Dental caries is the localised destruction of susceptible dental hard tissues by acidic by-products from bacterial fermentation of dietary carbohydrates.

(According to Shafer)It can be defined as the microbial disease of the calcified

tissues of teeth characterized by demineralization of the inorganic portion and destruction of organic substance of the tooth.

( According to WHO)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 .

The word diagnosis (plural, diagnoses) is derived from the 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.

The examination and evaluation of carious lesions has traditionally been limited to

physical criteria such as size, depth, and presence or absence of cavitation. The term

for this is caries lesion detection.

Caries lesion activity assessment is different from caries lesion detection.

The assessment of lesion activity together with lesion detection is essential to

arrive at the disease diagnosis and the appropriate clinical treatment decision.

In addition to caries lesion detection, lesion or disease activity assessment must

also consider etiologic factor evaluations, such as oral hygiene, count of cariogenic

micro-organisms in plaque and saliva, use of fluoride, sugar intake, and also some

socioeconomic aspects, such as family income and parents’ level of education.

The PRIMARY OBJECTIVE of caries diagnosis is to identify those lesions that

require restorative treatment, those that require non-surgical treatment, and those

persons who are at high risk for developing carious lesions.

Some decades ago, visual diagnosis (light and mirror) and probing,

supplemented by bitewing radiographs were the only tools available for clinical

diagnosis of caries. For epidemiologic surveys and for examination of most

patients, these are still useful tools.

However, a variety of innovative technologies have been developed and

introduced in the last few years to aid clinicians not only in early caries detection

but make a firm diagnosis and to treat cases conservatively.

These technologies use the alteration in fluorescence, reflectance, electrical

conductance or impedance, and ultrasound transmittal properties of enamel with

demineralization to monitor changes in caries lesion over time.

The Problem Of Diagnosis ?Sensitivity Vs Specificity

Sensitivity: It is defined by the probability of the test giving a positive finding when disease is present.

Sensitivity= true positives/(true positive + false negative)

Specificity: It is the probability of a negative finding when disease is absent.

False positive -- Questionable lesion

False negative -- Lesion redetected

The indications are that the use of the method of diagnosis gives sensitivities of the order of 60% and a specificity of 85%.

Specificity=true negatives/(true negative + false positives)

Tools…

The traditional method of detecting caries signs is by visual inspection of dental surfaces, with the aid of a bright light and dental mirror if necessary to see teeth from all angles.

Reflecting light onto the mouth mirror also can be done to search for dark shadows that could indicate dentin lesions.

While the use of a dental probe continues to be controversial, it is extremely helpful when used correctly and judiciously. A probe is unnecessary if visual inspection detects a cavity.

During a visual–tactile examination, the dentist will also use a syringe or drying tool to blast air on to the tooth, which makes it easier to see some lesions.

Other tools used in visual–tactile examination may include magnifying devices to look at teeth, or orthodontic elastic separators to separate teeth over the course of 2 to 3 days for a closer look between teeth prone to caries lesions.

Fiber-optic transillumination is also sometimes used. This is a method by which visible light is emitted through the tooth using an intense light source. If the transmitted light reveals a shadow, this may indicate a carious lesion.

Probing with Sharp Explorer…Ekstrand et al., 1987

Traditional probing with a sharp explorer has come into question as the ultimate determinant of caries activity. The exclusive use of a “catch” by the sharp explorer to diagnose caries in pit and fissure sites should be discontinued and

clinicians are being called upon to use “sharp eyes and a blunt explorer.” Also non-cavitated lesions can become cavitated

simply through pressure from the explorer during the typical examination. Thus, penetration by a sharp explorer can actually

cause cavitation in areas that are remineralizing or could be remineralized. An explorer can also transfer cariogenic bacteria

from one tooth surface to another.

VISUAL & TACTILE INSPECTION

Visual examination is the most commonly used method for detecting caries lesions,

because it is an easy technique that is routinely performed in clinical practice.

Visual examination has presented high specificity (proportion of sound sites correctly

identified), but low sensitivity (proportion of carious sites correctly identified), and low

reproducibility; the latter because of its subjective nature.

The use of detailed visual indices, however, may improve sensitivity and be an important

factor in minimizing the examiner’s interpretation of the clinical characteristics of a lesion,

and thus improve reproducibility. Such 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.

The use of indices has permitted early caries signs to be detected and recorded in a

reliable and accurate way in visual examination. However, initial caries lesion stages have

generated most of the disagreements between examiners in several studies, and their

evaluation demands more training and more time for examination.

A review found 29 different visual criteria

for detecting caries lesions.

