2. INTRODUCTION
Caries is an infectious microbiologic disease that results in
the localized dissolution of the calcified tissues of the
teeth and destruction of the organic part.
The primary objectives of caries diagnosis are to identify
• patients with lesions that require nonsurgical treatment,
• patients who are at high risk for developing carious
lesions.
Knowing which patients are at high risk for developing
caries provides an opportunity to implement specific
preventive strategies that may prevent caries.
3. Ideal requirements of diagnostic tests: (Pitts 1997)
1. Accurate.
2. Sensitive.
3. Specific.
4. Reproducible.
5. Reliable.
6. Not transfer S. Mutans or other bacteria from affected
area to unaffected areas.
7. Cost effective.
4.
5. TRADITIONAL METHODS
Patient’s Complaint:
may provide a hint about the presence of caries.
The patient may complain of sensitivity to thermal changes,
mild to moderate toothache, etc.
Patient History:
7. Nutritional Analyses:
• exposure to sucrose increases the likelihood of plaque
development by the more cariogenic MS organisms.
Salivary Analyses:
• may provide important information about
appropriateness of secretion rates and buffering capacity
and numbers of MS and lactobacilli.
• The correlation between salivary MS counts and the
number of MS-colonized tooth surfaces is relatively good
(Lindquist et al, 1989)
8. Caries activity tests
Caries activity:
• Refers to the increment of active lesions (new and
recurrent lesions) over a stated period of time.
• Measure of the speed of progression of a carious lesion.
• Caries activity tests measure the degree to which the
local environment challenge favors the probability of
carious lesions.
Caries susceptibility:
• Refers to the inherent tendency of the host and the target
tissue (tooth) to be affected by the carious process.
9. LACTOBACILLUS COLONY COUNT TEST
(Dentocult LB)
Introduced by Hadley in 1933
Principle: estimates the number of acidogenic and aciduric bacteria in
patient’s saliva by counting the number of colonies appearing on
tomato agar plates (pH 5.0) after inoculation.
Paraffin stimulated saliva 0.4 ml of 1:100 dilution
Spread on agar plate (20 ml cooled liquefied agar: Rogasa’a SL agar plate)
Incubated for 3-4 days at 37C
Colonies counted using light and magnifying glass
Number of lactobacilli per ml saliva is calculated by multiplying the
number of colonies on the agar plate by the dilution factor.
11. STREPTOCOCCUS MUTANS LEVEL IN SALIVA
Principle: measures the number of S. mutans CFU per unit volume of
saliva. Incubation is done on Mitis Salivarius Agar.
Samples of organisms obtained by tongue blades
Pressed against MSB agar
Incubated at 37C for 4 hrs in 95% and 5% CO2 gas mixture
Interpretation:
Levels of SM > 105 / ml of saliva ------ unacceptable
Colonization of a new surface does not occur readily unless SM levels
reaches 4.5 X 104 / ml for smooth surfaces and 103 / ml for occlusal
surfaces.
12. DIP SLIDE METHOD FOR S. MUTANS COUNT
• described by Jensen and Bratthall (1989)
Undiluted paraffin stimulated saliva poured on plastic slide coated with
MSA containing 20% sucrose.
Agar is thoroughly moistened and excess is drained
2 discs of 5 mg bacitracin placed on agar 20 mm apart.
Slide is screwed and incubated at 37C for 48 hrs in a sealed candle jar
14. Glucosyltransferase as a Marker for Caries Activity
• proven virulence factors in caries etiology identified from
Streptococcus mutans [DeStoppelaar et al., 1971; Hamada et al., 1984;
Tanzer et al., 1985; Yamashita et al., 1993].
Levels of active Gtf in saliva correlate with salivary populations of S.
mutans
[R611a et al., 1983; Scheie et al., 1987; Vacca-Smith et al., 1996].
The enzyme(s) is used as a marker(s) for caries detection.
BOWEN, WILLIAM H. et al (2004-06) attempted:
• To determine the quantities of Gtf B, Gtf C, and Gtf D of S. mutans in
the subjects' saliva using monoclonal antibodies in an enzyme-linked
immunosorbent assay.
• To correlate the assayed activity of Gtf with the concentrations of Gtf
B, Gtf C and Gtf D of S. mutans.
