Slide 1: A New Way to “Look” at DentalCaries Agenda Of Complex task : Agenda Of Complex task Important and timely agenda which is, in a sense, overdue.
Dental caries- chronic infectious disease, experienced by almost 80 percent of children by the age of 18 and over 90 percent of adults.
Agreeing where the evidence leads us on the Diagnosis Throughout Life is a complex task, but one in which we should be able to make significant and valuable progress. Slide 3: The ideal caries detection method-
Should capture the whole continuum of the caries process, from the earliest stages through the cavitation stage.
It should be accurate, precise, easy to apply and useful for all surfaces of teeth, as well as for caries adjacent to restorations.
Assessment of lesion activity also is of importance. Conventional aids : Conventional aids Traditionally,
visual examination, with or without tactile sensation
aided by radiography Limitations : Limitations Evaluation of caries status-
Dichotomous decision based on subjective signals such as color, translucency and hardness.
consensus using explorer to forcefully probe suspected carious pits and fissures does not add to diagnostic yield and may be damaging. (Warren JJ, Levy SM, Wefel JS-2003).
More appropriate strategies involve using explorers to remove plaque and lightly assess surface hardness.. Slide 6: End result low sensitivity and high specificity.
Early lesions undergo many demineralization and remineralisation.
only cavitated lesions are recorded.
consensus among researchers that understanding of the caries process has progressed far beyond the point of restriction. REMEDY : REMEDY Interventions to arrest or reverse the demineralization process.
Several strategies for identifying those persons representing the quarter of the population who will experience an elevated incidence of dental caries have been reported.
The growing sophistication in available interventions for prevention and nonsurgical treatment of dental caries is matched. The Advanced Techie : The Advanced Techie Several novel methods of caries detection:
Quantitative Light Fluorescence
Optical Coherence Tomography
Diagnodent Quantitative Laser Fluorescence : Quantitative Laser Fluorescence Enamel fluorescence was first described by Benedict.
Results from a change in characteristics of light.
QLF is a method of measuring the induced tooth fluorescence & quantifying tooth demineralization & lesion severity.
Intensity of emitted fluorescence measured by using a filter system.
QLF enhances early detection of carious lesion, particularly progression & regression of white spots of smooth surface caries. PROCEDURE : PROCEDURE Tooth illuminated with blue light emitted from headpiece & causes tooth surface to fluoresce & image is captured.
Data is then stored & then analyzed by image analysis computer software.
Tooth is seen on computer moniter as fluorescent green; dark areas indicate mineral loss. Slide 11: Sometimes red fluorescence appear which has an extrinsic source & is emitted by poryphyrins metabolized by bacteria in dental biofilm, calculus or an infected carious lesion & usually indicates a high caries activity.
Red fluorescence is also helpful for detecting leakage margins around restorations & leaking margins of sealants.
Green fluorescence Red fluorescence Limitations : Limitations It can only discern enamel demineralization & can not differentiate decay , hypoplasia, or unusual anatomic features .
Does not discriminate between- enamel & dentine lesions, Active & inactive lesion.
QLF rely on the fluorescence signal observed when teeth are exposed to blue light (488-514 nm) which causes sound tooth structure to fluoresce.
Consequently, sound tooth structure fluoresces at > 520 nm, whereas carious tooth tissue appears dark. Slide 13: Blue light tends to scatter substantially within caries lesions and therefore does not penetrate well through the lesion.
At high intensity, blue light induces free-radical production and induces phototoxicity in live tissue, which could injure the pulp (Girkin et al., 1999).
Time for a change
The choice of a longer wavelength of light for imaging reduces the scattering, allowing the light to penetrate more deeply within the tooth.
This may make any image of the tooth clearer and reduces the levels of phototoxicity. Multi Photon Imaging : Multi Photon Imaging In the multi-photon technique, two infrared photons (with half the energy of the blue photon) are absorbed simultaneously.
