New diagnostic approaches

The summary

Introduction

I/Traditional diagnostic methods

II/ New diagnostic approaches in cariology

1. Optical aids
2. Diagnostic devices using light transmission

1. Conventional intraoral cameras
2. Kavo Camera: DIAGNOcam
3. Fiber optic transillumination
4. Diagnostic devices using fluorescence
   1. Fluorescence systems only

→ Infrared laser fluorescence: DIAGNOdent

2. Combination of camera and fluorescence system
   1. QLF type fluorescence
   2. Intraoral Fluorescence LED Cameras III/New Approaches to Pulp Diagnosis
3. Methods based on the exploration of pulp vascularization
   1. Laser Doppler Flowmetry (LDF)
   2. Pulse oximetry

IV/ Interest of the three-dimensional image in OCE (ConeBeam Computed Tomography) Conclusion

Introduction

Diagnosis in Conservative Dentistry Endodontics is one of the main elements among the daily tasks of any dentist.

Early diagnosis of dental lesions is of capital importance, since it allows, if necessary

where appropriate, to implement appropriate prophylactic measures in a timely manner.

Today, it is the therapist’s duty to identify the 1/5 of lesions which constitute the basis of

the iceberg and which represent subclinical lesions that cannot be diagnosed by traditional examinations, to do this, new diagnostic aid tools are offered. I/Traditional diagnostic methods:

II/ New diagnostic approaches in cariology:

A conventional diagnosis is an examination that does not allow the detection of lesions at a subclinical stage but risks neglecting initial lesions and retaining only visible dentin lesions. There is therefore a real need for new diagnostic tools to detect lesions at their earliest stages and significantly improve the diagnosis of initial lesions. These early caries detection tools should be objective, quantitative, sensitive, easy to handle in the clinic and affordable.

1. Optical aids:

There are three categories of optical aids: simple loupes, binocular loupes and the operating microscope.

1. The simple magnifier: is the simplest magnification system. It has only one magnifying element for both eyes which can go from × 0.7 to × 2, its focal length is short so the working distance is also (about 12.5 cm), which in addition to monocular vision, is not compatible with our exercise
2. Binocular loupes: This is a stereo microscope that provides a low-magnification, three-dimensional image. It is also called a tele-loupe, which is a magnifying glass combined with a telescope.

→ Galileo type optical systems with a magnification of x 2.5 to x 3.

→ The Kepler system: Heine Zeiss magnifying glass (x 2.5, working distance 42/34/52 cm) with LED lighting mounted on a headband and not interfering with the wearing of corrective lenses.

• In dentistry, magnifications between × 3.2 and × 7 and working distances of 250 to 450 mm are usual.
• Magnifying glasses can be equipped with white light type front lighting systems (can be halogen, xenon or more recently LED type).
• The magnification and working distance which are initially defined according to the operator.
• The disadvantage of these systems is their bulk, weight and heat which can cause headaches.
• Telemagnifiers cause more eye fatigue due to constant visual accommodation.
• Their use requires training because the risk of false positives is increased.

3. The operating microscope: It was in 1978 that the microscope made its entrance into dentistry with doctors Ducamin and Boussens.

→ Magnification of the operating field from x 4 to x 21;

→ Working distance of 200 to 300 mm;

→ Binocular, stereoscopic vision;

→ Light source focused in the center of the working field (no shadow cast);

→ Light output 2 to 3 times greater than that of lighting mounted on magnifying glasses.

2. Diagnostic devices using light transmission:

Transillumination involves sending a beam of light through a tissue or part of the body, in order to examine it by transparency.

The dental structures are illuminated by the camera, areas that obstruct light transport (carious lesions) are represented as dark-colored areas.

1. Conventional intraoral cameras (VistaCam Digital):

Is a fluorescence intraoral camera that illuminates teeth with ultraviolet light (405 Nm) and captures the reflected light as a digital image.

This light is filtered and contains the yellow-green fluorescence of normal teeth as well as the red fluorescence of bacterial metabolites.

The camera is applied to the tooth, the images are recorded in specific software based on the caries values.