Each system has its own particularities and

methodology of teeth/surface evaluation.

Only about half of the technologies

recommend teeth to be cleaned and/or dried

before the examination process, which if not

included will increase the risk of missing

lesions.

Further, caries lesion activity assessment is

not considered by most of these indices,

which is a limitation in clinical practice.

In addition, some indices recommend

tactile examination to be performed in

conjunction with visual examination, and this

has been considered questionable.

Probing-related surface defects, enlargements, and

damage to dental surfaces have been observed on

surfaces with initial carious lesions.

Some previous reviews have shown inconclusive

results with regard to tactile examination performance,

and a lack of information concerning the examiner’s

training and manner of using the explorer (to remove

plaque, to gently probe).

The most recent trend is the use of the probe to

evaluate enamel surface texture (smooth or rough for

enamel lesions; hard or soft dentine for dentinal

lesions).

Another recommendation is evaluation of the

presence of discontinuities in enamel or

microcavitations by using the WHO probe, which is

ball-ended with a sphere presenting 0.5 mm in the

extremity, allowing this kind of evaluation.

In an attempt to propose an internationally accepted caries detection system, a new index for

caries diagnosis, the International and Caries Detection Assessment System, was created in

2002 by a group of cariologists and epidemiologists, based on visual examination aided by a

WHO probe.

The short name of this system is ICDAS.

This system is a modification of a previous visually ranked caries lesion scoring system that

has been shown to detect occlusal lesions in permanent teeth and to assess their depth with

acceptable accuracy and reproducibility.

ICDAS is a 2-digit identification system (X-Y).

Firstly, the status of the surfaces is recorded as unrestored, sealed, restored, or crowned. After

that, a second code is attributed (Y). This code ranges from measurement of first visual changes

in the enamel to extensive cavitation.

Before examination, teeth have to be carefully cleaned and examinations must be performed

with light illumination, an air syringe, plane buccal mirror and, if necessary, a WHO periodontal

probe.

The validity of ICDAS has been tested and expressed in many ways. For example,

ICDAS has presented content validity (the system is comprehensible for describing and

measuring different degrees of severity of caries lesions). Further, a significant

correlation with lesion depth in the histologic examination has been shown.

Criterion validity of ICDAS, which means how well the system is correlated with the

actual severity of the caries lesions, was also observed in vitro for permanent and

primary teeth.

Its performance has varied from moderate to good. In terms of figures, the sensitivity

for occlusal surfaces have varied from 0.63 to 0.82 and specificity from 0.63 to 0.94.

In primary teeth, ICDAS cannot distinguish accurately between lesions related to the

outer or inner half of the enamel; this can be done fairly accurately in permanent teeth.

One explanation for this difference in performance is that the enamel in primary teeth is

much thinner compared with permanent enamel.

Few studies have been performed in proximal surfaces using ICDAS.

The system has presented good performance (high sensitivity and specificity) for in vitro

conditions.

However, its sensitivity has been low for proximal caries in vivo, whereas the specificity has

been high, even when considering the noncavitated threshold.

These properties should encourage the use of ICDAS also in proximal caries detection,

although other additional methods should be added to improve sensitivity on these surfaces.

Initially, ICDAS was devised as a detection system for primary caries. Adjunct criteria have

recently been devised for activity assessment. Thus, the system can be used for caries lesion

activity assessment (LAA) also.

The LAA is based on the combined knowledge of clinical appearance (ICDAS) of the lesion,

whether or not the lesion is in a plaque stagnation area, and the tactile sensation when a ball-

ended WHO probe is gently drawn across the surface of the tooth. Such criteria related to

activity receive an individual score (points) based on predictive value in determining

activity status, and the sum of these points is judged based on a cut-off point.

• These individual criteria have presented moderate to good intra- and interexaminer reproducibility values as well as good reproducibility results for the system overall. This system also presented construct validity (i.e., the system is able to reflect theoretical concepts regarding the caries process).

• Using the ICDAS in combination with the LAA criteria described here, it is possible to detect a lesion, estimate its depth or severity, and assess its activity, which are all fundamental prerequisites for the diagnosis and management of the individual lesion.

Nyvad’s System

Nyvad’s system is another reliable option for activity assessment of noncavitated and cavitated caries lesions.

This system has presented construct and predictive validity (the different status of caries lesions can be predictive of different outcomes) concerning caries lesion activity status.

According to this system, a score can be attributed to all observed characteristics of the lesion, eventually classifying the lesion as inactive or active.

If a lesion presents at least 1 feature compatible to an active lesion, the examiner should classify the lesion as active.