To generate enough two-photon events, it has been calculated that a peak power of 2 kW would be required. Clearly, a tooth would not survive this substantial amount of power input for any length of time.
It is possible to resolve this difficulty by using ultrashort pulses, measured in femto seconds.
Ultra-short pulses (100 fs) of 850 nm laser light are generated at 200 MHz.
By scanning a focused beam, one can record, from the focal plane, the fluorescence resulting from two-photon excitation. Slide 15: With this technique, sound tooth tissue fluoresces strongly, whereas carious tooth tissue fluoresces to a much lesser extent.
One can move the plane of focus through the tissue and record the sectional images from the tooth to form a three-dimensional image.
Caries will appear as a dark form within a brightly fluorescing tooth.
To highlight the diseased tissue, the image may be displayed in its negative form so that caries appears bright within a dark tooth. Multi-photon imaging is able to collect information from caries lesions up to 500 microns in depth. ultrasound : ultrasound potential to complement conventional radiography as an imaging technique in clinical dentistry due to its short wavelength in hard tissues and associated high resolution.
ability to penetrate hard structures and can, in principle, detect hard tissue discontinuities or pathoses under existing radiopaque restorations, a task that is difficult for conventional radiography.
detecting physical discontinuities such as fractures or cracks, even if such discontinuities are smaller than the acoustic wavelength. Slide 17: A device for the detection of smooth surface lesions of dental caries on a tooth crown surface, having an ultrasonic transducer for transmitting ultrasonic waves and receiving ultrasonic wave reflections produced by lesions present on the surface, and an interface operatively connected to the transducer.
Interface has a contact surface which contacts with the tooth surface, generating ultrasonic waves by the ultrasonic transducer are imparted onto the tooth crown surface as surface ultrasonic waves which migrate along the tooth crown surface. Slide 18: Ultrasound waves are usually produced by an alternating voltage applied to a piezo-electric crystal
Sound waves produced as a result of minute changes in the crystal dimension may be emitted continually, as a burst of waves
To reach the target medium, sound waves have to travel through a coupling medium. Slide 19: ideal coupling agent- acoustic impedance similar to that of the specimen. This minimizes any reflection at the interface between the two media and maximizes the amount of ultrasound entering the specimen-
Mercury and aluminum rods bonded to the tooth surface
water and glycerine Diagnodent : Diagnodent New spectral investigations revealed- Good contrast between sound and carious regions can be achieved when fluorescence is excited in the red and detected in the near-infrared regions.
With irradiation at 655 nm, there is a decreased fluorescence intensity compared with that achieved at 488-nm excitation.
However, a more pronounced decrease for sound surfaces is found compared with carious surfaces, so that caries fluoresces much more strongly.
The shapes of the spectra for carious and sound areas are of same wavelength, so all fluorescence can be used for differentiation of healthy and diseased tissue, without the need for any spectral analysis Slide 21: Red light, as well as infrared fluorescence radiation, is less-absorbed and -scattered by enamel than is light of shorter wavelengths, so that they penetrate the tooth more deeply (Ertl et al., 1995). It is therefore possible for fluorescence to be measured from underlying carious dentin. Laser based diode- DIAGNOdent Use of infrared laser fluorescence for detection of caries The unit has a fiberoptic cable that transmits the light source to a handpiece that contains a fiber-optic eye in the tip. Slide 22: The unit is first calibrated with normal enamel tooth structure in the patient's mouth. After calibration, the handpiece is moved to inspect all surfaces.
When the light is absorbed it induces infrared fluorescence of organic and inorganic materials. This fluorescence is collected at the top of the handtpiece and transmitted back to the DIAGNOdent unit & then displayed & indicated acoustically Slide 23: The unit gives an adjustable sound and a digital numeric readout (0-99) to indicate the amount of fluorescence.
An increase in fluorescence is indicative of carious tooth substance, particularly when the displayed reading is = 20. A reading of 21 to 100 indicates a definite area of decay that may require operative intervention Electric Measurements : Electric Measurements HOW DO ELECTRICAL MEASUREMENTS OF DENTAL CARIES WORK?
as a tooth demineralizes in the caries process, the loss of mineral leads to increased porosity in the tooth structure.