2. Camera Kavo: DIAGNOcam (Kavo Dental):

A new system recently developed by Kavo is also based on high transillumination and a near-infrared wavelength. However, little research has been done so far, and the system appears to be more suitable for diagnosing proximal carious lesions, with promising results.

DIAGNOcam is placed directly on the tooth, light is directed onto the tooth surface, and the image is captured by the software. Images are recorded directly, and video recording is possible.

3.  fiber optic transillumination:

→ Single fiber optic transillumination or FOTI

The FOTI system uses the phenomenon of light scattering in the tooth and amplifies it using high intensity white light.

Illumination is delivered via fibers from a halogen light source placed at the tooth surface.

Light is transmitted into the tooth and when a structural change occurs in the light path, such as in the case of a cavity, this causes diffraction of the light which appears as a shadow in the enamel or dentin.

FOTI is used on all tooth surfaces and allows the detection of dentin lesions, but it is unreliable for enamel caries.

→ Fiber optic transillumination with digital imaging or DIFOTI

The evolution is towards transillumination by optical fiber with digital imaging or DIFOTI (digital imaging fiber optic transillumination).

Fiber optic transillumination was combined with a CCD (charge coupled device) camera and a digital image acquisition device, thus enabling data archiving and monitoring over time.

The CCD camera and the optical fiber are directly combined in the handpiece.

The DIFOTI emits a white light, which is emitted through the tooth and then captured by the CCD camera. The images acquired by the camera are sent to the computer, which will analyze them using a specific algorithm. This algorithm will thus make it possible to diagnose and locate the carious lesion. The system will instantly create a high-definition digital image of the surface.

analyzed. The practitioner will be able to study the images via the device’s computer screen and thus look for variations in contrast.

Studies have shown the superiority of DIFOTI over radiography for the detection of early caries, whether on proximal, occlusal or smooth surfaces.

2.  Diagnostic devices using fluorescence:

The phenomenon of light fluorescence (LF) occurs in all natural materials, including teeth. LF results from the absorption of high-energy light penetrating an object and then emitting it at lower energy within its structure. The tooth exhibits natural fluorescence or autofluorescence.

Tooth FL is attributed to several factors:

→ To the organic component rather than the mineral part and may indirectly result from proteins adsorbed by the enamel.

→ Morphological changes in tissues.

→ Metabolites derived from bacteria present in the decayed tissue.

→ Tartar, plaque, certain external discolorations as well as composite resins and residual particles from prophylactic pastes.

These are therefore confounding factors for diagnostic interpretation. The difference between the degrees of radiant fluorescence of healthy or demineralized dental tissues can be used to detect and measure enamel and dentin caries.

1.  Fluorescence systems only:

→ Infrared laser fluorescence: DIAGNOdent

• Developed for the detection of non-cavitated caries.
• The device is a laser diode with a wavelength of 655 nm.
• The emitted light is transported by a descending optical fiber which also collects the internal fluorescence (in an area of ​​approximately 2 mm below the surface); then this is transmitted by an ascending fiber to a detector photodiode, after filtering the signal which is modulated and amplified so as to provide a value (between 1 and 99) interpretable by the operator and indicating the degree of demineralization of the tested site.

The DIAGNOdent is considered a reliable system for diagnosing initial pit and fissure lesions and smooth surfaces, with good reproducibility, better sensitivity than conventional tools (visual examination and radiography) and acceptable specificity. This tool can also allow the practitioner to evaluate the results of preventive actions (remineralization of carious sites) by taking measurements every few months.

To obtain more reliable measurements, the DIAGNOdent tip should be positioned on perfectly cleaned and dried but not dehydrated surfaces.

For the detection of proximal caries, the presence of an adjacent restoration may interfere with the measurement.

→ The DIAGNOdent pen: a new presentation of this system whose reliability and performance are similar to the previous one. It is characterized by:

• Absence of optical cord.
• The handpiece is equipped with two types of beveled sapphire tips, one cylindrical for detecting occlusal caries and the other flat for detecting proximal caries.