• To determine the correlation between both the concentrations of Gtf
B, Gtf C, and Gtf D, and the overall assayed Gtf activity in saliva, with
the current levels of clinical caries of the subjects
15. COLORIMETRIC SNYDER TEST (Snyder in 1951)
Principle: measures the ability of salivary microorganisms to form organic
acids from a carbohydrate medium.
Bromocresol green: changes color form green to yellow in the range of
pH 5.4 to 3.8.
0.2 ml paraffin stimulated saliva + 10 ml melted agar containing medium
Cooled to 50 C; allowed to solidify; incubated at 37C
Amount of acid produced is detected by pH indicator, and compared with
uninoculated control tube after 24, 48, 72 hrs.
16. SWAB TEST (Graingar in 1965)
Principle: based on the same principle as Snyder’s test.
The oral flora is sampled by swabbing the buccal surfaces of
the teeth with a cotton applicator and incubated.
Change in pH is read on the pH meter after 48 hrs of
incubation.
17. ALBANS TEST
A simplified substitute for Snyder test.
60 gms of Snyder test agar + 1 liter water
boiled over flame
When melted, agar distributed (5 ml per tube)
Tubes autoclaved for 15 minutes, allowed to cool and stored
in refrigerator
2 tubes taken, Patient asked to expectorate saliva into tubes
Labeled and incubated at 37C for 4 days and observed daily
18. Final readings taken after 72 or 96 hrs of incubation.
Interpretation:
• Readings negative for the entire incubation period are labeled
“negative”.
• All other readings are labeled “positive”.
• Slower change or less color change is labeled “improved”.
• Faster color change or more pronounced color change is
labeled “worse”.
• When consecutive readings are nearly identical, they are
labeled “no change.
19. SALIVARY BUFFER CAPACITY TEST
Principle: measures the number of milliliters of acid required to lower the
pH of saliva through an arbitrary pH interval, such as from pH 7.0 to
6.0.
Evaluation:
There is an inverse relationship between buffering capacity of saliva and
caries activity.
20. SALIVARY REDUCTASE TEST
Principle: measures the activity of reductase enzyme present
in salivary bacteria.
Trade name: Treatex
Collected saliva is mixed with dye (Diazo-resorsinol)
Color changes observed after 15 minutes
21. ENAMEL SOLUBILITY TEST
Principle: when glucose is added to the saliva containing powdered
enamel, organic acids are formed. These in turn decalcify the enamel,
resulting in an increase in the amount of calcium in Saliva-Glucose-
Enamel mixture.
The extent of increased calcium is supposedly a direct measure of the
degree of caries susceptibility.
FOSDICK CALCIUM DISSOLUTION TEST
Principle: measures the mgs of powdered enamel dissolved in 4 hrs by
acid formed when patient’s saliva is mixed with glucose and
powdered enamel.
DEWAR TEST
Principle: similar to Fosdick calcium dissolution test. The final pH after 4
hrs is measured instead of amount of calcium dissolved.
22. According to the World Health Organization (WHO) system, the shape
and the depth of the carious lesion can be scored on a four-point
scale (D1 to D4):
• D1: clinically detectable enamel lesions with intact (noncavitated)
surfaces
• D2: clinically detectable "cavities" limited to the enamel
• D3: clinically detectable lesions in dentin (with and without cavitation
of dentin)
• D4: lesions into pulp
•Intact tooth (43)
•Primary enamel caries (42)
•Primary dentin caries with cavitation (41)
•Secondary caries with cavitation (31)
•Advanced secondary caries (32)
•Complete destruction of the crown (33)
23. Meticulous clinical examination (Visual Examination):
under clean and dry conditions using good illumination
n Brownish discoloration of pits and fissures
n Opacity beneath pits and fissures or marginal ridges
n Frank cavitation of the tooth surface.
Problem: discoloration of the pits & fissures may be mistaken
for the presence of caries.
Magnifying lens: enhances Visual examination
24. Tactile Evidence of Caries: Explorer and dental floss
curved explorers are used for examination of occlusal pits and fissures
interproximal explorers are used to detect proximal caries.
Tactile findings suggestive of caries:
• Softness at the base of a pit or fissure and discontinuity of enamel
surface
• Binding or catch of the explorer tip
• Cavitation at the base of pit or fissure.
25. Disadvantages:
1. May transmit cariogenic bacteria from one site to another.
2. May produce irreversible traumatic defects in potentially
remineralizable enamel.
