Pulp Vitality Tests with Classification and Recent Advances

A) INTRODUCTION

The accurate diagnosis of the true histological status of the pulp is of significant importance for treatment planning.

What is Pulp sensibility test?

Pulp Sensibility Testing- Assess the Neural sensitivity of the pulp

What is Pulp Vascularity Test?

Pulp Vitality Testing- Assess the vascularity of the pulp

What is Pulp Sensivity ?

Pulp Sensitivity- Condition of the Pulp Being Very Responsive to a Stimulus.

B) NEURAL SENSIBILITY TESTS

1) Thermal Tests- Cold Test, Heat Test
2) Electric Pulp Test
3) Anesthetic Test
4) Test Cavity

1) Thermal Tests

a) Heat Test

Materials used
Electrical heat carrier
Hot gutta-percha stick (>65.5° C)
Others
–– Hot water under rubber dam isolation
–– Hot burnisher
–– Hot compound

–– Dry rubber polishing wheel


Electrical Heat Carrier

Heat carrier instrument that can deliver a controlled temperature to the tooth is preferable

Hot Gutta Percha Sticks

The heat is applied to the occlusobuccal third of the exposed crown. 

If there is no response, the hot substance can be moved to the central portion of the crown or closer to the tooth cervical margin. 

When a response occurs, heat should be removed immediately. 

Care should be taken to avoid using excessive heat or prolonged application of heat to the tooth


Hot Burnisher

Held about 1–2 mm away from the labial or buccal surface of the tooth. Avoid touching the tooth surface as the hot instrument will burn the enamel and leave a black spot.

Other Tests

A different technique is required for the application of hot water. The tooth to be tested is isolated under a rubber dam. The tooth is then immersed in “coffee-hot” water delivered from a syringe, and the patient’s reaction is noted.

Mechanism of Action

How to do a cold test for teeth?

b) Cold Tests

Material Used

Endo ice → 1,1,1,2 tetrafluoroethane (-26 C)

Mixture of gases (propane/butane/isobutene)(-50 C)

CO2 snow (Dry ice) (-78 C)

Pencil of ice

Ice cold water under rubber dam isolation

Ethyl chloride- (-4 C)

Dichlorodifluoromethane- (-21 C) 

Endo ice → 1,1,1,2 tetrafluoroethane (-26 C)

The most common method is to apply a cotton pellet saturated with 1,1,1,2 tetra-fluoroethane to the tooth being tested.

it has a temperature of about −26°C when first sprayed from the pressurized can but this reduces to about −18.5°C in the mouth.

Another simpler method of applying cold to a tooth is by following these steps: wrap a sliver of ice in wet gauze, place it against the facial surface of the tooth, and compare the reaction to a control tooth.

Pencils of ice can be made by filling discarded anesthetic carpules with water and freezing them in an upright position in a refrigerator

Dachi and associates recommended that a quarter- inch-diameter cone of ice be placed against a tooth for 5 seconds to quantify cold testing.

CO2 snow (Dry ice) (-78 C) (Odontotest-Dry ice)

Carbon dioxide (dry ice) snow has also been used for application of cold to teeth. 

The use of dry ice has been described by Ehrmann. 

Because the temperature of dry ice is –78°C, one is able to penetrate full-coverage restorations and elicit a reaction from the underlying tooth to the cold.

Mixture of gases (propane/butane/isobutene)(-50 C)

The propane/butane/ isobutane mixture temperature is approximately −50°C and reduces to about −28°C in the mouth.

Mechanism

How to use a pulp tester?

2) Electric Pulp Test

The objective is to stimulate a pulpal response by subjecting the tooth to an increasing degree of electric current.

The electrode is placed against the incisal third enamel surface of the isolated and dried tooth crown using toothpaste as an electrolyte

The electrode is placed against the mid-third of the mesiobuccal cusp of molars and buccal cusp of premolars

Normal response: A positive response is a response that occurs at the same neural excitation threshold as the control tooth

Negative response: This denotes a nonvital tooth, which fails to respond even when the tester is set to the highest electrical excitation value.