2.  Combination of camera and fluorescence system

a) QLF type fluorescence:

The QLF (quantitative light fluorescence) technique uses, in the form of a small intraoral camera, diffuse light emitting systems produced either by argon laser in the blue-green region or by xenon arc in the blue region. The light is transported by liquid-conducting cables; the teeth being tested capture the radiation, which is returned after filtering at 370 nm, so as to eliminate the blue and give only green and red images. These images are recorded by a video camera, analyzed by software and returned for observation on a monitor.

With this process:

→ Demineralization of the enamel can be seen in the form of dark spots contrasting with the green color of healthy enamel.

→ The method detects initial enamel caries at a depth of 500 μm.

→ Detection of initial lesions of smooth surfaces or occlusal faces.

→ It is proposed for the detection of caries around orthodontic locks and the monitoring of demineralization/remineralization processes.

b. Fluorescence intraoral LED cameras

Derived from the QLF and DIAGNOdent systems, the new LED intraoral cameras using fluorescence represent the latest innovation among optical systems for assisting in the detection of caries and dental plaque. These optical systems illuminate the tooth and return fluorescence images analyzed by image processing software.

The principle is to observe the variations in autofluorescence of the decayed enamel-dentin areas compared to the healthy areas of the same tooth.

→ The Vista Proof camera, equipped with an LED emitting intense blue-violet light (405 nm):

• Healthy enamel appears green.
• The porous enamel absorbs the incident signal in the blue.
• Deeper lesions, reaching the dentin, give off a more complex signal in red or dark brown.

→ More recently, an experimental LED camera, the Sopro-Life fluoLED camera, has been proposed for the diagnosis of initial carious lesions and caries control during dentin curettage

.

III/New approaches to pulp diagnosis : Methods based on the exploration of pulp vascularization

Vascular exploration methods aim to detect the presence of blood flow. Pulp vascularization may persist without a nerve response being detected.

Two techniques are currently used clinically: laser Doppler flowmetry and pulse oximetry:

1.  Laser Doppler Flowmetry (LDF):

The Doppler laser flowmeter measures the flow of blood cells within a tissue without causing any alteration to it.

The incident helium-neon laser beam emits a monochromatic (red) beam with a wavelength ranging from 600nm to 800nm ​​at the tooth surface, transmitted through the enamel to the pulp.

This beam is transmitted to blood cells and static tissues of the pulp tissue. The frequency changes when the laser beam passes through moving blood cells but remains the same when the beam passes through static tissues. It allows for early diagnosis of pulp necrosis.

However, it is a technique that can be improved and requires a long recording time, up to an hour, and is prohibitively expensive.

The operating steps:

• Placement of an operating field to isolate the tooth from saliva and prevent the diffusion of light to other tissues.
• Fixing the probe using a probe holder glued to the center of the vestibular surface of the tooth, at the level of the tips of the gingival papillae, using a Glass Ionomer Cement, in order to ensure the stability of the positioning of the probe.
• The device is turned on and the results are read between 1 minute 30 seconds and 1 hour depending on the studies, with an average of 15 minutes/tooth.
• The data is displayed on a screen, can be processed and recorded by a computer for further analysis and archiving.

Interest of the technique:

→ It is a good way to monitor the pulp development of traumatized teeth,

→ It is a reliable method for determining the vitality of a tooth whose nerve plexus is damaged or in a state of shock but which has retained its functional blood flow.

→ It is painless and its non-invasive nature helps promote cooperation from the young patient.

→ Its effectiveness is also recognized on teeth with immature apexes.

However, the use of laser Doppler in dentistry is hampered by several parameters:

→ A significant cost for use in the office.

→ Lack of reproducibility due to calibration difficulties as no real standard has been established to measure tissue blood flow.

→ Several parameters interfere with flow recording: the thickness of hard tissues, their ability to transmit light, the presence of caries and pulp volume are factors limiting the amplitude of the signal (false negatives).

→ Due to light scattering, periodontal blood flow can contaminate the measurements (false positive).

2.  Pulse oximetry

The principle of pulse oximetry is based on the fact that we can know the concentration of an unknown solute (here, hemoglobin) in a known solvent (here, blood), thanks to the light absorption of this solute.

Pulse oximetry uses the properties of hemoglobin in the red and infrared: oxyhemoglobin absorbs more light in the infrared than deoxyhemoglobin, and vice versa in the visible red.

