Dental Caries
216
DENTAL CARIES
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Transcript of Dental Caries
DENTAL
CARIES
Contents
Introduction
Etiology of dental caries
Histopathology of dental caries
Diagnosis of dental caries
References
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Introduction
Dental caries continues to be a major problem
in dentistry and should receive significant
attention in everyday practice, not only from
the standpoint of restorative procedures but
also in terms of preventive measures designed
to reduce the problem.
Caries is on the decline in the industrial
countries but it is on the increase in the
developing countries due to increased sugar
consumption.
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Dental caries is an irreversible microbial disease of the calcified tissues of the teeth, characterized by demineralisation of the inorganic portion and destruction of organic substance of the tooth , which often leads to cavitation.
It is essential to understand that cavitation in teeth are signs of bacterial infection.
It has effected humans since prehistoric times, but the prevalence of this disease has increased greatly in modern times due to dietary changes.
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Dental caries 5
Tooth is covered by plaque, which consists mainly of bacteria. Plaque is often found close to the gum, in between teeth, in fissures and at other "hidden" sites.
Demineralization: When sugar and other fermentable carbohydrates reaches the bacteria, they form acids which start to dissolve the enamel - an early caries lesion occurs due to loss of Calcium and Phosphates
Remineralization: When sugar consumption has ceased, saliva can wash away sugars and buffer the acids. Calcium and Phosphates can again enter the tooth. The process is strongly facilitated by fluorides
A CAVITY occurs if the Demineralization "wins" over the Remineralization over time 6
1. A tooth surface without caries. 2. The first signs of demineralization. 3. The enamel surface has broken down. 4. A filling has been made but the demineralization has not been stopped. 5. The demineralization proceeds and undermines the tooth. 6. The tooth has fractured.
Progression of dental caries 7
Acc. to WHO it is defined as a localized post
eruptive pathological process of external origin
involving softening of the hard tooth tissue and
proceedings to the formation of a cavity.
It can also be defined as localized chemical
dissolution of the tooth surface caused by
metabolic events taking place in the biofilm
(dental plaque) covering the affected area.
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It may develop at any tooth site where biofilm
develops and remains for a period of time.
Biofilm is a prerequisite for caries lesion to
occur. Biofilm is characterized by continued
microbial activity resulting in continued
metabolic events in the form of minute pH
fluctuation.
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EPIDEMIOLOGY
Dental caries may be considered a disease of
modern civilization , since prehistoric man rarely
suffered from this form of tooth destruction .
Anthropologic studies of VON LENHOSSEK
revealed that the Dolicocephalic skulls of men
from pre Neolithic periods (12000 BC) did not
exhibit dental caries but skulls from
Bracycephalic man of the Neolithic periods
(12000 to 3000 BC) contained carious teeth.
The cervical areas of teeth in older persons
were frequently affected .
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CARIES SUSCEPTIBILITY OF
INDIVIDUAL TEETH
BREKHUS (1931 ) studied a group of students at the university of Minnesota and reported the following caries susceptibility incidence of the teeth
Upper and lower first molar : 95 %
Upper and lower second molars : 75 %
Upper second bicuspids : 45%
Upper first bicuspid :35%
Lower second bicuspids : 35%
Upper central and lateral incisor : 30 %
Upper cuspids and lower first bicuspids : 10%
Lower central and lateral incisors : 3 %
Lower cuspids : 3%
ETIOLOGY OF DENTAL
CARIES
Etiology
Development of dental caries depends on :
1. Microflora: acidogenic bacteria that colonize
the tooth surface.
2. Host :quantity and quality of saliva , quality of
the tooth.
3. Diet : intake of fermentable carbohydrates,
especially sucrose ,but also starch.
4. Time : total exposure time to acids produced
by the bacteria of the dental plaque.
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Caries Tetralogy[Newbrun 1982]
Includes a fourth
factor, time to the
still existing
concept of Keyes,
depicting the
significance of
changes taking
place over a
period.
15
Classification of dental caries
ACCORDING TO MORPHOLOGY
-Pit and fissure caries
-Smooth surface caries
ACCORDING TO CHRONICITY
-Acute dental caries
-Chronic dental caries
ACCORDING TO PROGRESSION
-Primary caries
-Secondary (Recurrent )caries
-Arrested caries
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ACCORDING TO SEVERITY AND PROGRESSION
-rampant caries
-nursing caries
-radiation caries
ACCORDING TO PART OF TOOTH STRUCTURE INVOLVED
-Enamel caries
-Dentinal caries
-Cemental caries
PIT AND FISSURE CARIES
Pit and fissure with high steep walls and
narrow bases are prone to develop caries.
Retention of food debris and microorganisms.
Early caries appear brown or black, soft ‘catch’
of a fine explorer point.
Lateral spread of caries through a narrow
opening at the DEJ.
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SMOOTH SURFACE CARIES
Early appears as a faint white opacity of the enamel without loss of the continuity of the surface.
Preceded by the formation of a microbial or dental plaque.
As caries penetrates enamel,it assumes bluish white appearance.
Proximal caries begins just below contact point.
The typical cervical carious lesion is crescent shaped cavity with chalky area.
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ACUTE DENTAL CARIES
Rapid clinical course resulting in early pulp
involvement with pain.
Progress rapidly so less time for secondary
dentin depositionis present
E.g.Nursing bottle caries commonly affects 4
deciduous maxillary incisors. It is a type of
RAMPANT caries which primarily affects all
deciduous incisors.
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CHRONIC DENTAL CARIES
Progresses slowly and tends to involve pulp
much later.
Sufficient time for sclerosis of dentinal tubules
and secondary dentin deposition.
Carious dentin stains deep brown.
PAIN is not a common feature.
21
RECURRENT CARIES
Caries occuring in immediate vicinity of a
restoration.
Usually due to inadequate extension of the
original restoration favoring retention of debris.
Poor adaptation of filling material to the cavity
which produces a leaky margin.
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ARRESTED CARIES
Static or stationary caries which do not show
any tendency for further progression.
Occurs exclusively in caries of occlusal
surfaces characterised by a large open cavity
which lack food retention.
EBURNATION OF DENTIN : gradual
burnishing of superficial softened and
decalcified dentin until it takes on a hard
brown stained, polished appearance.
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RAMPANT CARIES
It occurs as a sudden , rapid and almost
uncontrollable destruction of teeth , involving
surfaces of teeth that are ordinarily caries
free(proximal and cervical surfaces of anterior
teeth including the mandibular incisors get
affected)
A caries increment of 10 or more new lesions
over a period of about a year is characteristic
of rampant caries attack
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NURSING CARIES
It is a specific form of rampant decay of
primary teeth of infants and toddlers.
Affects maxillary primary incisors due to
prolonged nursing habit esp. when the child is
sleeping
Also named as baby bottle tooth decay or
early childhood caries
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RADIATION CARIES
Common complication of radiotherapy of oral
cancer lesions and radiation induced
xerostomia
Hypothesis concerning the etiology
of caries
Two hypothesis:
Older one : promotes the universal presence
of potential pathogens in plaque and assumes
that all accumulation of plaque are pathogenic.
