Methods for early diagnosis of caries.

1. Early Diagnosis of Caries
Presented by:-
•Dr. Faizan Ansari
•PG 1st Year
•Dept. of Paediatric and Preventive Dentistry

2. Contents
1. Definitions
2. Introduction
3. Various diagnostic aids
• Conventional techniques
• Recent advances
4. Conclusion
5. References

3. Definitions:
• Microbial disease of calcified portion of teeth characterized by demineralization of
inorganic & destruction of organic portions of teeth.
- Shafer (1958)
• Infectious microbiological disease of the teeth that results in localized dissolution and
destruction of calcified tissues.
- Sturdevant (1968)
• Caries is defined as a localized post eruptive, pathological process of external origin
involving softening of the hard tooth tissue and proceeding to the formation of a cavity.
- WHO (1979)

4. •Diagnosis is an art and science, which results from the synthesis of scientific knowledge
and clinical experiences in identifying the signs and symptoms of a disease process.
•Greek ‘ dia’ meaning ‘‘through’’and‘‘gnosis’ meaning ‘‘knowledge’’.
•Thus, ‘‘to diagnose’’implies that it is only through knowledge about the disease that a
diagnosis can be established.
Importance of diagnosis:
•Toidentify etiologicalfactors.
•Determine nature of the disease involved.
•Todetermine treatmentplanning.
•Toaccessprognosis.
Introduction:

5. An Ideal Diagnostic Tool:
Tools to assess future caries risk and present caries activity are required, as diagnostic
tasks are becoming more difficult and important from the standpoint of long-term oral
health.
Ideally, a diagnostic tool should:
1. Detect dental caries at its earliest stage possible
2. Provide valid prospective caries risk assessments for different age groups
3. Determine present caries activity and monitor lesions behavior over time.

6. Requisites of an ideal diagnostic tool:
• Accuracy
• Reliable
• Precise/simple
• Easy to apply
• Useful for all surfaces of teeth
• Identifying caries adjacent to restorations
• Objectivity
• Sensitivity
• Specificity
• Reproducibility
• Validity
• Quantitative analysis.

7. VARIOUS
DIAGNOSTIC
AIDS

8. Conventional Methods:
Visual
Eyes
Magnifying
lens
Tactile
Sensation
Probe
Mechanical
Separation
Dental Floss
Illumination
UV
Illumination
Dyes
Basic
fuchsin
Procion dyes
Radiography
Intraoral
periapical
Bitewing
Xeroradiogr-
aphy

9. Recent Advances
- Fiberoptic
transilluminati
on (FOTI)
- Wavelength
dependent
Fiberoptic
transilluminati
on (WFOTI)
- Digital
imaging
Fiberoptic
transilluminati
on (DIFOTI)
- Fluorescence
camera
- Endosco-
pically viewed
filtered
fluorescence
- White light
fluorescence
- Videoscope
- Ultrasonic
system
scanning
acoustic
microscope
- Ultrasound
caries detector
- Vanguard
electronic
caries detector
- Caries meter
- CarieScan
Pro
- Digital
radiography
- Digital
Subtraction
radiography
- Magnetic
resonance
microimaging
- Photo
stimulable
phosphor
radiography
- Tuned
aperture
computed
tomography
-DIAGNOdent
- Midwest
Caries ID
- Dye
enhanced laser
fluorescence
- D-Carie mini
- Species
specific
monoclonal
antibodies
- Intraoral
television
camera
- Infrared
thermography
Illumination Endoscopy Ultrasonic
Electrical
Conductance
measurement
Radiography
Lasers
Miscellan
ous

10. Visual diagnosis
• Most common because it is an easy technique that is routinely performed in clinical
practice.
• Permits early caries signs to be detected and recorded in a reliable and accurate way by
using visual indices.
• Indices may also describe the characteristics of all clinically relevant stages in the caries
disease process, making them a cost-effective method of recording caries lesions.

11. • Teeth should be cleaned and/or dried before the examination
process, which if not included will increase the risk of missing
lesions
• Some indices recommend tactile examination to be performed in
conjunction with visual examination, and this has been considered
questionable.
• Another recommend using the WHO probe, which is ball-ended with
a sphere presenting 0.5 mm in the extremity, allowing this kind of
evaluation.