3. May not be able to add any information to the visual examination.
4. Mechanical binding of an explorer tip in a fissure may not be because
of caries but because of other causes like:
a. Shape of the fissure.
b. Sharpness of an explorer.
c. Force of application.
26. Dental Floss: when sawed through the contact areas
between teeth, if it frays or shreds then it is a sign for
proximal caries.
overhanging restorations on the proximal side also give
the same features.
Tooth separation
can be achieved using wedges or mechanical separator.
Once the proximal surface is accessible, visual examination
and gentle probing may help in diagnosis of the carious
lesion.
27. Conventional Radiographs:
presents a 2-D picture of a 3-D object.
net mineral loss must exceed atleast 20%-30% in order to be
radiographically visible.
• intraoral periapical
• bitewing radiographs
(bitewing radiographs have more diagnostic value)
Advantages:
• Non-invasive method
• Disclose sites inaccessible to other diagnostic methods
• Permanent record for monitoring progress or arrest of the
carious lesion.
29. Problems encountered with radiographic methods are:
1. Overlapping of approximal contacts.
2. False diagnosis due to overestimation of lesion depth, due to
change in angulations.
3. Radiolucency may be because of caries or resorption or any other
defect i.e. wear, etc.
4. A superficial demineralization in the buccal & lingual surfaces may
be imaged on the radiograph as an approximal carious lesion.
5. Fracture of one lingual cusp may appear as radiolucent approximal
cavity.
6. Tilt of maxillary lateral incisors appears as caries on the mesial side
of lateral incisors.
7. Cervical burnout may mimic cervical caries.
30. Caries Diagnosis for Root Surfaces
exposed Root surfaces are at risk for caries and should be examined
visually and tactilely.
Discoloration is common and is associated with remineralization.
darker the discoloration, the greater the remineralization.
31. Dye Penetration Method
n qualitative assessment: to observe for color or differentiate colored
objects from the non-colored ones.
n quantitative assessment: intensity of color is to be determined.
The Intensity of color can be determined by absorption or fluorescence.
n Absorption: by quantitating the decrease of light intensity at a
particular wavelength
n Fluorescence: by quantitating the increase of light intensity at a
particular weave length.
Criteria for dye selection:
• should be absolutely safe for intra oral use
• should be specific and stain only the tissues it is intended to stain
• should be easily removed and not lead to permanent staining.
32. Dyes for detection of carious enamel
n 'Procion‘: stain enamel lesions, staining becomes
irreversible because the dye reacts with nitrogen and
hydroxyl groups of enamel and acts as a fixative.
n 'Calcein‘: makes a complex with calcium and remains
bound to the lesion.
n 'Fluorescent dye‘: like Zyglo ZL 22 is made visible by
ultraviolet illumination.
not suitable in vivo
n 'Brilliant blue‘: to enhance the diagnostic quality of
fiberoptic transillumination.
33. Dyes for detection of carious dentin
n Histopathologically, carious dentin is divided into two layers;
outer layer of decalcification, which is soft and cannot be
remineralized and the inner decalcified layer, which is hard and
can be remineralized.
n 0.3% Basic Fuchsin in propylene glycol has been tried to
differentiate between then two zones of dentin caries
n Demineralized dentin in which the collagen has been
denatured is stained while the inner one remains unstained.
n recommended as a clinical guide for complete removal of the
outer carious zone
n considered to be carcinogenic
Others:
acid red and methylene blue.
Methylene blue is slightly toxic so acid red is preferred.
34. A modified dye penetration method
n 'The Iodine penetration method' for measuring
enamel porosity of the incipient carious lesions
was developed by Bakhos et al. (1977).
n Potassium iodide applied for a specific period of
time to a well-defined area of the enamel and
thereafter the excess is removed.
The iodine, which remains in the micropores, is
estimated and that indicates the permeability of
enamel.
35. Ultraviolet Illumination
n has been used to increase the optical contrast between
the carious region and the surrounding sound tissue.
n Natural fluorescence of tooth enamel, as seen under UV
light illumination is decreased in areas of less mineral
content such as in carious lesions, artificial
demineralization or developmental defects.
n Carious lesion appears a dark spot against a fluorescent
background.
Advantages
more sensitive method than the visual tactile method.
Disadvantage
specificity is a problem between the carious lesion and
the developmental defect.
