Unlocking the Mysteries of Cracked Teeth and Vertical Root Fractures

Cracked teeth and vertical root fractures can be challenging to diagnose and manage, regardless of whether a root canal is needed as part of the patient’s treatment plan. In addition, dental offices are seeing more and more cases within the past year. In fact, both problems seem to be on the uptick as a result of stress-related tooth grinding during the pandemic, as well as an increased use of non-ergonomic desks and tables that can cause jaw and tooth pain — necessitating the importance of proper assessment and care.

In this article, we’ll take a closer look at how to tackle the intricacies of diagnosis and treatment of cracked teeth and vertical root fractures, and how cone beam computed tomography (CBCT) can be used in your practice to enhance the decision-making process. For insight, we spoke with Dr. Stephanie Tran, an endodontist with a private practice in New York City and Long Island, New York. She completed her undergraduate and doctoral studies at the University of the Pacific in San Francisco, California, and was chief resident at the University of Tennessee Health Science Center, where she completed her post-graduate endodontics specialty residency.

Understanding the main types of cracked teeth and vertical root fractures

The first step toward arriving at an accurate diagnosis is knowing how various conditions are defined. “A lot of times, the names and classifications get used interchangeably or mistakenly,” says Dr. Tran. Here are some common ones:

• Craze lines: These are markings in the enamel, rather than true fractures. They can be on marginal ridges, extend on buccal and lingual surfaces and are less extensive and shallower than cracked and split teeth. There may or may not be pulpal involvement, depending on how deep they are.

• Fractured cusp: This is where the cusp is fractured completely through; in other words, a complete fracture of the cusp itself. It starts from the coronal and then extends subgingivally, oftentimes losing the entire wall of the coronal part.

• Cracked tooth: This is an incomplete fracture that starts from the coronal and extends subgingivally, and oftentimes mesiodistally, but not always. It can extend through the marginal ridges both subgingivally and internally and through the proximal surfaces themselves. That internal extension is when pulpal involvement may be a consideration. The prognosis is anywhere from questionable to fair or poor, depending on the extent subgingivally and whether it can be restored.

• Split tooth: This is when a cracked tooth progresses to the point of involving either the tooth all the way down to the root, starting from the coronal, or all the way across. There may be a fracture through the pulp chamber floor. Because the split is so deep apically, the prognosis is poor.

• Vertical root fracture: A vertical root fracture starts at the root, so it is either apical up or midroot and both ways. Because it involves the root, the prognosis is quite poor.

Diagnosing cracked teeth and vertical root fractures

So, what are the best ways to diagnose cracked teeth and vertical root fractures? There are a number of methods you can use.

• An intraoral camera and intraoral photography. These are extremely helpful for high-definition shots, providing very specific detail about the tooth. “Magnification is of utmost importance,” says Dr. Tran.

• Transillumination. This is where you use a light, such as a transilluminating device or something as simple as a bore light to view fractures clinically. Ultimately, you need a beam of light focused closely on the tooth. If there is a crack, it will stop the illumination of the light.

• Dyeing. In endodontics, dentists often use methylene blue, because it has very tiny pigment molecule sizes. It is helpful in diagnosing very, very small fractures and small cracks.

• Caries-indicating solution. This is often used in restorative dentistry and found to be very helpful in diagnosing cracks as well.

• Thompson’s Marking Sticks. These can help move the dye into a crack and aid in visualizing it if you are in a pinch.

The patient’s symptoms can also give you clues. The following questions can help you make an assessment:

• Has the patient had a history of swelling?

• Is there a bump on the patient’s gums?

• Does the patient have biting or chewing tenderness?

• What is the patient sensitive to?

• Does the patient’s sensitivity linger or cause any pain?

• What increases the patient’s sensitivity? Do hot or cold beverages or meals have an effect?

• Does sensitivity happen more often when the patient is laying down or at night?

• What is the patient’s dental history?

Don’t worry if the patient doesn’t remember all of their dental history. Even a ballpark of the past five, 10, 15 or 20 years can be helpful in putting a current issue in context and understanding how long it has been a problem.

If you are evaluating a restoration, it is important to ask the following additional questions:

• How long has the restoration been there?

• What kind is it?

• Are there caries?

• What is the periodontal health around it?

When evaluating the problem teeth, it is essential to consider certain specifics. Bear in mind that if the crack is large enough for fluid to get through, it generally has a poor prognosis.

• Is it possible to determine the probing depth of a crack or vertical root fracture with a single narrow probing?

• Is it a wide pocket?

• Are there multiple cracks and if so, where?

• Is the crack associated with a fracture that is visible clinically?

• Is it in multiple areas?

• Does it involve furcation?

• What is the mobility of the tooth itself?

• Can you get in and explore the crack?

• Can the pieces of tooth move at crack level?

• How stained is the crack?

Additional tests of the tooth can help you detect the presence of a crack or vertical root fracture.