The original system used plaque as an indicator for caries lesion activity and used standard probes to assess roughness. Some recent studies have performed examinations using Nyvad’s scoring criteria exactly as published. However, to standardize the methodology used in the examinations, the Nyvad system was modified in several ways compared with the original version, adopting inspection after prophylaxis and the use of the WHO probe.

Benefits of Visual–Tactile Diagnosis Visual–tactile diagnosis is quick and easy to perform, does not need expensive equipment, and can be completed without unnecessary radiation. Currently, activity assessment according to the criteria suggested by Nyvad et al (1999) is considered the best choice for performing a caries diagnosis, because these are the only criteria that reflect the current evidence-based management options for different phases of caries formation, and the only criteria with predictive value. Surprisingly, data show that when non-cavitated lesions are included in classification, the yield of visual–tactile caries examination is greater than that of radiographic examination because minor mineral losses cannot be detected in radiographs.

Limitations of Visual–Tactile Lesion Diagnosis These include the fact that visual–tactile diagnosis requires subjective evaluations to be made by the practitioner, lesions can go undetected because teeth are typically examined by the naked eye, and there is need for supplemental analysis when faced with clinical signs that will leave a dentist uncertain, including dark occlusal or proximal shadows.2

Radiographic Methods Radiographic examinations include;

Bitewing radiographsIOPA radiographs using paralleling techniqueDental panoramic tomography

The most commonly used radiographic method for detecting caries lesions is the bitewing technique.

It is meant to find lesions that are hidden from a clinical visual examination, such as when a lesion is hidden by an adjacent tooth, as well as help the dental professional estimate how deep the lesion is.

To get the radiographic images, a central beam of X-rays is positioned to pass at right angles to the long axis of the tooth.

If film is used, a beam-aiming device on the film holder guides the position, directing the beam at right angles to the film.

However, digital radiography is replacing radiography based on film. It has been proven as accurate as traditional radiography for detecting caries, but it comes with additional advantages of using a lower radiation dose, being less time-consuming, and does not require wet chemicals in the processing of the image.

Incipient occlusal lesions

Moderate occlusal lesions

Severe occlusal lesions

Incipient proximal lesions

Advanced proximal lesions

Moderate proximal lesions

Facial & Lingual caries

Root surface caries

Recurrent caries

Other radiographic shadows

Factors that Influence the Quality and Interpretation of Radiographic Images

There are a number of factors that affect the usefulness and quality of the radiographic examination.

A certain amount of mineral must be lost before it can be detected in a radiograph.

Technical aspects, such as film contrast and viewing conditions, determine this minimum amount of mineral loss.

The shape, extent, and location of the lesion, together with the anatomy of the tooth, also influence the radiographic depiction.

A shallow, widespread lesion may create an image of being deeper than a deep lesion that is narrowly spread on the surface.

The direction of the X-rays affects the image. Most dentists now use film-holders or beam-aiming devices that prevent deviations of the rays that cause a decreased image contrast, and could result in the under- or over-estimation of the extent of a lesion.

Bitewing Radiography as a Complement to the Visual–Tactile Examination

Occlusal caries lesions (which develop on surfaces that contact an opposing surface of a tooth in the opposing jaw) are difficult to diagnose by visual examination only.

Using bitewing radiography raises the sensitivity of the diagnosis if obvious dentin caries activity is to be detected, but can be inaccurate if diagnosing enamel occlusal caries activity.

Visual–tactile examination alone also fails to detect a number of occlusal and proximal caries lesions in deciduous teeth in children.

Complementing the clinical examination with bitewing radiography has also been found to increase the sensitivity of detecting caries lesions in these teeth.

Another way in which bitewing radiography complements the visual–tactile examination is in the diagnosis of recurrent caries lesions. A radiolucent area typically indicates that residual carious tissue was left behind when the restoration was placed.

It is not invasive, and does not damage tooth structure like an incorrectly used dental probe might.

Limitations of Bitewing Radiography Diagnosis

Besides concerns about low-dose radiation and variations in how images are interpreted by dentists, the main limitation is that the validity in diagnosing early lesions is rather low.

Also, the bitewing radiograph cannot always distinguish between sound surfaces, those with initial caries activity and cavitated lesions, or non-carious demineralisations, so clinical inspection is still needed to determine what is happening to the tooth.

