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77 Tamarack Circle, Montgomery, NJ 08558The third patient I saw on New Year’s Eve was the one with the most severe pain. She was a middle-aged Chinese woman who regularly went to the dentist, but a few days ago she suddenly started having pain in her upper right tooth. Her dentist was on vacation and she couldn’t get an appointment, and the pain was too unbearable for her to wait until after the holidays. Fortunately, she finally found us and was able to come to the emergency room on December 31st.
The examination revealed that her upper right premolar had fractured longitudinally, with the crack extending to the root below the gum line. She was extremely sensitive to touch, experiencing sharp pain at the slightest touch and significant sensitivity to hot and cold. She said the tooth felt like it had “grown a piece out of its original size,” and she hadn’t been able to eat normally for several days. Unfortunately, the tooth could not be saved and had to be extracted, with implant restoration to be considered later.
She asked me, quite upset: even though she had always brushed her teeth diligently and had them professionally cleaned regularly, why had things turned out this way?
I understand her confusion and agree with her desire to understand things clearly. Many dental problems, if only the symptoms are treated without addressing the underlying cause, are difficult to prevent from recurring.
This is a good opportunity to explain the causes of non-caries tooth fractures. Based on this tooth’s condition, I think there are three main reasons. First, this tooth had a large amalgam filling previously, which weakened its structure. Second, her teeth were misaligned, lacking proper canine protection. Third, she had a long-standing habit of bruxism (teeth grinding) and jaw clenching.
So ultimately, the tooth fracture wasn’t caused by bacteria, but rather by long-term excessive force that accumulated gradually. In other words, while brushing your teeth properly and getting regular cleanings are important, they primarily prevent cavities and periodontal disease, and offer limited help for problems related to physical force.
Can this situation be avoided in advance? Actually, most of the time it can; it doesn’t happen completely randomly. The key to treatment is identifying the risk, controlling the risk, and treating and reducing occlusal trauma.
Let’s first discuss the issue of amalgam fillings. Unlike resin, amalgam doesn’t adhere to the tooth; it’s more like it’s mechanically secured within the tooth. If the area is small, the tooth itself has sufficient structure to withstand the force. However, as the area increases, the remaining portion of the tooth becomes thinner, making it prone to developing internal cracks under long-term stress.
It’s like a piece of glass with tiny cracks; it looks fine, but it’s actually quite brittle. You might not feel it normally, but one day you might bite into something hard and it could suddenly shatter.
As such, dentists sometimes recommend replacing large amalgam crowns or, in cases of microcracks in critical areas, directly placing a crown for protection. However, many patients hesitate because they are not currently experiencing pain, and may even ask, “How much longer can this tooth hold up?” This question is actually difficult to answer because it is a gradual, cumulative process, and no one can accurately predict when the “critical point” will be reached. Once a crack does appear, it depends on where it has spread. If it’s only on the surface or near the dental nerve, it might be possible to save the tooth through root canal treatment and a crown; but if the crack extends below the root, it is beyond saving.
The second aspect is occlusion. Normally, our canines provide protection during lateral movements; their position, shape, and robust roots allow them to withstand relatively large lateral forces. This prevents the posterior teeth from bearing excessive stress.
However, this patient’s canines were mispositioned, what we commonly call “protruding canines,” which meant that her canines were essentially ineffective when she bit or ground her teeth. The force that should have been borne by the canines was then transferred to her premolars.
If the premolar itself were healthy, it might have held up for a while. But it has a large area of amalgam filling, which makes it more brittle to begin with, and with long-term stress, it’s more likely to develop problems.
The third crucial factor that cannot be ignored is nighttime teeth grinding and jaw clenching. Many people might say, “I’ll just be careful during the day and avoid chewing on that side.” But the problem is, while you can control it during the day, you can’t control it at night. Many people grind or clench their teeth while asleep, often with more force than during the day, and this is continuous.
Over the long term, the damage to teeth is actually quite obvious.
So how do we prevent it? There are two main approaches.
One approach is to fundamentally adjust the bite, such as through orthodontics to align the teeth and return the canines to their proper positions. This results in more balanced force distribution, which is very helpful for long-term dental protection. This is the ideal treatment that addresses the root cause of the problem!
Another, more direct method is to wear a night guard. This prevents the teeth from directly contacting each other at night, transferring wear and pressure to the night guard. This is a crucial protective measure for those who don’t plan to or are unsuitable for orthodontic treatment. However, the lack of canine protection is not addressed: the back teeth still experience excessive force when performing biting function.
In summary, some tooth fractures are not caused by cavities, but by uneven stress over a long period. Straightening teeth during adolescence is crucial for future bite health. Adults undergo orthodontic treatment not only for aesthetics but also for functional improvements. If orthodontic treatment is not desired, at least consider getting a night guard or repairing worn canines to protect the teeth.
Additionally, during regular checkups, if your dentist indicates that a particular tooth is at high risk, such as having a hidden crack or an overly large filling, it’s advisable to carefully consider the next protective measures. Often, problems can be controlled in their early stages; once they progress to fracture, it becomes an outcome we don’t want to see.
Many dental problems do not occur suddenly, but are the result of long-term accumulation.
For patients, the most difficult part is often not treatment, but whether they are willing to deal with those high-risk teeth that “seem usable” when there are no obvious symptoms.
From a doctor’s perspective, we want to promote better risk control before the tooth breaks or causes pain.
If you have any of the following conditions, you might want to pay a little more attention:
• A tooth had a relatively large filling
• Occasionally feeling a slight discomfort when biting, but not being able to pinpoint the exact location
• A habit of grinding teeth at night or clenching teeth during the day
• Your dentist has recommended crowns or protective restorations, but you are hesitating because you aren’t experiencing any immediate problems
These may not necessarily cause immediate problems, but they often indicate that the tooth has entered a “high-risk stage”.
The fates of teeth are not determined once they are in pain; the seeds of their eventual demise are almost always sown before the pain begins.
If you can take extra precautions early on, you avoid having to get a tooth extracted.
Author: Joyce Guojun Ma (马国珺), DDS, PhD
Translated by Eddy Tian
About the Author
Author｜Joyce Guojun Ma, DDS, PhD
General Dentist | MAGD | DABOI/ID | DICOI | DABDSM
Practicing medicine in the three eastern states (NJ / NY / PA)
Peking University School of Stomatology | New York University School of Dentistry |
Johns Hopkins University Neuroscience PhD
Specializing in: Preventive dentistry, Occlusal function, Full mouth reconstruction, Periodontal laser treatment, Implants and bone grafts, Cosmetic orthodontics, Temporomandibular joint disorder (TMD), and Sleep-disordered breathing (OSA).
Part 2:
https://eddytian.substack.com/p/is-periodontal-disease-destiny-dental
Part 1:
https://eddytian.substack.com/p/the-dangers-of-ignoring-a-toothache