Early response: This denotes a diseased state of pulp as the tooth responds to a threshold which is less than that of the control tooth

Delayed response: This also denotes a diseased state of the pulp wherein the tooth responds at a significantly higher electrical excitation level than compared to the control tooth

False Positive Response-

1)Partial Pulp Necrosis

2)High Anxiety

3)Ineffective tooth isolation

4)Contact with metal restoration

False Negative Response-

1)Calcified Canals

2)Recently Traumatized tooth

3)Immature apex

4)Drugs that increase pain threshold

5)Poor contact of pulp tester

The diagnostic accuracy of cold test is 86%, the electric pulp test is 81%, and heat test is 

71%. Hence, clinically, a combination of cold test followed by EPT is recommended.

Cold test is the most effective sensitivity test for immature permanent teeth

3) Anesthetic Test

The objective is to anesthetize one tooth at a time until the pain disappears and is localized to a specific tooth

Using either infiltration or the intraligament injection, inject the most posterior tooth in the area suspected of being the cause of pain.

The anesthetic test is obviously a last resort test and has an advantage over the “test cavity,” during which iatrogenic damage is possible

4) Test Cavity

It is performed when other methods of diagnosis have failed. The test cavity is made by drilling through the enamel–dentin junction of an unanesthetized tooth.

The drilling should be done at high speed and with a water coolant. Sensitivity or pain felt by the patient is an indication of pulp vitality

C) PULP VASCULARITY TESTS

True vitality status can be ascertained only when we are able to assess the vascular or blood supply to the tooth

(1) Laser Doppler Flowmetry

(2) Pulse oximetry

(3) Others

(i)Dual-wavelength spectrophotometry

(ii)Crown surface temperature

(iii)Transillumination with Fiberoptic Light

(iv)Plethysmography

(v)Radiation Probe Using Xenon Radioisotope

1) Laser Doppler Flowmetry

Noninvasive method of assessing and accurately measuring the rate of blood flow in a tissue

Developed by Tenland in 1982 and later by Holloway in 1983

Uses a laser source that is aimed at the pulp, and the laser light travels to the pulp using the dentinal tubules as guides.

This principle is used to ascertain the presence of blood movement within the pulp space

The laser light is transmitted through a fiberoptic source and placed on to the tooth surface. 

The light enters the tooth and gets absorbed by the red blood cells which lead to a shift in the frequency of the scattered light. 

This occurs due to the Doppler principle. 

This shift in frequency does not occur in light that is absorbed by stationary objects. 

The proportion of Doppler shifted light is detected with the help of a photodetector

it is potentially used to differentiate a healthy, traumatized tooth with reduced blood supply from a nonvital tooth

2) Pulse Oximetry Test

Noninvasive method to measure the oxygen saturation levels with the help of a finger, ear, or foot probes

Two light-emitting diodes

Red light (660 nm)

Infrared light (940 nm)

Photodetector on the opposite side of the vascular bed

Oxygenated hemoglobin and deoxygenated hemoglobin absorb different amounts of red and infrared light

The pulsatile change in the blood volume causes periodic changes in the amount of red and infrared light absorbed by the vascular bed before reaching the photodetector.

Pulsatile change in red and infrared light detected by photodetector

3) Dual Wavelength Spectrophotometry

Uses visible light that is filtered and guided to the tooth by  fibreoptics.

Thus unlike Laser light, added eye protection is unnecessary for the patient and  the operator.

Noninvasive and yields objective results.

4) Measurement of Surface Temperature of Tooth

Pulp becomes nonvital, the tooth no longer has internal blood supply, thus should exhibit a lower surface temperature than that of its vital counterparts.

Fanibund in 1985 showed that it is possible to differentiate by means of crown surface temperature, distinct difference between vital and nonvital teeth.

5) Transillumination with Fiberoptic Light

It is a system of illumination whereby light is passed through a finely drawn glass or plastic fibers by a process known as total internal reflection.

By this method, a pulpless tooth that is not noticeably discolored may show a gross difference in translucency when a shadow produced on a mirror is compared to that of adjacent vital teeth

6) Plethysmography

Assessing the changes in volume and has been applied to the investigation of arterial disease because the volume of the limb or organ exhibits transient changes over the cardiac cycle.

The same principle can be used to assess tooth vitality. Presence or absence of a wave form can indicate the status of the tooth.

7) Radiation Probe Using Xenon Radioisotope

The tooth to be tested  injected with xenon in saline.

A lead shield  placed over the tooth and radiation counts taken every 10 seconds for 15 minutes, using a small cadmium telluride radiation probe.

Radiation counts detected from both vital and pulpless teeth

Pulpless teeth report relatively constant counts for the duration of the experiment (200-300).

In vital teeth the initial counts were much higher (718-981).