12. Tactile diagnosis
•The visual-tactile method has been a mainstay of
clinical dentistry for more than 100 years and is based
on the use of a dental mirror, sharp probe, and a 3-in-1
syringe and clean and dry tooth surface.
•The examination is primarily based on subjective
interpretation of surface characteristics such as
integrity, texture, translucency or opacity, location, and
color.
•Use of dental floss for tactile evidence of proximal
caries has been shown to be effective, wherein
shredding of dental floss indicates a proximal cavity.

13. Disadvantagesof Probingwith SharpExplorer:
• Traditional probing with a sharp explorer has come into question as the ultimate
determinant of caries activity.
• Tactile examination using a sharp probe has been criticized because of the possibility of
transporting cariogenic bacteria, may cause irreversible traumatic defects in potentially
remineralizable enamel and may not be able to add any information to the visual
examination.
• In vitro studies by Beltrami et al. in 1990 and scanning electronic microscopic study by
Kuhnisch et al. in 2007 confirmed that using a sharp probe for caries detection can
cause mechanical damage to the enamel.
• Ekstrand et al. in 2005 showed that dentists were not able to reliably and reproducibly
determine the subtle visual and tactile differences between active and inactive enamel
lesions.

14. Examples showing the benefit of cleaning and drying to detect caries (A–C) and
harmful effect of probing with a sharp explorer

15. Internationally accepted caries detection system
• DMFT/S index (Klein, Palmer, Knutson 1938, 1987,1997)
• Nyvad’s System (Nyvad et al.,1999)
• Significant caries index (Sic) (Bratthal D in 2000)
• International and Caries DetectionAssessment System (2002,2005 Baltimore,
Maryland, USA)
• Universal Visual Scoring System(UNIVISS) (2008)
• Pulpal Ulceration, Fistula, Abscess Index(PUFA) (Monse et al 2010)
• Caries Assessment and TreatmentInstrument (CAST) (Frencken JE 2011)

16. Detection with chemical dyes
• Fusayama introduced a technique in 1972 that used a basic fuchsin red stain to aid in
differentiating layers of carious dentin.
• Fuchsin was replaced by another dye, acid red52,which showed equal effectiveness.
• Caries-detecting stains differentiate mineralized from demineralized dentin in both vital
and nonvital teeth.
• Outer carious dentin is stainable because the irreversible breakdown of collagen cross-
linking loosens the collagen fibers.
• Inner carious dentin and normal dentin are notstained because their collagen fibers are
undisturbed and dense.
• Dyes do not stain bacteria but instead staintheorganic matrix of poorly mineralized dentin.

17. Yip et al .,1994
•Dyes neither stained bacteria nor delineated the bacterial front but did stain collagen
associated with a less mineralized organic matrix.

18. Commercially available caries detector dyes
• Caries check (CC), containing 1% acid red in polypropylene glycol has been recently
introduced.
• Cd dyes caries detector (cad),
• Caries marker (cam),
• Seek (see),
• Sable seek (ses),
• Carbolan green,
• Coomassie blue,
• Lissamine blue,
• Snoop

19. RADIOGRAPHIC
METHOD

20. Radiographic methods includes:
1. Bitewingradiographs
2. IOPAradiographs
3. Digitalradiography
4. Digital subtractionradiography
5. TunedAperture computed Tomography

21. • Radiographic examination is useful in monitoring caries lesion development, in view of
the fact that non-cavitated lesions can be reversed by non- invasive intervention,
providing changes in mineral content of dental tissues.
 Ratledge et al.(2001)
• 50-90% of dentin caries lesions radiographically observed on the proximal surface might
present cavitation.
Krick R et al.,(2009)
•Caries are not visible on radiographs untilthey penetrate more than one half the enamel
thickness and enamel lesions are usually not visible until 30 - 40% of the lesion has become
demineralized.
E Onem(2012)
•40-60% of tooth demineralization required foralesion to be seen radiographically.

22. (Ricketts et al., 1997)
•Clinically "sound" and apparently intact occlusal surfaces, however, may develop lesions
which penetrate into the dentin, which can be observed only through radiographic
examination.

