Here’s a disappointing and frustrating event that sometimes takes place in the world of dentistry. A patient comes in with a tooth that is broken or has a large cavity. The tooth hasn’t been bothering the patient but it obviously needs repair. The dentist takes a look at the tooth and decides that the damage the tooth has sustained is significant enough that the tooth requires the placement of a dental crown. The needed work is begun (and even possibly completed) without incident. Then sometime during the next few days, weeks, or even months the scenario changes. Now the tooth does hurt. The dentist tells the patient that they need root canal treatment. So what has happened? Why have things changed?
The apparent answer is that the patient’s “good” tooth has been damaged by the crowning process and because of that it now needs root canal treatment. After all, the tooth didn’t hurt until after the crown procedure had been performed. Well, in response to this train of thought, sometimes the “obvious” isn’t correct. And while creating a dental crown for the tooth no doubt did play a role in the tooth’s subsequent need for root canal treatment, it probably wasn’t the initiating cause. Here’s why.
The housing for a tooth’s nerve tissue is unlike most any other tissue in the body. The nerve, a soft tissue, is encased in a hard shell (the tooth). And because of this, the following complication can occur. When a tooth is traumatized (such as receives a blow, is irritated by the presence of tooth decay, is drilled upon) the response of the dental nerve is to swell (an inflammation reaction). That’s what tissues do when they are insulted. It’s just like when you traumatize (twist) your ankle the tissue surrounding the ankle becomes swollen.
The complication that arises is that this swelling tissue is contained by the confines of the hard tooth. So even though a swelling response occurs, the size of the space in which the nerve lies doesn’t. The net effect is that the nerve tissue is placed under a compressive force, several times what is normal for it.
Now, here’s where the real problem comes into play. As the forces build, the blood vessels contained in the tooth’s nerve tissue become compressed. The net effect of this is that the blood flow to the pulp becomes restricted. So, those necessary duties that the circulatory system provides (carrying oxygen and nutrients to the pulp, carrying away excess fluids) are inhibited. As a result, the nerve tissue’s ability to rebound healthily from the insult is compromised. In the most extreme cases, the nerve tissue will die.
So, with our situation where the patient had a tooth that seemed just fine initially, the dental crown procedure was started (and possibly even finished) and now the tooth hurts, what has taken place? Was the dental crown procedure too traumatic for the tooth? Is it what has caused the nerve in the tooth to become damaged to the point that it now needs root canal treatment?
Well, the answer is both yes and no. Just from the timing alone you would have to suspect that this was the case. The reality of the matter, however, is that the dental crown procedure most likely only precipitated the timing of an event that would have happened anyway. Here’s why.
When teeth experience a traumatic episode, such as that described above, they might sustain enough damage to their nerve tissue that it does die. With many episodes, however, the experience may only result in damaging the nerve, in the sense that it is still alive but debilitated. Because of this, in the future when other traumatic episodes (one or many, each of varying intensity) are experienced, the nerve’s resiliency (ability to healthily rebound) will be subpar. Any one episode might create enough stress for the nerve tissue to push it over the edge, thus causing its death and creating a need for root canal treatment. No one would ever be able to anticipate which specific traumatic episode might trigger this course of events. It’s simply that the potential always exists.
So, in the case of our dental crown, yes the trauma of having the dental crown made could have been stressful enough that it is what caused the degeneration of the nerve. But more likely the tooth was already in a compromised state due to some other experience (most likely the very one that cause need for the placement of the dental crown in the first place). The dental crown procedure was simply the last straw. The debilitated nerve tissue just wasn’t resilient enough to survive the procedure.
This exact same type of scenario can occur with other types of dental treatments. Anything that involves stressing a tooth, either during a procedure or once a restoration has been placed into use, can be the culprit. This means that the placement of fillings, dental bridges, partial dentures or even a person continuing or renewing a teeth grinding habit can set off a course of events just like those described here.
By: Phil Peters
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Complications With Dental Crowns – The Crowned Tooth That Now Needs Root Canal Treatment