36. Fiber Optic Trans Illumination (FOTI)
Principle: a carious lesion has a lowered index of light
transmission, an area of caries appears as a darkened
shadow that follows the spread of decay through the
dentine.
n consists of a halogen lamp and a rheostat to produce a
light of variable intensity.
n Two attachments are used; a plane mouth mirror
mounted on a steel cuff and a fiberoptic probe of 0.5 mm
diameter so that it can be placed in the embrasure region.
n It produces a narrow beam of light for transillumination.
37. Advantages
No hazards of radiations.
Non-invasive method
Simple and comfortable for the patients.
Lesions, not diagnosed radiographically, can be diagnosed by this
method.
Useful in patients with posterior crowding
Not time consuming.
Disadvantages
Permanent records are difficult to maintain as can be kept in
radiographs.
It is subjected to Intra and Inter observer variations.
• Difficult to locate the probe in certain areas.
38. RECENT METHODS OF CARIES DIAGNOSIS
VISUAL EXAMINATION
Magnification Aids
• Loupes: provide larger image size for improved visual
acuity, while allowing proper upright posture.
Magnifications used are 2X,3X, 4.5X
Higher magnification systems are heavier, expensive and
require more light than lower power systems.
Average working distance (focal length) 13-14 inches.
• Dental microscopes allow the clinician to view intraoral
structures at a higher level of magnification.
Areas 1m in size can also be viewed to identify minute
decay.
39. Digital FOTI
n Resultant changes in light distribution as light traverses the tooth are
recorded as an image for analysis.
n Reduces shortcomings of FOTI -combines FOTI & digital CCD camera.
Images captured by the camera sent to a computer for analysis, which
produces digital images that can be viewed.
DIFOTI to conventional radiographs
DIFOTI twice sensitive in detecting approximal lesions & 3 times as
sensitive in detecting occlusal lesions with a difference of less than
10% in specificity.
Buccal-lingual lesions: sensitivity 10 times that of conventional
radiographs, again with a 10% loss of specificity.
Detect incipient or recurring caries before they are visible on
radiographs.
41. Advantages:
• Instantaneous image projection
• Image quality is easy to control
• Can detect incipient and recurrent caries very early
• Non-invasive
Disadvantages:
• Does not measure the depth of the lesion
• Difficult to distinguish between deep fissure, stain and
dental caries.
42. Endoscope/Videoscope
Pitts and Longbottom (1987) explored the use of EFF
(Endoscopic filtered fluorescence) method for the clinical
diagnosis of carious lesions.
Principle: when a tooth is illuminated with blue light in the
wavelength range of 400-500 nm, sound enamel and
carious enamel demonstrate different fluorescence.
• When this is viewed through a specific broadband gelatin
filter, white spot lesions appear darker than sound
enamel.
• a white light source can be connected to an endoscope by
a fiberoptic cable so that the teeth can be viewed without
a filter - white light endoscopy.
43. The integration of the camera with endoscope is called a videoscope.
v A miniature color video camera is mounted in a custom-made metal
mirror holder.
v image of the surface of enamel can be viewed directly over a
television screen.
Advantages
It provides a magnified image
Early diagnosis of incipient enamel caries
More accurate than radiographs
Clinically feasible.
Disadvantages
Requires meticulous drying and isolation of teeth.
Time consuming
• Very costly
44. Ultrasonic imaging
Principle: The interaction of ultrasound depends on the
acoustic properties of the tissue, such as the attenuation,
absorption and scattering impedance and velocity.
Acoustic parameters depend on the frequency of
ultrasound as well as other parameters such as
temperature.
The demineralization of enamel is assessed by ultrasound
pulse echo technique.
there is a definite correlation between the mineral
content of the body of the lesion and the relative echo
amplitude changes.
Ultrasound in ultrasonography is a sound wave with a
frequency ranging from 1.6 to about 10 MHZ.
45. The ultrasonic probe sends longitudinal waves to the surface
of the tooth and also receives the waves.
Normal enamel produces no echoes
• initial white spot lesions produce weak surface echoes
• areas with cavitation produce echoes of high amplitude.
This method may be more sensitive than visual, tactile or
radiographic methods for detecting early caries.
46. AIR-ABRASIVE TECHNOLOGY
developed in 1940s. The S.S White Company introduced the Airdent air-
abrasive unit in 1951.
Principle: uses a pressurized stream of microscopic non-toxic abrasive
powder, and rapidly removes enamel, dentine, decay and previous
restorations.