Latter one promotes that accumulation of
plaque could be regarded as normal in the
absence of disease.
Plaque is assumed pathogenic only when
signs of disease are present.
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The difference between two hypothesis was
identified and discussed by Loesche:
First one : non specific plaque hypothesis
Second one: specific plaque hypothesis
Problem with non-specific hypothesis was that
it requires a therapeutic goal that completely
eliminates plaque in all patients that requires a
continuous therapy directed to total plaque
elimination.
28
Acc . to specific theory ,plaque can be
identified as pathologic only when they are
associated with clinical disease. So treatment
can be aimed at elimination of the specific
pathogenic organisms.
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Caries- latin word –rot or decay.
Its etiology is agreed to be a complex problem
complicated by many indirect factors that
obscure the direct causes.
Many theories have evolved through years of
investigation and observation attempting to
explain its etiology.
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The early theories
1. The legend of worms : the earliest reference is from the ancient sumerians known as legend of worms. This dates back around 5000 BC . The idea behind this was that caries was caused by worms and worms are the cause of toothache.
2. Endogenous theory: it was advocated by Greek physicians, who proposed that dental caries is produced by internal action of acids and corroding humors.They also proposed the Vital theory of tooth decay,which postulated that tooth decay originated from within the tooth itself.
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3. Chemical theory:Parmly in 1820 observed that dental decay affected externally and not internally. He proposed that unidentified chemical agent was responsible for caries.
4. Parasitic theory:Erdl in 1843 was first to relate microorganisms to caries as a positive agent. Ficnus in 1847 attributed dental caries to denticolae(decay related to microorganisms). But this was soon disseminated as it was proposed that dental caries commenced as a purely chemical process and bacteria were essential for caries as an exogenous source of the acids.
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Miller‟s chemico-parasitic theory OR
Acidogenic theory
Proposed by Willoughby D Miller in1882.
He stated that caries is caused by acids
produced by microorganisms of the mouth.
“Dental decay is a chemico-parasitic process
consisting of two stages , the de-calcification
of enamel , which results in its total
destruction and the de-calcification of dentin
as a preliminary stage,followed by dissolution
of the softened residue”
33
The acid that affects the de-calcification is
derived from the fermentation of starches and
sugars lodged in the retaining centres of the
teeth.
He isolated numerous microorganisms, some
were acidogenic and others were proteolytic.
A no. of these bacteria were capable of
producing lactic acid.
34
He proposed that caries was not caused by
any single organism but a variety of
microorganisms.
Essential factors in caries process:
1. Microorganisms
2. Carbohydrate substrate
3. Acid production
35
This theory is the backbone of current
knowledge and understanding of the etiology
of dental caries.
Drawbacks : theory was unable to explain the
predilection of specific sites on a tooth to
caries and the initiation of smooth surfaces
was not accounted by this theory.
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The proteolytic theory
The previous theory was not wholly accepted.
Then this theory came into existence.
Proposed by Gottlieb and Gottlieb(1944).
This theory proposed that the organic
material(enamel lamellae and rod sheaths) or
protein elements are the initial pathway of
invasion by microorganisms.
They also admit that acid formation
accompanied the proteolysis.
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Pincus(1949) proposed that enamel proteins
are mucoproteins, yielding sulphuric acid upon
hydrolysis.
In support of this theory Gram negative bacilli
capable of producing sulfatase were also
isolated.
This acid dissolves the enamel, combining
with the calcium to form calcium sulphate.
38
Drawbacks : no sulfatase has been
demonstrated at the site of carious lesion.
No such enzyme has also been demonstrated
in the oral cavity.
The proteolysis of organic matrix of dentin may
indeed occur after demineralization and there
is no satisfactory evidence to support the claim
that the initial attack on enamel is proteolytic.
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The proteolysis-chelation theory
Proposed by Schatz et al (1955).
Proposed a simultaneous microbial
degradation of the organic components
(proteolysis) and the dissolution of minerals of
the tooth by the process known as chelation.
Chelation is a process involving the
complexing of a metallic ion to a complex
substance through a coordinate covalent
bond(highly stable , poorly dissociated).
40
This theory considered caries to be a bacterial
destruction of teeth where the initial attack is
essentially on the organic components of the
enamel. this breakdown product has chelating
property hence dissolves the minerals in
enamel (at a neutral or alkaline ph).
Thus this theory suggested that
demineralization of enamel could arise without
acid formation.
41
Drawback : it was concluded that saliva and
plaque do not contain substances in sufficient
amount to chelate calcium in detectable
amounts from enamel.
Also chelation is unlikely to be involved in the
initiation of the lesion, it may play a minor role
in the established lesion.
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Sucrose chelation theory
Proposed by Egglers-Lura (1967).
He proposed that sucrose itself and not the
acid derived from it cause dissolution of
enamel by forming an ionized calcium
saccharates.
This theory stated that calcium saccharates
and calcium complexing intermediaries require
inorganic phosphate which is subsequentaly
removed from the enamel by phosphorylating
enzymes.
43
Drawback : since saliva is an abundant source
of inorganic phosphates for bacterial
utilization, it is highly improbable that depletion
of phosphate in plaque by oral microbial
metabolism results in phosphate withdrawl
from enamel.
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Role of plaque in dental caries
Dental plaque is soft, translucent and
tenaciously adherent material accumulating on
the surface of teeth and not readily removed
by rinsing with water .
It is composed of bacteria and their by-
products.
Accumulation of plaque on teeth is highly
organized and ordered sequence of events
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It is estimated that 1mm³ of plaque weighing
about 1mg contains more than 200 million
bacteria.
A few specialized organisms (streptococci )
are able to adhere to oral surfaces like mucosa
and tooth surface.
These bacteria produce a sticky matrix that
allows them to coadhere to each other .
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Plaque growth
The initial bacteria are called pioneer bacteria
or colonizers. (mainly streptococcal strains).
These bacteria proliferate and spread laterally
to form a mat-like covering over the tooth
surfaces.
When the entire surface is covered ,growth of
colonies increases the thickness of plaque .
Further growth of bacteria produces a vertical
growth away from the tooth surface forming
vertical columns called palisades .
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These bacteria allow the adherence of other
organisms like filamentous bacteria,which are
unable to adhere directly to the tooth surface.
Proliferation of new invading bacteria produce
entangled masses of filaments forming
“corncob” like structure.
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Early stages of plaque
succession
After professional removal of all organic material and bacteria from the tooth surface , a new coating of organic material begins to accumulate immediately.
Within 2 hrs, a cell free , structureless organic film, the pellicle, covers the tooth surface.
Some of the proteins of pellicle are biologically active and have a significant impact on microorganisms attemptimg to colonize the tooth surface.
49
The early stages of recolonization of the
cleaned tooth surface involves adhesion
between the pellicle and the pioneering
bacteria.
S. sangius , A. viscosus and
peptostreptococcus are the main pioneering
species capable of attaching to the pellicle
within 1 hr after tooth cleaning.