Bitewing radiographs also tend to underestimate the depths of lesions, so a lesion that appears confined to the inner enamel on an image is often actually in the dentin, and this can lead to insufficient or improper treatment.2

CARIES ACTIVITY TESTS:

1. Lactobacillus colony count test

Saliva is collected by chewing paraffin

before breakfast

The specimen is vigorously shaken and

after that 0.1 cc of sample is withdrawn

Dilute and undiluted samples are then

spread evenly over a rogosa’s SL agar

plate

The plate is incubated for 4 days & no. of

lactobacillus colonies that developed are

counted.

No of organisms

1-1000

1000-5000

5000-10,000

More than 10,000

Symbolic

designation

+

+

++

+++/++++

Degree of caries

activity suggested

Little or none

Slight

Moderate

Marked

SNYDER TEST

This test measures the ability of salivary microorganisms to form organic acid from a carbohydrate medium.

The classical formula of Snyder’s agar per litre of purified water is

pancreatic digest/ casein -13.5 gm

yeast extract -6.5 gm

dextrose -20 gm

sodium chloride -5 gm

agar -16 gm

Bromocresol green -0.029 gm

24 hrs 48 hrs 72hrs

Color : yellow yellow yellow

Caries activity: marked definite limited

Color : green green green

Caries activity: continue test continue test caries inactive

ALBAN’S TEST

• Alban modified the Snyder test to make it easier and for use in regular dental office.

• In this method lesser amount of agar is used.

• The agar is taken from the refrigerator but is not heated. To this saliva is added and incubated for 4days.

• Color observations are same as that of Snyder test.

SWAB TEST

Advantage is no collection of saliva is necessary

Valuable in evaluating caries activity in very young children

Principle is same as Snyder test

The oral flora is sampled by swabbing the buccal surface of tooth with cotton.

REDUCTASE TEST

This test measures the activity of reductase enzyme present in salivary bacteria

The sample is mixed with fixed amount of diazo-resorcinol

The change in color after 15 min is taken as a measure of caries activity

color Time score Caries activity

Blue

Orchid

Red

Red

pink

15min

15 min

15 min

Immediately

Immediately

1

2

3

4

5

Non conductive

Slightly conductive

Moderately

conductive

Highly conductive

Extremely conductive

ENAMEL SOLUBILITY TEST

It is based on the fact that when glucose is added to saliva containing

powdered enamel, organic acids are formed

Organic acid decalcifies the enamel, resulting in an increase in the amount

of soluble calcium

The extend of increase of calcium is a direct measure of caries activity

SALIVA FLOW TEST

Flow rate is determined by collecting paraffin stimulated saliva in a test tube

over 5 min

Severely decreased flow is related to caries susceptibility

As salivary flow rate decreases viscosity increases

PATIENT EDUCATION WITH METHYL RED

A simple and effective technique that may be of assistance in

educating child patient to the problem of dental caries control

involves the use of aqueous solution of methyl red

Indicator dye changes colour in the pH range from 6.3(distinct

yellow) – 4.2(red)

Aqueous methyl red is then applied to the surface of the tooth

with dropper

Red colour is developed in the area of plaque accumulation

This is interpreted to patient as evidence of continuous acid

formation

Newer Methods of Caries

Detection and Assessment

Digital radiographs

Digital radiography has offered the potential to increase the diagnostic yield of dental radiographs and this has manifested itself in subtraction radiography.

A digital radiograph (or a traditional radiograph that has been digitised) is comprised of a number of pixels. Each pixel carries a value between 0 and 255, with 0 being black and 255 being white.

The values in between represent shades of grey, and it can be quickly appreciated that a digital radiograph, with a potential of 256 grey levels has significantly lower resolution than a conventional radiograph that contain millions of grey levels.

This would suggest that digital radiographs would have a lower diagnostic yield than that of traditional radiographs.

Research has confirmed this; with sensitivities and specificities of digital radiographs being significantly lower than those of regular radiographs when assessing small proximal lesions.

However, digital radiographs offer the potential of image enhancement by applying a range of algorithms, some of which enhance the white end of the grey scale (such as Rayleigh and hyperbolic logarithmic probability) and others the black end (hyperbolic cube root function).

When these enhanced radiographs are assessed their diagnostic performance is at least as good as conventional radiographs, with reported values of 0.95 (sensitivity) and 0.83 (specificity) for approximal lesions.

When these findings are considered, one must remember that digital radiographs offer a decrease in radiographic dose and thus offer additional benefits than diagnostic yield.

Digital images can also be archived and replicated with ease.

Subtraction radiology

Digital radiographs offers a number of opportunities for image enhancement, processing and manipulation.

One of the most promising technologies in this regard is that of radiographic subtraction which has been extensively evaluated for both the detection of caries and also the assessment of bone loss in periodontal studies.

