New diagnostic approaches
Introduction :
The modern concept of diagnosis in cariology is based on three considerations:
-Detection of carious lesions.
-Assessment of the severity and activity of these lesions according to their stage of development
-Identification of caries risk factors and evaluation of caries risk indicators.
Carrying out pulp diagnosis is a daily act in the practice of dentistry.
However, although this is a routine procedure, it is crucial that it be performed with precision and accuracy. Indeed, determining the state of the pulp leads to a multitude of different treatments, each with its own indications and consequences.
Currently, existing tests are based on two principles: the assessment of pulp sensitivity and the determination of pulp vascular flow.
I. New diagnostic aid tools in cariology :
Early diagnosis of hard tissue damage caused by caries is of paramount importance in order to be able to initiate appropriate preventive measures.
In this context, the development of new diagnostic methods has proven essential in order to help the practitioner meet the requirements of modern dentistry based on the concept of prevention.
- Electrical systems:
- Principle:
The tooth has poor electrical conductance. When it becomes porous, during demineralization, the conductance increases. Conversely, the impedance (capacity to retain current) decreases: more current flows. This difference can be detected by electrical measuring instruments such as the Electronic Caries Monitor (EMC®).
1.1.2 Interest:
ECM has been shown to be more effective in detecting root caries and in measuring the degree of remineralization after topical fluoride treatments .
Its effectiveness remains limited on the proximal faces
- Fiber optic transillumination (FOTI and DIFOTI systems)
1.2.1 FOTI System:
1.2.1.1 Principle:
Devices using fiber optic transillumination or FOTI send a beam of bright white light to the tooth surface. The light is then directed toward the tooth.
During a demineralization process, light transmission is reduced while dispersion is increased.
1.2.1.2 Interest:
FOTI is indicated in the diagnosis of proximal lesions.
FOTI is reliable for the detection of dentin caries and unreliable for enamel caries.
- DIFOTI System:
1.2.2.1 Principle:
Digital fiber optic transillumination with imaging, or DIFOTI, emits, like FOTI, white light using an optical fiber. This light is emitted through the tooth and then captured by the CCD camera. The images of the tooth acquired by the camera are sent to the computer, which analyzes them using a specific algorithm.
1.2.2.2 Interest:
DIFOTI allows the carious lesion to be located, visualized and quantified.
1.3 Fluorescence optical systems
Fluorescence is a phenomenon present in all natural materials, including teeth. When high-energy light is absorbed by an object, it is re-emitted at a lower energy within the structure: this is the phenomenon of fluorescence.
Tooth fluorescence is attributed to its organic component rather than its mineral portion. It can also be emitted by metabolites derived from bacteria in decayed tissue as well as tartar and plaque.
1.3.1 Fluorescence of QLF:
1.3.1.1 Principle:
“Quantitative Light Fluorescence” uses the principle of fluorescence coupled with an intraoral camera. This emits blue light, either by argon laser or xenon arc (290-450nm).
This produces an image composed of greens and reds on the monitor screen, with green being the predominant color of the enamel.
1.3.1.2 Interest:
QLF remains limited in proximal lesions as well as in deep dentin lesions because light penetration does not exceed 400 µm.
Soprolife®
1.3.2 Fluorescence intraoral LED cameras:
Dürr Dental’s VistaProof camera, equipped with an LED emitting intense blue-violet light (405nm), is coupled with DBS Winn software (Eberhardt et al 2007). Healthy enamel appears green. Porous enamel absorbs the incident signal in the blue, while deeper lesions reaching the dentin produce a more complex signal in the red or dark brown.
VistaProof Camera
1.3.3 Laser fluorescence (DIAGNOdent®):
1.3.3.1 Principle:
The device is a laser diode with a wavelength of 655nm and a peak power of 1mW. The emitted red light is transported by a descending optical fiber which also collects the internal fluorescence (in an area of approximately 2mm 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.
DIAGNOdent 2095® KaVo®
1.3.3.2 Interest:
-A reliable system for diagnosing initial lesions with good reproducibility.
-Better sensitivity than other conventional tools and acceptable specificity .
-Evaluate the results of preventive actions, by taking measurements every few months .
Limit values provided by the manufacturers of DIAGNOdent® (KaVo)
1.4 Operating microscope:
Composed of an optical part (the magnifying prisms, the objective, the eyepiece), a mechanical part (the pantographic arm; the stand) and a light source.