50
The adhesion process is selective and
requires specific organism receptor capable of
binding to certain areas on the precipitated
salivary proteins of the pellicle.
The enzyme glucosyltransferase may be
crucial in the adherence of organisms to the
pellicle when sucrose is present as it
enhances the polymerization of the
extracellular matrix that helps in the formation
of tenaciously adherent colonies.
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Late stages
Late stages are mainly responsible for causing
caries.
In early stages there are primarily aerobic
communities lacking pathogenic potential.
As the plaque matures,more and more acid is
produced from metabolism mainly lactic acid.
This increased production of acid leads to
prolonged drop in pH , increasing the potential
for enamel demineraliztaion.
52
Tooth habitat for pathogenic plaque
The tooth surface is stable and covered with
the pellicle and thus the ideal site for the
attachment of many oral streptococci.
If left undisturbed , plaque builds rapidly to
sufficient depth to produce anaerobic
environment.
Some favorable tooth habitats for plaque are:
Pit and fissures
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Smooth enamel surface immediately gingival
to the contact area and in the gingival 1/3 of
facial and lingual surface.
Root surface near the cervical line.
Subgingival areas.
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Pits and fissures
Highest prevalence of all dental caries.
Provide excellent shelter for organisms.
The relative proportion of organisms most
probably determine the cariogenic potential of
the pits and fissures.
The appearance of microorganisms in pits and
fissures is followed by caries 6-24 months
later.
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Sealing the pits and fissures just after tooth
eruption may be the most important event in
their resistance to caries.
56
Smooth enamel surfaces
The proximal enamel surfaces gingival to the
contact area are the 2nd most susceptible area
to caries.
In very young patient,gingival papilla fills
completely the interproximal spaces under the
proximal contact.
So proximal caries are less likely to develop
where the favorable soft tissue architecture
exists.
57
Conversely, apical migration of papilla creates
more habitats for surface colonizing bacteria.
The gingival aspect of the facial and lingual
smooth enamel surface is not rubbed by the
bolus of food and not properly cleaned by the
brush.
These surface areas are habitats for the
caries- producing mature plaque.
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Root surface
The proximal root surface , often is unaffected
by the action of oral hygiene procedures,
because of its concave anatomic surface.
This favors the formation of mature, caries
producing plaque and thus root caries lesion.
Also, the facial and lingual root surface when
exposed to the oral environment harbors
caries producing plaque.
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Role of microorganisms
To initiate carious lesion in enamel , the
organisms must also be able to colonize the
tooth surface.
The most important bacteria responsible for
carious lesion are- Strepococcus mutans.
The second bacteria closely related to caries
is Lactobacillus.
It was proposed that one or more organisms
are implicated in the initiation of caries
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While others distinctly different organisms may
influence the progression of disease.
Cariogenic bacteria:
S . mutans
S. salivarius
S. mitior
S.oralis
S.milleri
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S. sangius
Peptostreptococcus intermedius
Lactobacillus acidophillus
L . casei
A. viscosus
A. neaslundii
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Localization of bacteria related to
caries
Type of caries
1. Pit and fissure
2. Smooth surface
organisms
S. mutans (very significant)
Lactobacillus (very significant)
S . Sangius (uncertain)
Actinomyces (by chance)
S. mutans (very significant)
S. salivarius (by chance)
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3. Root surface
4. Deep dentinal
caries
A. viscosus (very significant)
A. naeslundii (very significant)
S. mutans (significant)
Lactobacilli sp. (very significant)
A. naeslundii (very significant)
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Role of acids
Carbohydrate degradation occurs through
enzymatic breakdown and the acid formed are
chiefly lactic acid although others such butyric
acid are also formed.
The mere presence of acid in the oral cavity is
of far less significance than the localization of
acids upon the tooth surface.
Generally , monosaccharides and disaccarides
result in the greatest fall in plaque pH.
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Anaerobic catabolism of carbohydrates called
fermentation predominates in plaque. After
breakdown one molecule of glucose breaks
down into two molecules of lactic acid.
Bacteria :
Homofermenters (streptococci, lactobacilli)
Heterofermenters
67
Organisms which produce 90 % or more lactic
acid as the end product are called homo-
fermentative.
Organisms which produce a mixture of
metabolites including other organic acids such
as propionic , Butyric acid, Ethanol etc are
called hetero-fermentative.
The proportion of lactic acid and other organic
acid formed by plaque may be markedly
affected by growth conditions and the type of
bacteria present.
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Caries is a multifactorial disease in which there is interplay of four primary factors :
Host
Microbial flora
Substrate
Time
Thus, caries require a susceptible host, a cariogenic flora, and a suitable substrate that must be present for a sufficent time.
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Factors
A. Tooth
B. Saliva
Components
Composition
Morphologic characteristics
Position
Composition
pH
Quantity
Viscosity
Antibacterial factors
70
C. Diet
D. Systemic conditions
Physical factors (quality
of diet)
Local factors
(carbohydrate content,
Vitamin
content,Fluoride
content)
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Tooth factors
Composition of teeth : the composition of teeth
undoubtedly influence the initiation and the
rate of progression of a carious lesion .
Composition of enamel : enamel is the hardest
calcified tissue in the body, because of its high
content of mineral salts and their crystalline
arrangement.
Enamel: inorganic=96%, organic=4%.
72
Enamel attains a maximum thickness of
2.5mm on the cusps of the molars, thinning
down to almost a knife edge at the neck of the
tooth.
Acc. to Brudevold et al surface enamel is more
resistant to caries than subsurface enamel.
Surface enamel is more highly mineralized .
73
Tends to accumulate greater quantities of fluoride, zinc , lead, iron etc than subsurface enamel.
Also initial carious lesions indicate that marked decalcification is observed in subsurface enamel while the outer surface is relatively intact.
The surface dissolves at a slower rate in acids, Contains less water and has more organic material than subsurface enamel.
These factors apparently contribute to caries resistance and are partly responsible for slower degradation of surface enamel than the underlying enamel in initial carious lesion
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Composition of dentin: dentin forms the bulk
and general form of the tooth.
Dentin : inorganic=65%
organic=35%
The dentinal tubules form a passage for
invading bacteria , resulting in rapid
penetration and spread of caries to the pulp.
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Composition of cementum: cementum is the
mineralized dental tissue, covering the
anatomic roots of human teeth.
Cementum : inorganic=45-50%
organic=50-55%
Cementum has the highest fluoride content of
all the mineralised tissues.
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Physical characteristics
Tooth size:it has been assumed that low caries
may have smaller teeth and the larger teeth
were found more caries susceptible and are
found in the oral cavity for a shorter time
period .
the effect of tooth size would be negligible in
comparison with the combined effects of other
factors.
77
Morphologic characteristics
The morphologic characteristics of tooth have
been suggested as influencing the initiation of
dental caries.
Caries susceptibility in the permanent dentition
may be ranked in the following order :
1. Fissures of molars
2. Mesial and distal surface of first molars.
3. Mesial surface of 2nd molars and Distal
surface of 2nd premolars.