The basic premise of subtraction radiology is that two radiographs of the same object can be compared using their pixel values. If the images have been taken using either a geometry stabilising system (i.e. a bitewing holder) or software has been employed to register the images together, then any differences in the pixel values must be due to change in the object.

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. It is clear from this description that the radiographs must be perfectly, or as close to perfect as possible, aligned. Any discrepancies in alignment would result in pixels being incorrectly represented as change.

Fiber-optic transillumination Fiber-optic transillumination FOTI as a caries detection technique is based on the fact that carious enamel has a lower index of light transmission than sound enamel.

The light is absorbed more when the demineralization process disrupts the crystalline structure of enamel and dentin. In essence this gives that area a more darkened appearance.

This method of caries detection uses a light source, preferably bright, to illuminate the tooth. Caries or demineralised areas in dentin or enamel show up as darkened areas with this technique.

This effect can be achieved with a fiber optic illuminator, which is readily available at the handpiece coupler of the dental operatory and has been used for detection of approximal and occlusal caries.

Posterior approximal caries can be diagnosed with the light probe positioned on the gingivae below the cervical margin of the tooth, whereby the light passes through the tooth structures and approximal decay produces a dark shadow on the occlusal surface.

Although this device has the advantage that the examination is done with an operating light source already available in general practice, it is only useful for approximal and occlusal lesions; its sensitivity and specificity are not sufficient for detection of very early caries. Besides, it is not quantitative and therefore not useful as a caries monitor over time. However, studies on the diagnostic efficacy of this device present conflicting results.

Digital imaging fiber-optic transillumination This is a digitized and computed version of the FOTI.

While FOTI was designed for detection of approximal and occlusal caries, digital imaging fiber-optic transillumination DIFOTI is used for detection of both incipient and frank caries in all tooth surfaces.

DIFOTI can also be used to detect fractures, cracks, and secondary caries around restorations.

DIFOTI uses white light to transilluminate each tooth and to instantly create high-resolution digital images of the tooth. It is based on the principle that carious tooth tissue scatters and absorbs more light than surrounding healthy tissue.

Decay near the imaged surface appears as a darker area against the more translucent brighter background of surrounding healthy anatomy.

A single fiber-optics illuminator in the mouthpiece delivers light to one of the tooth’s surfaces. As this light travels through layers of enamel and dentin, it scatters in all directions toward the nonilluminated surface usually the opposite surface. The light is then directed through the mouthpiece to a miniature electronic charge coupled device CCD camera in the handpiece.

The camera digitally images the light emerging from either the smooth surface opposite the illuminated surface or the occlusal surface.

These images are displayed on a computer monitor in real time and stored on the hard drive for easy retrieval for comparative review of images over time.

Image acquisition is controlled with software and a foot pedal.

Images of the teeth can be viewed by both the clinician and patient, and therefore can be used for patient education and motivation.

It is important to note that DIFOTI images the light emerging from surface closest to the CCD camera. It does not image the tooth material between the light source and the CCD camera, and therefore cannot indicate the depth of lesion penetration.

Schneiderman et al. demonstrated a method of using DIFOTI to quantitatively monitor lesion progression and reported a successful result. Inherent with the high sensitivity of the device, dark areas in DIFOTI images may sometimes be due to stains or calculi on tooth surface; therefore it is suggested that prophylaxis should becarried out prior to the use of the device in order to increase the specificity.

Quantitative Light-induced Fluorescence Another dental diagnostic tool for detection of early carious lesions is quantitative light-induced fluorescence (QLF), which is based on auto-fluorescence of teeth.

When the teeth are illuminated with high intensity blue light, the resultant auto-fluorescence of enamel is detected by an intraoral camera which produces a fluorescent image.

The emitted fluorescence has a direct relationship with the mineral content of the enamel.

Thus, the intensity of the tooth image at a demineralised area is darker than the sound area.

The software of QLF systems can process the image to provide user quantitative parameters such as lesion area, lesion depth, and lesion volume. These parameters can detect and differentiate the lesions at very early stages, and make the QLF system more sensitive to changes of caries over time.

The image can be stored for longitudinal study and be used as patient motivatorsin a preventative practice.

QLF uses a blue light (488 nm) to illuminate the tooth, which normally fluorescence a green colour.

Teeth should be dried before its application.

Hafström-Björkman et al found a sensitivity of 0.72-0.76 and a specificity of 0.79-0.81 for this technique.

This can also be used to image plaque and calculus, and therefore be useful in identifying active caries.

