Pulp Testing: Endodontics HY Notes

• Pulp testing determines the responsiveness of pulpal sensory neurons.
• Tests involve thermal or electrical stimulation of a tooth to obtain a patient’s subjective response.
• Objective tests can also be used to assess the integrity of the pulpal vasculature.
• Histological examination is necessary for a quantitative evaluation of pulp tissue status.
• Objective clinical signs and symptoms do not always correlate well with pulpal histology.

Thermal pulp testing

Cold Testing:

• Normal response: Sensation felt but disappears upon removal of the cold stimulus.
• Abnormal responses: Lack of response, lingering or intensified pain after stimulus removal, or immediate, excruciating pain upon stimulus placement.
• Frozen carbon dioxide (dry ice) or refrigerant spray are reliable methods for cold testing.
• Frozen carbon dioxide is effective for evaluating pulpal response in teeth with full coverage crowns when other tests like electric pulp testing are not possible.
• CO2 stick is prepared by delivering CO2 gas into a plastic cylinder and applied to tooth surface.
• Refrigerant spray is applied to a large cotton pellet placed on the tooth.

Heat Testing:

• Useful when patient complains of intense dental pain upon contact with hot substances.
• When a patient is unable to identify which tooth is sensitive, a heat test is appropriate
• Isolate each tooth with a rubber dam and use an irrigating syringe to apply liquid of similar temperature.
• Immediate, intense painful response indicates the offending tooth.
• Delayed response may occur, so waiting 10 seconds between tests is recommended.
• Heated gutta-percha or compound stick can be used, with lubricant applied to prevent adherence.
• Electronic heat-testing instruments are also available.

Complementary Tests:

• Cold and heat testing should be used in conjunction with electric pulp testing for verification.
• Lack of response to both cold and electric pulp testing in a mature, nontraumatized tooth indicates pulp necrosis.

Clinical Application:

• Heat testing helps identify sensitive teeth when the specific tooth is unknown.
• Cold application can alleviate pain and aid in diagnosis for teeth sensitive to heat.
• Tooth responding to heat and relieved by cold is typically necrotic.

Electric Pulp Testing

• Electric pulp testing assesses pulp vitality by measuring the response to electric stimulation.
• Vitality is determined by the health of the vascular supply, not the status of nerve fibers.
• Electric pulp testers should be part of dental practice, but blood supply-based vitality determination is not yet perfected for routine use.
• Limitations of electric pulp testing: Response does not reflect histologic health, only indicates presence of viable nerve fibers.
• Numeric readings are significant if significantly different from control tooth readings.
• Lack of response to any electric current often indicates necrotic pulp.
• False-positive and false-negative responses can occur, influencing the diagnosis.
• Proper use requires tooth isolation, drying, and coating the probe tip with a medium like toothpaste.
• Testing involves placing the coated probe on the incisal third of the tooth’s facial or buccal area and completing the circuit with patient touch or lip clip.
• Electric pulp testing can be limited by the inability to complete the circuit when wearing rubber gloves for infection control.
• Some electric pulp testers require patients to place their finger(s) on the probe to complete the circuit, while lip clips can serve as an alternative.
• Isolating and drying the evaluated teeth is crucial for accurate electric pulp testing.
• A control tooth of similar type and location should be tested first to establish a baseline response.
• The suspected tooth should be tested at least twice to confirm results.
• Bridging technique can be used for teeth with complete coverage crowns or extensive restorations.
• Sensitivity and specificity vary among thermal and electric pulp testing methods.
• Cold tests are more reliable in younger patients with less developed root apices.
• Results should be verified and compared with other testing methods.
• Thermal and electric pulp testing will continue until vascular supply assessment methods improve.

Laser Doppler Flowmetry

• Laser Doppler flowmetry (LDF) assesses blood flow in microvascular systems.
• Adaptation of LDF technology is being explored to assess pulpal blood flow.
• A diode projects an infrared light beam through the tooth crown and pulp chamber.
• The scattered infrared light beam’s frequency shift indicates the velocity of moving red blood cells using the Doppler principle.
• LDF has been found to be accurate, reliable, and reproducible in assessing pulpal blood flow.
• Objective data are collected, eliminating reliance on subjective patient responses.
• LDF is particularly useful in cases of luxation injuries where electric and thermal pulp testing may be inaccurate.
• Despite its effectiveness, routine use of LDF in dental practice is not common.

