|Year : 2015 | Volume
| Issue : 2 | Page : 41-46
Pulp vitality tests - an overview on comparison of sensitivity and vitality
A Arun1, H Mythri2, Dale Chachapan1
1 Department of Conservative Dentistry, Sri Siddhartha Dental College and Hospital, Tumkur, Karnataka, India
2 Department of Public Health Dentistry, Sri Siddhartha Dental College and Hospital, Tumkur, Karnataka, India
|Date of Submission||03-Apr-2013|
|Date of Acceptance||05-Jun-2015|
|Date of Web Publication||11-Aug-2015|
Department of Public Health Dentistry, Sri Siddhartha Dental College and Hospital, Tumkur, Karnataka
Source of Support: None, Conflict of Interest: None
Pulp vitality testing is only one facet of oral diagnosis, which is crucial in monitoring the health of the dental pulp. A pain response to hot, cold, or an electric pulp tester indicates the vitality of only a tooth's pulpal sensory supply. Although the sensitivity of these traditional tests is high, the response does not give any idea about the state of the pulp. They often yield false-negative and false-positive response. The newer pulp testing considers the vascular supply is more important to determine the health of the pulp than the sensory supply. Hence, pulp testing has been always an 'overvalued' and 'underused' diagnostic aid. This article attempts to give a comprehensive view of all the tests based on sensitivity as well as vitality.
Keywords: Pulp vitality test, sensitivity test, laser, pulse oximetry
|How to cite this article:|
Arun A, Mythri H, Chachapan D. Pulp vitality tests - an overview on comparison of sensitivity and vitality. Indian J Oral Sci 2015;6:41-6
|How to cite this URL:|
Arun A, Mythri H, Chachapan D. Pulp vitality tests - an overview on comparison of sensitivity and vitality. Indian J Oral Sci [serial online] 2015 [cited 2017 May 25];6:41-6. Available from: http://www.indjos.com/text.asp?2015/6/2/41/162622
| Introduction|| |
The assessment of pulp vitality is a crucial diagnostic procedure in the practice of dentistry. ,,, Dental pulp tests are investigations that provide valuable diagnostic and treatment planning information for the clinician.  The determination of pulpal vitality or nonvitality can't be directly inspected because the pulp is enclosed within calcified barrier.  Therefore, indirect methods must be used to determine pulpal vitality. The three key uses of pulp testing in clinical practice according to Ehrmann are; ,
- Prior to operative procedures where pulp health may be in question
- Diagnosis of pain
- Investigation of radiolucent areas.
In addition to these, Mumford and Bjorn suggested three further uses such as, 
- Posttrauma assessment
- Assessment of anesthesia
- Assessment of teeth that have been pulp capped or required deep restoration.
Current routine methods rely on stimulation of A-delta nerve fibers and give no direct indication of blood flow (BF) within the pulp. These include thermal stimulation, electrical or direct dentine stimulation. They stimulate the pulpal nerves either by the flow of dentine liquor at temperature changes, which leads to movement of odontoblast process and subsequent mechanical stimulation of the pulpal nerves or by an electrical current conducted through the tooth, giving an electrical stimulation of the pulpal nerves.  These testing methods have the potential to produce an unpleasant and occasionally painful sensation, and inaccurate results (false-positive or false-negative can be obtained in many instances). In addition, each is a subjective test that depends on the patient's perceived response to a stimulus as well as the dentist's interpretation of that response. 
Chambers suggested that the technique for evaluation of dental pulp status must be simple, objective, standardized, reproducible, nonpainful, noninjurious, accurate, and inexpensive way of assessing the exact condition of the pulp tissues at any given time. Unfortunately, the traditional methods fall short of nearly all the above criteria.  From a technical perspective, all current tests have shortcomings, especially in terms of accuracy, reliability, and reproducibility.  From a technical perspective, all current tests have shortcomings, especially in terms of accuracy, reliability, and reproducibility.  But, recent studies have shown that blood circulation and not innervation is the most accurate determinant in assessing pulp vitality as it provides an objective differentiation between necrotic and vital pulp tissue. 