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4. Mesial and distal surfaces of the maxillary first
premolars.
5. Distal surfaces of the canines and mesial
surface of md. 1st premolar
6. Proximal surface of max. incisors.
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Fissures : the only morphologic feature which
conceivably might predispose to the
development of caries is the presence of deep,
narrow, occlusal fissures or buccal or lingual
pits.
Such fissures tend to trap food, bacteria and
debris, so caries may develop rapidly in these
areas.
80
But as the attrition advances, the inclined
planes become flattened , providing less
opportunity for entrapment of food in the
fissures, and the predisposition towards the
caries diminishes.
81
Surfaces: certain surfaces of teeth are more
prone to decay , whereas other surfaces rarely
show decay.
md. 1st molar: occlusal > buccal > mesial >
distal >lingual.
Max. 1st molar: occlusal >mesial>lingual>
buccal>distal.
Max. LI: lingual surfaces are more susceptible.
82
All available evidences indicate that alteration
of the tooth structure by disturbances in
formation or in the calcification is of only
secondary importance in dental caries. The
rate of caries progression may be influenced ,
but caries initiation is affected only to a very
little extent.
83
Morphology of CEJ
An exposed CEJ is a potential area of plaque
retention . So root caries tend to develop along
the CEJ.
84
Exposure of root surfaces
In the young , healthy adult, root surfaces like
the CEJ are not exposed to the oral cavity.
Prevalence of exposed root surfaces is age-
related or from gingival recession associated
with periodontal disease.
Morphologically, the surface of intact
cementum and the CEJ are very rough ,
compared to the enamel surface. And the
rough surface is highly retentive to plaque .
85
Position of tooth
Teeth which are malaligned, out of position ,
rotated or otherwise not normally situated may
be difficult to cleanse and tend to favor the
accumulation of food and debris.
This in susceptible persons would be sufficient
to cause caries in a tooth .
The position seems to be a minor factor in the
etiology of caries.
86
Saliva and dental caries
Introduction :saliva is the primary means by
which the pt. exerts control over its oral flora.
Who made the 1st observation of the influence
of saliva on caries is hidden in the mists of
time, but around 1900 there were several case
reports on the deleterious effects of absence
of saliva.
87
Functions of saliva
Saliva has manifold functions in protecting the
integrity of the oral cavity from food residue ,
debris and bacteria :
1. Saliva has some buffering effect against
strong acids and bases.
2. Saliva provides the ions needed to
remineralize the teeth.
3. Saliva has antibacterial, antifungal and
antiviral capacities.
88
The principal properties of saliva that protects
the teeth against caries are:
1. Dilution and clearance of dietary sugars.
2. Neutralization and buffering of the acids in
plaque.
3. Supply of ions for remineralization.
4. Both endogenous and exogenous antiplaque
and antimicrobial factors.
89
An important function of saliva is dilute and
eliminate substances. This is a physiological
process referred to as salivary clearance or
oral clearance.
After an intake of sugar, the salivary glands
will be stimulated by the taste or chewing to
increase the flow rates, resulting in swallow,
which eliminate some of the sugar from the
oral cavity which inturn helps in caries
prevention
90
pH of saliva:
The pH at which saliva ceases to be saturated
with calcium and phosphate is referred to as
critical pH .
Critical pH= 5.5
The main determinants of critical pH are the
total calcium and phosphate conc. in saliva.
This value was determined by Schmidt-
Neilsen, 1946.
91
At this pH no demineralization or
remineralization will take place.
Below this pH, demineralization occurs as
phosphate ion of apatite crystals get converted
to hydrogen phophates by increased hydrogen
ion.
Thus, solubility of tooth depends on the pH of
surrounding medium.
92
In the pH range of 2-6 the solubility increases by a factor of 10 for each pH drop of one unit.
Stephan curve: he stated that inspite of saliva buffer capacity the plaque pH will drop immediately after the sugar intake to values below critical pH, whereafter it slowly returns to normal.
93
94
95
Under resting conditions,pH of plaque is reasonably constant,6.9-7.2
Following exposure to sugars the pH drops very rapidly(in few minutes) to lowest level(5.5 to 5.2-critical pH) and at this pH,the tooth surface is at risk
During this critical period,the tooth mineral dissolves. Repeated fall of pH over a period of time leads o more and more mineral loss from the tooth surface,resulting in initiation of dental caries
Later slowly it returns to original value over a period of 30-60 minutes,approximately
Quantity of saliva:
In patients with reduced quantity of
saliva(salivary gland aplasia or xerostomia) ,
the cleaning properties of saliva in the mouth
are impaired.
Which leads to low oral sugar clearance,
which increases caries risk.
the unstimulated flow rates has been found to
be diagnostically more important than the
stimulated one.
96
Individuals with unstimulated flow rates <0.2
ml/min have an elevated demineralization rate
and a high risk of developing caries.
This low flow rates also favors acidic
environment, with an increase in cariogenic
microflora.
97
Thus, a low saliva flow rate not only will
prolong clearance time and periods with low
plaque pH, but may also change the ecology
of mouth.
In such cases the rate of progression of caries
is also faster as compared to cases with
normal flow rates.
98
Viscosity :
Occasional workers have reported that a high
caries incidence is associated with thick
mucinous saliva.
The viscosity of saliva is due largely to the
mucin content derived from submaxillary,
sublingualand accessory glands.
The significance of this factor is not clear.
99
Role of diet
The role of diet and nutrition factor deserves special consideration because of the often observed differences in caries incidence of various population who subsist on dissimiliar diets.
A diet rich in fermentable carbohydrate is indisputably a very powerful risk factor for caries.
Following consumption , depending on the quality of salivary gland function , a certain amount of saliva is stimulated by particular characteristic of food, such as taste, intensity of mastication.
100
Fermentable carbohydrates
1.Monosaccharides
Glucose
Fructose
2. Disaccharides
Sucrose
Maltose
Lactose
101
3. Polysaccharides
Glucan
Fructan
Mutan
Starch
102
Sucrose is regarded as the most important in
dental caries.
Sucrose is refined from sugar cane or beet
and is the most common dietary sugar .
The dietary sugar all diffuse rapidly into the
plaque and are fermented to lactic acid or can
be stored as intracellular polysaccharides by
the bacteria.
103
This mechanism prolongs the fall in pH and
promotes a suitable environment for acidogenic
bacteria.
Sucrose is unique as it is the substrate for
production of extracellular polysaccharide
(fructans and glucan) and insoluble matrix
polysaccharide (mutans).
Thus , sucrose favors colonization by oral
microorganisms and increase the stickiness of
plaque, allowing it to adhere in larger quantities to
the teeth.
104
Because of this effect on the quality of plaque ,
sucrose is considered to be somewhat more
cariogenic than other sugars.
Also other dietary disaccharides and
monosaccharides are regarded as risk factors.
All are rapidly fermented on plaque-covered
tooth surfaces.
Glucose, fructose, maltose give identical fall in
pH but for lactose fall in pH is smaller.