23. Wenzel, 1995,2004
•The performance of bitewing radiography, have found a high sensitivity (50-70%) to detect caries lesions
in dentin of both proximal and occlusal surfaces, compared to clinical visual detection.
•The validity of detecting enamel lesions islimited on the proximal surfaces and low for the occlusal
surfaces.
Espelid et al., 1994; Neuhaus et al.,2009
•Validity of detecting enamel lesions is limited onthe proximal surfaces and low for the occlusal surfaces.
•This difference can be explained by the fact that radiography is a 2-dimensional image of a 3-
dimensional anatomy of the tooth structure. So, the superimposed cuspal tissues obscure initial changes
in occlusal surfaces.
Dove2011
•There are great chances to occur false-negative diagnosis in the presence of caries than false positive
diagnosis in the absence of disease i.e high specificity and low sensitivity.

24. Digital
Radiography

25. Digital imaging is an image formed and represented by a spatially distributed set of
discrete sensors and pixels. There are two types:
Direct – The direct image receptor that collects X-ray directly, for example, RVG.
Indirect – For example, video camera is used for forming digital images of a
radiograph.

26. Digital detectors
• Charged couple device (CCD)
• Complementary metal oxide semiconductor
• Photo Stimulable Phosphor plate (PSP).
Digital image enhancement
• Resolution of unenhanced digital image is lower than radiographs
• Range of gray shades is limited to 256, whereas in a radiographic film, over 1 million
shades of gray appear
• Contrast can be digitally enhanced using a mathematical rule often decided by the
algorithm/filter
• They are not practically used because they are very time-consuming

27. Advantages of digital radiography comparedwith conventional radiography:
•Image acquisition process in real time.
•Reductions in radiation dose.
•Time savings.
•Digital manipulation of the image to enhance viewing.
•Avoiding unnecessary or repeated radiographs.
•Facilitate communication and case discussion among dental professionals.
•Visual aid to be shown to the patient on the computer screen, increasing the confidence
and credibility in the treatment-decision making process.
•Primary disadvantages include the rigidity and thickness of the sensors, the high initial
system cost and unknown sensor lifespan.

28. Digital
subtraction
radiography

29. •A digital bitewing radiograph is taken and later a second radiograph of exactly the same
region is produced with identical exposure time, tube current, and voltage
•By subtracting gray values for each coordinate of the first radiograph from equivalent
coordinate of second, a subtraction image is obtained.
•If no changes have occurred, the result of subtraction is zero.
•Nonzero result will be obtained in case of onset or progression of demineralization.
•It is not yet routinely applied in clinical caries detection due to difficulty of image
registration.

30. •Introduced into dentistry in1980
•Based on theprinciple:
•Two digital radiographic images obtained under different time intervals, with the same
projection geometry, are spatially and densitometrically aligned using specific software.

31. Advantages:
•Detects onset or progression of demineralization.
Disadvantages:
•Difficulty of image registration

32. Tuned-aperture computed tomography
This method constructs radiographic section through teeth. The slices can be viewed for
the presence of radiolucency
Mechanism of action:
•As exposure begins, the tube and film move in opposite directions simultaneously through
a mechanical linkage. With this synchronous movement, images of objects in the focal
plane remain in fixed positions on radiographic film and are clearly imaged.
•On the other hand, images of objects located outside focal plane have continuously
changing positions on the film. As a result, images of these objects are blurred beyond
recognition by motion unsharpness. Slices can be brought together in a three-dimensional
computer model called pseudo-hologram.
•TACT slices and pseudo-hologram can adequately detect small primary and secondary
carious lesions.

33. Figure : Tuned-aperture computed tomography.

34. TRANSILLUMINATION

35. •Fiber optics was introduced in 1970’s.
•It refers to flexible, thin cylindrical fibers of high-
optical-quality glass or plastic.
•Theory:
•Single optical fiber that consists of glass or plastic
material with an outer cladding of a material with
lower refractive index.
•Fiber core has a higher refractive index.
•Individual fibers are grouped together to form a
fiber optic bundle.
•Fibers can be as small as 0.01mm for glass and 0.1
mm for plastic.
FOTI

36. •It is based on the changes in the scattering and absorption phenomenon of light photons
that increases the contrast between sound and enamel caries.
•The illumination is delivered via fiber-optics from alight source to a tooth surface.
•The light propagates from the fiber illuminator across tooth tissue to non-illuminated
surfaces.
•The resulting images of light distribution arethen used for diagnosis.