So, this paper attempts to review the newer pulp vitality testing methods along with the traditional sensory methods and highlights the advantages and disadvantages of each test.
| Insight to Older Concepts|| |
Diagnostic methods that assess the nerve supply (sensitivity)
The application of heated water (hot water bath) or softened, heated Gutta-percha to the tooth is commonly used to deliver heat to the pulp. These methods may produce sufficient heat to stimulate the C fibers and produce pain that lingers, is prolonged and is usually delayed about 2-4 s. It is important to use heat cautiously to avoid any damage to the pulp tissue. ,
Several methods are used to apply cold to the teeth, such as ice sticks (0°C), CO 2 sticks (−78°C), ethyl chloride (−5°C) and refrigerant spray, dichlorodifluoromethane (DDM−50°C). Fuss and others, who assessed the reliability of thermal tests and electrical tests for adults and young patients, found that CO 2 and DDM are more effective than ice and ethyl chloride. CO 2 produces a greater decrease in pulp temperature than DDM and a quick response from the pulp. This greater decrease in temperature has no detrimental effect on the pulp tissue. ,
Electric pulp tester
The electric pulp tester (EPT) is widely used to differentiate between lesions of endodontic origin and those not seen on radiographs. This device is designed to deliver an electric current to stimulate the closest myelinated A-delta fibers; the device does not usually stimulate the unmyelinated C fibers because of their higher threshold. The EPT indicates the neural transmission and presence of vital nerve fibers but does not measure the health or integrity of the pulp. Recently traumatized teeth that may temporarily lose their sensory function have no response to the device, even though their vascularity is intact (false-negative) whereas teeth that are partly necrotic may give a response, even though they lack a blood supply (false-positive). ,
Location of the electrode was crucial and various responses showed placement of electrode in the incisal one-third, occlusal one-third of the buccal surface and centered between gingival margin and occlusal edge.  Recent studies showed placing the electrode more apically and to the center of the supporting cusps showed an increase in the threshold response level. These results were related to the presence of pulp horns, where there is a high concentration of neural elements.  EPT remains an important aid and when properly used, it is a safe clinical test that can provide useful information regarding health and disease. 
Test cavity preparation
This test may serve as a last resort in testing for pulp vitality. It is only considered when the results of all other tests have proved inconclusive. Its value in clinical practice has been largely anecdotal as there is no evidence base to support its effectiveness. The test cavity is made by drilling through the enamel-dentine junction of an unanesthetized tooth with good isolation. This may be achieved under rubber dam with a small round diamond bur in a high-speed handpiece with adequate coolant. The patient is asked to respond if any painful sensation is felt during the drilling procedure. If the patient feels pain once the bur contacts the sound dentin, the procedure is terminated, and the cavity is restored.
Local anesthetic test
When dental symptoms are poorly localized or referred, an accurate diagnosis is extremely difficult. Sometimes, patients may not even able to specify whether the symptoms are from the maxillary or mandibular arch. In such cases, and where pulp testing has proved inconclusive, an anesthetic test may be helpful. The technique is as follows: Using either infiltration or an intraligamentary injection, the most posterior tooth in the area suspected of causing the pain is anaesthetized. If pain persists once the tooth has been fully anesthetized, the tooth immediately mesial to it is then anaesthetized, and so on, until the pain disappears.
If the source of the pain cannot be even localized to the upper or lower jaw, an inferior alveolar nerve block injection is given; cessation of pain indicates involvement of a mandibular tooth. This approach has an advantage over a test cavity, which may incur iatrogenic damage.
Validity of sensitivity tests
- Sensitivity: It is The proportion of cases identified correctly by means of the diagnostic test
- Specificity: It is The proportion of noncases identified correctly by means of the diagnostic test
- Positive predictive value (PPV): It is The proportion of positive test results that are cases
- Negative predictive value (NPV): It is The proportion of negative test results that are noncases.
The validity of any diagnostic test is the best described by its sensitivity and specificity, whereas its clinical usefulness is described by its positive predictive value (PPV) and negative predictive value (NPV): ,
Comparison among sensitivity (thermal, cold, and electrical) tests
Establishing an accurate and expedient diagnosis is one of the most important and sometimes difficult situations for the clinician treating a patient with traumatized teeth. 
Studies have shown that cold test is more reliable than EPT,  and EPT was reliable in concussion injuries. , While EPT is a valuable test, no single technique can reliably interpret and diagnose all pulpal conditions. In adults, both cold testing and EPT accurately diagnose pulp vitality in 80% of the cases. 
Limitations of sensitivity tests
As response to these tests indicates only that sensory fibers are vital. However, 10-16% of the results of these tests are false. The nervous system, which is highly resistant to inflammation, may remain reactive, even though all surrounding tissues have degenerated; therefore testing the sensory supply may give a positive response when the pulp is damaged (i.e., a false-positive result). This test may also leave the patient with an unpleasant sensation. A false-negative result (i.e., no response) may be obtained in cases of calcific metamorphosis, recently traumatized teeth and incomplete root formation. 