Pulsatile changes in blood volume therefore induce variations in the absorbed light which make it possible to determine blood oxygen saturation.

It uses an emitter consisting of two diodes that emit light at 660nm (red) and 900-940nm (infrared), as well as a photoreceptor and a microprocessor that measure the rates of absorbed light. The computer then calculates the blood oxygen saturation rate using pre-recorded absorption curves.

Conditions of use:

• The patient must remain still during the recording.
• The sensor must fit the anatomy of the tooth being tested and be securely fixed.
• The emitting diodes and the photoreceptor must be parallel throughout the measurement so as not to lose any light emission.
• The tooth should also be isolated with a rubber dam to avoid interference from gum tissue.
• The sensor should be located at the middle 1/3 of the crown.
• The results are read after approximately 30 seconds. A value greater than or equal to 75% indicates a vital tooth.

→ It is a non-invasive, objective method and considered effective in determining pulp vitality.

→ It provides reliable, reproducible and comparable results between two measurements.

→ It allows the measurement of pulp circulation through enamel and dentin, independently of gingival circulation.

→ This is a method that seems suitable for pediatric use since it does not cause any unpleasant sensations and the measurement is carried out fairly quickly.

→ It is also applicable to temporary and immature teeth whose incomplete innervation reduces the effectiveness of other methods.

→ It is useful in cases of injury where blood circulation remains intact but nerve endings are damaged.

However, this technique has limitations:

• Anomaly of this flow will give erroneous results,
• Extrinsic or patient-related abnormalities may confound results.
• It is only applicable to natural tooth structure; coronal restorations diffract light and diffuse it into the surrounding tissues. Similarly, dental stains can distort the results.
• The signal source must be large because too low a flow does not allow reliable measurements.
• Some false negatives may be encountered on immature, calcified or traumatized teeth.
• Finally, this technique remains at the research stage within the framework of dentistry.

IV/ Interest of the three-dimensional image in ocean: Cone Beam

Over the years, progress in dento-maxillary imaging, from conventional radiography to CT scanning, has been considerable.

The objective was to overcome the limitations of imaging, the main drawback of which is the lack of precision.

Currently, among the three-dimensional imaging procedures, a so-called “revolutionary” tool has been developed, representing an alternative to conventional scanners for multiple clinical situations: Cone Beam Computed Tomography (CBCT).

The latter was originally dedicated to the field of implantology but its indications have increasingly broadened to ensure multidisciplinary care.

This technique has been established for years in the world of dental imaging, dedicated particularly to the orofacial sphere, thus reinforcing sectional imaging techniques and allowing access to the third dimension (3D) which we lack with 2D images.

These latest imaging technologies allow for complete or limited digital acquisition of the jaws and offer a variety of flat or curved reconstructions in coronal, sagittal, oblique, panoramic orientations as well as three-dimensional reconstructions allowing the entire volume to be scanned in a single resolution, while being economical in terms of radiation dose, which is its main advantage over the scanner.

Operating principle

CBCT is based on a generator which emits an open and attenuated beam of conical X-rays of constant width crossing the anatomical volume to be explored.

This system will perform a single rotation of 180 to 360 degrees around the patient’s head, allowing the entire volume of the area concerned to be scanned, thus several hundred analyses (shots, photographs or projections) are carried out in the different planes of space, followed by the acquisition of raw data in the different planes of space.

Subsequently, this digital data will be transmitted to a computer for a volumetric reconstruction of the object.

Indication:

• When the information provided by the clinic and 2D radiology is not sufficient to establish an accurate diagnosis.
• For the search and location of an additional root canal.
• For periapical or pre-surgical assessment, particularly in the posterior maxillary region or in the mental foramen region.
• In cases of alveolar-dental trauma.
• For the assessment of a root pathology, type of fracture, internal and external resorption, periapical or latero-radicular.

Conclusion :

The development of techniques for detecting dental lesions has become a major concern.

All studies show the effectiveness of the different tools if they are used wisely, with sensitivity and specificity values ​​that make it possible to avoid overtreatment . In order to improve diagnosis, it is possible to combine several of these techniques.

New diagnostic approaches

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New diagnostic approaches