The final pulpal and periapical diagnosis is based on a synthesis of information collected from the patient’s history of the chief complaint, dental and medical histories, radiographs, sensibility, and clinical tests. The process is challenging since no single test can be considered definitive.

The clinician should have a keen ear capable of interpreting subtle clues in the patient’s narrative and be able to put the clues together with other diagnostic information. At the same time, the clinician must recognize false leads that can result in misdiagnosis and treating the wrong tooth or providing treatment that is not necessary. Tests provide information, but the critical part of the diagnostic process is the ability of the clinician to synthesize information into a rational meaningful complete picture.

There is more than one set of terms used to describe pulp and periapical pathosis. Terminology varies among different organizations to describe the pulp and periapical tissues. Variation in terminology can cause confusion during communication with other dentists (as can different dental numbering systems).

It must be understood that inflamed pulp tissue is in a dynamic state and may have more than one condition existing in the tissue at the same time. For example, underlying deep caries there may be an area of acute inflammation adjacent to chronic inflammation and/or necrosis all of which is in flux. These states may coexist asymptomatically for a long period of time or degenerate rapidly to total necrosis with or without pain. It has been clearly demonstrated that clinical symptoms do not correlate well with histologic findings [7, 9].

The dynamic state of the tissue can produce confusing results during sensibility testing. For example, a root canal may contain necrotic tissue but still have some neural tissue capable of conducting an impulse. In such cases a positive response to testing with cold or electric could mislead the clinician into a diagnosis of a normal responsive pulp. Similarly in a multi-rooted tooth, one root may contain responsive pulp tissue, while the other is completely necrotic. In that case, pulp testing would not indicate the presence of pulp necrosis.

The American Association of Endodontists (AAE) recently published (2012) a revised list of pulp and periapical diagnostic terms and definitions (Table 4.1). The terminology is useful in categorizing cases and their treatment. There are other pulp classifications, but the AAE provides the most recent revision available. There is no universal agreement concerning the validity of this terminology.

A major development in the field of pain physiology was the discovery of neuroplasticity in the late twentieth century. According to this concept, experiences like thinking, learning, and habits (addiction) can significantly change both the brain’s physical structure (anatomy) and its functional organization (physiology). Neuroplasticity has an obvious positive side, including all forms of learning and adaptive responses to injury or other personal experiences. However, it also can have a destructive effect due to negative experiences [3].

Neuroplasticity may explain expanded areas of patients’ perception of pain beyond what might be expected (i.e., the area of the body feeling pain is more extensive than that which was actually injured) or as chronic pain (i.e., the original injury or disease has resolved, but the pain remains and may even increase). Both of these are examples of a negative manifestation of neuroplasticity, which explains many previously misunderstood phenomena but also poses a significant management challenge for pain therapists and dentists. All dentists and physicians should appreciate the implications of neuroplasticity since it helps understanding their patients’ complaints of pain [3].

“Neuroplasticity” is a term that describes how the nervous system changes in response to painful and other stimuli. To understand this process, it is important to recognize that the simple model of a painful stimulus leading to a proportional response has been replaced by a much more complex model of nervous system behavior.

The following sections will amplify each of the diagnostic terms.

This highly subjective term is based on the history of the chief complaint as well as information drawn from radiographs and sensibility tests. A reversible pulpitis must be seen in the context of tissue in a dynamic state. There is no single diagnostic test that provides defining data about the exact histologic state of the pulp or its prognosis. The clinician must synthesize all available data including history of the pain, its severity, and the treatment plan. The patient’s narrative is extremely important.

Important questions for the patient include:

Radiographic findings may include the presence of decay, old pulp caps, large restorations, periodontal disease, all of which add to the picture. The patient’s response to the above questions, combined with diagnostic findings point the way to determining if the diagnosis is of odontogenic or non-odontogenic origin. It helps to clarify if there is reversible pulpitis, not requiring intervention, or requires treatment.

The clinician should explain his diagnosis and treatment plan to the patient and note that additional follow-up may be required.

A complaint of cold sensitivity after an operative procedure requires follow-up to determine if the symptom of cold sensitivity disappears, remains the same, or gets worse over days, weeks, or months. A particularly difficult question occurs when there is a persistent moderate level of pain that neither progresses toward less pain nor does not increase in severity. Clearly, there is a time period beyond which it is not reasonable to wait any longer to make a decision about treatment from patient to patient. There is no simple answer to the question of how long to wait, and the variables include patient’s dental history, severity of pain, and the ultimate treatment plan.

For example, if the tooth in question is to be restored with a crown, there should be no question about the status of the pulp when the restoration is completed and ready to be cemented. If moderate pain persists over a number of weeks or there is an inability to use the tooth during function, it becomes increasingly clear that endodontic therapy is necessary.

At no time should the patient be pushed into treatment that he/she does not fully understand or desire. In cases where there is severe pain that suddenly disappears, it is advisable to apply sensibility tests again in order to determine if the absence of pain is due to healing or devitalization.

This diagnosis is based on subjective and objective findings that lead to a conclusion that the pulp in question does not have the capacity to heal. Important factors to consider include the presumed cause of the pain, its severity and duration, as well as the patient’s ability to use it during function.

For example, a large pulp exposure due to caries or a traumatic fracture represents serious problems that would not be considered reversible. In contrast, pain sensitivity following a crown preparation may not be immediately recognized as reversible or irreversible. Severe lingering pain after the application of cold or heat sensitivity is taken as a classic sign of irreversible pulpitis. Irreversible pulpitis can be treated by endodontic therapy or extraction.