Theories &Diagnosis of Dental 
caries
Lecture ( 6 )

Dr.Baha, H. ALAL-Amiedi
Amiedi
Ph.D.Microbiology 

NORMAL TOOTH
Classification of Dental caries
caries:: 
Dental caries can be classified with 
respect to the site of the lesion and
of lesion as diagrammatically in
1- Bit and fissuer 
2- Smooth Surface 
3- Root surface 
4- Recureent caries 
Bacterial associated with caries type 
caries type
pit and fissure
Smooth surface
Dental caries
Root caries
microorganisms isolate 

S . mutans , S.sanguis 
S .mitis, lactobacilli
Actinomyces 
S. mutans 
lactobacilli 
S. mutans 
A. naeslundii 
Filumentous Rods 
A viscosus 
A. viscosus
. 
A naeslundii, 
A salivarius 
S mutans, S sanguis 
Filamentous Rods 

Dental Caries
Demineralization of the tooth surface caused by
bacteria
Theories of etiology of caries : 
1-Early Theories : 
A-Worms tooth aches caries caused by worm 
B-Humors : unbalance between the humors : 
( blood , black bile , yellow bile )
2-Vital Theory : origination of dental caries 
with in tooth it self extensive penetration
into the dentin & into pulp
3-Chemical Theory : chemical agents 
responsible for caries
4-Parasitic or septic Theory : filmentous 
microorganisms caused decomposition of
the enamel and the dentin
5-Chemo - parasitic Theory (Miller 1890
1890)) : caries is 
caused by acids produced by oral cavity
microorganisms of the mouth miller 1890
concluded that the process was mediated by
microorganisms produced acids and digestion
proteins .
6-Proteolytic Theory(Gottlib 1944
1944)) : it has been 
proposed that the organic matrix or protein
elements of enamel are the initial pathway of
invasion by oral cavity microorganisms
7-Proteolysis – chelation Theory : this theory 
considers dental caries to be bacterial destruction
of teeth where the initial attack essentially on
organic component of enamel and the end
products of proteolysis acts as a chelatingchelating- agent.
Bacterial caries susceptibility test(synder test): 
Many attepts have been made to develop sutable 
diagnosis test for the determination of caries 
susceptibility of an individual. most of these tests
have been based on differences in type of bacteria
present in the microflora of caries & whether these 
microflora of caries are capable of producing acid
when incubated with sugar, usually glucose.
There have have been number of modifications of 
this test in 1965 Grainger introduced a swab for
the buccal surface of teeth, the placing in
semifluid synder type medium& incubating at 37 C
for 96 hr
Test reading by color comparison to standard test. 
Reading of synder modification test Diffusion acid 
color change to from yellow top down one fourth 
or less of tube, from top down
+ 

color change to yellow, one half of tube
++ 
from top down


color change to yellow, three fourths of
+++ 
tube , from top down


color change to yellow, entire tube
++++ 
No color change
_ 
Interactions among dental plaque bacteria
The current approach to diagnose
The current approach to diagnose 
dental caries 
1-Naked eyes
X-ray
2-Mechanical probing
3-X-ray
“Gross” Visual
Examination
Mechanical Probing and X-ray
The current approach to treat 
dental caries 
Surgical repair 
Fluoride treatment 
Mechanical removal 
The end 
