Dental caries

 Dental caries and periodontal disease are
probably the most common chronic disease in
the world.
 Although caries has affected humans since
prehistoric times, the prevalence of this disease
has gently increased in modern times on a world
while basis, an increase strongly associated with
dietary change.

DEFINITION
SHAFER - “Microbial disease of
the calcified tissues of the teeth,
characterized by demineralization
of the calcified tissues and
destruction of the organic
substance of the teeth”

STURDEVANT-“An infectious
microbiological disease of the teeth
that results in localized dissolution
and destruction of calcified tissues”

CLASSIFICATION : -
 STURDEVANT : -
Based on - Location
- Extent
- Rate of progression

 ACCORDING TO LOCATION : -
a. Primary caries
b. Caries of pit and fissure origin
c. Caries of enamel smooth surface origin
d. Backward caries
e. Forward caries
f. Residual caries
g. Root surface caries
h. Secondary (recurrent) caries

 ACCORDING TO EXTENT : -
a. Incipient (reversible) caries
b. Cavitated (irreversible) caries
 ACCORDING TO RATE OF PROGRESSION : -
a. Acute (rampant) caries
b. Chronic (slow or arrested) caries

ACCORDING TO TREATMANT & RESTORATION DESIGN- by
G.V.BLACK
 CLASS I  CLASS II

Mount’s Classification
Site Size
Minimal Moderate Enlarged Extensive
1 2 3 4
Pit/fissure 1 1.1 1.2 1.3 1.4
Contact area 2 2.1 2.2 2.3 2.4
Cervical 3 3.1 3.2 3.3 3.4

 Mount in 1998 classified the carious lesion according to
site and size.
 The explanation of size is :
 “1” minimal involvement of dentin. Treatment by
remineralization alone
 “2” moderate involvement of dentin. Treatment by
cavity preparation
 “3” the cavity is enlarged beyond moderate size
 “4” extensive caries with bulk loss of tooth structure

 Explanation of site:
 Site 1 (pit and fissure)
 Site 2 (contact areas)
 Site 3 (cervical area)
 Drawbacks
 It becomes difficult to differentiate between different
sizes
 Treatment planning varies from operator to operator

ETIOLOGY OF DENTAL CARIES:
Dental caries is a multi factorial disease.
 Caries occurs in different individuals at
different ages, at different sites and at different
rates of progress, no single theory can explain
the phenomenon of caries.

1. THE WORM THEORY : -
According to concept of that time, the cause of
caries was thought to be invasion of ‘worms’
into teeth.
Therefore the character of caries was shown as
a worm over tooth surface.

2. THE HUMORAL THEORY : -
The four recognized humors of the body were
blood, phlegm, black bile and yellow bile.
The imbalance in these humors resulted in the
disease process.

3. VITAL THEORY : -
Towards the end of the eighteenth century, it
was postulated that tooth decay originated
from within the tooth itself .

4.CHEMICAL / PARASITIC THEORY : -
In the early 19th century, a new concept was
emerging, that teeth were destroyed by acids
formed in the oral cavity.

ACIDOGENIC THEORY : -
Miller (1889) propagated the concept of acid
formation in the oral cavity and attributed the
synthesis of acid to the action of micro –
organisms.
He was of the view that micro-organisms of
the mouth, by secretion of enzymes or by their
own metabolites degrade the carbohydrates
into acids.

The food containing carbohydrate lodged onto
the tooth surface is the source of acid
production which demineralizes the enamel.
Subsequently, demineralized enamel is
mechanically removed by the forces of
mastication.
After the disintegration of enamel, the
organisms and acids penetrate dentinal tubules
and bring about the dissolution of dentin.

6. PROTEOLYTIC THEORY : -
Gottlieb (1944), the initial action is due to the
proteolytic enzymes attacking the lamellae, rod
sheaths, tufts and walls of tubules etc. i.e. all
organic components.

 7. PROTEOLYSIS CHELATION THEORY : -
Schatz et al (1955) describing a new theory
observed that there is a simultaneous microbial
degradation of organic component by
proteolysis and the dissolution of inorganic
part by the process of chelation.