The scouring action can clean out both stains and organic debris and can
open areas of early caries for replacement with resin restorative
materials.
47. stained pits and fissures Revealed hidden vein of decay
3-mm depth of the lesion
48. Advantages:
• minimizes heat, vibration and bone-conducted noise.
• Patients treated with the air-abrasion system rarely require
anesthesia.
• advantage in examining darkened areas in the bottom of pits and
grooves.
• roughens the tooth surface, leaving it suitable for direct bonding
techniques without acid etching.
Disadvantage:
• Not well-suited for removing all decay. Moist and resilient decayed
dentin cannot be abraded effectively with the air-abrasion unit.
• cut dentin more readily than enamel, which allows overhanging
enamel to develop.
49. Electrical resistance or Electrical conductance Measurements
1878-Magitot: Sound tooth enamel is a good electrical insulator
due to its high inorganic content.
Principle:
Carious enamel has a measurable conductivity, which increases
with the degree of demineralization.
Caries / enamel demineralization results in increased porosity.
Saliva fills these pores and forms conductive pathways for
electric current.
The electric conductivity is directly proportional to the amount
of demineralization that has occurred.
Electrical resistance is measuring the electrical conductivity
through these pores.
50. 2 instruments (1980s):
1. Vanguard electronic caries detector.
2. Caries Meter L.
Measure electrical conductance between tip of probe placed
in a fissure & a connector attached to an area of high
conductance. (Gingiva or skin)
scale: 0 to 9 for Vanguard system.
4 colored lights for Caries meter:
n Green-no caries
n Yellow-enamel caries.
n Orange-dentin caries.
n Red-pulpal involvement.
To prevent polarization, both systems used a low frequency
alternating voltage, 25Hz and 400 Hz, respectively.
52. Advantages
1. Very effective in detecting early pit and fissure caries.
2. It can monitor the progress of caries during caries control
programme.
• Verdonschot et al: high sensitivity & specificity in diagnosing
occlusal caries. (Compared to clinical, radiographic, FOTI)
• sensitivity-92% & specificity-82%.
Disadvantages
can only recognize demineralization and not caries specifically. The
hypomineralization areas may be of developmental origin or carious
origin will give similar type of readings.
Presence of enamel cracks may lead to false positive diagnosis. A
sharp metal explorer is utilized which is pressed into the fissure
causing traumatic defects.
• Separate measurements are required for different sites making full
mouth examination quite time consuming.
53. 'Electronic Caries Monitor' (Lode diagnostic, Groningen, the
Netherlands)
not only detects caries at a single point on tooth but also can
screen whole of the occlusal surface for caries by covering
the surface
The sensitivity and specificity for ECM was 0.78 and 0.80 for
the diagnosis of occlusal dentinal caries and 0.65 and 0.73
for enamel lesions.
Other Use:
Can be used to predict the probability that a sealant or a
sealant restoration will be required within 18-24 months.
54. RADIOGRAPHY
Xeroradiography:
n Simulates the photocopying machine.
n Image is recorded on an aluminium plate coated with a
layer of selenium particles.
n Selenium particles are given a uniform electrostatic
charge and are stored in a unit called “conditioner”.
n When X-rays are passed on to the film, it causes selective
discharge of the particles, which forms a latent image.
This is converted into a positive image by “development” in
the processor unit.
55. Advantages:
Twice as sensitive as conventional D-speed films and a phenomenon
of 'Edge Enhancement' is possible.
Edge enhancement means differentiating areas of different densities
especially at the margins or edges.
Less radiation exposure.
No wet processing.
Both positive and negative prints are possible.
Disadvantages:
Expensive
The electric charge may cause discomfort to the patient since the oral
cavity has a humid environment, which acts as a medium for flow of
current.
The process of development can't be delayed and is to be completed
within 15 minutes.
56. Digital imaging
A digital image is an image formed and represented by a
spatially distributed set of discrete Sensors and Pixels.
When viewed from a distance, the image appears
continuous, but closer inspection reveals individual pixels.
Digital radiographs can be obtained by 2 methods:
• Video recording and digitization of conventional
radiograph.
• Direct digital radiograph.
Digital Image Receptor works on a charged couple device
(CCD), which is electronically connected, to a computer.
57. CCD
• a semiconductor made up of metal oxides such as silicon
that is coated with x-ray sensitive phosphorous.
• sensitive both to x-rays and visible light.
