The medium contains an indicator or dye, formocresol green which
changes it colour as the pH drops from 5.4 to 3.8.
• The classical formula of Snyder’s agar per litre of purified water is:
 Pancreatic digest/casein – 13.5 gm
 Yeast extract - 6.5 gm
 Dextrose -20 gm
 Sodium chloride - 5 gm
 Agar - 16 gm
 Bromocresol green - 0.029 gm

13. PROCEDURE
• Saliva is collected by chewing paraffin
• A tube of snyder glucose agar is melted and then cooled to 500C
• 0.2 ml of saliva is spit into the tube and mixed
• The agar is solidified and incubated
• Amount of acid produced by acidogenic organisms is detected by
changes in the pH indicator and then compared to the uninoculated
control tube against a white background after 24, 48 and 72 hours
• The rate of colour change from green to yellow is indicative of
degree of caries activity.

14. 24 hours 48 hours 72 hours
If yellow
Marked caries
activity
If yellow
Definite caries
activity
If yellow
Limited caries
activity
If green
Observe- 48 hours
If green
Observe- 72 hours
If green
Caries inactive
INTERPRETATION

15. ADVANTAGES
• Relatively simple to carry out
• Cost effective
DISADVANTAGES
• Time consuming
• Colour changes are not very clear
MODIFICATIONS
• A smaller volume of culture media is inoculated with saliva using
calibrated wire loop. This avoids use of pipettes and saves
medium and space.
• The buccal surfaces are swabbed and the cotton applicator
incubated in semi-fluid Snyder medium.
• Alban’s method

16. A longitudinal study conducted in Okayama, Japan to
investigate the predictive value of cariostat indicated caries
prevalence of 9% at 18 months, 21% at 24 months. It stated thet
cariostat was an effective method of carrying out caries
prediction in young children
ASDC journal of dentistry for children 62 (1), 34-37, 1995

17. SWAB TEST
Grainger et al in 1965
PRINCIPLE
It measures the ability of salivary micro-organism to form organic
acids from a carbohydrate medium. The medium contains an indicator
dye, bromocresol green which changes as the pH drops from 5.4 to
3.8
PROCEDURE
The oral flora is sampled by swabbing the buccal surface of tooth
with cotton and is subsequently incubated in the medium.

18. pH CARIES ACTIVITY
< 4.1 Marked caries activity
4.2 to 4.4 Active
4.5 to 4.6 Slightly active
> 4.6 Caries inactive
INTERPRETATION
ADVANTAGES
• No collection of saliva is required
• Predicts caries increment

19. STREPTOCOCCUS MUTANS LEVEL IN SALIVA
PRINCIPLE INVOLVED
• Measures the number of S. Mutans colony forming units per unit
volume of saliva and plaque samples from discrete sites, such as
occlusal fissures and proximal areas.
• Incubation is done on Mitis Salivarius agar, selective
streptocoocal medium with addition of high concentration of
sucrose and 0.2 U Bacitracin, supress the growth of most non-
mutans colony.
PROCEDURE
• Sample collection by the use of tongue blades
• Incubation at 370C for 48 hours at 95.5% CO2 gas mixture.
INTERPRETATION
Levels >105/ml of saliva is unacceptable.

20. ADVANTAGE
Useful in caries management as S. mutans are the main causative
agents.
DISADVANTAGES
• Difficulty of distinguishing between a carrier state and cariogenic
infection
• S.Mutans may constitute less than 1% of total flora of plaque
• S. Mutans tends to be located at specific sites only

21. STREPTOCOCCUS MUTANS SCREENING
TEST
PLAQUE/ TOOTH PICK METHOD
PRINCIPLE INVOLVED
• Simple screening of dilutes plaque sample streaked on a selective
culture media.
• Semi quantitative screening of dental plaque for S. Mutans.
EQUIPMENTS
• Sterile tooth picks
• Sterile ringer’s solution (5ml)
• Platinum loop
• Mitis Salivarius Agar plates (MSA) containing sulphadimetine.

22. PROCEDURE
• Plaque samples are collected from the gingival thirds of buccal
tooth surfaces one from each quadrant and placed in Ringer’s
solution
• The sample is shaken until homogenized.
• The plaque suspension is stretched across MSA plates
• Aerobic incubation at 370C for 72 hours.
• Cultures are examined and total colonies in 10 fields are recorded

23. SALIVA/ TONGUE BLADE METHOD
PRINCIPLE INVOLVED
Estimation of the number of S.Mutans in paraffin stimulated saliva
when cultured in MSB agar.
EQUIPMENTS
Paraffin wax
Sterile tongue
Disposable petri dish containing MSB agar
PROCEDURE
• The subjects chew a piece of paraffin wax for one min to displace
plaque micro-organisms to increase their proportion in saliva.
• Sterile tongue blades are rotated in the tongue 10 times
• Tongue blades are then pressed into MSB agar
• Incubation is done at 370C.
• Numbers of colonies are counted

24. ADVANTAGES
• Simple practical method for field studies as there is no
requirement of transport media/dilution.
• Suitable for use in studies involving school children

25. DIP-SLIDE (DENTOCULT-SM) METHOD
FOR S.MUTANS COUNT
PRINCIPLE INVOLVED
Estimation of S.Mutans levels in saliva
PROCEDURE
• Undiluted paraffin stimulated saliva is poured on a special
plastic slide coated with MSA containing 20% sucrose.
• The agar surface is thoroughly moistened and excess saliva is
allowed to drain off.
• 2 discs containing 5 mg of bacitracin are placed on agar 20 mins
apart.
• The slide is tightly screwed into a cover tube and incubated at
370C for 48 hours in a sealed candle jar.