The word ‘chelate’ refers to compounds that
are able to bind metallic ions such as calcium,
iron, copper, zinc etc. by valence bonds.

LEVINE’S THEORY : -
Levine (1977) established the chemical
relationship of enamel, plaque and the factors
which determined the movement of minerals
from saliva/plaque to enamel and vice-versa,
which he termed as the ionic ‘see-saw’
mechanism.

The four factors contributing to the caries
process

1.THE HOST FACTOR : -
A. Tooth factor
a. Morphology and position in the arch
b. Chemical nature
B. Saliva
a. Composition, pH and antibacterial activity
b. Quantity and viscosity of flow

2. THE MICROFLORA
3. THE SUBSTRATE OR DIET
a. Physical nature
b. Chemical nature
4. TIME

1.The Host Factor
A . TOOTH FACTOR
1) . MORPHOLOGYAND POSITION IN THE ARCH
Tooth morphology is recognized as an important factor
for initiation of caries.

 Deep pits and fissures in any tooth make then susceptible
to caries because of food impaction and bacterial
stagnation.
 That is why the occlusal surfaces are more prone to caries.

 Irregularities in the arch form, crowding and overlapping
of the teeth also favour the development of caries.
 Partially impacted third molars are more prone to caries
and so are the buccally or lingually placed teeth.

2) . CHEMICAL NATURE:-
It has been observed and proved scientifically, that surface
enamel is more caries resistant than the subsurface
enamel.

B . Saliva :-
1) Composition, pH and Antibacterial activity
Caries prone individuals have low calcium and
phosphorous levels.

 The pH at which any particular saliva ceases to be
saturated with calcium and phosphorous is referred to as
the ‘critical pH’.
 Under normal conditions the critical pH is 5.5, below this
value, the inorganic material of tooth may dissolve.

2) Quantity and Viscosity of flow : -
The quantity and viscosity of saliva has definite influence
on caries incidence.
Human beings suffering from decreased flow of saliva or
lack of salivary secretions (xerostomia) usually
experience increased rate of dental caries.

 The caries susceptibility has been observed to increase in
numerous patients following radiation therapy
 Certain drugs influence salivary flow, and in turn result in
rampant caries.

 Since there is less or no saliva to buffer and wash away
fermentation products of plaque during sleep.
 The most important time for plaque removal is before
sleeping to avoid caries.

2 . THE MICROFLORA : -
 It was observed that for caries to occur, bacteria
played a definite role.
 Clarke (1924) discovered the species Streptococcus
mutans .
 Streptococcus mutans, it is considered to be the
significant micro organism out of all the oral flora in
occlusal and pit & fissure caries.

 Streptococcus mutans ferments manitol and sarbitol
(synthesized insoluble polysaccharide from sucrose ) and
lactic acid former which easily colonise on tooth surface .

 As the environment is different in deep dentinal
lesion, it is certain that the flora of deep caries would
be different .
 The predominantly present micro – organism are
lactobacilli which account for one third of the oral
flora .

 The organisms involved in root caries are different from
those in other smooth surface lesions.
 Predominantly Actinomyces viscosus, A. Nocardia etc.
have been isolated
 Streptococcus mutans and Streptococcus salivarius
have been shown to produce root caries.

 The following factor prove the role of bacteria in
caries.
Caries will not occur in complete absence of micro –
organism .
Caries can occure in animals even if kept on single type
of bacterial growth .
All micro – organism are not cariogenic .

3. THE SUBSTRATE OR DIET : -
a.PHYSICAL NATURE OF DIET : -
Modern diet includes refined foods, soft drinks which
lead to collection of debris predisposing to more caries.

B. CHEMICAL NATURE OF DIET : -
 By chemical nature of diet we are mainly concered with
the nutrient present in our meals, frequency of intake and
also their cariogenic potential.
The main ingredient is carbohydrate, which is accepted
as one of the most important factor in dental caries
process. Only refined carbohydrates are effective.

