Pulp Vitality Tests literally means to check the vitality of the pulp tissue which helps in diagnosis and treatment planning. Vitality tests help in not only determining the vitality of the pulp but also to determine the pathological status of pulp. Among the various methods used pulp testing procedures are Thermal, electrical or direct dentine stimulation. Blood circulation is the most appropriate method to determine the vitality of the pylp as it provides an objective differentiation between necrotic and vital pulp tissue.
Objectives of Pulp Vitality Testing:
To assess health of pulp based on its qualitative sensory response prior to restorative, endodontic procedues.
To help in diagnosing the reason for oral pain and differentiate between Pulpal or Periodontal pain.
Help in Differentially diagnosing pulpal pathology vs periodontal pathology
To determine the status of the pulp after trauma to the tooth
To check status of tooth especially that has past history of pulp capping or deep restoration
Types of Pulp Testing Procedures:
1 Thermal test:
- Cold Test
- Heat Test
2 Electrical Pulp testing
3 Test Cavity
4 Anesthetic testing
5 Bite test
How are Responses to Pulp Testing used in determining condition of pulp:
Normal Pulp – Mild, transitory response to stimulation
Pulp Necrosis – No response to any type of test
Irreversible Pulpitis – Exaggerated and persistent pain response which is present even after removal of stimulus.
False Negative Response – Tooth shows no response even in Vital Pulpin conditions like – recently erupted tooth with open or immature apex. Recent trauma to the tooth leading to lack of nerve supply at the apical foramen or presence of inflammaory exudates around the apex which interfere with the nerve function. It is also seen in calcifications of the pulp which interferes in the nerve conduction.
Under Thermal test the application of heat and cold is used to note the response of pulp to the rapid temperature change.
Normal Response to Thermal test for a healthy pulp is – painful sensation on application but disappears immediately.
Abnormal Response to Thermal test for a Injured or infected pulp is – pain sensation persists even after the removal of stimulus (Cold or Heat)
Cold Test: It is the most commonly used test as cold causes contraction of the dentinal tubules which results in outward flow of fluid from tubules resulting in pain. Cold test helps in differentiating between reversible and irreversible pulpitis. In case of Irreversible Pulpitis the pain persists after removal of cold stimuli whereas in case of Reversible pulpitis the pain disappears on removal of stimuli.
Substances used in Cold test are – Ice piece, Ice Sticks, spray cold air directed towards the tooth, ethyl chloride can be used by dipping Ethyl chloride in cotton pellet and placing it on the tooth. Spray of Ethyl chloride after isolating the suspected tooth using a rubber dam. Frozen carbon dioxide or dry ice which is available in the form of stick, in case of a tooth covered with a Crown or restoration, Dry Ice can elicit a pulpal reaction because of its -78 degree centigrade. Dichlorodifluoromethane (Freon) and 1,1,1,2-tetrafluoroethane (-15 to -26 degree Centigrade) are also used as cold testing material.
Heat Test: It is mostly indicated when the patient complaints of dental pain when the particular tooth comes in contact with any hot food or liquid. The temperature to help in heat test is 65.5 degree centigrade or 150 degree F.
The various methods used for Heat test are – Directing Hot air to the tooth affected and note the patient response. Using a heating gutta-percha stick, place the heated stick on the affected tooth after applying petroleum jelly to it to prevent the stick from sticking to the tooth surface. The heated gutta-percha stick is placed at the junction of cervical and middle third of facial surface of tooth. The response of the patient is observed to determine the state of the tooth. Frictional force is used by applying a Rubber Polishing disc on Micromotor against the tooth surface and noting the response of the patient. Less useful procedure is to apply hot water (150 degree F or 65.5 degrees) from a syringe on to the isolated tooth to determine the pulp response. This is recommended in tooth with full coverage restorations or crowns. Heat a burnisher tip or heat the impression compound and apply it on the facial surface of the tooth to check the patients response. Use of Laser Beam (Nd:YAG laser) to stimulate the pulp.
Electric Pulp Testing: It helps in determining the condition of pulp by evaluating the condition of the pulp using electrical excitation of neural elements within the pulp. A positive response from the patient shows Vital Pulp while no response means a non-vital pulp.
The Pulp tester is the instrument used to determine the vitality of pulp using gradations of electrical current to excite the nerves and get a response. It follows the same principal as a Apex locator of working only when a full circuit is formed. So the patients finger should be placed on the metal electrode handle or by clipping a ground attachment to the patients lip.
Place the Pulp tested tip on the facial surface of the tooth after isolating it from the adjacent teeth, start the Pulp tester and slowly increase the current and ask the patient to raise their hand when they feel any sensation. The tester should be used 2-3 times to attain an average to know the response. There are many limitations of Electric Pulp tester and it is not as accurate as the Cold and Heat test.
Bite Test: It is helpful in identifying a cracked or fractured tooth. This test is done when the patient is complaining of sensitivity or pain on mastication. Sensitivity to biting is seen when the pulpal necrosis has extended to the periodontal ligament space. The materials used to bite on for Bite test are – cotton Swab, tooth pick or orange wood stick. Tooth Slooth is the commercially available for conducting bite test. Anyone of the item is placed between the suspected tooth and its controlateral upper or lower teeth and patient is asked to bite on it.
If pain is present on Biting – Apical Periodontitis which if pain is present on Release – cracked or fractures tooth.
Anesthesia Testing: It is used when we fail to identify the tooth which is painful with other diagnostic tests. Intraligamentary injection is given to the most posterior tooth in the maxillary or mandibular arch and each tooth is given an injection until the patient gets relief from pain.
Test Cavity: This should be the last test to be performed as we tend to cause damage to the tooth structure. The teeth are not anesthetized and a small cavity is prepared using a high speed aerotor with running water. If pain is felt while cavity preparation it indicates Vital Pulp if there is no pain then the cavity is extended till the pulp chamber followed by Root Canal Treatment.
Recent Advancements in Pulp Vitality Tests:
- Laser Doppler Flowmetry (LDF)
- Pulp Oximetry
- Dual wavelength spectrophotometry (DWLS)
- Measurement of temperature of tooth surface
- Transillumination with fiber optic light
- Detection of interluekin-q
- Hughes probeye camera
- Gas desaturation
- Radiolabeled microsphered
- Electromagnetic flowmetry
Radiograph is the final determination of the diagnosis of the tooth vitality or infection based on multiple radiographic features such as extension of caries to the pulp chamber, Periodontal ligament widening, periapical inflammation etc. Pulp Vitality test in Primary teeth also is recommended in Trauma to the tooth which is most common.