26. INTERPRETATION
SCORE 1- low: the colonies are discrete and could be easily counted
at 15X magnification with the total count of CFU inside the initiation
zone less than 200.
SCORE 2- medium: the colonies are discrete and the number in the
zone of inhibition is more than 200 and 32X magnification.
SCORE 3- high: the colonies are tiny and almost completely or
totally cover the zone of inhibition zone with the number of colonies
uncontrollable even with 32X magnification

27. THE SWAB TEST
PRINCIPLE INVOLVED
Same as Snyder’s test
PROCEDURE
• The oral flora is sampled by swabbing the buccal surfaces of
teeth with a cotton applicator, which is subsequently incubated in
the medium.
• The change in the pH following 48 hours incubation is read on a
pH meter or colour change is read by the use of a colour
comparator

28. INTERPRETATION
pH CARIES ACTIVITY
4.1 OR <4.1 Marked
4.2 to 4.4. Active
4.5 to 4.6 Slightly active
4.6 or >4.6 Caries inactive
ADVANTAGE
Useful in predicting caries increments or changes, particularly in
children as no collected of saliva is required.

29. SALIVARY BUFFER CAPACITY TEST
PRINCIPLE INVOLVED
• Buffer capacity can be quantitated using either a pH meter or
colour indicators.
• The test measures the number of millimeters of acid required to
lower the pH of saliva through an arbitrary pH interval (6 to 7) or
the amount of acid/base necessary to bring colour indicators to
their end point
EQUIPMENTS
• Titration equipment
• 0.05 N lactic acid
• 0.05 N base, paraffin
• Sterile glass jars containing a small amount of oil
•

30. PROCEDURE
• 10 ml of stimulated saliva is collected under oil atleast one hour
after eating
• 5 ml of this is measured into a beaker
• After correcting the pH meter to room temperature, the pH of
saliva is adjusted to 7 by addition of lactic acid or base.
• lactic acid is then added to the sample until a pH of 6 is reached.
• The number of ml of lactic acid needed to reduce pH from 7 to 6
is a measure f buffer capacity.
INTERPRETATION
Inverse relationship between buffering capacity of saliva and caries
activity

31. ADVANTAGE
Simple to carry out
DISADVANTAGE
Doesn’t correlate adequately with caries activity

32. ALBAN’S TEST
PRINCIPLE INVOLVED
Same as that of Snyder’s test
PROCEDURE
To prepare the Alban’s test medium
MATERIALS REQUIRED
• Snyder’s test agar
• A small scale to measure 60 grams
• A 2 litre Pyrex glass, to melt the medium
• A funnel to dispense the medium into test tube
• 100, 16 mm test tubes with screw caps

33. INTERPRETATION
LEVEL OF COLOUR CHANGE SCORING
No change ¾
Beginning of colour change +
One half colour change ++
3/4th colour change +++
Total colour change to yellow ++++

34. INFERENCES
• Readings negative for the entire incubation period are labelled
negative
• All other readings are labelled positive
• Slower change or less colour change is labelled improved
• Faster or more pronounced colour change is labelled worse
• When consecutive readings are nearly identical, it is labelled as no
change
ADVANTAGES
• Use of somewhat softer medium that permits the diffusion of saliva
and acids without the necessity of melting the medium.
• Use of simpler sampling procedure
• Low cost
• High diagnostic value
• Motivational value

35. DISADVANTAGES
• More armamentarium required
• Subjective evaluation of colour change

36. SALIVARY REDUCTASE TEST
PRINCIPLE
Measures the activity of the reductase enzyme present in salivary
bacteria, using a dye- Diazoresorcinol
PROCEDURE
• Saliva is collected in a plastic container
• The sample is then mixed with a dye
• The caries conductiveness is measured by colour changes seen
after 15 mins.

37. INTERPRETATION
COLOUR TIME SCORE CARIES
ACTIVITY
Blue 15 mins 1 Non-
conducive
Orchid 15 mins 2 Slightly
conducive
Red 15 mins 3 Moderately
conducive
Red Immediately 4 Highly
conducive
Pink/white immediately 5 Extremely
conducive

38. ADVANTAGES
• Quick results
• No incubation period required
DISADVANTAGE
Test results vary with time after food intake and after brushing

39. FOSDICK CALCIUM DISSOLUTION TEST
PRINCIPLE INVOLVED
Measurement of amount of powdered enamel dissolved in 4 hours by
acid formed, when the patient’s saliva is mixed with glucose and
powdered enamel
PROCEDURE
• Saliva is stimulated by having the patient to chew gum or paraffin
• 25 ml of saliva is collected
• One part of this is used to analyze the calcium content
• The remain is taken into an 8 inch sterile test tube in which 0.1 gm
of powdered enamel is added.
• Test tube is sealed and shaken for 4 hours at body temperature
• Then the calcium content is analyzed
• When paraffin is used to stimulate saliva, 5% glucose is added

40. INTERPRETATIION
Amount of calcium increases as the caries activity increases
ADVANTAGE
In the limited studies, correlation reported is good
DISADVANTAGES
• Requires complex equipment and trained personnel
• Expensive
MODIFICATION
Dewar test
Final pH after 4 hours is measured instead of calcium dissolved

41. LIMITATIONS OF CURRENT CARIES ACTIVITY
TESTS
• Measures single parameters hence not reliable
• Time consuming
• There is need to develop chair side tests

42. CONCLUSION