105
In frequently consumed snack food such as
sweets and drinks less fermentable and non-
cariogenic sweeteners are increasingly being
used as substitute for potentially cariogenic
sugars.
These are : caloric or non-caloric sweeteners.
Caloric: sorbitol, xylitol, mannitol
Non-caloric : saccharin, cyclamate, aspartame
They cannot be fermented by acidogenic
bacteria.
106
Physical properties of food and cariogenicity:
The Physical properties of food may be significant by affecting food retention, food clearance, solubility and oral hygiene.
Physical properties of food may improve the cleansing action and reduce retention of food with in the oral cavity and increase saliva flow
Physical nature of Diet:
Roughage food cleans the teeth from adherent debris during mastication.
Soft refined food tends to adhere to the teeth and are not removed because of general lack of roughage.
Mechanical cleansing by detergent foods may have some role in caries control.
107
Carbohydrate content of diet
Most important factor in dental caries
Vitamin content of Diet
Vitamin A: Definite effect on developing teeth in animals. No effect on humans.
Vitamin D: Children suffering from Vit. D deficiency may exhibit slightly higher degree of caries experience.
Vitamin K: It may act as a anticaries agent by virtue of its enzyme inhibiting activity in carbohydrate degradation cycle.
Vitamin B complex: Vit. B6 acts as an anticaries agent by selectively altering the oral flora by promoting the growth of non cariogenic organisms which suppress the non cariogenic forms.
108
Calcium and phosphorus dietary intake :
Disturbance in calcium and phosphorus
metabolism during the period of tooth
formation may result in severe enamel
hypoplasia and defects of the dentin.
Fluorine content of diet: Dietary fluoride is
relatively unimportant compared to fluoride in
drinking water because of its metabolic
unavailability.
109
Dietary studies
Vipeholm study: (Gustafsson et al -1954):
This study was conducted in a mental
institution for 5 yrs in Vipeholm hospital.
The institutional diet provided was nutritious ,
with little sugar, and no provision for between
meal snacks.
The dental caries rate experienced was
relatively low.
110
7 groups:
1. Control group
2. Sucrose group(300gm sucrose)
3. Bread group (345gm bread-50gm of sugar)
4. Chocolate group(65gm – daily-for last 2yrs)
5. Caramel group((22caramel-70gm sugar)
6. 8-toffee group (60gm sugar- for 3 yrs)
7. 24- toffee group(120 gm sugar-18 months)
111
Conclusions
Increased caries risk-
1. Increase in sugar content.
2. if sugar consumed in a form that will be retained on tooth.
3. If sugar is consumed in between meals.
4. It varies widely in between individuals.
5. Upon withdrawl of the sugar rich foods, the increased caries activity rapidly disappears.
6. Clearance time of the sugar correlates closely with caries activity.
112
This study showed that the physical form of
carbohydrates is much more imporatnt in
cariogenicity than the total amount of sugar
ingested.
113
Hopewood house study (Sullivan- 1958):
The dental status of children between 3-14 yrs
of age at Hopewood house was studied for
10yrs.
All lived on a strictly institutional diet.
The absence of meat and a rigid restriction of
refined carbohydrate were the two principal
features.
114
The meals were supplemented by vitamin
concentrates and an occasional serving of
nuts and a sweetening agent such as honey.
DMFT /child after 10 yrs -1.6
53% of the children were caries free.
Conclusion: the children‟s oral hygiene was
poor, calculus uncommon but gingivitis in 75%
of children.
115
This showed that dental caries can be reduced
by diet control even in the presence of
unfavourable oral hygiene.
116
Turku sugar study (Scheinin, Makinen -1975):
This study was done to test the effects of
chronic consumption of sucrose, fructose and
xylitol on dental caries.
3 groups:
1. Sucrose group-35 people
2. Fructose group-38 people
3. Xylitol group-52 people
117
A dramatic reduction in the incidence of dental
caries was found after 2 yrs of xylitol
consumption.
Fructose was cariogenic as sucrose for the
first 12 months but became less so at the end
of 24 months.
It was also found that frequent between meal
chewing of a xylitol gum produced an
anticariogenic effect.
118
Hereditary fructose intolerance (Froesch 1959):
It is caused by the remarkably reduced levels of hepatic, fructose -1-phosphate aldolase into two or three carbon fragments to be further metabolized.
Persons affected with this rare metabolic disorder have learned to avoid any food that contains fructose or sucrose, Because the ingestion of these foods causes symptoms of nausea, vomiting, malaise, tremor , excessive sweating , and even coma due to fructosemia.
Newburn 1969, found that caries prevalence was extremely low in persons with HFI.
119
Systemic factors
Heredity :it has been linked with the dental
caries incidence in scientific literature for many
years.
In 1899, acc to GV Black when the family
remains in one locality , the children living
under the conditions similar to those of parents
in their childhood , the susceptibility to caries
will be very similar in the great majority of
cases.
120
But there is still no such evidence that heredity
has a definite relation to dental caries
incidence.the possibility exists that if there is
such relation, it may be mediated through
inheritance of tooth form structure, which
predisposes to caries immunity or
susceptibility.
121
Pregnancy and lactation: it is a common
clinical observation that a woman during the
later stages of pregnancy or shortly after birth
of the child will manifest a significant increase
in caries activity.
In nearly all cases it is revealed that the
woman has neglected her oral care.
So caries incidence is actually a local problem.
122
Intake of medicine containing sucrose – fiber
supplements for constipation, cough mixtures
and antibiotics may affect caries risk
Psychiatric patients: carbohydrates favor
uptake of tryptophan to the brain and serotonin
production is enhanced. Thus its intake may
induce relaxation.
Also psychiatric drugs impair salivary gland
functioning.
123
Occupation: in which frequent food sampling is
required, may be associated with increased
caries risk.Eg.Confectionary industry, bakery
workers.
Socio-economic status: higher caries
prevalence in children with low socio-
economic background.
This is due to lesser parental knowledge , their
lesser involvement in oral hygiene and lesser
involvement in topical and supplementary F
regimes.
124
HISTOPATHOLOGY OF
DENTAL CARIES
Caries of enamel
Smooth surface caries: The earliest manifestation of incipient enamel caries is the appearance of an area of decalcification, beneath the dental plaque, which resembles a smooth, chalky white area. There is loss of interprismatic substance, with increased prominence and roughening of the ends of the enamel rods.
It forms a cone shaped lesion with the Apex towards the DEJ and the base towards the surface of tooth. There is loss of continuity of the enamel surface and the surface feels rough to the point of an explorer.
126
Pit and fissure caries:
Pit and fissures are often of such depth that food
stagnation with bacterial decomposition in the
base to be expected. The enamel in the bottom of
the Pit or fissure may be very thin, so that early
involvement frequently occurs.
When caries occurs it follows the direction of
enamel rods and forms a cone shaped lesion with
its apex at the outer surface and its base towards
the DEJ. Because of its shape it tends to produce
more undermining of enamel.