• Percussion and palpitation testing: These can help give you clues as to the presence of a crack or a vertical root fracture. In combination with a bite test, these tests evaluate the periodontal ligament and the inflammation around it. When palpation testing takes place in cases of lateral pain or occlusal pain from the bite itself, it is important for you to localize it using a Tooth Slooth® or a bite stick.

• A bite stick: Having patients bite on larger sticks is not always the most helpful for diagnosing a crack or vertical root fracture, as it is very hard to localize exactly where the crack or fracture is. A Tooth Slooth or a bite testing instrument can be helpful, thanks to the small divot that the cusp goes into and its ability to localize a crack or vertical root fracture. You’ll want to look for pain upon biting and then pain on the release. This tells you when the Tooth Slooth or bite testing instrument is flexing and when that pain is being caused by the flexing.

• Hot and cold testing: Heat testing is usually done with warm gutta-percha because it is very hard to localize a heat-tipped area, as it can damage the pulp. Cold testing is always done with a cotton pellet, never a cotton-tipped applicator, because the wood in the cotton-tipped applicator isn't able to hold enough of the cold. Ice sticks should be avoided as well.

Your evaluation of the crack itself will depend on how deep the probing depth is and if there is even a probing depth associated with it. Generally, if there are multiple deep probings — or multiple probings to the apex — there is a poor prognosis. A very, very wide periodontal pocket that goes to the apex often also has a poor prognosis.

If you are looking at restoration, it is important to determine if the tooth is even restorable. You’ll need to look at how extensive the crack is, if the cusp is completely fractured subgingivally to the point that it is non-restorable, if the crack is stained, if there are deep caries and if the piece or pieces themselves are mobile.

One common misunderstanding is that a J-shaped lesion is always a vertical root fracture or cracked tooth. The shape may be due to the radiographic angle or, if the lateral canal is also involved, just the sucular sinus tract. When looking at radiographs, it is important to identify where the bone loss is. Is there a widened periodontal ligament at a particular spot? Does it involve the entire side of the tooth or is it in one particular area, such as the apical region?

When CBCT can transform diagnostics

CBCT can be very helpful in assessing a patient’s situation, but you will need to use a limited field of view for endodontic treatment. This gives a high-definition, zoomed in picture of the tooth itself. When there are fewer anatomical structures, there are fewer anatomical structures that can cause interferences. In addition, the voxel sizes are much smaller, so resolution is enhanced. The limited field of view also helps visualize all of the structures from an endodontic standpoint, as well as aid in detecting bone loss. CBCT can be used to detect a lesion, its extent, how far up the tooth it is, how much bone loss there is and whether it involves other anatomical or vital structures.

That said, you can’t see a fracture every single time using CBCT. Without root canal filling material, the fracture needs to be a certain width in order to be visualized. If this material is present, it is even harder due to beam hardening — little light and dark streaks — which cause visual interference.

The answer is not to use the CBCT alone. Dental professionals can’t officially diagnose a crack or fracture unless they actually see it with their eyes. If they can’t see it, they’ll have to confirm that it is present using all of their findings, not just the CBCT.

Evaluating whether a tooth can be maintained

Prognostic considerations for a tooth include knowing survival rates for various conditions and how involved the tooth is. Cracked teeth don’t always deem a tooth non-restorable. In fact, some papers show long-time tooth survival up to 60 months. Incomplete fractures may have a survival rate of 84% or more. A 2006 paper showed that teeth with root canal fillings had a survival rate of 85.5%. Managing patient’s expectations when there is a slightly guarded or questionable prognosis is essential.

Using CBCT can help you determine some key factors in evaluating the prognosis, such as how involved the root canal treatment is, how large it is, how much of the tooth’s structure has already been lost, the kind of post, the position of the post itself, whether there are any endodontic mishaps present and how much bone loss there is.

Patients’ medical history is also important to consider. Some patients have had more anxiety during COVID-19 and grind their teeth. There has been an increase in clenching, grinding and malocclusion, as well as an increase in caries and delayed treatment.

If a tooth has a crack, the best route may be what is known as restoratively-driven endodontic treatment. This may mean making the access more caries-driven or restoration-driven. The idea is to save as much structure as possible.

Even if a tooth has had root canal treatment, there are a lot of different materials you can use to save it. You will need to make decisions about post versus no post, biomimetic, hardcore bionic dentistry and whether or not there should be cuspal coverage or an onlay or crownlay.

Certain recommendations should be kept in mind as you do this. First, don’t place an endocrown, unless it is on a tooth with a poor restorative prognosis. Second, don’t place a post in the area of a crack. And finally, use some type of cuspal coverage to prevent the cusps from flexing so much.

Conclusion

Cracked teeth and vertical root fractures are challenging to diagnose at best and can require extensive exploration and testing. CBCT can be a powerful evaluation tool, enabling you to gather the information you need early and make the right calls when it comes to the diagnosis, management and long-term survival of a patient’s teeth.

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