Pulse Oximetry

• Pulse oximeter is a noninvasive device used to measure oxygen concentration in the blood and pulse rate.
• It transmits red and infrared light through a translucent body part (e.g., finger, earlobe, tooth) and detects the absorbed light on the opposite side.
• Microprocessor calculates pulse rate and oxygen concentration based on the difference between emitted and received light. (ref)
• Obstruction from restorations can limit the effectiveness of pulse oximetry for pulp vitality testing.
• Custom-made sensors have been developed and found to be more accurate than electric and thermal pulp tests.
• Useful for evaluating teeth with traumatic injuries, especially in the short term.
• Studies on pulse oximetry for pulp vitality diagnosis yield mixed conclusions.
• Some studies support its reliability, while others suggest current technology limitations.
• Cumbersome and complicated devices for pulp testing hinder routine use in dental practice.

Bite Test

• Percussion and bite tests are performed when a patient experiences pain while biting.
• These tests help to determine the specific tooth causing the pain when the patient is unsure.
• Sensitivity during biting can be due to pulpal pathosis extending into the periodontal ligament space (symptomatic apical periodontitis) or a crack in the tooth.
• Periradicular periodontitis will elicit pain during percussion and bite tests, regardless of the applied pressure on the coronal part of the tooth.
• A cracked tooth or fractured cusp will typically cause pain when pressure is applied in a certain direction to a specific cusp or section of the tooth.
• Devices such as cotton tip applicators, toothpicks, orangewood sticks, rubber polishing wheels, Tooth Slooth, and FracFinder can be used for the bite test.
• Adjacent and contralateral teeth should serve as controls to determine the normal response to the tests.
• During the bite test, a device is placed on the cusp to be tested, and the patient applies biting pressure to the opposite side of the device’s flat surface.
• Biting pressure should be applied slowly until full closure, maintained for a few seconds, and then released quickly.
• Each cusp can be tested individually.
• The clinician should observe whether pain is elicited during the pressure phase or upon quick release of the pressure.
• Pain upon release of biting pressure is commonly associated with a fractured cusp or cracked tooth.

Test Cavity

• The test cavity method is an invasive and irreversible test used as a last resort when other tests are not possible or inconclusive.
• It is typically employed when a tooth with a full coverage crown is suspected of having pulpal disease.
• If electric pulp tester and cold test results are inconclusive and bridging techniques are not applicable, a small class I cavity is prepared through the occlusal surface of the crown.
• The procedure is performed without anesthesia, and the patient is asked to report any painful sensations during drilling.
• If pain is felt upon reaching sound dentin, the procedure is stopped, and the class I cavity is restored. This indicates the presence of viable nerve tissue in the pulp but does not confirm complete pulp health.
• If the patient does not feel any sensation when the bur reaches the dentin, it suggests pulp necrosis, indicating the need for root canal therapy.

Staining and Transillumination

Staining:

• Staining is useful for detecting surface cracks in teeth.
• Methylene blue dye is commonly used, applied with a cotton tip applicator.
• The dye penetrates into cracked areas, indicating the possible location of the crack.
• Excess dye can be removed with 70% isopropyl alcohol.

Transillumination:

• Transillumination involves using a bright fiberoptic light probe on the tooth’s surface.
• Directing the light at the cementum-enamel junction (CEJ) can reveal the extent of the fracture.
• Fractured teeth block transilluminated light, causing the affected area to appear gray compared to the glowing area proximal to the light source.
• While dyes and transillumination can detect the presence of a fracture, they may not provide information about the depth of the fracture.

Selective Anesthesia

• Selective anesthesia is useful when symptoms are not localized or referred, making diagnosis challenging.
• If the patient cannot specify the arch causing the pain, the maxillary arch is selectively anesthetized first.
• Periodontal ligament (intraligamentary) injection is administered starting from the distal sulcus of the most posterior tooth in the suspected quadrant.
• Anesthesia is then administered anteriorly, one tooth at a time, until the pain is eliminated.
• If the pain persists, the same technique is repeated on the mandibular teeth.
• Periodontal ligament injections may also anesthetize adjacent teeth, making them more helpful in identifying the arch rather than a specific tooth.

Reference:

1. Cohen’s Pathways of the Pulp; 11th Edition; by Louis H. Berman DDS FACD (Author), Kenneth M. Hargreaves
2. Grossman’s Endodontic Practice; 14th Edition