127
Enamel Caries :
Zone 1-translucent Zone
Zone 2- Dark Zone
Zone 3- Body Of The Lesion
Zone 4- Surface Zone
128
Four zones are clearly distinguishable.
Zone 1: The translucent Zone: Advancing front of the
enamel lesion. It is not always present.
Zone 2: Dark Zone: It is referred to as the positive
zone, because it is always present. It is formed as a
result of demineralization.
Zone 3: Body of the Lesion: It is the area of greatest
demineralization.
Zone 4: Surface Zone: Appears relatively unaffected.
129
Caries of dentin
It begins with the natural spread of the process
along the DEJ and the rapid involvement of
great numbers of dentinal tubules. The initial
penetration of the dentin by caries may result
in dentinal sclerosis resulting in calcification of
dentinal tubules, that tends to seal them off
against further penetration by microorganisms.
It most commonly occurs in older adults.
130
The destruction of dentin through a process of
decalcification followed by proteolysis, forming
necrotic mass of dentin of a leathery
consistency.
As the carious lesion progresses, various
zones of carious dentin may be distinguished
which tends to assume a triangular shape with
the apex towards the pulp and the base
towards the enamel.
131
Dentin caries:
Zone 1: Zone of fatty degeneration of
Tomes fibres
Zone 2: Zone of Dentinal sclerosis
Zone 3: Zone of decalcification of dentin
Zone 4: Zone of bacterial invasion
Zone 5: Zone of decomposed dentin
132
Following zones are seen:
Zone 1: Zone of fatty degeneration of Tomes
fibres.
Zone 2: Zone of Dentinal sclerosis-
characterized by deposition of calcium salts in
dentinal tubules.
Zone 3: Zone of decalcification of dentin – a
narrow zone, preceding bacterial invasion.
Zone 4: Zone of bacterial invasion of
decalcified but intact dentin.
Zone 5: Zone of decomposed dentin.
133
Caries of cementum (Root
caries)
Dental plaque and microbial invasion are an essential part of the cause and progression of this lesion.
Microorganisms involved in root caries are filamentous rather than coccal. Microorganisms invade the cementum either along sharpey’s fibers or between bundles of fibers.
Lesion spreads laterally between the various layers.
As carious process continues there is invasion of microorganisms in to dentinal tubules, subsequent matrix destruction and finally pulp involvement.
134
DIAGNOSIS OF DENTAL
CARIES
Clinical inspection of the teeth at the chairside
does not allow the dentist to observe the
caries process itself. What dentists can do is to
examine the consequences of microbial
metabolic activity when looking for signs of
lesions that have formed as a result of it. This
is what caries diagnosis is about: detection of
signs and symptoms of caries
136
Diagnosis is defined as the “art or act of
identifying a disease from its signs and
symptoms”(Merriam-Webster,2003)
The logic is that the course of the diseases
may be changed for the better if they are
detected and treated before they reach a stage
at which they elicit symptoms or require more
invasive intervention. Therefore, in dental
practice, diagnosis is closely linked with the
management options.
137
The primary objective of caries diagnosis is to
identify those lesions that require surgical
(restorative) treatment , those that require
nonsurgical treatment , and those who are at
high risk for developing carious lesions.
138
Why do we diagnose caries?
Diagnosis is important in:
Detecting and excluding disease
Assesing prognosis
Contributing to the decision making process
with regard to further diagnostic and
therapeutic management
Informing the patient
Monitoring the clinical course of the disease
139
Diagnostic tests need to be valid and reliable.
Validity means that test should measure what it is intended to measure e.g. a white spot lesion with a matt surface indicates an active lesion which has not yet cavitated
Reliability or reproducibility means that the test can be repeated with the same result e.g. dentist would recognize the same white spot lesion with matt surface as an active lesion. There should be intra- as well as inter-examiner reproducibility
140
Differential diagnosis
When performing a caries diagnosis it should
be appreciated that not all opaque lesions on
the tooth surface represent dental caries.
All opacities reflect a decreased mineral
content in the enamel, but may be caused by
different mechanisms,either during enamel
formation or posteruptively.
141
Dental fluorosis has a symmetric distribution on homologous teeth & in mild cases,appears as fine white horizontal striae reflecting the perichymatal pattern of enamel.
When such white lines merge in the gingival part of the tooth,they are suggestive of inactive non-cavitated carious lesions(smooth on probing). Such lesion is arch,banana or kidney shaped, reflecting the retention of plaque along the curvature of the gingival margin
142
143
Prerequisites for detection and
diagnosis
The diagnosis of caries require good lighting and dry,clean teeth
When teeth have been cleaned,each quadrant of mouth is isolated with cotton wool rolls to prevent saliva wetting the teeth once they have been cleaned
Thorough drying should be carried out by gentle blast of air from three-in-one syringe as white spot lesions are more obvious when the teeth are dry and saliva can obscure small cavities
144
Methods of caries detection
Conventional techniques:
Visual observation
Tactile inspection
Radiography:
• Intra-oral periapical radiographs
• Bitewing radiographs
145
Recent advances:
Dental digital
radiography
Caries-detector dyes
Fiber-optic
transillumination
Quantitative light-
induced fluorescence
Laser fluorescence
Ultrasound
Xeroradiography
Electroconductivity
measurements
Microbiologic methods
146
Visual observation
It encompasses the use of criteria such as detection of white spot, discoloration & frank cavitations.
Careful examination of teeth under clean & dry condition using good illumination reveal:-
- brownish discoloration of pit and fissures
- opacity beneath pit & fissure or marginal ridge.
- frank cavitation of tooth surface.
147
For practical purposes,begin with the upper
right molars and move tooth by tooth and
surface by surface to upper left molars,then
jump to the lower left molars and finish up with
the lower right molars. A consistent
examination pattern ensures that no teeth or
surfaces are missed
148
Various aids-
Magnification loupes
Slides have been used to gather information
about caries. With the use of slides pictures of
posterior teeth tell us more about
discoloration, decalcification & translucencies
Use of separators in detection of proximal
caries
149
Magnification loupe
150
Loupes are comfortable to wear
Inexpensive
Freely available in various magnifications
E.g:
• 2.5 Flip Up Loupes
• 3.0x and 3.5x Galilean Flip-Up Optics
• 2.5 Custom TTL Loupes
• NEW Custom TTL Loupes on Safety Frame
151
Tactile inspection
The teeth are examined by the aid of
dental mouth mirror and a sharp probe
The mouth mirror is used to displace the
cheeks and lips and to facilitate vision in
difficult to reach areas on the teeth
152
Reflected light from the mouth mirror can be
applied to search for dark shadows,which may
be suggestive of dentinal lesions
Transmitted light from the operating lamp is
particularly helpful for examining the approximal
surfaces of anterior teeth
153
An explorer is useful in caries diagnosis
as a tool to remove plaque and debris and
check the surface characteristics of
suspected carious lesions.
- curved explorer is used for examination of pit and fissures .
- inter proximal explorer is used to detect proximal caries.