• The intraoral DIR is placed in the mouth instead of the x-
ray film.
The image area is limited by the size of the CCD present in
the digital image receptor.
Once the image is captured by the CCD, it can be can be
stored in the computer memory for image processing and
displayed for viewing.
58. Radio Visio Graphy (RVG): first direct digital radiography system
introduced in 1989. (Trophy; Japan)
Flash Dent (Villa; Italy)
Sens A Ray (Regarn; Sweden)
Advantages:
1. Darkroom is not required, instant image is viewed.
2. The quality of image is consistent.
3. Elimination of the hazards of film development.
4. Radiation dose is decreased.
5. Capability for teletransmission
6. Image can be magnified. Contrast and density of image can be
enhanced.
Disadvantages
1. High cost of system
2. The life expectancy of CCD is not fixed.
59. n Digital mode can enhance density and contrast upto
70%.
Digital method is 50% more sensitive in detecting occlusal
caries as compared to conventional films.
The Digora image plate system
• alternative to the CCD systems
• Radiographic information is recorded on a phosphorous
storage screen called the image plate.
• outer dimensions of the scanning unit are 483 X 452 X 135
mm.
• After exposure to radiation, the image plate is placed in a
scanner, which uses a laser beam to scan image. This is
then digitized and displayed on the computer screen.
61. Advantages:
• Image plate takes less than 30 seconds for the image to appear on the
computer screen.
• Wide exposure range.
• Image brightness and contrast can be adjusted
• Edge enhancement and gray scale inversion possible
• Different measurements can be made
Wenzel et al-compared (CCD based units):
n Trophy RVG
n Sens-A-Ray
n Visualix
n Phospor storage plate (PSP) based units
Detection of occlusal caries: performed almost equally well.
Radiography is of no value in detection of initial enamel lesions or for
detection of approximal dentinal lesions, especially for lesions
confined to enamel.
62. Magnetic Resonance Micro-Imaging
Principle: proton of hydrogen ion behaves as small spinning
magnet and when placed in magnetic field, they tend to
move parallel to the field.
If a coil is now wound around a volume of proton, the tube
can be arranged to turn the magnetization through 90
(90 pulse).
The protons now process at 90 around the magnetic field at
the same frequency and induce a minute current in the
coil (Free Induction Decay) and lasts for some seconds.
This energy is utilized in scanning procedures
63. High intensity signal from water penetrated into the porous
decayed regions of tooth is contrasted with lack of signal
from mineralized tooth tissue, and this allows for
visualization of the presence and extent of caries.
The black area of the image: corresponds to the mineralized
tooth tissue,
(Martin M. Tanasiewicz et al.)
Panoramic radiographic sensitivity for caries is 18%, but 41%
when combined with bite-wing radiographs. This
sensitivity is low when compared with a full mouth series
with overall sensitivity of 70%.
The specificity of diagnosis of healthy surfaces varies from
98% to 99% from panoramic, bite-wing and full series
radiographs.
64. TACT: TUNED APERTURE COMPUTED TOMOGRAPHY
• local computed tomography (CT) for caries diagnosis
has been demonstrated.
• produces stacks of axial and vertical slices of teeth
• caries diagnosis on vertically reformatted CT slices
was significantly better than on conventional
radiographs.
(Van Daatselaar et al 2003)
In local CT the size of the beam is just enough to cover a standard
dental
CCD detector (roughly 6 cm2).
65. TACT requires multiple images of the same
object of interest –called source, basis or component
images –obtained from different projection angles.
TACT uses presumably larger amount of information
contained in the multiple views of an object while a
single plain film or digital radiography image uses the
presumably smaller amount of information contained
in a single view of this object.
66. Computer Image Analysis
n based on the "expert system" which contains facts about
the pathologic conditions.
n clinician enters the patient's data and the programme
compares the patient's data with the basic knowledge of
the pathology.
n provides a graphic visualization of the size and progression
of carious lesions especially proximal lesions.
Example: Trophy 97 System with an integrated software-
Logicon Caries Detector.
67. Advantages:
1. may provide sensitive and objective observation of smaller lesions
which otherwise are not perceptible to naked eye.
2. It is possible to monitor the lesion.
Disadvantages:
1. need for standardization of exposure geometry.
2. Sensitivity is higher but specificity is lesser.
3. Time consuming and less economical.
68. Digital Subtraction Radiography
Principle:
• Structured noise is reduced in order to increase the detectability of
changes in the radiographic pattern.