These limitations may be due to,
- Tissue vitality versus nerve vitality
- Lack of correlation with the histological condition of the pulp
- Lack of objectivity
- Lack of reproducibility
- Unpleasant sensation
- Effect of maturation status of the tooth
- Effect of trauma
- Multi-rooted teeth
- Effect of drugs
- Age influence
- Effect of periodontal disease.
| Importance of Assessing the Blood Supply as an Indication for Pulp Vitality|| |
All these limitations of the sensitivity made the vitality of the pulp to be determined according to the health of the vascular supply. The tests for pulpal sensitivity do not always reflect the degree of pulpal disease but serve as a guide or an indication of the degree of vitality through responses under certain circumstances. 
| Diagnostic Methods to Assess the Blood Supply|| |
To determine the vitality of a pulp, the ideal tests should be objective, painless, and reliable.  Several experimental methods have been used to evaluate pulpal circulation. These include invasive techniques such as, radioisotope clearance, local hydrogen-gas desaturation, and noninvasive methods such as laser Doppler flowmetry (LDF), pulse oximetry, dual wavelength spectrophotometry (DWLS), photoplethysmography, and measurement of surface temperature. ,
They rely either on:
- The detection of changes in the light absorption as it passed through the tooth, as in photoplethysmography, pulse oximetry, and DWLS
- The shift in light frequency as it is reflected back from a tooth, as in LDF. 
| Dual Wavelength Spectrophotometry|| |
DWLS is a method independent of a pulsatile circulation. The presence of arterioles rather than arteries in the pulp and its rigid encapsulation by surrounding dentine and enamel make it difficult to detect a pulse in the pulp space. This method measures oxygenation changes in the capillary bed rather than in the supply vessels and hence does not depend on a pulsatile BF. 
Even though the instrument was not specifically designed for dental use, it can be developed as a pulp tester. A major advantage is that it uses visible light that is, filtered and guided to the tooth by fiber optics. Thus unlike laser light, added eye protection is unnecessary for the patient and the operator. The test is noninvasive and yields objective results. 
The instrument is small, portable, relatively inexpensive, and suitable for use in a private dental office. This instrument may be useful for determining pulp necrosis and the inflammatory status of the pulp. Pulse oximetry is a method based on DWLS. 
| Pulse Oximetry|| |
The pulse oximeter is a well-accepted, noninvasive oxygen saturation monitoring device ,, widely used in medical practice for recording blood oxygen saturation levels during the administration of intravenous anesthesia.  It contributes to the increased safety of general anesthesia. , Pulse oximetry is an entirely objective test, requiring no subjective response from the patient.  It was invented by Takuo Aoyagi in 1974. , The principle of this technology is based on a modification of Beer's law, ,, a determination of the fraction of HbO 2 to total functional hemoglobin is performed using an algorithm built in microprocessor of the device. The SaO 2 is calculated and displayed as a percentage value onscreen. 
The system consists of a probe containing a diode that emits light in two wavelengths:
- Red light of approximately 660 nm
- Infra-red light of approximately 850 nm.
A silicon photodetector diode is placed on the opposing surfaces of the tooth, which is connected to a microprocessor. The probe is placed on the labial surface of the tooth crown and the sensor on the palatal surface. Ideal placement of the probe is in the middle third of the crown. If placed in the gingival third, disturbances from gingival circulation or any gingival trauma or bleeding will interfere with the readings. Incisally, less of pulp tissue is present for adequate detection of the pulse. 
A number of clinical studies have proved that the pulse oximetry is an effective and objective method of evaluating dental pulp vitality ,,,,,,,,,, in primary as well as permanent teeth.  This estimates the arterial oxygen saturation of the hemoglobin (SaO 2 ) by measuring the light absorbance of pulsatile vascular tissue at two wavelengths. , Though the surrounding insulation of the enamel and dentine are hindrances to the detection of a pulse in the pulp, it has proved to be a successful method in 70% of the clinical trials and further work is still in progress.  It is also useful in cases of impact injury where the blood supply remains intact, but the nerve supply is damaged.  Also, current results indicate that pulpal circulation can be detected by the pulse oximeter independent of gingival circulation. Smaller and cheaper commercial oximeters are now available for routine clinical use in an average dental office.  It is called as a "sleep on the cheap" because it generates significant data at a lower cost. 