 For caries production following factors are responsible.
Type of carbohydrate
Frequency of intake
Time of stagnation

4 ) TIME : -
 During the long intervals of undistrurbed plaque
stagnation, the plaque PH is lowered favouring the
production of organic acids that demineralize tooth
structure.

TRADITIONAL METHOD
 Patient’s Complaint
 Clinical Examination
 Tactile Examination
 Radiographic Examination

PATIENT’S COMPLAINT
 Patient complaining of sensitivity to the thermal
changes ,mild to moderate toothache, etc may provide
a hint about the presence of dental caries.

CLINICAL VISUAL EXAMINATION
 Careful examination of the patients teeth under
clean and dry conditions using good illumination
may reveal visual signs of caries like
 Brownish discolouration of pit and fissure
 Opacity beneath pit and fissures or marginal ridges
 Frank cavitation of the tooth surface

A major short coming of this method is very limited
for detecting noncavitated lesions in dentine on the
posterior proximal and occlusal surfaces.

CLINICAL TACTILE METHOD
 This method is based on a combination of light,
mirror, and gentle probing and is used in most
epidemiologic surveys
 Caries is diagnosed if the tooth meets the American
dental association criteria of softened enamel that
catches the explorer and resists its removal or allow
the explorer to penetrate proximal surfaces under
moderate to firm probing pressure.

I. Probing has been criticized for several reasons
a. It may allow transmission of cariogenic bacteria
from infected sites to uninfected areas
b. It can irreversibly traumatize potentially
remineralizable noncavitated lesions of enamel
and dentine.

C. And it may provide no more accuracy in diagnosis
than visual inpection alone particularly in fissures
and in posterior approximal surfaces

DIGITAL RADIOGRAPHY
The first dental radiograph is attributed to Dr. Otto
Walkhoff of Braunschweig, Germany, who on January
14, 1896 made images of the crowns of teeth on both sides
of his own jaw using silver halide emulsion on glass
plates.
The exposure time was 25 minutes.

Dr. C. Edmund Kells gave the first clinic in this
country on the use of the X-ray for dental purposes.
Three years later (1899), Kells was using the X-ray to
determine tooth length during “root canal therapy“.

Digitization of ionizing radiation first became a realty in
the late 1980s with the development of the RVG system
by Dr. Francis Mouyen.
Direct digital system have three components
a) Radio component
b) Visio component
c) Graphy component

The Radio component consists of a high – resolution
sensor with an active area that is similar in size to
conventional film.

 The sensor is protected from x – ray degradation by a
fiber optic shield.

The Vision component , consist of a video monitor
and display processing unit.
As the image is transmitted to the processing unit, it is
digitized and stored by the computer.
The unit magnifies the image for immediate display on
the monitor, it also can produce colored image.

 The Graphy component consist, a high – resolution
video printer that provides a hard copy of the screen
image, using the same video singal.

The two major technologies presently used intraoral
digital X-ray systems are as follows:
1. Solid-state detectors
a. Charge-coupled device (CCD)
b. Complimentary metal oxide semiconductor (CMOS)
2. Storage phosphor detectors
a. Photo stimulable phosphor (PSP)

Working Principles of Digital Systems
DigitaJ systems utilize computer technology in the
capture, display, enhancement, and storage of
radiographic images.
Computers work on the binary number system
consisting of two digits (0 and 1) to represent data.

These two characters are called bits (binary digits),
and they form "words" of eight or more bits in length
called bytes.
The total number of possible bytes for 8-bit language
is 2
8 = 256.
The analog to digital converter (ADC) transforms
analog data to digital data based on binary number
system.

 The strength of the output signal is measured and
assigned a number from 0 (black or white depending
on designation) to 255 (white or black- opposite of“0")
according to the intensity of the electric signal.
 These numeric assignments translate into 256 shades
of gray in an 8-bit system.

 A digital image consists of a number of pixels (picture
elements), and each pixel is represented by a number
corresponding to its gray level.
 The pixel is the smallest picture element of the image,
and the resolution of an image is directly related to the
pixel size among other factors.

 Solid-state detectors (CCD and CMOS) can be indirect
detectors using a scintillating screen such as Cesium
Iodide or Gadolinium Oxysulfide, or (less
commonly) can use direct conversion of X-ray photons
to electrons (e.g., Cadmium-Telluride technology).