This technique has found many applications in clinical trials, research, patient education, and preventive clinical practice it can effectively monitor demineralization and remineralisation of teeth in vitro and a good correlation has been reported with other techniques measuring mineral loss, such as transverse microradiography analysis. Also it can be used to measure erosive potential of a range of mouth washes in vitro and to see early secondary caries beneath the amalgam restorations.

However it cannot differentiate between decay and hypoplasia; has inability to detect or monitor interproximal lesions and is limited to measurement of enamel lesions of at most several hundred micrometers depth.

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 tip both emits the excitation light and collects the resultant fluorescence.

Unlike the QLF system, 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.

A small twist of the top of the tip enables the machine to be reset and ready foranother site examination and a calibration device is supplied with the system.

DIAGNOdent was designed for the detection of caries lesions in occlusal and smooth surfaces.

For this purpose, the method has been extensively studied and has demonstrated the high reliability of the device in detecting occlusal caries lesions and a moderate correlation with mineral loss in smooth-surface caries lesions.

With regard to validity, studies have demonstrated good sensitivity and specificity values, but the magnitudes of these values have been variable due to different cut-off points used in the different studies.

Another possible explanation for the high variability found in these studies could be due to several possible factors that can alter the LF readings. The drying time of the site before the LF assessment, presence of plaque or pigmentation, and some toothpastes or prophylaxis pastes are possible factors that influence the LF readings.

The sensitivity values for detection of occlusal caries lesions have been higher than the specificities, and the values have been usually described between 0.80 and 0.90.

The specificity values obtained in different studies have been between 0.60 and 0.70.These results, therefore, indicate that the device could be used as an adjunct to visualinspection, and could be an alternative for radiography.

DIAGNODent pen Due to this limitation, a new version of the method was designed and introduced, named DIAGNOdent pen.

This new version permits the assessment of both occlusal and proximal surfaces.

The device works on the principles of the old version, but the design is different. 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.

Another cylindrical tip is recommended for occlusal surfaces, and the direction of its light is perpendicular to the axis of the length of the tip. After excitation, the tip collects the fluorescence and translates it into a numerical scale from 0 to 99.

This device could be used as an alternative to the radiographic method to aid the dentist in the decision-making process after visual inspection.

Nevertheless, the evidence concerning the use of the method in clinical practice is limited, and further studies are necessary to evaluate whether the method could be useful.

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

This can be undertaken at either a site or surface level.

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.

Tooth demineralization due to caries process causes increased porosity of tooth structure. This porosity contains fluid containing ions. This leads increased electrical conductivity, conversely, leads to decreased electrical resistance or impedance.

There are also a number of physical factors that will affect ECM results. These include-

• 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)• the surface area.

A major advantage of the ECM is to present objective readings, which have the potential for monitoring lesion progression, arrest, or remineralization.

The sensitivity and the specificity of this machine have been reported to be very high, 0.75 and 0.77, respectively, when used to detect occlusal caries in vivo and ex vivo, indicating that it is a valid indicator for detecting the presence or absence of lesion porosity.

A strong relationship between both lesion depth and mineral content in enamel has been shown with ECM readings.

The only drawback is the fact that it is time consuming to use in a routine full-mouth examination.

Endoscopic filtered fluorescence method Pitts and Longbottom explored the use of EFF for the clinicaldiagnosis of carious lesions and compared results with conventionalalternatives on occlusal and approximal site.

The EFF method has been shown to be highly sensitive forocclusal caries in enamel but sensitivity is poor for occlusal caries indentin.

Specificity is poor for occlusal surfaces but high for approximallesions at both thresholds. The method is reasonably good atdetecting approximal lesions in enamel but not lesions in dentin.

Midwest Caries I.D. The Midwest Caries I.D. detects differences of optical behaviour inside the tooth related to change in the tooth structure and it is therefore not sensitive to bacterial content.

The Midwest Caries I.D. uses infrared and red light emitting diodes LEDs and a fiber optic to distribute light to the observed area present at the probe tip.

A second fiber optic collects light from the observed area to a photodetector that measures returned collected light. This photodetector then transmits the signal to a microprocessor that compares signal levels with defined parameters.

When the result is positive, the processor deactivates the third green LED and pulses at a higher intensity than the red LED.

When the detection is negative i.e., healthy tooth area, the green LED is dominant resulting in a green illumination when healthy structure is detected and red illumination when caries are detected.

A buzzer also beeps with different frequencies to indicate the intensity of demineralization detected.

The Midwest Caries I.D. can be used for approximal caries detection during theexamination by slightly angling and moving the probe along the marginal ridge just over the vulnerable approximal area.

Interproximal detection using the Midwest Caries I.D. and x rays as a gold standard showed a sensitivity of 80% and specificity of 98%.