38. DIFOTI
• INTRODUCED IN YEAR1998
• Developed by Schneidermann et al, Department of
Oral Pathology, Radiology and Diagnostic
Sciences, New Jersy Dental School, University of
Medicine and Dentistry of NewJersey.
• Employs digital image processing for quantitative
diagnosis and prognosis in dentistry.
• It uses fiber-optic transillumination of safevisible
light to image the tooth.
• In this system, light delivered by a fiber-optic is
collected on the other side of the tooth by a mirror
system and recorded with a CCD imaging camera,
instantaneously.
• The acquired information is sent to a computerfor
analysis with dedicated algorithms.

39. • Digital images produce can be viewed by the dentist and patient in real time or
stored for later assessment.
• It can also be used to detect other changes in coronal tooth anatomy, such as tooth
fractures and fluorosis.

40. Advantages:
•Detects initial areas of demineralization
•Inspects integrity of teeth
•Detects cracks, tooth fractures, and wear
•No harmful radiation
•Uses safe white light
•Images all coronal surfaces including interproximal, occlusal, smooth surfaces
•Determines depth of lesion accurately
•Only dental diagnostic imaging instrument approved by the Food and Drug
Administration for detection of incipient and recurrent caries
•Magnification of up to ×16
Disadvantages:
•Technique sensitive
•High cost

41. CariVu
• DEXIS CariVu™ is a compact, portable caries detection device that uses
transillumination technology to support the identification of occlusal, interproximal
and recurrent carious lesions and cracks.

43. FLUORESCENCE

44. 1. QLF
2. DIAGNOdent
3. DIAGNOdent Pen
4. Vistaproof
 MECHANISM OF FLUORESCENCE
• Benedict (1928) was first to describe enamel fluorescence.
• Fluorescence results from a change in the characteristics of light caused by an
alteration in the wavelength of the incident light rays following reflection from the
surface of a material

45. • Through these filter system only fluorescentrays pass and inherent fluorescence of a
material is often referred to as auto-fluorescence.
• The exact identity of the material responsibleforthe fluorescence in enamel remains to
be established.
• The intensity of the emitted fluorescence canbemeasured by using a filter system.

46. NATURE OF FLUORESCENCE ON ENAMEL SURFACE
•Near-ultraviolet light-blue
•Incident light in the blue and green - yellowandorange fluorescence.
•Incident light in the red or near-infraredregion- red fluorescence
Booij & ten Bosch(1982)
•Dityrosine are the chromophores responsible forblue fluorescence.
Scharf (1971)
•Yellow fluorescence is attributable tocross- linked chains of structural proteins.
 Konig et al., (1998;1999)
• Red fluorescence may be attributed to the presence of various protoporphyrins that
are considered to be products of bacterial decomposition and other oral bacterial
metabolites.

47. PRINCIPAL OF LASER FLUORESCENCE
• Laser devices are based on the principle that a monochromatic light source (655 nm
wavelength) passes unhindered through a mature enamel crystal with little or no
alteration.
• The 655 nm light has the ability to excitebacterial photoporphyrins, resulting in
fluorescence.
• With decalcification in the enamel, increasing amount of the light is scattered, and the
changes in fluorescence can be quantified to describe the presence and severity of the
caries.

48. Quantitative light-induced fluorescence (QLF)
QLF measures:
•The degreeoffluorescence,
•Change ofdemineralised enamel
compared with surrounding sound
enamel, and
•Relates it directly to the amount
of mineral lost by
demineralisation.

49. •QLF system consists of a hand-held intraoral colour micro video CCD camera,
interfaced with a personal computer and custom software.
•The software enables to capture and analyze images of the tooth during clinical
examination.
•QLF uses a 50-watt xenon arc-lamp and anoptical filter in order to produce a blue light
with a 290- to 450-nm wavelength, which is carried to the tooth through a light guide
fitted with a dental mirror.
•The fluorescence images are filtered by a yellow high-pass filter (λ ≥ 540 nm) and then
captured by a colour CCD camera.
•When the tooth surface is illuminated by this high-intensity blue light, auto-fluorescence
of the enamel is obtained by the intraoral camera, since all excitation light reflected or
diffused is filtered.
•The exact nature of thefluorescing chromophores is still unidentified.

50. •Red fluorescence which has been detected in QLF images has been supposed to be
associated with caries risk.
•Red fluorescence isfound in more advanced lesions (dentinal lesions), progressive white
spots and in aged plaque as well as in calculus
Figure: Quantitative light/laser-induced fluorescence.

