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Pulpal Diagnosis
Johnah C. Galicia1 and Asma A. Khan2
1 College of Dentistry, Manila Central University, EDSA‐Monumento, Caloocan City, Philippines
2 Department of Endodontics, School of Dentistry, UT Health San Antonio, San Antonio, TX, USA
Introduction
Over the last few years, there has been a significant shift towards maintaining the dental pulp (1–4). From a research perspective, this push can be viewed as a triumph resulting from years of data gathering to understand the biology of the dental pulp.
To practice a conservative approach in the treatment of pulpitis, an accurate diagnostic method that is quick, non‐invasive and quantifiable should be available for chairside use. This test should be able to stage pulpal inflammation accurately, ideally identifying the threshold between pulp tissue that can be saved and tissue that cannot. However, clinicians have had to rely on tests that have been shown over decades to correlate poorly with the histopathology of the pulp (5–9).
The current diagnostic techniques using thermal and electric pulp testers have good sensitivity and specificity in eliciting a positive response on teeth with vital tissues (10, 11). The lingering predicament with these tests is their inability to stage the severity of pulpal disease. In teeth with vital pulp tissue, eliciting a reliable and unambiguous response using these tests is often achieved without too much complexity. The problem lies in determining the extent of inflammation, which these tests cannot decipher. Another concern with the currently used clinical sensibility tests like thermal and electric pulp testing (EPT) is the purpose that these tests were designed for. Rather than measuring blood flow, which is the hallmark of tissue vitality, these tests stimulate nerves. An assumption is made that a positive response to these tests means that vital pulp tissue remains; however, it has been suggested that nerve tissue can remain even after necrosis of the pulp tissue and associated blood vessels (12). In this scenario, a positive response to EPT or cold is a misleading measure of pulp vitality. A more common misleading scenario is of teeth which have recently been traumatized and do not respond to cold or EPT, even though the pulp is vital and a blood supply remains.
Advocates of vital pulp treatment (VPT) and minimally invasive endodontics strongly support a change in diagnostic terminology to better reflect the extent of pulpitis (2). With currently available terminologies, the fate of the dental pulp is categorically dictated by the clinician’s educated interpretation of the patient’s subjective description of the sensation elicited by the tests. Traditionally, the dental pulp can either be kept intact or removed entirely based on the diagnostic terminology emanating from the results of the tests (13). Future efforts should be shifted towards developing non‐invasive, biologically‐based pulpal diagnostic techniques that accurately measure the extent of pulpal inflammation and towards introducing diagnostic terminologies that favour conservative treatment of the dental pulp.
Diagnoses of Pulpal Status and Their Associated Diagnostic Terminologies
Medical diagnosis is the process of determining which disease or condition explains a person’s symptoms and signs, but for pulpitis, this is not exactly the same. Although it is an inflammatory disease, generally caused by bacterial infection, the diagnosis of pulpitis has remained a conundrum for reasons including the anatomical location of the dental pulp and limitations of current diagnostic tools (14, 15). Over the years, different classifications and diagnostic systems have been advocated for pulpitis, reflecting the challenges and lack of consensus amongst experts (12). Although histology is the gold standard in diagnosis, attempts to classify pulp disease based on histology and symptoms failed due to the lack of correlation (7, 9) and because the pulp must be removed in order to examine it histologically. A more pragmatic approach based on signs and symptoms was introduced, and a different classification was proposed (12). The American Association of Endodontists (AAE) called for a consensus on classification and terminology used for pulp disease that resulted in the current widely used classification (13). This classification describes pulpitis as reversible, indicating that the inflammation should resolve following appropriate management, or irreversible, indicating that the inflamed pulp is considered incapable of healing and for which root canal treatment is indicated. These terms, however, do not take into consideration the current evidence showing that in carious teeth, pulpal inflammation and necrosis may be locally limited to the pulpal tissue adjacent to the carious lesion, while the rest of the pulp remains relatively normal (6). Furthermore, an improved understanding of pulp biology provides evidence of the regenerative capabilities of the pulp. We now know that pulpal inflammation is part of the healing response of the pulp to infectious or noxious stimuli. With the advent of hydraulic calcium silicate cement materials, VPT can be used to predictably save at least part of the pulp in teeth which were preoperatively diagnosed with “irreversible pulpitis” (16, 17).
For these reasons, calls have been made to revise the existing pulpitis terminology and a proposed classification in which the level of pulpitis was graded and described as mild, moderate and severe was introduced (2). This new classification proposed for the first time VPT as an option for treating different stages of pulpits and that root canal treatment can be reserved for cases with advanced pulpal inflammation in which pulpal haemorrhage cannot be controlled during the operative procedure. The classification, however, needs to be validated, and results from recent studies showed that preoperative symptoms could be used to predict the outcome that teeth with moderate pulpits can be successfully treated with partial pulpotomy compared with teeth with severe pulpitis (18) (Table 3.1).
