Tooth Pulp Research Methods

Methods for studying tooth pulp are used to determine the health status of tooth pulp. Diagnostic information obtained as a result of testing dental pulp is used together in combination with anamnesis , clinical and radiological data to determine the diagnosis and prognosis of treatment.

Studies of tooth pulp (IPZ) is applicable for the following procedures in dentistry:

• diagnostics of endodontic pathology
• tooth pain localization
• the difference between odontogenic and non odontogenic pain
• assessment of pulp after tooth injury
• establishing the health of the pulp before prosthetics .

Tests can be performed by stimulating the sensory fibers inside the pulp (sensitivity test) or by evaluating the pulpal blood flow (viability test). It is reported that all available methods have limitations in terms of accuracy and reproducibility and therefore require careful interpretation in clinical practice ^[2] .

A sensitivity test evaluates the tooth's sensory response to an external irritant, the results of which can be extrapolated to indirectly determine the health status of the pulp . Sensory stimuli (heat, cold, or electric current ) are used to stimulate nociceptors inside the pulp. The response of the patient depends on the stimulus used. Sensitivity testing is based on the hydrodynamic theory of Brannström according to which the activation of nocireceptors is caused by the movement of fluid within the dentinal tubules in response to thermal, electrical, mechanical or osmotic stimuli ^[3] .

Indicators

There are three main results of the pulp sensitivity test.

• The norm: that a healthy pulp will react to testing causing a short, sharp pain that passes when the stimulus is removed, indicating the presence of nerve fibers and their response.
• Long answer: this result indicates a certain degree of pulp inflammation. If the pain is pronounced, but subsides after the stimulus has been removed, a diagnosis of reversible pulpitis is likely. However, the prolonged pain that is present despite the removal of the stimulus indicates irreversible pulpitis.
• No response: lack of response to sensitivity suggests that the nerve supply of the tooth has decreased, as in the case of necrosis of the pulp or in previously treated root canals.

Effect of temperature changes

Includes exposure to the tooth with hot or cold irritants, is the most common form of sensitivity test. For carrying out such tests, various irritants are available to the dentist, the most accessible of which is ordinary ice (0 ° C) ^[4] . Despite the clear advantages in price and availability, it does not guarantee the necessary diagnostic accuracy. Dry ice (-78 ° c) has much better performance, but there are concerns about its effects on such products with such a low temperature in the mouth (despite evidence of the absence of a negative effect on the mucous membrane or structure of the tooth). Chloroethane (-12.3 ° C), 1,1,1,2- tetrafluoroethane (-26.5 ° C) or the gas mixture propane / butane / isobutane is also used in this test (in nebulizers). It is assumed that the cold test stimulates type A fibers in pulp tissue, which cause short acute pain ^[5] .

Heat tests include the use of heated instruments such as a ball probe or gutta percha . Such tests are used less frequently, since they are believed to be less accurate than cold tests, but are more likely to cause damage to the teeth and the surrounding mucosa .

Electrodontometry

Electrodontonometry (EOM) is widely used in modern medicine. In comparison with dental tissues, pulp is saturated with water (4-5% water), which makes it the best conductor of electric current in a tooth. According to the works of Professor LR Rubin, sensitive points are located on the tooth, from which irritation is caused at the lowest current strength. On the frontal teeth, these points are located in the middle of the cutting edge, and in the chewing teeth , on the top of the tuber. At these points, the reaction of the teeth will fluctuate in a radius from 2 to 6 mA ^[6] . Any other indicators below or above this level can be considered pathology . Reduced excitability can be observed in older people (due to age-related changes, often on the molars) ^[7] . In this case, it is necessary to orient in the premolars on the buccal, and in the molars - the cheek-medial tubercles. The EOM is carried out by applying a conductive medium (for example, toothpaste) on a pre-dried tooth and placing the tip of the probe of an electrical pulp tester on the surface of the tooth closest to the pulp horn. Then the patient must pass the end of the conductive probe to complete the contour and agree that he releases him when he feels tingling. The use of such tests is undesirable for patients with pacemakers . Care should be taken when using the electric pulp test on a tooth adjacent to metal restorations, as they can create electrical conductivity and produce false-negative results.

Biting Test

The patient is asked to bite a solid sterile object (cotton swab, toothpick ). Bite pain may indicate damage to the tooth.

Painkiller Test

Anesthesia of one tooth. If the pain continues, the procedure is repeated on the tooth, located mesially to the previously anesthetized tooth. If the desired effect was not achieved and the source of the pain was not identified, a similar procedure was performed on the opposite dental arch.

Cavity Education Test

This method is considered as a last resort if the results of the previous four tests were inconclusive. In this case, using high-speed burs without anesthesia, a small hole is drilled in the patient's tooth. If the patient claims that he felt pain during perforation , this indicates the preservation of the functions of the pulp. The pain arises during the passage of the dentin , which over time can partially recover. At the same time, the partially necrotized pulp will not reveal an excessively painful reaction. This invasive method is used extremely rarely due to the presence of a factor of psychological pressure on the patient.

Limitations in sensitivity tests

Possible obtaining of false-positive or false-negative results during the test. A false positive response occurs when the patient feels irritant despite the absence of sensory tissue in the test tooth. Such reactions may occur due to the innervation of the adjacent teeth, due to inadequate isolation of the test tooth, either in anxious patients or in multi-rooted teeth that have pulp tissue in one canal. False-negative results can be observed in newly injured teeth, also in teeth that have a significantly reduced pulp size due to the formation of tertiary or sclerotic dentin .

These tests determine the vascular supply of a tooth, which is a more accurate and reliable indicator of pulp health than sensitivity testing; however, conducting such tests in clinical practice is difficult because of the costs, time and equipment requirements.

Laser Doppler flowmetry method

A laser beam directed to the tooth follows the path of the dentinal tubules to the pulp ^[8] . Laser radiation is delivered to the tooth or gum through a light guide probe. The radiation scattered by red blood cells moving in the microvasculature undergoes a frequency change ( Doppler effect ) proportional to the speed of their movement. Radiation reflected from erythrocytes enters the analyzer for further processing via a light guide probe. At the output of the device, an analog signal is formed that is proportional to the amount of blood flow perfusion in the probed region. Special programs allow you to register an LDF gram and calculate microhemodynamic parameters ^[9] .

Pulse Oximetry

This method uses the difference in the absorption of red and infrared light by oxygenated and deoxygenated red blood cells in the blood circulation to determine the level of oxygen saturation (SaO2).

Two-Wave Spectrophotometry

Using light with two wavelengths sets the contents inside the pulp chamber.

• Borovsky E. V. et al. Therapeutic dentistry. - Moscow, 1998. - ISBN 5-225-02777-6 .