Dental Detectives

When a patient comes into the dentist’s office with tooth pain, it’s not always clear which tooth is acting up or where the pain originates. We discuss the various technologies and methods that can help dental Joe Fridays crack the case.

When detectives go to a crime scene, they usually have the help of a team of technicians dusting for prints, looking for fibers and scouring the site for clues. When dental practitioners are faced with the often-puzzling scenario of tooth pain, they’re on their own as far as rooting out the perpetrator. Or are they?

The point of origin in tooth pain cases can be hard to track down. The situation isn’t helped by the fact that patients can’t always just point to the miscreant tooth. Tooth pain can be caused by issues ranging from dentinal hypersensitivity to infected root canals — and worse. For that reason, you’ll want to provide backup for your dentist customers by ensuring they are armed with the right diagnostic arsenal that can help them solve even the most confounding whodunits.

FOLLOW THE CLUES

Aside from patient reporting, the first step usually taken by tooth investigators to determine the source of tooth pain is to gather patient history. “A good diagnostician has to listen to the patient carefully and not make snap decisions,” says nationally recognized speaker and author Edward M. Feinberg, DDS, who practices restorative dentistry in Scarsdale, New York. “Snap decisions could result in iatrogenic treatment that does not address the real cause of the problem.”

Eugene Pantera, DDS, retired director of the Division of Endodontics at the University at Buffalo School of Dental Medicine, adds that there are several things to take into account when determining the source of tooth pain. “Recent restorative treatment, deep caries, large restorations, or a history of a pulp capping can help determine which tooth may be the problem,” Pantera says, adding, “Determining which tooth is the source of a problem is almost an art form.”

Following information gathering, Feinberg says that his typical M.O. is to start with a clinical examination and X-rays. This process usually involves extraoral and intraoral visual and tactile exams, which might reveal obvious caries, swelling or issues involving the jaw.

Among the technologies that can come in handy in this portion of an exam are intraoral cameras, which are becoming invaluable for capturing hard-to-see details. They have easy learning curves and turn in high-quality images that support accuracy in diagnostics and treatment. These wand-like handheld devices snap high-resolution still or video images inside the oral cavity. Some recent versions also are designed to detect caries and capture macro-images for documentary purposes. They offer magnifications as high as 100x. And when images are transmitted onto a screen, they are beneficial in patient education and treatment acceptance, allowing the patient and clinician to view detailed images of the teeth and oral cavity in real time.

If the visual and tactile exams don’t solve the mystery, the next step is radiography.


POINT OF SALE: JUST THE FACTS, MA’AM

  • Thermal testing is a standard means of diagnosing tooth pain in many offices. While simple ice sticks can be used, convenient commercial products are readily available.
  • Radiography is basic to good dental care, and can reveal dental disasters in the making.
  • Many clinicians rely on electric pulp testers as a backup diagnostic tool, when thermal tests are inconclusive.
  • Transillumination devices and intraoral cameras are increasingly available combined into one device. This objective testing measure can reveal cracks and carious lesions not yet visible on an X-ray.
  • Objective technologies such as laser Doppler flowmetry and pulse oximetry are increasingly gaining attention for use in dental diagnostics.

When it comes to X-rays, digital radiography reigns supreme in many of today’s offices. But some cases are better resolved in 3D, and for those lacking in-office cone beam computed tomography (CBCT), a referral is sometimes the answer. Says Feinberg, “In a small percentage of cases, I cannot find the answer, so I turn to the specialists I work with for assistance. They have more sophisticated testing equipment and the expertise to identify the problem.”

But as sophisticated as today’s radiography is, it doesn’t always render a clear indication of the source of pain. As a result, both Feinberg and Pantera say they’ll resort to an assortment of tests that can be employed to pinpoint the problem.

SENSE AND SENSIBILITY

One way to determine which tooth is acting up is through patient response to stimuli. While such sensibility tests don’t necessarily determine the condition of a tooth and the cause of pain, they can reveal which tooth is the source of the pain, and give the clinician an inkling as to what may be going on. And that’s a good place to start.

After X-rays are taken, the first diagnostic measures used by many clinicians are percussion, or tapping on teeth with the handle of a mouth mirror; bite pressure tests, in which patients are instructed to bite down on a cotton roll or other type of aid; and thermal testing.

“I test all the teeth in the offending quadrant for percussion and for hot and cold sensitivity, using ethyl chloride on a cotton pellet for cold, and warm gutta percha for heat,” Feinberg notes.

