Diagnosis of dental caries

محاضره طب مجتمع—مرحله رابع

د.خوله محمد

Diagnosis of 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 .
For the WHO caries assessment system , the examiner recorded a surface as decayed only if it presented with detectably softened floor, undermined enamel or a softened wall.
According to this criterion, all the stages that precede cavitation as well as other conditions similar to the early stages of a carious lesion were considered sound.
Code Description Sound tooth : A crown is recorded as sound if it shows no evidence of treated or untreated dental caries. The stages of caries that precede cavitation as well as other conditions similar to the early stages of caries are considered sound because they cannot be reliably diagnosed.
Decayed crown Caries is recorded as present when a lesion in the pit and fissure or on a smooth tooth surface has an unmistakable cavity, undermined enamel, or a detectably softened floor or wall. Where any doubt exists, caries should not be recorded as present
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.
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.
conventional methods of caries detection:
1. visual-tactile method
2. radiography
3. caries detecting dyes


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.
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.
Visual methods:
1. Detection of white spot, discoloration / fran cavitations
2. Without aids, unreliable
3. Magnification loupes- Head worn prism loupes (X 4.5) or surgical microscopes(X 16) may be used
comfort, relatively inexpensive, available in various
magnification
4. Use of temporary elective tooth separation.

Tactile methods:

Explorers are widely used for the detection of carious tooth structure
- Right angled probe- no.6
- Back action probe- no.17
- Shepherd's crook- no. 23
- Cow horn with curved ends- no.2
Use of explorer is not advocated because;
1. Sharp tips physically damage small lesions with intact surfaces
2. Probing can cause fracture & cavitation of incipient lesion. It may spread theorganism in the mouth
3. Mechanical binding may be due to noncarious reasons
Shape of fissure
Sharpness of explorer
Force of application
Path of explorer placement
Use of explorer:
• Explorer is useful to remove plaque and debris and check the surface characteristics of suspected carious lesions.
• gentle pressure just required to blanch a fingernail without causing any pain or damage
• All surfaces of a tooth are cleaned of debris and plaque, using an air syringe and examined visually.
Suspicious areas are explored to check for the surface texture.
All discolored areas should be explored using gentle pressure.
Caries in Pit or Fissure Surfaces:
1. All discolored areas should be explored using gentle
2. There is no need to penetrate a suspected lesion with an explorer.
3. If a discolored and non-cavitated area is soft when explored, it is recorded as non-cavitated carious pit or fissure.
4. A cavity is detected when there is an actual hole in the tooth in which an explorer could easily enter the space.
5 . An active cavity has soft walls or floors (detected using gentle exploring).
6. If there is visual enamel opacity under an ostensibly sound or stained pit or fissure, then the enamel is undermined because of dental caries and the tooth surface is classified with a non-cavitated carious lesion in dentin.
Root Caries
Root surface caries comprises of a continuum of changes ranging from minute discolored areas to cavitation that may extend into the pulp For diagnostic purpose; they may be:


Active root surface lesion:
well-defined area showing yellowish or light brown discoloration
covered by visible plaque
presence of softening/ leathery consistency on probing with moderate pressure.

Inactive root surface lesion (arrested):

• well-defined dark brown/ black discoloration
• smooth and shiny
• hard on probing with moderate pressure
Active lesion

Arrested Caries:

Arrested (remineralized) lesions can be observed clinically as intact, but discolored, usually brown or black spots.

The change in color is presumably due to trapped organic debris and metallic ions within the enamel.

These discolored, remineralized lesions are intact and are highly

resistant to subsequent caries .
The arrested caries need not be removed.

Recurrent caries:


It is diagnosed whenever there is softness due to caries at a defective margin, and when the tip of a periodontal probe can enter the defect without any resistance.
A restoration with a discolored margin or a small marginal ditch (<0.5 mm or the head of the probe) is recorded as an early recurrent carious area. A larger defect should be
classified as advanced recurrent carious area

There are two valid indicators of recurrent

(secondary) caries:
• softness at the margin of a filling that is detected
using an explorer or
• presence of a large defect (a minimum diameter of
0.4 mm) at a margin of a filling with softness in the area.
Large defects are associated with a high level of colonization with cariogenic bacteria. Marginal discoloration by itself is not a valid sign for dental caries.