Despite its advantages, limitations include background absorption associated with venous blood and tissue constituents,  excessive carbon dioxide in the blood stream interfering with deoxygenated hemoglobin.  The critical requirement is the sensors that should conform to the size, shape, and anatomy of the tooth. ,
| Laser Doppler Flowmetry|| |
LDF is a noninvasive, electro optical technique, which allows the semi-quantitative recording of pulpal BF. ,, Its use in teeth was first described in 1986.  Since then, the technique has been widely used to monitor dynamic changes in pulpal BF in response to pressure changes and following administration of local anesthesia.  The Laser Doppler technique measures BF in the very small blood vessels of the microvasculature. 
The technique depends on the Doppler principle whereby light from a laser diode incident on the tissue is scattered by moving red blood cells and as a consequence, the frequency broadened. The frequency broadened light, together with laser light scattered from static tissue is photo detected and the resulting photocurrent processed to provide a BF measurement. The Doppler shifted laser light, back-scattered out of the tooth is detected by a photocell on the tooth surface. The output is proportionate to the number and velocity of the blood cells. ,
LDF has been shown to be valuable in monitoring revascularization of immature incisors following severe dental trauma. LDF was also used to assess gingival BF in flaps after ridge augmentation and during Le Fort I osteotomy and to assess BF in intact teeth in animals and in man. 
Many studies were carried out to compare LDF with conventional pulp tests, EPT and thermal tests, in children with certain dental injuries which showed that LDF was significantly better at 3, 6, and 12 months compared to others.  It identified more vital and nonvital teeth correctly at earlier time periods following injury than conventional tests.  In young children whose responses are unreliable and its noninvasive nature helps to promote patient co-operation and acceptance. , Increased laser power enhances its useful in monitoring BF and assessing pulp vitality. 
The limitations of this method include a too expensive device for use in a dental office. , It is technique-sensitive: Its readings are affected by the movement of the patient, a nonfixed probe or a mobile tooth. ,, It takes about an hour to produce recordings, making it impractical for dental practices.
The technique yields false-positive results when used for endodontically treated teeth and when the gingival BF is measured. Moreover, intracoronal and extracoronal scattering of the laser beam calls for special precautions such as covering the gingiva and the crown of the tooth. 
| Comparison Among Sensitivity Versus Vitality Tests|| |
Pulse oximeter gave constant positive vitality reading compared to thermal and EPT methods , and considered more reliable compared to EPT and cold test. 
The perfect diagnostic test would always be positive in the presence of disease and negative in the absence. The concepts of sensitivity, specificity, PPV, and NPV have developed to check the accuracy. The ideal method would have sensitivity and specificity of 1.0. LDF was found to be more reliable and effective method than Pulp oximetry and EPT especially where conventional methods are of compromise. 
| Surface Temperature Measurement|| |
The concept of diagnosing tooth vitality by temperature measurement can provide valuable information on the integrity of the underlying pulp. Howell et al. used liquid cholesteric crystals and found that nonvital teeth have lower temperature than vital teeth. Fanibund in 1985 concluded from a laboratory study that it is possible to differentiate by means of crown surface temperature, distinct differences in vital and nonvital teeth. The feasibility of temperature measurement as a diagnostic procedure in human teeth was again demonstrated in 1986 by Fanibunda. Further research is being undertaken with the sole aim of increasing the detectable difference between vital and nonvital teeth, so that a method of temperature measurement may be evolved which is of diagnostic significance under routine clinical conditions. 
| Other Noninvasive Testing Modalities|| |
- Transilliumenation with fiber optic light
- Ultraviolet light photography
- Transmitted laser light
- Detection of interleukins
- Gas desaturation
- Radiolabeled microsphere
- Electromagnetic electrometery
- Hughes probeye camera. 
| Conclusion|| |
The unreliability of testing tooth pulp nerve response is well documented. When nervous sensations are inhibited or abolished in the tooth, conventional tests are of little value. However, a method based on the vascular response of the pulp need not be restricted under such conditions. Recording the pulpal BF would be an objective assessment of the status of the pulpal blood circulation, a true indicator of pulp vitality. They offer the advantages of being objective, noninvasive and atraumatic testing modalities, which result in greater patient acceptance and co-operation.
Attempts at measuring the true pulp BF clinically had mixed success, with LDF being one of the popular techniques. Currently, no vitality tests have been proven to be superior in all aspects compared to pulp sensitivity tests.  Hence, sensitivity testing even with its limitations has been and remains a very helpful aid in endodontic diagnosis.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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