This porosity is filled with fluid from the oral environment which contains many ions.
Increased ionic content in the pores leads to increased electrical conductivity, or,conversely, increased porosity leads to decreased electrical resistance or impedance. Slide 25: Establishing intimate electrical contact between tooth sample and impedance-sensing device is important to achieve reliable impedance sensing. Three accomplishments have been achieved:
(1) the employment of a miniature liquid tip that can create intimate and penetrating electrical contact;
(2) the application of a shielding air-flow that insulates the liquid tip from surrounding saliva
(3) the development of a consistent detection scheme that can even be applied to detect approximal caries, which is barely sensed by existing techniques. Slide 26: A fluidic probe with liquid tip and shielding air sleeve has been developed as its working principle.
The liquid tip is actually a saline solution continuously supplied from an upstream reservoir.
It is preferred to have the liquid tip self-regulated, so that its shape and volume can be self-adapting to the tested sample through the scanning process.
The liquid tip is actually a saline solution continuously supplied from an upstream reservoir. Slide 27: The fluidic probe, whose liquid tip spontaneously spreads on hydrophilic tooth surfaces and into underlying caries, is employed to create intimate electrical contact for impedance sensing.
A tubular air sleeve shaped by the probe casing is applied around the liquid tip to insulate it from surrounding saliva, and to regulate its spreading.
In addition, a friction damper that acts against gravity, air pressure, and surface tension is integrated to stabilize the actuation of fluidic probe. Slide 28: In the prototype demonstration, following results were verified-
>20-fold impedance differences between sound and carious teeth, by which caries could be identified in a consistent manner .
The fluidic probe has been applied to detect approximal caries, which hides between adjacent teeth and is barely detected by existing techniques. Slide 33: Ultrasound has the potential to complement conventional radiography as an imaging technique in clinical dentistry due to its short wavelength in hard tissues and associated high resolution. Ultrasound has the ability to penetrate hard structures and can, in principle, detect hard tissue discontinuities or pathoses under existing radiopaque restorations, a task that is difficult for conventional radiography. In addition, ultrasound is highly effective in detecting physical discontinuities such as fractures or cracks, even if such discontinuities are smaller than the acoustic wavelength. Therefore, ultrasonography may provide a significant benefit to patients by allowing early detection of dental pathology, especially cracks. Additionally, ultrasonography lacks the hazards of ionizing radiation. We have recently demonstrated the ability to image the dentino-enamel junction (DEJ), to detect narrow cracks, and to penetrate various restorative materials with ultrasound (see references below); Improvements in transducer technology, coupling efficiency, and signal processing to accurately image features like fractures, caries, and pulp are currently under development. Slide 34: Typically, to evaluate the caries status of a patient, we make a dichotomous decision (absence or presence) based on subjective signals such as color, translucency and hardness using relatively crude instruments such as explorers and radiographs. Often, the end result is low sensitivity and high specificity, meaning a large number of lesions may be missed. It is well-recognized that dental caries is a dynamic disease process, in which early lesions undergo many demineralization and remineralization cycles before being expressed clinically. Generally, only cavitated lesions are recorded; however, there is a consensus among researchers that the understanding of the caries process has progressed far beyond the point of restricting the evidence for dental caries at the cavitation level involving enamel or both enamel and dentin.11 In the research arena, recording lesions only at the cavitation level is no longer acceptable, as determined at the 2004 International Consensus Workshop on Caries Clinical Trials Slide 35: The widespread use and availability of fluoride has changed the behaviour of carious lesions dramatically.
Resulting slower progression of carious lesions has afforded the dentist the opportunity to diagnosis and manage caries at an early stage, and this has led to renewed interest by researchers, clinicians and manufacturers of diagnostic tools in caries. qlf : qlf Slide 38: New Way to “Look” at DentalCaries