The Diagnostic Process
Obtaining an accurate diagnosis is essential for the provision of appropriate treatment. The pulpal diagnostic process requires the gathering of information via detailed history taking, followed by thorough clinical examination and application of special investigations. The objective of pulpal diagnosis is to determine the condition of the dental pulp, i.e. not just in an absolute sense (vital versus non‐vital), but also the degree of pulp inflammation if present.
Table 3.1 Current classifications systems of pulpitis.
| Wolters et al. 2017 | Hashem et al. 2015 | AAE 2013 |
|---|---|---|
| Initial pulpitis Heightened but not lengthened response to the cold test, not sensitive to percussion and no spontaneous pain Mild pulpitis Moderate pulpitis Severe pulpitis |
Mild reversible pulpitis Patients’ descriptions of sensitivity to hot, cold and sweet lasting ≤15–20 seconds and settling spontaneously Severe reversible pulpitis Irreversible pulpitis |
Reversible pulpitis Discomfort is experienced when a stimulus such as cold or sweet is applied and goes away within a couple of seconds following the removal of the stimulus Symptomatic irreversible pulpitis Asymptomatic irreversible pulpitis |
Pain History
Obtaining a detailed pain history is an important component of patient assessment and the overall diagnostic process. The mnemonic OPQRST is commonly used in the medical field and can easily be adapted to dental pain as well. In this mnemonic, O stands for onset of event, P stands for palliation/provocation, Q is quality, R is region/radiation, S is severity and T is time when the pain started. Patients who have inflamed pulps may present with a chief complaint of spontaneous pain or one that is only elicited by cold or hot stimuli. Although subjective, the nature, duration and onset of pain are important factors that can help determine whether pulpitis is reversible or irreversible. Severe pain (19), history of previous pain (20) and presence of spontaneous pain (6, 20) have been considered to be poor prognostic factors and often associated with severe inflammation suggestive of irreversible pulpitis. On the other hand, non‐spontaneous pain in response to thermal changes often indicate reversible pulp inflammation.
Pain can be reported as a symptom in the patient history but can also be elicited as a sign during clinical examination. For example, tenderness to percussion and pain on thermal stimuli can be of diagnostic value. In cases where the patients have severe spontaneous pain, the resulting afferent barrage results in central sensitization (increased responsiveness of neurons of the central nervous system) and referred pain, making diagnosis challenging. This was elegantly demonstrated in a clinical study in which patients presenting for endodontic treatment were asked to localize the symptomatic tooth (21). Patients who did not have percussion sensibility (i.e. those who only had pulpal pain) were less likely to accurately localize the right tooth as compared to those who had percussion sensitivity (30% versus 89.1%). Notably, in patients who did not have percussion sensitivity, the pain intensity was inversely correlated with the patients’ ability to accurately localize the right tooth (21).
Relying on only pain symptoms for diagnosis can be misleading. It should be emphasized that pain is subjective, and pulpitis can be painless in approximately 40% of cases (22), while it was also shown that 40% of cases with salvageable pulps were associated with pain (19). In addition, most patients who presented with a toothache usually have odontogenic pain (and not pain referred to the teeth from a non‐odontogenic source). However, astute clinicians understand that non‐odontogenic pain can also be perceived by the patient as a toothache. These sources of non‐odontogenic pain include the muscles of mastication, temporomandibular joint, maxillary sinus and cardiac tissues (23–25).
Pulp Sensitivity/Sensibility Testing
The patient’s response to pulp sensibility tests plays a critical role in determining the diagnosis and subsequent treatment. However, the lack of standardized methods for performing these tests results in unpredictable results and misinterpretation. Commonly performed sensibility tests are done with thermal (cold and heat) or electrical stimuli. Cold testing is often done using refrigerant spray (1,1,1,2‐tetrafluoroethane), and there are many variations in how the test is performed (for example, the size of the cotton pellet, how long the pellet is applied for, the location where the cotton pellet is placed, etc.). This noxious cold stimulus is not physiological and elicits a painful response, which is subjectively reported by the patient. The interpretation of the patients’ response by the clinician is neither quantitative nor is objective. There continues to be a lack of a uniform consensus on what constitutes an exacerbated and/or lingering response as compared with a so‐called ‘normal’ response. Heat is used less commonly to determine pulpal status, being only used when the chief complaint is that hot foods elicit pain or as a test of last resort. This test is commonly done after isolation with a dental dam and by rinsing the tooth with hot water or using a rubber wheel to generate heat. Unfortunately, there is a lack of consensus regarding the ideal temperature or duration of the stimulus. Electrical pulp testing (EPT) is another common diagnostic test that is recommended for routine use in combination with thermal tests (26). This non‐physiological stimulus is essentially used to determine the responsiveness of the nerves innervating the pulp. It cannot be used to detect the presence or extent of inflammation.
Diagnostic Accuracy of Sensibility Tests
The ability of sensitivity tests to accurately determine the vitality of the dental pulp and, to some degree, the pulpal condition has been summarized in a recent systematic review (14)
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