Theories &Diagnosis of Dental 
caries
Lecture ( 5 )

Dr.Baha, H. AL-Amiedi 
Ph.D.Microbiology 

NORMAL TOOTH
Dental Caries:
Dential caries can be thought of chronic 
of enamal or dentine in which microbial
agents cause lesion result from the
demineralization of enamel or dentine by
acid produce by plaque microoganisms as
they metabolize dietary carbohydrate
Once the surface layer enamel has been 
lost progress via dentine & with in the
pIup becoming firstly inflamed & later
necrotic.
Classification of Dental 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
Recurrent 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
Aetiological
factors in dental caries
Major Factor involved in dental caries
1- Dental plaque( Microorganism). 
2-Saliva. 
3-Diet 
4-Time 
Minor factor involved in dental caries:
1-Morphology of the tooth. 
2-position of the tooth . 
3- Enemal composition 
4-Immunity. 
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) : 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) : 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 chelating- 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 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 caries 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 