In conservative dentistry, the main advantages of MO are:
-Minimally invasive cavity preparation
-Precise cavity filling
II. New diagnostic aid tools in endodontics :
2.1 Exploration of pulp vitality:
2.1.1. Pulse oximetry:
2.1.1.1 Principle:
Pulse oximetry is a technique developed by Takuo Aoyagi in the early 1970s. It measures the oxygen saturation level of arterial blood.
It is based on the application of Beer’s law, which states 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.
It uses an emitter composed of 2 diodes which emit lights at 660nm (red) and
900-940nm (infrared), as well as a photoreceptor and a microprocessor that measure
the rates of light absorbed. Oxyhemoglobin tends to absorb more light
infrared and vice versa for deoxyhemoglobin, the pulsatile change in blood volume results in variations in the amount of red and infrared light absorbed by the vascular bed before reaching the receptor. The computer then calculates the
blood oxygen saturation rate using pre-recorded absorption curves.
Principle of pulse oximetry
2.1.1.2 Implementation
Carrying out a vitality test by pulse oximetry requires a certain number of conditions:
The sensor must first and foremost adapt to the anatomy of the tooth being tested.
The emitting diodes and the photoreceptor must be parallel throughout the duration of
the measure.
Testing the custom-made sensor.
The sensor must be securely attached to the tooth, and the patient must remain still.
Isolate the tooth using a rubber dam and aluminum foil placed at the neck of the tooth.
The sensor should be located at the middle 1/3 of the crown.
The results are read after a period of approximately 30 seconds: a value greater than or
equal to 75% indicates a vital tooth.
2.1.1.3 Advantages:
-Pulse oximetry is a non-invasive, objective and effective method 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.
-A method suitable for pediatric use (temporary and immature teeth).
-Today’s oximeters are small, inexpensive, and therefore perfectly suited for office use.
-Pulse oximetry is a safe and definitive means of diagnosis.
2.1.1.4 Limits
Since pulse oximetry relies on measuring blood flow, any abnormality in this
flow will give erroneous results.
We distinguish between intrinsic, extrinsic and patient-related anomalies.
Intrinsic anomalies:
– Blood CO2 level too high which interferes with the deoxyhemoglobin level
– Hemoglobin bound to a gas other than oxygen (carbon monoxide type)
– Increased metabolic acidity which leads to deoxygenation of hemoglobin
Extrinsic anomalies:
– Sensor movement
– Cannot be used on crowned teeth (light cannot pass through)
– Interference from a xenon arc lamp
Patient-related anomalies:
– Intense peripheral vasoconstriction
– Hypotension
– Hypovolemia
– Hypothermia
No sensor suitable for dental use
Coronal dental staining.
2.1.2. Laser Doppler flowmetry
2.1.2.1 Principle
Laser Doppler fluxmetry is based on the Doppler effect, which is defined by the frequency shift of a wave between the measurement at emission and the measurement at reception when the distance between the transmitter and the receiver varies over time.
Laser Doppler, used in dentistry, is an electro-optical technique that detects the presence or absence of blood flow in the area being studied. It involves a beam of infrared (780-820 nm) or near-infrared (632-638 nm) light directed onto the tissues by an optical fiber contained in a special probe. The monochromatic light is transmitted through the tooth to the pulp, where it is diffracted by moving cells and then recaptured by a photoreceptor located in the probe.
Photons reflected by moving cells undergo a frequency shift according to the Doppler principle. Photons interacting with stationary cells are diffracted but do not undergo a frequency shift.
The proportion of frequency-shifted light in the total recaptured light gives a measure of blood flow in the tissue, recorded by the device and expressed in
Perfusion Unit (1 PU=10 mV).
Principle of laser Doppler flowmetry
2.1.2.2 Implementation:
Before laser Doppler flowmetry, the tooth must first be isolated from the surrounding gum tissue using a rubber dam to avoid any interference with the measurement.
The probe is then placed at the middle 1/3 of the tooth and must remain motionless throughout
the duration of the test.
During the first session, it is possible to create a spacer for the probe using heavy silicone and a rubber dam clamp. If the measurements need to be repeated, it is a good idea to create a custom-made splint.
Probe holding device made of silicone
2.1.2.3 Advantages
-Laser Doppler flowmetry is a reliable, non-invasive, high-precision technique.
-A method suitable for pediatric use (temporary and immature teeth).
2.1.2.4 Limits:
Laser Doppler flowmetry is an accurate method, but its results can be easily distorted. Indeed, several parameters interfere with the flow recording.
blood, such as:
-Ambient light
-Gum tissue
-Vasoconstrictors (which decrease blood flow)
-Blood pressure
-Dental stains.
– Not usable on crowned teeth
-Total immobility for the entire duration of the recording (1 min 30 and one hour).