51. Figure: (a-c) Tooth is seen on the computer monitor as fluorescent green and dark
areas indicate mineral loss.
a b c

52. •Heinrich et al.,2005, compare the outcome of quantitative laser/lightinduced
fluorescence (QLF) and visual inspection (VI) for the detection of initial caries lesions on
all maxillary and mandibular smooth surfaces in caries-risk adolescents.
•The subjects were 34 students, age 15yr.
•A total of 879 buccal and 882 lingualwere examine
•Fluorescence images of each smoothsurface were captured with QLF, displayed, store, and
analyse the images.
•Fluorescence loss and area of the lesion, and fluorescence loss integrated over the lesion
area, were determined.
•4.9% were detected by VI alone and 7.9% byQLF alone

53. It was concludedthat:
i. QLF seems to be a sensitive method that is suitable for the detection of visually
undetected initial caries lesions; and
ii. that the clinical use of QLF is limitedbyseveral confounding factors in caries risk
adolescents.

54. DIAGNOdent 2095
• DIAGNOdent was intorduced by KaVo, Biberach, Germany in 1998.
• It emits a red light(λ=655 nm), which is absorbed by bacterial by-products such as
porphyrins.

55. •DIAGNOdent contains a laser diode (655 nm, modulated, 1 mW peak power) as the
excitation light source, and a photo diode combined with a long pass filter (transmission
> 680 nm) as the detector.
•The excitation light is transmitted by an optical fiber to the tooth, and a bundle of 9
fibers arranged concentrically around it serves for detection.
•The long pass filter absorbs the backscattered excitation and other short wavelength
light and transmits the longer wavelength fluorescence radiation.
•To eliminate the long wavelength ambient light also passing through the filter, the laser
diode is modulated, and only light showing the same modulation characteristic is
registered.
•Thus, the digital display shows quantitatively the detected fluorescence intensity (in
units related to a calibration standard).

56. • The emitted light reaches the dental tissues through a flexible tip.
• As the mature enamel is more transparent, this light passes through this tissue
without being deflected.
• In contact with affected enamel, this light will be diffracted and dispersed.
• The latter is able to excite either the hard dental tissue, resulting in the tissue
autofluorescence, or fluorophores present in the caries lesions.
• These fluorophores derived from the products of the bacterial metabolism and has
been identified as porphyrins 22.
• The emitted fluorescence by the porphyrins is collected by nine concentric fibers
and translated into numeric values, which can vary from 0 to 99.
• Two optical tips are available: tip A for occlusal surfaces, and tip B for smooth
surfaces. This device has shown good results in the detection of occlusal caries,
however, it might not be used as the only method for treatment decision-making
process.

57. Diagram illustrating working of a DIAGNOdent

58. Advantages:
•Early detection of caries
•High sensitivity and specificity
•Precise and extremely reliable method
•Reproducible results permit checking, stabilization, and documentation
•Even very small lesions missed out by conventional methods can be detected at the
earliest stages
•Over 90% accurate to diagnose pit and fissure caries
•Early detection of pathological changes that are undiagnosed by conventional methods
•Easy and quick to use
•Safe and no radiation exposure
•Noninvasive and pain-free
•Readily transportable with flexible unit which is battery operated
Disadvantages:
•False results with plaque and debris
•Not useful for proximal caries detection
•Cannot be used for the detection of recurrent caries
•Readings do not relate to the amount of dentinal decay
•High cost

59. DIAGNOdent PEN
• The device works on the principles of
DIAGNOdent, but the design is different.
• The device weights 140g and only one battery
(1,5V) is needed.
• The tip is rotatable around the axis of its length,
enabling the operator to assess mesial and distal
surfaces from both sides (buccal and lingual).
• The tip designed for proximal surfaces is made
of sapphire fiber with a prismatic shape, and the
light is directed laterally to the longitudinal axis
of the tip.

60. •Another cylindrical tipisrecommended for
occlusal surfaces, and the direction of its
light is perpendicular to the axis of the
length of the tip.
The DIAGNOdent penis-
•lessbulky,
•more flexibleand
•cordless mobile instrument with differently
shaped tips for different surfaces as compared
to DIAGNOdent.