154
The surface texture of lesion is sensed through
minute vibrations of the instrument by the
supporting fingers when moving the tip of the
probe at an angle of 20-40 degrees across the
surface
155
One should definitely abstain from poking
vigorously into the tissue,thereby running the
risk of causing irreversible damage to the
surface layer of an incipient lesion,which may
potentially accelerate localized lesion
progression
156
Some researchers are concerned that probing
of suspected carious lesions may serve to
spread infective plaque(i.e. mutans
streptococci) to other teeth in the same
mouth,thereby facilitating carious lesion
development. However,this this concern has
not been confirmed as transferred
microorganisms would not survive unless their
new econiche favored their existence
157
Tactile finding suggestive of caries are:- • „binding‟ or „catch‟ of explorer tip • Frank cavitation at the base of pit or fissure • Softness at base of pit or fissure • Opacity surrounding the pit or fissure
Feeling of „catch‟ may be due to non carious reasons also, this may depend on:
• shape of fissure
• sharpness of explorer
• force of application
• path of explorer placement
158
Radiographs
Conventional , intra-oral periapical & bite wing radiographs are used to diagnose dental caries.
159
Advantages:-
- non-invasive method
- disclose site inaccessible to other diagnostic methods.
- keeps a permanent record for maintaining progress or arrest of carious lesions.
Disadvantages:-
- only a 2-D image of 3-D object.
- doesn‟t reveal the earliest stages of caries development..
- radiolucency may be due to caries, wear, fracture, or due to cervical burn out.
- radiographic diagnosis is subjective , prone to observer bias.
- extent of caries as seen in the radiographs is usually lesser than actual defect.
160
BITEWING RADIOGRAPH:
Role For detecting occlusal caries:-
• Initial enamel caries are difficult to detect on bitewing radiographs due to 3 D shape of occlusal surface.
• caries involving the buccal and lingual grooves on molars mimic occlusal lesions due to superimposition.
Role in detecting proximal caries:-
• Early proximal enamel lesions are seen as small radiolucent notch below contact area.
• Advanced proximal caries are seen as dark triangular area in proximal enamel with its base towards the external tooth surface.
161
162
Diagrammatic representations of
caries on bitewing radiograph
163
Uses:
Detecting incipient proximal caries.
Examining many teeth in one radiograph.
Checking cervical margins of restoration.
Noting the size of pulp chamber.
Monitoring the progress or arrest of caries.
164
Fiberoptic transillumination
Diagnostic method by which visible light is transmitted through the tooth from an intense light source,e.g a fine probe with an exit diameter of 0.3-0.5 mm
Principle of it is that there is a different index of light transmission for decayed & sound tooth
Tooth which is decayed has a lower index of light transmission than the sound tooth structure
It is effective specially when used in anterior region.
It is used as an adjunct to visual and radiographic method
165
If the transmitted light reveals a shadow when the tooth is observed from the occulusal surface this may be associated with the presence of a carious lesion
The narrow beam of light is of crucial importance when the technique is used in premolar and molar region
For optimal performance the probe should be brought in from the buccal or lingual aspect at an angle of about 45 degrees to the approximal surfaces pointing apically,while looking for dark shadows in the enamel or dentin
Shadows are best noticed when the office light is switched off
166
167
Advantage:
Does not produce overlapping images as in
case of posterior crowding
Can be easily used in pregnant women when
radiation has to be avoided
Disadvantage :
FOTI fails to detect incipient proximal caries
168
169
Digital fiberoptic Trans
illumination
Image captured by the camera are sent to a
computer for analysis , which produce digital
images that can be viewed.
Advantages:-
- instantaneous image projections
- image quality is easy to control
- can detect incipient & recurrent caries very
early
- non invasive
170
171
Disadvantages :-
- doesn‟t measure the depth of lesion
- Difficult to distinguish between deep
fissure , stain and dental caries.
172
Tooth separation
Neither radiographs nor FOTI can help to
identify the presence of a cavity on contacting
approximal surfaces. Therefore, tooth
separation has been introduced
Orthodontic elastic separators are applied for
2-3 days around the contact areas of surfaces
to be diagnosed,after which assess to
inspection and probing is improved
173
174
This technique may create some
discomfort,especially in patients with
established dentitions.
It requires an extra visit
Therefore,at present this technique is not
recommended for routine use in general
practice
175
Xeroradiography
Advance technique alternative method to
conventional radiography
In xero radiography image is recorded on
photo conductive selenium coated plate rather
than X ray film. Selenium coated plate is
charged & placed in to light tight cassette. This
photoreceptor is placed intra orally & exposed
to X ray beam causing selective discharge.
The amount of discharge is related to radiation
striking photoreceptor.
176
During developing the selenium plate is
exposed to cloud of charged powder particle
called TONER , next the plate is dried to
remove the liquid vehicle of toner particles.
Processed image is transferred to opaque
elastic base with the help of clear adhesive
tape.
USES:
help to diagnose initial caries
177
ADVANTAGES:-
-“Edge enhancement” can demarcate area of varying dentition specially at margins.
-Less radiation exposure.
-no wet processing.
-Both -ve & +ve prints are possible.
DISADVANTAGES:-
-Expensive
-Development process should be completed within 15 minutes
-Electric charge over the film may cause discomfort to the patient.
178
Digital radiographic method
This method offer a more superior means of detecting caries than conventional radiographs.
Introduced in 1987
The application of computer technology to
radiography.
Has allowed image acquistation, manipulation,
storage, retrieval & transmission to remote sites
in digital format.
179
Digital imaging sensor is used (CCD) instead
of radiographic film.
The signal from CCD is sent to computer
where it is digitized in 256 gray levels & is
viewed on screen with enhanced density &
contrast.
It is of two types:
• Direct digital radiography
• In-Direct digital radiography
180
Direct digital radiography:
Image is acquired by detector that is sensitive to electro magnetic energy & data is converted into digitized form
It is of two types:
1: photo stimulable phosphor {PSP}
2: charged couple device sensor {CCD}
Other type:
-complementary metal oxide semiconductor {CMOS}
181
PSP:
The interactions between X-ray photons & crystals of PSP excite the electrons of phosphor. Further on irradiation with ruby laser,trapped electrons are released causing emission of shorter wave length of light in blue region of spectrum. The intensity of emitted blue light is proportional to amount of X ray absorbed by phosphor which can be detected by photo multiplier tube. The output of tube is digitized to form image.
182
CCD:
Consists of a chip of pure silicon. When CCD interacts with X ray, an electric charge is created. After exposure, electric charge is sequentially transferred to computer which is acquired as an image later.
USES of digital radiography:
1: Early detection of caries.
2: In endodontics, it helps to measure root canal length, working length & distance between apex and obturating material.
3: It also helps to assess bone loss.
183
184
The software has been designed to assist in
locating and classifying proximal surface
caries in digital intraoral radiographs
The analysis is completed in seconds and an
enlarged image of the radiograph being
evaluated is displayed, along with the possible
decay area
185
This helps to identify and calculate the
probability of enamel and dentin caries based
on a unique histological database.
We simply select the area of interest and the
software automatically outlines any consistent
alignment of radiolucent features directing our
attention to the area of interest for closer
examination.