-Need to make a gutter, which further extends the appointment time.
-This method is very expensive (around €6,000 for a monitor) for a purely diagnostic procedure and therefore seems inaccessible to the majority of dentists.
2.1.3. Photoplethysmography:
2.1.3.1 Principle:
Plethysmography involves recording pressure variations within a vascular segment.
Photoplethysmography or photoelectric plethysmography records the relationship between the intensity of light reflection, or light transmission through a tissue, and the blood flow through the area being studied.
The curves are plotted on an oscilloscope screen and/or on a plotter.
Photoplethysmography uses an optoelectronic system to capture the pulse of the dental pulp.
2.1.3.2 Interest:
It is part of non-destructive methods for assessing the anatomo-physiological integrity of the pulp-dentin organ and therefore constitutes a valuable aid to diagnosis.
2.2 Exploration of the canal system:
2.2.1 RX scanner: Computed tomography = computer-calculated axial tomography:
CT scanning is a medical imaging technique that involves calculating a 3D reconstruction of tissues from a tomographic analysis obtained by subjecting the patient to scanning with an X-ray beam.
Interest :
-A detailed diagnosis of pathologies not detected on conventional dental images.
-Navigation of the endo-canal anatomy as a treatment (working length, canal permeability, curvatures, angulations, innate dysmorphoses or acquired remodeling, resorptions).
-Exploration of bone or cystic induced pathologies, their proximity to vascular-nervous elements, neighboring organs, in particular the lower sinuses.
-Informs about the durability and watertightness of the root canal filling.
2.2.2 Cone beam computed tomography or CONEBEAM:
2.2.2.1 Principle of cone beam imaging:
The cone beam technique is based on the principle of tomosynthesis, in which the pulsed, non-continuous, open X-ray beam of conical geometry performs a single rotation around the dento-maxillary structures.
The movement can be linear or circular.
The devices:
*Narrow-field devices: whose resolution is in principle optimal and whose main indications are endodontics. The reference model is the Accuitomo , which explores a reduced volume of the arch.
*Wide-field devices: allow for an overall exploration of the facial area but also allow for sectoral explorations. The NewTom 3G with a 9-inch field is the most commonly used.
*Medium field devices: the most preferred, exploring all or part of the dental arches.
NewTOM= supine position.
Cone beam = sitting position.
2.2.2.2 Interest of the cone beam in endodontics:
– The cone beam allows obtaining precise information on the extent, shape and location of periapical lesions while avoiding the superposition of anatomical structures.
-Evaluation of anatomical structures related to the lesion of endodontic origin: such as the maxillary sinus; mental foramen, inferior dental canal, etc.
-The cone beam allows for more precise visualization of the canal anatomy: the contours of the roots, their number, position of each of the canals and to specify the canal entries before endodontic treatment.
– The cone beam allows us to understand the causes of failure of endodontic pathology, namely:
-Inadequate filling or possible presence of an untreated canal.
-Anatomical features: C-shaped canals on lower pemolars, double canal system on upper incisors.
-Perforations and lacerations created at the time of tenon placement.
-External resorptions are revealed late, which compromises the diagnosis of the tooth.
– The cone beam allows the visualization of root fractures regardless of their location, with the exception of fine vertical cracks.
2.3 Operating microscope:
Composed of an optical part (the magnifying prisms, the objective, the eyepiece), a mechanical part (the pantographic arm; the stand) and a light source.
In endodontics, the main advantages of MO are:
• precision in operating instruments and carrying out work.
• variable magnifications.
• lighting that eliminates shadow areas in the operating field.
• a comfortable working position for the practitioner.
• improved surgical assistance thanks to visualization of the surgical field .
• a possibility of direct documentation by photo or video.
Conclusion :
Early diagnosis of initial enamel lesions is very important in order to be able to initiate appropriate therapy at the optimum time to remineralize these lesions. Therefore, the practitioner in his daily practice must equip himself with the means to diagnose these lesions in time.
Failing this, clinical examination supplemented by a retrocoronary radiographic assessment provides significant assistance. Finally, it must be recognized that there are few studies that have evaluated the interest of the combination of several diagnostic tools on sensitivity and specificity values.
The ultimate goal of pulp diagnosis is to determine the precise histological status of the pulp at the time of examination. Although they represent a significant advance in this field, blood flow measurement tests cannot achieve this level of accuracy. Pulp vitality must therefore be assessed using a combination of information from clinical and radiological examination, patient history, vitality tests, and the practitioner’s clinical experience.
New diagnostic approaches
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