The goal, of course, is to reproduce the pain described by the patient to identify the offending tooth. To best achieve this, experts say it’s a good idea to start sensibility testing by establishing a baseline. Says Pantera, “Sometimes the patient can subjectively point to the tooth. However, the dentist objectively determines which tooth is causative by diagnostic testing on the suspected tooth and adjacent teeth. Adjacent teeth (or control teeth) are used to assess how a patient normally reacts to the different stimuli used. When the diseased tooth is tested, the response is generally going to be different.”

Such a strategy has the added benefit of familiarizing the patient with the process. This helps them to relax and allows the clinician to get a more reliable result.

Thermal testing has a long track record of reliability. Cold testing can be done using commercial refrigerants. On the other hand, practitioners may simply make their own ice sticks, which will do the job nicely.

Heat can also be an effective diagnostic measure. It can be applied in the form of warmed compounds, or through the use of methods that include commercial heating devices, spinning prophy cups or even hot water.

The characteristics of pain in response to stimuli can also aid diagnoses. For instance, pain in response to a stimulus that goes away once the stimulus is removed, may be indicative of a fracture, exposed dentin as a result of gingival recession, or caries. Lingering pain may be a telltale sign of an endodontic problem. Says Pantera, “The reaction testing with cold or heat may be severe and lingering. But it may be absent if the pulp in the tooth has necrosed. A diseased tooth may or may not be sensitive to percussion.”


SHEDDING LIGHT ON CARIES, CRACKS AND FRACTURES

USAS/ISTOCK/THINKSTOCK

USAS/ISTOCK/THINKSTOCK

One objective diagnostic measure that seems to be picking up steam is transillumination. This technology uses infrared and white light to hunt for caries, cracks and fractures that otherwise go unseen — even in X-rays. In this diagnostic measure, light is shown through the enamel and dentin. Healthy tooth structure typically appears light — even glasslike. In contrast, damaged or decayed structure takes on a shadowy appearance due to light absorption.

“Transillumination can be helpful, except when a full crown is present,” says Eugene Pantera, DDS, retired director of the Division of Endodontics at the University at Buffalo School of Dental Medicine. He adds that is it is generally used when coronal fractures are suspected.”

Several manufacturers offer transillumination as caries detection devices in combination with intraoral cameras. In fact, some come with interchangeable heads and documentation software. Technologies vary in these systems. For instance, one uses a pulsating laser light that generates photothermal and luminescence responses to detect caries and cracks. Another system employs autofluorescence and color mapping of teeth in a video camera to allow visualization of everything from plaque and calculus to cracks and caries.

Probably the best thing about this technology is that it identifies dental anomalies without radiation. It also detects damage in its earliest stages, before it would even show up on an X-ray. In this way it supports the concept of minimally invasive dentistry.


CURRENT EVENTS

While they should not be used on patients with pacemakers, electric pulp testers (EPT), are often the next step on the diagnostic ladder. Particularly valuable when cold testing fails to elicit a response, handheld EPTs can help determine whether a tooth is capable of feeling, and can record the degree of feeling. These diagnostic devices feature probes, that, when placed on a tooth, along with a conductant such as toothpaste or even saliva, emit mild electrical currents.

Starting at a low level, the intensity is increased until the patient feels what may register as a tingling sensation. A tooth whose pulp is diseased may exhibit a stronger or quicker reaction to EPT than a normal tooth would, while no reaction may indicate pulp necrosis. But lack of feeling is not necessarily indicative of vitality, as in cases of trauma, pulps that are still very much alive are frequently rendered temporary insensible. For that reason, measures that depend on neural response, such as EPT, are not really considered “vitality testers.”

“If the pulp is necrotic, there will not be any sensitivity to electric testing,” Pantera says. But, he cautions, “It should be noted that electric pulp testers only register sensation or no sensation. They cannot determine the health of the pulp, and can deliver false positives.”

Even a battery of sensibility tests may fail to unravel tooth pain mysteries, but this is no reason to dismiss them. “Just because a test is negative or nothing shows up in an X-ray does not mean that nothing is wrong,” Feinberg cautions. “Our tests are far from foolproof, and in my experience, the problem is almost never ‘in the patient’s mind.’”

OBJECTIVE DIAGNOSTICS

Not all diagnostic measures rely on a patient’s subjective neural response. Other technologies are gaining attention that can be used to objectively assess not just sensibility but vitality of a tooth, while helping to counter false positives and negatives. This is especially helpful in cases of trauma. Laser Doppler flowmetry bounces infrared light, emitted from a diode laser, off of red blood cells as they move. In this way, blood flow through tissues is measured, and can confirm pulp vitality. This type of test, however, while found to be highly accurate, is problematic in that both the patient and the probe must remain stock-still.