However, this device can give false positive signals in cases of teeth with growth malformations in the enamel or the dentin, teeth with thick, dark stains, hypermineralization, hypocalcification, dental fluorosis, and atypically shaped teeth due to alteration in the translucency of enamel caused by these conditions.

Light penetration is limited into the enamel and up to 3 mm in approximal area. Midwest Caries I.D. cannot be used on composites or amalgams but can be used to check the marginal ridges of occlusal amalgams.

If the probe is tipped at too much of an angle when checking for approximal caries, total surface light reflection can occur giving a false positive.

Opaque artifacts plaque, calculus, and organic plug can cause false positives.

Detection with chemical dyes Dyes are a diagnostic aid for detecting caries in questionable areas (i.e., for locating soft dentin that is presumably infected).

Fusayama introduced a technique in 1972 that used a basic fuchsin red stain to aid in differentiating layers of carious dentin.

Because of potential carcinogenicity, basic fuchsin was replaced by another dye, acid red 52, which showed equal effectiveness.

Products based on acid red 52 are marketed by a number of manufacturers e.g. Caries Detector, Kuraray, Osaka, Japan.

Many clinicians also have had good success with acid reds 50, 51, 54, and other commercially available caries detectors.

Some caries detection products contain a red and blue disodium disclosing solution (e.g., Cari-D-Tect, Gresco Products, Stafford, Texas). These products stain infected caries dark blue to bluish-green.

Studies show dye stains are about 85% effective in detecting all caries in a tooth. Clinical removal of caries without the aid of a dye is 70% effective.

Technique:

1.The area to be tested is rinsed with water and then blotted dry (excess water dilutes a stain).

2.The tooth is treated with a 1% acid red 52 solution for 10 seconds

3.The tooth is rinsed with water and suctioned and then excess water is removed. After rinsing with water for 10 seconds, some tooth structure shows Discoloration

4.Stained decay is removed with a spoon excavator and evaluated by tactile sensation.

When removing stained caries, it is important to be conservative near the pulp. Any questionable stained dentin should be left in place; remineralization will occur in this area, and the bacterial activity will be arrested once the tooth is restored.

CarieScan This device is based on the proven technology of alternating current impedance spectroscopy and involves the passing of an insensitive level of electrical current through the tooth to identify the presence and location of the decay.

The frequency domain is based on a sinusoidal signal applied to a sample at known amplitude and frequency. The response waveform is then measured and the impedance calculated by a transfer function relationship of the applied voltage perturbation and acquired response current.

It is the first dental diagnostic tool to use ac impedance spectroscopy to quantify dental caries early enough to enhance preventative treatment.

The device is indicated for the detection, diagnosis, and monitoring of primary coronal dental caries occlusal and accessible smooth surfaces, which are not clearly visible to the human eye.

For assessment of caries, while tufted sensor brush contacts the tooth surface beingexamined, a soft tissue contact, which is a disposable metal clip that is placed over the lip in the corner of the patient’s mouth, connects to the CarieScan via a soft tissue cable to complete the circuit.

During measurement, a green color display indicates sound tooth tissue, while a red color indicates deep caries requiring operative, and a yellow color associatedwith a range of numerical figures from 1 to 99 depicts varying severity caries, which require only preventive care.

Infrared fluorescence This technique has seldom been reported.

In theory, the tooth is exposed to light (irradiation) with a wavelength of between 700 and 15,000 nm.

Barrier filters are used to observe any resulting fluorescence.

Studies by Alfano et al. mention exposure of teeth to wavelengths exceeding 700 nm, but the results were not presented.

Unpublished reports commented upon by Longbottom suggest that the technique is able to discriminate between sound and carious enamel and dentin.

Further work is required to determine if the fluorescence signal from exposure to infrared irradiation is greater than that from other wavelengths.

Additionally, any heating effects from absorption of infrared irradiation may have potentially damaging effects on the dental pulp, given the increased penetration and decreased scattering of the longer wavelength.

Frequency-domain infrared photothermal radiometry and modulated luminescence Although still under development, the most recent technology in the field of caries diagnosis is the combined frequency-domain laser-induced infrared photothermal radiometry and modulated luminescence PTR/LUM.

Some of the inherent advantages of the adaptation of PTR to dental diagnosis in conjunction with LUM emission as the dual probe technique have been reported in recent literature.

The PTR technique is based on the modulated thermal infrared blackbody or Planck radiation response of a medium, resulting from optical radiation absorption from a low intensity laser beam mW and optical-to-thermal energy conversion followed by modulated temperature rise “thermal waves” usually less than 1 °C in magnitude.