RADIOGRAPHY:

Carious lesions are detectable radio graphically when there has been enough demineralization to allow it to be differentiate from normal
They are valuable in detecting proximal caries which may go undetected during clinical examination.
On average they have around 50% to 70% sensitivity in detecting carious lesions. 40% demineralization is required for definitive decision on caries

§ Radiographic examinations include;

Bitewing radiographs
IOPA radiographs using paralleling technique
Dental panoramic tomograph


The two important decisions related to
radiographic examination are

(1) when to take a radiograph and

(2) how to evaluate a radiograph for presence of signs of dental caries.

Limitations of radiography:

1.Exposure of child to ionizing radiation
2.Limitations of dental film
3.Physical limitation based on anatomic consideration
4.High degree of inter- examiner variabitity
5.Amount of labor time required for processing
6.Variabitity in the image produced

3.Tooth separation

Separating the teeth for visualizing the posterior a proximal surfaces has been known since the last century. this method uses orthodontic modules or bands and achieves slow separation b

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.
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.


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.

They selectively complex with carious tooth structure

which is later disclosed with the help of fluorescence
Aids in both quantitative & qualitative analysis of the
lesion
DYES FOR ENAMEL CARIES:
Procion: N2 & (OH) groups irreversibly complex
with caries Acts as a fixative
Calcein: complexes with calcium & remains bound
to the tooth
Zyglo ZL-22: fluorescent tracer dye, not used in vivo
Brilliant blue: 10% aqueous Brilliant Blue, not used in vivo
DYES FOR DENTIN CARIES:
Ø 1% acid red 52 in propylene glycol complexes specifically with denatured collagen, hence used to differentiate infected and affected dentin
Ø Iodine penetration method (Pot iodide) for evaluating enamel permeability
DISADVANTAGES
• Dye staining and bacterial penetration are independent
phenomena, hence no actual quantification
• They also stain food debris, enamel pellicle, other organic
matter
• Dye aided carious removal- laborious
• Stains DEJ

Newer Methods of Caries Detection and Assessment
DIGITAL IMAGING
A digital image is an image formed & represented by a spatially distributed set of discrete sensors & pixels
2 types of non- film receptors
Direct digital imaging – digital image receptor
Indirect digital imaging – video camera for forming
Advantages:
1.Images are available in seconds
2. Exposure is reduced 50-90%
3. Image size, contrast and density can be manipulated to improve interpretation
4. Record keeping is vastly improved. All films are labeled, filed and retrieved easily. Duplicate hard copies are the same as originals and simple to make.


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.
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.
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 autofluorescence 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.
QLF uses a blue light (488 nm) to illuminate the tooth, which normally fluorescence a green colour.
Teeth should be dried before its application.

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.


DIAGNODent pen:
Ø Due to this limitation, a new version of the method was designed and introduced, named DIAGNOdent pen.
Ø This new version permits the assessment of both occlusal and proximal surfaces.
Ø 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).
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.
Electrical Conductance Measurement:
In this method of detecting Dental Caries, the main motive is to measure the electrical conductance by the various teeth. In this method the teeth with affected part was supposed to show high electrical conductivity and the other with low. In this method all the teeth are cover with conducting media and then the electrical conductance has to be measured to detect Dental Caries.
But the problems in this method are the differences that come when A.C. Or D.C. current is used

Factors affecting electrical measurements

1. Porosity
2. Surface area
3. Thickness of the tissues
4. Hydration of enamel
5. Temperature
6. Concentrations of ions in the dental tissue fluids

Diagnodent

This is the main method of detecting Dental Caries by the advanced technique and the main principle behind detection is that the bacterial metabolites with in the lesion exhibits increased fluorescence when illuminated with diagnodent.
By this method it is easy to find out the residual and minimal caries. A laser diode is used in this method with particular wavelength of 655nm and this causes the stimulation of light of various wavelengths that reaches the control unit and the control unit provides the reading that is compared with the sound enamel reading and thus the damage can be detected.
Other advance diagnostic method
Xeroradiography
Optical caries moniter
Magnetic resonance micro-imagery
Ultrasound