Charge-Coupled Device The CCD is composed of an electronic circuit
embedded in several thin layers of silicon.

 The silicon chip usually is composed of an array of
light sensitive pixels (picture elements), and each pixel
consists of a small electron well into which the X-ray or
light energy is deposited upon exposure.
 Each silicon atom in the detector chip is covalent with
another silicon atom.

 When light photons strike the silicon and the energy
exceeds the strength of the covalent bond, an electron
hole pair is formed.
 an electric charge is established by release of electrons.
 The electric charge in each "pixel" well is proportional
to the incident X-ray or photon energy.

 The charge of each pixel is converted from an analog
electric signal representing the energy absorbed by the
solid-state chip to a digital signal representing the
discrete numeric pixel values for image display on a
compute monitor.

Complimentary Metal Oxide
Semiconductor - Active Pixel
Technology (CMOS-APS)

 CMOS chips are commonly used in digital cameras,
video cameras, and computers.
 CMOS detectors appear similar to CCDs, but the
former use an active pixel technology, that has an
active transistor built into each pixel.
 This has permitted the introduction of wireless radio
frequency (RF) transmission of the acquired image.

 The APS system eliminates the need for charge
transfer between adjacent pixel wells extending the
exposure latitude by suppressing "pixel blooming“.

Photo Stimulable Phosphor
 The PSP imaging plate works on the principle of
radiation-induced emission of photostimulated
luminance.
 PSPs generally contain Barium Fluorohalide crystals
with small amounts of bivalent Europium atoms as an
activator.

 When a storage phosphor imaging plate is exposed to
X-radiation, the europium atoms in the phosphor
crystalline lattice are ionized liberating a valence
electron.
 This results in the formation of electron vacancy.

 The valence electrons are exited to the level of
conduction band where they travel freely until trapped
by so-called Farbzentren Centers present in halide
crystals to form metastable electrons with an energy
level slightly lower than the conduction band but
greater than that of the valence bond.

 These trapped metastable electrons constitute the
latent image and their number is proportional to the
number of incident X-rays.
 When the latent image is exposed to the red light of
solid state laser, the metastable electrons are again
exited to reach high-energy conduction band where
they recombine with Eu3+ atoms and return to low-
energy valence bond (Eu3+ + e- = Eu2+ ).

 This results in the liberation of energy, emitted as blue
light.
 The light is registered by a photo multiplier tube and
converted into an analog electric output signal that is
digitized, resulting in a digital image.
 Each pixel has a numeric value that is proportional to
the amount to light emitted from the corresponding
area of the PSP imaging plate.

 The basic premise of subtraction radiology is that two
radiographs of the same object can be compared using
their pixel values.
 The value of the pixels from the first object are
subtracted from the second image.
 If there is no change, the resultant pixel will be scored
0; any value that is not 0 must be attributable to either
the onset or progression of demineralisation, or
regression.

 Subtraction images therefore emphasise this change
and the sensitivity is increased.
 However, uptake of this system has been low,
presumably due to the need for well aligned images.
 Recent advances in software have enabled two images
with moderate alignment to be correctly aligned and
then subtracted.

Electronic Caries Monitor (ECM)

 The ECM device employs a single, fixed-frequency
alternating current which attempts to measure the
‘bulk resistance’ of tooth tissue.

 When measuring the electrical properties of a
particular site on a tooth, the ECM probe is directly
applied to the site, typically a fissure, and the site
measured.

 There are also a number of physical factors that will
affect ECM results.
 These include such things as the temperature of the
tooth, the thickness of the tissue, the hydration of the
material (i.e. one should not dry the teeth prior to use)
and the surface area.

Fibre optic trans - illumination The basis of visual inspection of caries is based upon
the phenomenon of Light Scattering.
 FOTI is designed for the detection of proximal caries.

 When enamel is disrupted, for example in the
presence of demineralisation, the penetrating photons
of light are scattered, which results in an optical
disruption.