61. VISTA PROOF [FLUORESCENCE
CAMERA, (FC) ]
• VistaProof (FC; VistaProof, D€urr Dental,
Bietigheim- Bissingen, Germany) is a
fluorescence-based camera and software
system.
• It is ideal for the integrated diagnosis,
prophylaxis and therapy concept of modern
surgeries.
• It emits blue light at 405 nm and captures
images of occlusal surfaces

62. Principle of FC
• The FC device works at a different wavelength than the LFpen device and is based on
different principles.
• Special light-intensity LEDs project high-energyviolet light onto the tooth surface (405 nm
wavelength).
• Light of this wavelength stimulates porphyrins (special metabolites of cariogenic bacteria)
to emit red light.
• Sound enamel sends out greenlight.
• These light signals are recorded by thehighly developed optics and analysed by software.
• On the monitor the fluorescent image of theporphyrins appear in a bright red colour tone,
and are thereby easily detected.
• The denser the colonisation, the more intensivethered fluorescent signal

63. •Light-intense blue LEDs with a wavelength of 405 nm stimulate the porphyrins of
cariogenic bacteria to emit red light. Sound enamel emits green light

64. Optical and numerical analysis of the caries activity

65. LED technology (Midwest Caries I.D.)
• The handheld device emits asoft light emitting diode
(LED) between 635 nm and 880 nm.
• It analyzes the reflectance and refraction of the emitted
light from the tooth surface, which is captured by fiber
optics and is converted to electrical signals for analysis

66. •The microprocessor of thedevice contains a computer-
based algorithm.
•It identifies the differentoptical signature (changes in
optical translucency and opacity) between healthy and
demineralized tooth.
•Demineralization leads to a change in the LED from
green to red with a simultaneous audible signal, which is
directly related to the severity of caries lesions.

67. ELECTRICAL
CONDUCTANCE
MEASUREMENT

68. • Electrochemical machining (ECM) is based on the principle that a demineralized tooth
has more pores filled with water or saliva, and this is more conductive than intact tooth
surface.
• It was first proposed by Magitot in 1878. Greater the amount of demineralization,
higher is the electrical conductivity through enamel. Demineralized sites and sites with
high pore volume and cavities can be detected by measuring the conductance.
• This technique has two methods of application:
1. Site-specific
• Applies probe as electrode into fissures and the electrical conductance of that site is
measured. To prevent current from leaking through superficial layer of moisture
through the gingival, airflow is applied to dry the tooth surface around the probe.
• Disadvantage is that only small areas of occlusal surface can be measured at one time.
2. Surface-specific
• This technique measures the entire occlusal surface, which is covered with an
electrolyte-containing medium where the electrode is placed. ECM uses a fixed
frequency of 23 Hz alternate current.
• Two instruments based on the difference in electrical conductance of carious and sound
enamel were developed.

69. Figure: Site specific. Figure: Surface specific.

70. • A strong relationship between both lesiondepth and mineral content in enamel has been
shown with ECM readings.

71.  VANGUARD ELECTRONIC CARIES DETECTOR:
• It used a current of 25 Hz. Measured conductance was then converted to an
ordinary scale of 0–9. Moisture and saliva were removed by a continuous stream of
air to prevent surface conductance.
 CARIES METER:
• It used a current of 400 Hz. Measured conductance was then converted to four
colored lights.
 Green: No caries
 Yellow: Enamel caries
 Orange: Dentin caries
 Red: Pulpal involvement.
• This method requires pits and fissures to be moistened with saline.

72. SOPROLIFE
•SOPROLIFE is a more recently released device using a light induced
fluorescence evaluator for diagnostic and treatment.
•Cost – ₹150,000

73. 0 Fissure appears as shiny
green, enamel appears
sound
1 Tiny, thin red shimmer in the
pit and fissure systems
viewed.
No red dots
appeared

75. The Canary System
•The Canary System is a precise, low-powered, laser-based instrument with an integrated
intraoral camera that detects the presence of cracks and caries (tooth decay) before they are
large enough to appear on dental X-rays.
•Intraoral camera images can be displayed for immediate chair side review with the patient.
A patient report is generated containing an odontogram with Canary Numbers, which are
color-coded for the examined teeth, along with the dentist’s treatment recommendation.
•Named after the "canary in the mineshaft" was used for centuries to protect people
from undetectable hazards.
•Canary Number scale of 0 to100

76. SCORE INTERPRETATION
0 to 20 (green) Health tooth structure
21 to 69 (yellow) loss of crystallization of the
tooth structure
70 to 100 (red) significant loss of crystal
structure within the tooth
•21 to 40 tends to respond well to
remineralization therapy
•>45 often requires a conservative
restoration

77.  Advantages:
• Detects caries under sealants and around the margins of restorations.
• Detects caries on all tooth surfaces, as smallas50 microns up to 5 mm below the
surface.
• Not affected by stain orcalculus.
• Does not require isolation or dryfield.