The generated signals from PTR/LUM instrument carry subsurface information in the form of a spatially damped temperature depth integral.

Thus, PTR has depth-profilometric ability: it can penetrate and yield information about an opaque or highly scattering medium well beyond the range of optical imaging.

Terahertz Pulse Imaging This method uses waves with tetrahertz frequency(=1012 Hz or a wavelength of approximately 30μm) for an image to be obtained by tetrahertz irradiation, the object is placed in the path of the beam.

It is possible to record tetrahertz images using CCD detector. It has no adverse thermal effects, it is non ionising low signal to noise ratio, but the cost of equipment is high, and careful interpretation is required.

Dental Applications for this technique have been limited but promising.

Longitudinal sections through three teeth have demonstrated increased terahertz absorption by early occlusal caries and an apparent ability to discriminate dental caries from idiopathic enamel hypomineralisation.

Work in progress to image intact teeth with early carious lesion.

Multiphoton Imaging Infra red light of 850 nm has been used for multiphoton imaging of teeth.

In conventional fluorescence imaging (QLF), a single blue photon is used to excite a fluorescent compound in the tooth.

In the multiphoton technique two infrared photons (with half the energy of blue photon) are absorbed simultaneously.

With this technique, sound tooth tissue fluoresces strongly, whereas carious tooth tissue fluoresces to a much lesser extent.

In practice, by using motors with micron accuracy, one can move the plane of focus through the tissue and record the sectional images from the tooth to form a 3D image.

Caries will appear as a dark form with in a brightly fluorescing tooth.

To highlight the diseased tissue, the image may be displayed in its negative form so that caries appear bright with in dark tooth.

Other optical techniques There are a number of other techniques for detecting caries using optical methods.

These systems are in their infancy and many are based solely in laboratories.

However, such technologies may prove useful in the future. Examples include optical coherence tomography (OCT), and near infra-red imaging.

OCT has been shown to be able to image early enamel caries lesions in extracted teeth, and also on root lesions.

There is significant work involved in developing these systems into clinically and commercially acceptable applications and so it could be some time until these new methodologies can be properly assessed in clinical trials.

Cone beam computed tomography The application of cone beam computed tomography CBCT in dental caries diagnosis has not been widely studied.

The first and only study that compared caries diagnosis ability of two CBCT systems, NewTom 3G Quantitative Radiology and 3DX Accuitomo, and two intraoral modalities, Digora-fmx Soredex and film Kodak Insight, with histological technique serving as the validation standard concluded that the NewTom 3G CBCT had a lower diagnostic accuracy for detection of caries lesions than intraoral modalities and the 3DX Accuitomo CBCT.

The Accuitomo CBCT had a higher sensitivity than the intraoral systems for detection of lesions in dentin, but the overall true score was not higher.

The investigation to apply in caries diagnosis stems from its numerous advantages when compared to all current forms of x-ray imaging.

CBCT utilizes the least amount of radiation to obtain a diagnostic image while remaining cost effective for patients.

Ultrasound techniques The use of ultrasound in caries detection was first suggested over 30 years ago, although developments in this field have been slow.

The principle behind the technique is that sound waves can pass through gases, liquids and solids and the boundaries between them.

Images of tissues can be acquired by collecting the reflected sound waves.

In order for sound waves to reach the tooth they must pass first through a coupling mechanism, and a number of these have been suggested, but those with clinical applications include water and glycerine.

A number of studies have been undertaken using ultrasound, with differing levels of success.

A final in vivo study was undertaken using a device described as the Ultrasonic Caries Detector (UCD) which examined 253 approximal sites and claimed a diagnostic improvement over bitewing radiography.

Despite these encouraging findings, no further research has been undertaken using the device and the research has only been published as abstracts.

Current research and new technologies have extended the dentists’ armamentarium to detect early lesions of caries.

It is suggested that laser fluorescence is the leading technology there is, At the current state of development, early caries detection tools such as QLF, Electronic caries monitor, DIAGNODENT, DIFOTI or FOTI should be used as an adjunct to clinical decision making and serve primarily as a support tool for making preventive treatment plan decisions in conjunction with caries risk assessment.

It is important that all these tools be used as diagnostic adjuncts to aid in early caries detection and not as a justification for premature restorative intervention.

However, a need to further extend knowledge and understanding of other techniques in the field of dentistry is needed.

Unfortunately no one device has all the advantages and can be called as ideal.

New devices do offer promise in the monitoring of early incipient lesions of caries, and therefore preventive dentistry techniques may be more appropriately targeted and assessed.