Dr. Shnall's Dental Blog
By Dr. Jeff Shnall
The title of this article, the cracked tooth, is almost enough to make anybody cringe, yet teeth we dentists deal with cracked teeth on an almost a daily basis.
This topic is worthwhile discussing because of the fact that the development of crack in a tooth (as pictured left) is a common reason that teeth may eventually require root canal treatment or extraction.
How do teeth develop cracks?
First, consider the following facts: Our teeth are generally strong. In fact, they're covered with a layer of hard, protective enamel, which makes the surface of a healthy tooth harder than bone.
However, if a tooth develops a cavity this weakens the tooth.
And even if a tooth is filled it will still be weaker than it was before it became decayed.
When we chew on a tooth that is weakened by a cavity or filling, a crack can result.
This is understandable when you consider the many thousands of times you may chew on a tooth as well as the heavy biting forces some people place on their teeth, many hundreds of pounds of pressure in some cases.
Cracks can also develop in a tooth that has never been filled. I have seen this occur in patients who (i) have pointed teeth and who (ii) clench or grind these pointed teeth. We refer to teeth with a pointed shape as having high or pointed cusps. The combination of clenching and high cusps puts heavy stress on the tooth. I have seen patients with high cusps develop severe cracks in several of their teeth, leading to the need for extraction.
People who grind or clench develop very strong chewing muscles which can make it even more likely they will break a tooth or cause a crack to worsen.
Sudden trauma can cause a tooth to develop a crack. Two examples of traumatic mishaps that I have come across are patients who bite unexpectedly on a hard olive pit in a salad or a hard kernel of popcorn, which can result in very large forces capable of causing a deep crack in a tooth.
Teeth that have had root canal treatment can suffer major cracks that can sometimes lead to the need to remove the tooth. This is because a tooth that has had a root canal treatment will always have a filling located right down the middle of the tooth. This weakens the tooth. After daily chewing on the root treated tooth, crack(s) can develop in the weakened tooth and on occasion can cause the tooth to split. This often dooms the tooth to extraction.
Accidents: Falling off a bike or being hit in the jaw with an elbow are but two examples of trauma that can cause a crack in a tooth. Accident related traumatic injuries will be dealt with in a future article as there is much more to consider in those cases.
Signs and symptoms of a Cracked Tooth
Most often, cracks are visible to the naked eye however sometimes they are microscopic and are too fine to see so they are diagnosed on the basis of symptoms only.
Factors to consider if you have a cracked tooth
Many factors will determine the how we treat a cracked tooth and also can be a predictor of whether tooth can be saved. Some of these are the following:
(i) The location of the crack.
Is the crack running straight down the middle of the tooth or is it off to the side?
If the crack runs straight down the middle of the tooth, there is a higher chance the tooth will require root canal treatment now or in the future.
If the crack runs off the side off the tooth, there is less chance the root canal of the tooth will be involved.
(ii) The severity of the crack
Is it a shallow, moderate or deep crack?
A shallow or moderate crack can have a better chance of treatment success.
A tooth with a deep crack may not be savable, especially if the crack is running down the middle of the tooth or if it extends far under the gum line.
(iii) Has the tooth with the crack had a previous root canal treatment?
A tooth that has had root canal treated is weaker than a tooth that has not. This is due to the fact that in order to do a root canal a portion of the tooth has to be drilled through to get at the canals. This means that a tooth that has root canal treatment will have less solid tooth and more filling. A root canal tooth is therefore weakened right down the centre of the tooth. If a crack does develop in a tooth that has had a root canal, it can be more severe and result in the tooth splitting into two or more pieces. This almost always means the tooth will require extraction.
Treatment of the cracked tooth
Treatment for the cracked tooth depends on a number of factors.
If the tooth has a brief sharp pain to biting and/or cold but no ache or lingering pain we normally will not do a root canal treatment.
The ideal treatment for a cracked tooth is a crown. This is especially true if the cracked tooth had a root canal treatment.
The crown encases the tooth and usually (but not always) prevents the crack from becoming deeper in the tooth. A crown is the surest way to save a tooth with a crack.
If a crown is to be placed, usually any old filling is removed from the tooth. A new filling is placed and a crack is then placed over the filling.
The next best way to save a tooth with a crack would be with a filling only. This would be done in the following way:
Most often, a tooth with a crack already has a filling. So if a crack is seen or suspected in a tooth, the filling can be removed and the tooth can be examined visually for a crack. If the crack is detected, the part of the tooth affected by the crack can be removed and replaced with filling.
For extra strength and to prevent the crack from worsening, the entire tooth can be shortened and covered with a bonded, tooth coloured filling.
Although a crown is a longer lasting, stronger way to reinforce and save a cracked tooth, the cost of a crown is significantly higher than a filling so some people do opt for the filling only. The choice is yours.
If the tooth is a bit uncomfortable to chewing but is otherwise not bothering you, you may opt to do nothing i.e leave the tooth as is, crack and all. However, the risk of doing nothing is that a crack that is left untreated can extend deeper into the tooth, increasing the risk of the tooth needing a future root canal or extraction.
Prevention: How to prevent cracks from developing in your teeth
Some people are very hard on their teeth: they may either clench and/or grind their teeth during the day and/or night. This is often due to stress. Habitual grinding wears teeth down and puts very large biting forces on the teeth, which can result in cracks developing in teeth.
People who clench or grind their teeth during sleep can definitely benefit from wearing a protective night guard while they sleep and also seeking out stress management help from health care providers.
Night guards are even more important in patients who have the combination of teeth with high pointed cups and a clenching or grinding habit. This combination can lead to significant cracks forming in the teeth and can result in the need for extraction of the tooth. I have seen this type of patient develop severe cracks in teeth that have never even been filled.
Maintaining regular checkups every six months, daily brushing, flossing and a proper diet (not overdoing the sugar) all can reduce cavities or catch them while they're small. A tooth that never decays is less likely to develop a crack.
Placing crowns on teeth that have had root canal treatment, especially on the teeth towards the back of the mouth can prevent severe cracks that often result in the tooth requiring extraction.
Well, this has been an overview of the cracked tooth. If you have any comments, please feel to leave them below.
Dr. Jeff Shnall