 Fibre optic trans - illumination takes advantage of
optical properties of enamel and enhances them by
using a high intensity white light that is presented
through a small aperture in the form of a dental
handpiece.

 Light is shone through the tooth and the scattering
effect can be seen as shadows in enamel and dentine,
with the device’s strength the ability to help
discriminate between early enamel and early dentine
lesions

Quantitative Light-induced
Fluorescence (QLF)

 Quantitative Light-induced Fluorescence (QLF) is
a visible light system that offers the opportunity to
detect early caries and then longitudinally monitor
their progression or regression.

 The QLF equipment is comprised of a light box
containing a xenon bulb and a handpiece, similar in
appearance to an intraoral camera.
 Light is passed to the handpiece via a liquid light guide
and the handpiece contains the bandpass filter.
 Live images are displayed via a computer

 Fluorescence is a phenomenon by which an object is
excited by a particular wavelength of light and the
fluorescent (reflected) light is of a larger wavelength.
 When the excitation light is in the visible spectrum,
the fluorescence will be of a different colour.

 In the case of the QLF the visible light has a
Wavelength (l) of 370 nm, which is in the Blue
region of the spectrum.
 The resultant auto-fluorescence of human enamel is
then detected by filtering out the excitation light using
a bandpass filter at l > 540 nm by a small intra-oral
camera.

 This produces an image that is comprised of only
green and red channels (the blue having been filtered
out) and the predominate colour of the enamel is
green

Laser Fluorescence—
Diagnodent

 The DIAGNODENT (DD) instrument (KaVo,
Germany) is another device employing fluorescence to
detect the presence of caries.
 Using a small laser the system produces an excitation
wavelength of 655 nm which produces a red light.
 This is carried to one of two intra-oral tips; one
designed for pits and fissures, and the other for
smooth surfaces.

 The DD does not produce an image of the tooth;
instead it displays a numerical value on two LED
displays.
 The first displays the current reading while the second
displays the peak reading for that examination

ACCORDING TO WHETHER THE LESION IS NEW OR AROUND
MARGINS OF A RESTORATION
 PRIMARY CARIES  SECONDARY CARIES

ACCORDING TO LOCATION
 PIT & FISSURE CARIES  SMOOTH SURFACE
CARIES

ACCORDING TO RAPIDITY OF THE PROCESS
 ACUTE:
 NURSING BOTTLE CARIES
 CHRONIC:
 RECURRENT CARIES
 ARRESTED CARIES

 PIT AND FISSURE CARIES : -
Deep pits and fissures are developmental defects found on
the tooth.
Pits and fissures with high steep walls and narrow bases
are those most prone to develop caries.

They favour the retention of food debris and micro
organisms and caries may result from fermentation of
this food and the formation of acid.
When caries occurs here, 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.

Thus, there may be a large carious lesion with only a
tiny point of opening.
Pits and fissures affected by early caries may appear
brown or black and will feel slightly soft & “catch” a
fine explorer point.
The enamel bordering the pit or fissure may appear
opaque bluish white, as it becomes undermined

SECONDARY CARIES:
Secondary caries can be defined as caries around a
restoration. It is also known as ‘recurrent caries’ The
main etiological factor for secondary caries, is marginal
leakage around the restorations.

Smooth Surface Caries
 Develops on - proximal surfaces of the teeth
- gingival third of the buccal and
lingual surfaces (cervical caries)
 Preceded by the formation of dental plaque
 Usually initiate just below the contact point
 Clinically- initially as faint white opacity or
yellow brown pigmented area
 Adjacent enamel appears bluish white

Forward Caries
 Caries cone in enamel is larger
or at least the same size as that
in dentin

Backward Caries
 Lateral spread of the lesion along
the DEJ exceeds the caries in the
contiguous enamel, caries extends
into this enamel from the junction.