• Structured noises are the images, which are not of diagnostic value
and interfere in routine interpretation of radiographs.
Digitization: achieved by taking a picture of the radiograph using high
quality video camera.
fed to computer imaging device, termed as “digitizer”.
Two standardized radiographs produced with identical exposure
geometry: a
first one is the ‘Reference Image’ and the subsequent images are for
comparison.
The reference image is displayed on the screen over which the
subsequent images are superimposed.
69. The difference between the original and the subsequent
images will show as dark bright areas, which can be
interpreted readily.
n Digitization turns the image into a form, which can be
read by the computer.
90% accurate in detecting as little as 5% mineral loss of bone
compared to the 30-60% of the mineral content of the
bone that has to be lost before a radiographic lesion could
be seen on a conventional radiograph.
70. LASER AUTO FLUORESCENCE (LAF)
n Light scattering: measure of observed whiteness of a
carious lesion –correlated with degree of mineral loss.
n bacterial metabolites within caries produce fluorescence
that can be enhanced by a laser light.
QLF (Quantitative Laser Fluorescence) is a means by which
the laser-induced fluorescence can be measured to
quantify tooth demineralization.
n visible light has been used as the light source for the
detection of smooth surface and fissure caries at an early
stage.
(Bjelkagen et al., 1982).
71. The Oral Health Research Institute (OHRI) of the Indiana University
School of Dentistry has used two fluorescent dyes, Pyrromethane 556
and Sodium fluorescein, in conjunction with laser fluorescence for
detection of carious lesions.
Advantages
• It is convenient and a relatively fast method.
• Carious lesions can be detected and their mineral loss measured.
• Lesions with a diameter of less than 1 mm and a depth of 5-10 mm
have been detected and measured with this technique.
• Preventive measures can be evaluated.
• developed for quantification of enamel changes.
Disadvantages
• Expensive
• Cannot differentiate between caries, hypoplasia, stains and calculus.
• Cannot differentiate between active or inactive lesions.
72. Carious tooth structure produces considerable fluorescence, which is
revealed as a digital numerical readout (0-99) on the display.
• Numeric data between 5 and 25 indicated initial lesions in the enamel
• Values grater than this range indicated early dentinal caries.
• Advanced dentine caries is said to yield values greater than 35.
For detection of dentinal caries,
sensitivity values 0.19 to 1.0
Specificity values 0.52 to 1.0.
In comparison with visual assessment methods, the DD exhibited a
sensitivity value that was almost always higher and a specificity value
that was almost always lower.
(JAMES D. BADER, DAN A. SHUGARS, 2004)
73. Optical Coherence Tomography:
Principle: Based on principle of confocal microscopy and low
coherence interferometry.
Initially, OCT referred to longitudinal imaging only and no
quantitative analysis been provided with OCT.
74. Alternating Current Impedance Spectroscopy Technique
sophisticated approach to lesion detection and measurement
is to characterize the electrical properties of the tooth and
lesion by using ACIST, which scans multiple frequencies.
Has 100% sensitivity and specificity at the D1 and only a
marginal decrease in specificity at D3 level
(Longbottom et al 1996).
75. INFRARED THERMOGRAPHY
Principle: When fluid is lost from a lesion by evaporation,
some changes takes place in the thermal energy, which
can be compared with sound tooth structure.
determines lesion activity rather presence or absence of a
lesion.
Advantages:
• show targets and surroundings in complete darkness and
through smoke
• improved vision through fog
• works equally well day and night
76. TERAHERTZ IMAGING
Principle: This method uses waves with terahertz frequency
(1012 or a wavelength of approx 30 m).
This wave-form is short enough to provide reasonable
resolution but long enough to prevent serious loss of
signal due to scattering.
Effectiveness:
• relative transparency of human tissues to terahertz rays
• low powers used for imaging
• no alteration of the electrical charges of the tissues
examined
78. CONCLUSION
Presently, we are at crossroads in caries detection
where along with the conventional methods, the
newer methods of early caries detection are still
being developed or are not yet widely
disseminated.
Although currently there is no single diagnostic
method on the horizon that can reliably detect
precavitated carious lesions on all the tooth
surfaces, the prospects look favorable that, with
continued research, newer methods will provide
the high degree of sensitivity and specificity
needed to detect early dental caries.