78. Newer Technologies in Store for the Future
•Current and future technologies lay emphasis on the objective measurement of the
properties of lightwaves, namely, scattering reflection, absorption, and
fluorescence.
Newer technologies include
1. Multiphoton imaging
2. Infrared fluorescence
3. Infrared thermography
4. Terahertz imaging
5. Optical coherence tomography
6. Polarized Raman spectroscopy
7. Modulated (frequency-domain) infrared photothermal radiometry.

79. Mechanism of light in detection of dental caries:
• The regular structure of teeth ensures good propagation of light through the crystalline
enamel and tubules of dentin and disruption to structure of a tooth increases likelihood of
scattering
• Uptake of fluid into pores created by demineralization in addition to the uptake of
exogenous stain, bacterial breakdown products, and other contaminants present as a
result of caries process will change the normal interaction of light with tooth structure
• In addition to scattering, these changes will include absorption and fluorescence
• Many of the newer techniques use one or more of these interactions.

80. Terahertz Imaging:
This method uses waves in terahertz frequency (10¹² Hz or a wavelength of 30μm). This
wavelength is short enough to provide reasonable resolution but long enough to prevent
loss of signal due to scattering. Several advantages of this system are as follows;
• Human tissue is relatively transparent to terahertz rays
• Low powers are used for imaging
• Non- ionizing radiation is used
• The electrical charge of the tissues examined remain unchanged
• The images are clear but due to long wavelength of the source spatial resolution is low.
Studies concerning this method of imaging are limited but promising.

81. Infrared Termography:
•Thermal radiation energy travels in the form of waves. The changes in thermal energy can be measured when fluid is
lost from a lesion by evaporation.
•The thermal energy emitted from sound tissues is compared to that of the carious structures.
•This technique has been described by Kaneko et al. in 1999 and has been proposed as a method of determining lesion
activity rather than its presence or absence.
•The studies carried out using this technique revealed that the early carious lesions in enamel can be distinguished
from the sound areas. This technique was considered efficient for in vitro studies. More studies must be carried out in
order to investigate the efficacy of thermographic imaging in vivo.
Infrared Fluorescence:
•There are limited studies regarding this technique.
•In theory, the tooth is irradiated with 700- 15000 nm wavelength light. Barrier filters are used to measure the resulting
fluorescence. In an unpublished study carried out by Longbottom, it was concluded that this technique was able to
discriminate between sound and carious enamel and dentin. Further studies need to be done for evaluating the efficacy
of this technique.

82. Multiphoton Imaging:
•Infrared light of 850 nm wavelength is used in this imaging technique.
•While conventional fluorescence imaging (QLF) uses a single blue photon to excite
fluorescence compound of the tooth, multi photon imaging uses two infrared photons
(with half the energy of the blue photon) which are absorbed simultaneously.
•With this technique, sound tooth structure shows strong fluorescence whereas carious
tissues fluoresce weaker.
•The carious regions appear as dark areas in strongly fluorescing tooth

83. Optic Coherence Tomography:
•This technique uses a high penetration near infrared light at a wavelength of 780- 1550
nm.
•No potential biological side effects had been reported of this system so far.
•OCT generates high-resolution cross sectional images of the oral structures. OCT is
found to be more sensitive in the detection of recurrent caries and evaluation of the
marginal adaptation of the restorations compared to other tools.
•Similar to ultrasonics, OCT uses near infrared emissions to determine not only the
presence of the caries lesions but also measures the depth of them.
•Another important advantage of this technique is that the patient is not exposed to x-
rays.

84. CONCLUSION
• Early diagnosis of initial enamel lesions is very important in order to be able to
create at an optimum time, an appropriate treatment allowing the re-
mineralization of these lesions.
• Many methods are available to the clinician; however, it is imperative that methods
with suitable levels of sensitivity and specificity are used in conjunction to obtain
a valid diagnosis which will inform the correct and appropriate treatment for the
patient.

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