A second method of objective measuring is pulse oximetry. Most of us are familiar with this as the clip that gets put on your finger when you visit the doctor. Using infrared and red light-emitting diodes, these devices measure vascular circulation and blood oxygen levels with the help of a photodetector. Pulse oximetry shows promise as an effective means of assessing vitality, especially in traumatized teeth that do not respond to more subjective diagnostic measures.1 But a device has yet to be designed for dental applications.

There is a need to further develop objective testing technologies. Measures being explored include thermography, which evaluates nonvital and vital pulp temperature differentials, and spectrophotometry, another method to assess oxygen saturation in the pulp.


LEXICON

  • Autofluorescence: Natural emission of light by biological structures.
  • Ethyl chloride: An anesthetic skin refrigerant.
  • Gutta percha: A substance derived from tree sap that is used in endodontic obturation.
  • Histology: Study of microscopic anatomy.
  • Luminescence: Creation of light without heat.
  • Pathophysiology: Changes in a tooth resulting from disease.
  • Photothermal: Refers to responses to heat and light.
  • Quadrant: Refers to the half of the dental arch in which the pain is felt.
  • Sensibility: The ability to sense stimulation.
  • Vitality: Refers to a vital, or living, tooth.

Work is also being done in the area of diagnostics at the molecular level. For instance, some researchers are examining the use of biomarkers present in gingival crevicular fluid and dentin fluid that can be collected with noninvasive or minimally invasive methods. The markers can help clinicians determine whether pulp is healthy or diseased. This is because biomarkers for irreversible pulpitis are expressed differently than they are for normal pulp.2

THE WAITING GAME

Pantera and Feinberg both note that there are times when answers elude them despite all the testing methods at their disposal. Pantera says this is true particularly when the patient has extensive direct or indirect restorations or a history of trauma. Says Pantera, “When there is no corroboration between the clinical findings during endodontic diagnosis and the histology of the diseased tooth, the practitioner’s experience and knowledge of the histopathophysiology of endodontic disease is used to make a clinical decision.”

In other words, Pantera says, “Understanding what the heck is going on, knowing the underlying pathology, and applying all this to the problem is a key challenge. Periodically new instrumentation is introduced, but nothing has been shown to be more predictable than what dentists have been doing for a long, long, time. Experience is the best tool along with having a systematic approach to diagnosing pain.”

Indeed, experience may indicate that when all else fails, it is sometimes wise to simply take a wait-and-see approach. Until the etiology of tooth pain can be identified, Feinberg suggests that treatment such as antibiotic therapy often can give immediate relief. Says Feinberg, “A problem that cannot be identified today will be manifested as obvious later in a clinical exam or in a new X-ray. This scenario is a common occurrence. The first time around, symptoms could be diffuse and vague, and the X-ray examination might be negative. The second time the symptoms manifest, they might be focused on a particular tooth and the X-ray may show pathology.”

Feinberg reiterates that referral is always an option. “I am a big believer in using specialists to help with problems that I can’t solve. Occasionally there is a relatively simple answer that I missed. But I never feel embarrassed, because I will learn something that will make me a better diagnostician.”

Until the day comes when clinicians can simply plug their patients into computers to figure out the source of tooth pain, their best shot at solving these mysteries appears to remain the diagnostic tools that are available, and new ones yet to see the light of day. But perhaps the most important tool of all is experience. For, in the hands of seasoned dental gumshoes, diagnostic tools have the best chance of spelling relief for patients and ensuring that pain doesn’t return to the scene of the crime.

Featured photo by JACOBLUND/ISTOCK/THINKSTOCK

REFERENCES

  1. Caldeira CL, Barletta FB, Ilha MC, Abrao CV, Gavini G. Pulse oximetry: a useful test for evaluating pulp vitality in traumatized teeth. Dent Traumatol. 2016;32(5):385-389. Available at: ncbi.nlm.nih.gov/pubmed/27140332. Accessed March 8, 2017.
  2. Rechenberg DK, Galicia J, Peters OA. Biological markers for pulpal inflammation: a systematic review. PLoS ONE. 2016;11(11). Available at: journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0167289&type=printable. Accessed March 8, 2017.

From MENTOR. April 2017;8(4):22-24,26.

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