CARIES ACTIVITY TESTS
DENTAL CARIES
It
is
an
irreversible
progressive
disease
of
multifactorial in nature
affecting
the
calcified
tissues
of
the
teeth
characterized
by
demineralization
of
inorganic
portion
&
destruction
of
organic
portion of the tooth.
CARIES ACTIVITY
• Refers to the increment of active lesion (new and
recurrent lesions) over a stated period of time
• Caries activity is a measure of speed of progression
of a carious lesion.
CARIES SUSCEPTIBILITY
• Refers to the inherent tendency of the host & target
tissue, the tooth to be affected by the carious process
REQUIREMENTS OF CARIES ACTIVITY
TESTS
• Test should be reproducible & valid
• There should be good correlation between the caries activity
scores & 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 & applicable to any
clinical setting
CARIES ACTIVITY
TESTS:
1.
Lactobacillus colony count test
•
Saliva is collected by chewing paraffin
before breakfast
The specimen is vigorously shaken and
after that 0.1 cc of sample is withdrawn
Dilute and undiluted samples are then
spread evenly over a rogosa’s SL agar
plate
The plate is incubated for 4 days & no. of
lactobacillus colonies that developed are
•
•
•
counted.
No of organisms
Symbolic
designation
Degree of caries
activity suggested
1-1000
+
Little or none
1000-5000
+
Slight
5000-10,000
++
Moderate
More than 10,000
+++/++++
Marked
SNYDER TEST
• This test measures the ability of salivary
microorganisms to form organic acid from a
carbohydrate medium.
• 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
24 hrs
48 hrs
72hrs
yellow
yellow
Caries activity: marked
definite
limited
Color
green
Color
: yellow
: green
Caries activity: continue test
green
continue test continue test
ALBEN’S TEST
• It is a modified Snyder test
• At the time of test 5 ml, tube of semisolid agar is removed
from refrigerator but is not heated
• The patient is asked to spit unstimulated saliva directly in to
the tube. Tube is incubated for 4 days.
SWAB TEST
•
•
•
•
Advantage is no collection of saliva is necessary
Valuable in evaluating caries activity in very young children
Principle is same as Snyder test
The oral flora is sampled by swabbing the buccal surface of
tooth with cotton.
REDUCTASE TEST
• This test measures the activity of reductase enzyme present in
salivary bacteria
• The sample is mixed with fixed amount of diazo-resorcinol
• The change in color after 15 min is taken as a measure of
caries activity
color
Time
score
Caries activity
Blue
15min
1
Non conductive
Orchid
15 min
2
Slightly conductive
Red
15 min
3
Red
Immediately 4
Moderately
conductive
Highly conductive
pink
Immediately 5
Extremely conductive
ENAMEL SOLUBILITY
TEST
• It is based on the fact that when glucose
is added to saliva containing powdered
enamel, organic acids are formed
• Organic acid decalcifies the enamel,
resulting in an increase in the amount of
soluble calcium
• The extend of increase of calcium is a
direct measure of caries activity
SALIVA FLOW TEST
• Flow rate is determined by collecting paraffin stimulated
saliva in a test tube over 5 min
• Severely decreased flow is related to caries susceptibility
• As salivary flow rate decreases viscosity increases
PATIENT EDUCATION WITH METHYL RED
• A simple and effective technique that may be of assistance in
educating child patient to the problem of dental caries control
involves the use of aqueous solution of methyl red
• Indicator dye changes colour in the pH range from 6.3(distinct
yellow) – 4.2(red)
• Aqueous methyl red is then applied to the surface of the tooth
with dropper
• Red colour is developed in the area of plaque accumulation
• This is interpreted to patient as evidence of continuous acid
formation