186
ADVANTAGES:-
- Reduce radiation dose.
- Instant image visualization
- No need for dark room
- No processing error
- Image can be magnified
- Contrast and density of image can be enhanced.
DISADVANTAGES:-
- Expensive
187
Electric conductance
measurement
sound enamel is an insulator due to its high inorganic content . On the other hand , carious enamel has a measurable conductivity which increase with degree of demineralization.
Two devices were developed in 1980‟s
- vanguard electronic caries detector.
- caries meter
• Both instrument measures the electrical conductance between the tip of a probe placed in a fissure and connector attached to an area of high conductance.
188
Low conductance of tooth is primarily caused
by enamel
Increased conductance & decreased
resistance are indicative of the presence of
hypo &/or demineralization
When a potential of less 1volt applied,
resistance of above 6,00,000 ohms indicates
caries free tooth. Resistance below 2,50,000
indicates caries.
189
Factors affecing electronic resistance
measurement:
Porosity
Surface area
Thickness of tissues
Hydration of enamel
Temperature
190
191
192
Advantages
-More accurate in diagnosis of early occlusal caries than visual method , radiographs or FOTI .
-Can monitor the progress of caries.
Disadvantages
-Hypomineralized area , enamel cracks can cause misleading reading.
-time consuming procedure
-Requires the use of sharp metal explorer which can cause traumatic defect in pits and fissures.
193
Caries detecting dyes
Principle-
Increased porosity- through the development of capillary like micro voids- is earliest change in carious lesion
For detection of enamel caries • Calcien • Zyglozl-22
For detection of dentin caries • Fuschin • Acid red system • 9-aminoacridine
194
Limitations:
Does not stain bacteria but organic collagen
matrix of less mineralized dentine
No differentiation between infected and
affected dentine possible
High risk of over treatment
Also stains healthy dentine with naturally high
collagen content: circumpulpal dentine
195
196
Laser Fluorescence
Use of fluorescence for detection dates back
1929, when Benedict observed that normal
teeth fluoresce under UV illumination.
Aids in the detection of occlusal caries
The machine emits light at a wavelength of
655nm and this is transported through a fibre
bundle to the tip of a handpiece. The tip is
placed against the tooth surface & rotated
197
198
The laser light will penetrate the tooth. Different fibers in the tip receive the reflected light and fluorescence from the lesion,thought to be produced from bacterial porphyrins
The received light is measured & its intensity is an indication of size and depth of carious lesion
The machine does not detect the mineral loss
Reproducibility has shown to be good but can be confused by staining and calculus,giving high reading when active caries is not present
199
Monochromatic light is used at 350,410 &
530nm on carious & non carious teeth.
In carious teeth emission spectra shifts to
more than 540nm i.e. red range of EM
spectrum.
It has been recently found that when
illuminated with argon laser,carious tissue
appears as dark, fiery, and orange-red in color.
200
201
Diagnodent:
Based on principle of fluorescence.
It uses a diode laser light source & a fiber optic
cable that transmits light to a hand held
probe.
Emitted fluorescence is collected at probe tip,
processed & presented on display as an
integer between -9 to99.
-9 indicates healthy teeth & increased
fluorescence indicates caries particularly value
above 20.
202
203
The Diagnodent operates at a wavelength of 655 nm.
At this specific wavelength, clean healthy tooth structure exhibits little or no fluorescence, resulting in very low scale readings on the display.
However, carious tooth structure will exhibit fluorescence, proportionate to the degree of caries, resulting in elevated scale readings on the display of the Diagnodent.
An audio signal allows the operator to hear changes in the scale values. This enables the focus to be on the patient, not solely on the device.
204
Limitations:
Cannot determine the depth of lesion.
Reading may alter due presence of food debris, plaque.
Not able to detect recurrent caries. Alloy restoration exhibits little or no fluorescence, while the composites, ceramics & cements emit their own fluorescence.
Reading changes at different angulations of probe tip.
Caries indicator dyes cannot be used simultaneously with diagnodent.
205
Quantitative light fluorescence
This methodology began with observation in1978 by a scientist in Sweden that the use of a laser light of selected wavelength markedly enhances the visibility of early non carious lesions
QLF uses light with wavelengths around 405 nm to excite yellow fluorescence at wavelengths above 520 nm.
Its diagnostic capacity is based on the mechanism that the intensity of natural fluorescence of a tooth is decreased by scattering due to a caries lesion.
206
Two-photon image of a carious tooth
Carious area shown in green
207
The initial work was based around the use of
multiphoton microscopy to build up a three
dimensional image of the tooth.
This revolutionary technique enables the
dentist to see right into the tooth but is
complex to use and not suitable for general
dental practitioners.
208
Ultrasonography
Involves use of sound waves for detection
With the use of this instrument, sonic velocity
& specific accoustic impedance can be
determined for dentin & enamel as well as for
soft tissue & bone.
In ultrasound frequency vibration is greater
than 20 Khz. which is more than audible
range{1500-20,000hz/sec}.
In sonography, sound waves are used in
frequency of 1-20Mhz.
209
Scanners used for sonography generate electric impulse that are connected into ultra –high frequency sound waves by transducer{ device which convert electric energy into sound energy}
Transducer is a thin piezo electric crystals made up of great number of dipoles arranged in geometric pattern. Electric impulse generated by scanner causes dipole in crystals to re-align themselves with electric field & thus sudden change causes a series of vibrations that produce the sound waves that are transmitted into the tissues being examined.
210
When ultra sonography beam passes
through or interacts with tissues of
different sound, energy causes
obstruction, reflection , refraction diffusion.
Sonic waves that reflected back towards
transducer cause change in the thickness
of piezoelectric crystal, which produces an
electric signal which is amplified and
displayed on monitor.
211
Fluorogenic enzyme assay: it is a new method to count cells “in situ”, based on a fluorogenic enzyme assay that measures the activity of alkaline phosphatase. Increasing cell number has close correlation with alkaline phosphatase activity and this relationship did not change with time in culture. This method is able to estimate relative cell numbers over a range from about 104 to 105×105 for many cell types. The method is rapid and efficient, making it a useful method for studying streptococcus and lactobacillus activity in active root lesions.
Microbiologic method 212
Lactobacillus colony count test : This test estimates the number acidogenic Lactobacillus bacteria in the patient’s saliva by counting the number of colonies appearing on the tomato peptone agar plates (pH 5.0).
Streptococcus mutans count test: This test measures the number of S.mutans colony forming units per volume of saliva from the root lesion. It is cultured on the Mitis Salivarius Agar (MSA), selective streptococcal medium.
213
All the above mentioned methods may be used as an adjunct to visual inspection. However to be used in practice the methods must be better than clinical-visual and radiographic examination.
They must be convenient to use,not too expensive and must be reproducible
Only laser fluorescence(diagnodent) and digital radiography are currently used in practice and seem to be suitable techniques for detection of caries
214
References
Fejerskov Ole, Kidd Edwina.Dental caries:the disease and its clinical management.2nd Ed.
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