Residual Caries
 Caries that remains in a completed cavity preparation
 Not acceptable if- present at DEJ
- prepared enamel wall

Incipient (reversible) caries:
 First evidence of caries activity in
enamel
 Subsurface demineralization has
occurred but no cavitation
 Clinically as white opaque region
 May take up extrinsic stains
 May undergo remineralization-
called as “caries reversibility” or
“consolidation” of early enamel
carious lesion

Cavitated (irreversible) caries:
 Lesion that has advanced into
dentin with broken surface
 Remineralization is not
possible

Xerostomia induced caries (radiation caries)
 Complication of radiation
therapy of oral cancer lesion
 Radiation induced xerostomia
produces caries conducive
environment
 Carious lesion develops as
early as 3 months after onset
of xerostomia
 May be caused by other
factors like salivary gland
tumors, autoimmune diseases,
prolong illness

ROOT CARIES
Root Caries is defined as “a soft,
progressive, lesion that is found anywhere
on the root surface that has lost
connective tissue attachment and is
exposed to the oral environment”.
Micro organisms invade the cementum,
either along sharpey’s fibers or between
bundles of fibers.
Since cementum is formed in concentric
layers and presents a lamellated
appearance, the micro organisms tend to
spread laterally between the various layers

DIAGNOSIS OF DENTAL CARIES Diagnosis is the “ the art or act of identifying a
disease from its signs and symptoms “ ( Webster’s
Dictionary, 1967 )

TRADITIONAL METHOD
 Patient’s Complaint
 Clinical Visual Examination
 Tactile Examination
 Radiographic Examination

RADIOGRAPHIC EXAMINATION
 Conventional, intraoral periapical and bitewing
radiographs are employed for diagnosis of dental
caries.

The conventional bitewing
radiographic method
 Conventional bitewing radiographs used for
diagnosis of inter proximal carious lesion of
posterior teeth.

 Recurrent caries at the cervical margins is best
observed in bitewing radiographs since central ray is
directed along the direction of cervical areas.

 Bitewing radiographs is useful in monitoring and
evaluating the progress or arrest of caries.
 Care should be taken to standardize positioning,
exposure and processing conditions.

RADIOGRAPHY
ADVANTAGES :
 Discloses sites inaccessible to
other methods
 Detects at early , reversible
stage
 Depth of lesion can be
evaluated and scored by index
given by Grondahl et al (1977)
 Permanent record
 Non-invasive

DIGITAL RADIOGRAPHIC METHODS
1. Digital radiographic methods offer a more superior
means of detecting caries than coventional methods
 Digital radiographs can be obtained by two methods
1. Video recording and digitization of conventional
radiograph
2. Direct digital radiograph

 The first direct digital radiography is Radiovisiography
invented by FRANCIS MOUYEN in 1989
 It uses a charged couple device which works like a
miniature video camera

 This records the image produced by conventional x-
rays and stores it in the computer memory for image
processing and viewing.
 ANN WENZAL journal of dental research 2002 pgs
590-593

DIGITAL RADIOGRAPHY
ADVANTAGES OF DIGITAL RADIOGRAPHY:
Less patient exposure
Poor darkroom procedure- high doses, loss of diagnostic
information
Development is time consuming
Solutions, lead foils are hazardous
No new film position to learn
Image can be transferred without loss of quality
Image manipiulation

DIGITAL SUBTRACTION RADIOGRAPHY
 RICHARD WEBBER was the first one to introduce the
digital subtraction radiography
 Here the digitization is achieved by taking a picture of
the radiograph using high quality camera.
 This is fed to a computer imaging device called
digitizer .

 Two standardized radiographs produced with identical
exposure geometry are used.
 The first one is called the “reference image” and the
subsequent images are taken for comparison.

 The reference image is displayed on the screen over
which the subsequent images are superimposed
 The difference between the original and subsequent
images can be seen as dark areas

ADVANTAGES
 Superior to conventional radiography for detecting
recurrent caries
 It is sensitive it can detect a 0.12mm change
 Approximal caries can be visualized better
 Assesses the progression of the carious lesion

DISADVANTAGE
 EXPENSIVE
 J.EBERHARD et al (caries research 2000, vol 34 pgs
219-224)

FIBRE OPTIC TRANSILLUMINATION
Used in anteriors,
premolars
 ≥ bitewing
radiography
Mechanism
Can detect En– crazing,
cracks

Dental caries

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