Q. How do you accurately perform an endodontic diagnosis?
A. The comprehensive endodontic examination is a “three-step” diagnostic process comprised of the clinical examination, the radiographic examination and vital pulp testing. This examination should be performed on patients regardless of whether they are asymptomatic or symptomatic. In the instance where there is a chief complaint, it is important to inquire as to the region, magnitude and duration of the pain. Additionally, the dentist should ask if the sensitivity is diffuse or localized, intermittent or continuous, and if there is a specific stimulus that provokes the pain. It is important to listen, clarify and then accurately record this information. The purpose of a full mouth endodontic examination is to differentially diagnose between odontogenic versus nonodontogenic problems. Specifically, the endodontic examination serves to identify endodontically involved teeth and additionally enables the clinician to classify any given tooth into one of four categories:
1) Teeth that are asymptomatic and do not have a LEO
2) Teeth that are asymptomatic and have a LEO
3) Teeth that are symptomatic and do not have a LEO
4) Teeth that are symptomatic and have a LEO
Q. How many xrays do you recommend taking during the radiographic examination?
A. The endodontic radiographic examination is optimized when three different, well-angulated, and high quality images are obtained. A straight-on diagnostic film should be taken such that the xray cone is aimed perpendicular to both the facial aspect and long axis of the tooth. A second, mesially angulated film is attained by horizontally aiming the xray cone up to 30° mesial to the straight-on angle and perpendicular to the long axis of the tooth. A third, distally angulated film is attained by horizontally aiming the xray cone up to 30° distal to the straight-on angle and perpendicular to the long axis of the tooth.
Frequently, dentists inquire as to the need for three pre-operative radiographs when, indeed, a single film, in conjunction with the results from a vital pulp test and the clinical examination, will generally confirm a definitive diagnosis. The answer is simple: The best film is still a two-dimensional image of a three-dimensional object. A single film, along with the other diagnostic information, may endodontically condemn a tooth; however, a single radiographic image will not adequately prepare the clinician for optimal treatment planning and patient communication.
Q. What is the purpose of vital pulp testing and how are these tests initiated?
A. The clinical and radiographic steps of the examination oftentimes cast suspicion of endodontic involvement of a specific tooth. Vital pulp tests (VPT) are essential components of the endodontic examination and serve to disclose the status of the dental pulp. Frequently, patients present reporting pain to a thermal stimulus in a specific quadrant. In these instances, vital pulp testing schemes should be performed first on presumably “pain-free” teeth, away from the area of the chief complaint. Specifically, the preferred sequence is to test contralateral teeth first, opposing teeth second, then presumably healthy teeth within the thermally painful quadrant, and finally, the most suspicious tooth last. This strategy of sequencing the vital pulp tests allows both the doctor and the patient to appreciate the range of “normal” pulpal responses exhibited by asymptomatic teeth. Importantly, performing repetitive pulp tests, as described, will tend to relax the patient, build confidence and reduce the probability of a false positive or false negative report.
VPT procedures are initially performed to establish a normal “baseline” for any given tooth on any single patient. Once a baseline has been established then, and only then, should the appropriate VPT be performed in the quadrant where the patient is experiencing symptoms. Performing VPT on asymptomatic teeth establishes the baseline for testing and comparing an “abnormal” response in a symptomatic tooth. In fact, when VPT schemes are conducted in this manner, patients will frequently question why another tooth is either overreactive or nonreactive to the specific test. In these instances, additional diagnostic evaluation may be required to clarify the endodontic status of any given tooth.
Q. What are the various methods that can be employed for vital pulp testing?
A. There are four methods that may be employed to determine the vitality of the dental pulp: the cold, hot, electric, and cavity tests. Selection of the cold test or the hot test is based on the patient’s chief complaint. If a patient does not report any history of thermal pain then, for ease, the cold test is selected. However, it should be recognized that once the pulp is stimulated with cold, there is a refractory period of several minutes before a second cold or hot test can be accurately conducted. The electric pulp test is more technique sensitive, requires a dry field and is oftentimes impractical to utilize in teeth with full restorative coverage. The cavity test is rarely used, and only considered when the clinical and radiographic information and pulp test results prove inconclusive. In these instances and, when the patient situation supports intervention, then the cavity test could be considered as a last resort. If employed, the cavity test is initiated on a suspicious tooth, without anesthetic, and involves drilling a small window through either enamel or a restoration to dentin. The cavity test will stimulate a vital pulp and provoke a painful response when dentin is invaded. In the event of a vital response, a simple restoration is placed. On the contrary, the cavity test will not stimulate a partially necrotic pulp to the same extent as a vital pulp. In this situation, the dentist initiates the access cavity, invades progressively deeper into dentin and often reaches the pulp chamber uneventfully.
Q. How are thermal tests best conducted?
A. Thermal tests should be conducted on the cervical aspect of a tooth, and as close as possible to the free gingival margin. This location represents the thinnest aspect of enamel or a restoration and, importantly, the closest distance to the pulp chamber. When performing a thermal test, the clinician is evaluating the “immediacy”, the “intensity”, and the “duration” of the response. The immediacy and intensity of a response to thermal testing can vary significantly depending on, as examples, the depth of a carious lesion, the placement of a new restoration, or recent periodontal surgery. It is useful to have the patient subjectively rate the intensity of a response utilizing a zero to ten (0-10) scale where zero (0) is a no response and ten (10) represents maximum pain. Regardless of the immediacy and intensity, if the response rapidly dissipates upon removing the thermal stimulus, then although the pulp may have tested inflamed, this may be a reversible condition. Importantly, it is the “duration” of the response, compared to the baseline that was established by testing other teeth, that is most diagnostic.
Before initiating any thermal pulp test the diagnostician needs to establish reliable hand signals. The patient is instructed to raise their hand when they first feel the sensation from the thermal stimulus in the tooth, to keep their hand up as long as this sensation lingers, and to lower their hand when the sensation dissipates. It is wise to repeat and clarify these instructions as both asymptomatic and, especially, symptomatic patients are frequently nervous and may inadvertently not follow directions. This is precisely why thermal pulp tests should not be initially performed on suspicious or symptomatic teeth. As such, before instituting any pulp test, advise the patient how this test works, ask permission to test, and then initiate the test on pain-free teeth.
In certain instances, a tooth tested with a thermal stimulus may elicit a “no response” which could infer the pulp is necrotic. It should be recognized a patient may not respond to a thermal test if the pulp chamber has significantly calcified or receded apical to the crest of bone. Further, a no response to a thermal test could imply a tooth has been involved in a recent episode of trauma, has an immature apex, or the patient may have premedicated. Additionally, a patient will not generally respond to a thermal stimulus on a tooth that has had root canal treatment. However, an endodontically failing tooth with a missed canal will, at times, illicit a painful response when tested with a hot stimulus.