A Cracked Tooth – Something to Worry About?

One of the most common dental problems that we see is a cracked tooth. Cracked teeth are so common, that we probably see them every day at the clinic. You may or may not know that you have a cracked tooth, as the tooth in question may not even hurt. Signs that you may have a cracked tooth include sensitivity to bite on a particular tooth or sensitivity to hot and cold. Whether or not a crack in a tooth is a significant dental problem, depends on a number of factors.

Often, patients are concerned about fracture lines that they have seen in their front teeth. These are called “craze lines” and are nearly always nothing to worry about. They are usually confined to the enamel only and do not penetrate into the dentine layer of the tooth. Most adults have craze lines in their front teeth, when they are examined closely enough. They hardly ever cause a problem and rarely need treatment. However, occasionally these fracture lines become stained and can be of a cosmetic concern to patients.

Below is an example of multiple innocent craze lines in an adult’s front teeth. Note the fine, vertical hair-line cracks. These would be of no concern.

Cracked Tooth

Below is an example of when a stained craze line may be of cosmetic concern.

Stained Cracked Tooth

More concerning are fracture lines around old fillings in back teeth. These can usually be picked up by your dentist at your routine dental examination. Your dentist should be able to advise you what may happen if the tooth is left as it is, and what possible treatments are available to attempt to prevent these consequences if you feel you would like to avoid them. Potential consequences of leaving cracks in back teeth around old fillings include:

The tooth becoming painful to hot and cold.

The tooth becoming painful to bite against.

Part of the tooth breaking away.

Bacteria could leak through the crack, under the filling and cause decay.

The fracture could spread into the nerve.

The tooth could split.

If you decide you would like to do something about the cracked tooth, usually the best starting point is to remove the old filling to assess the cracks better. Depending on the spread of the cracks, the tooth may sometimes need just re-filling with a bonded composite filling, or sometimes, something stronger and more rigid like an onlay. An onlay is used when the cracks are multiple and spread far under the old filling. The purpose of the onlay is to rigidly bind the cracks together to attempt to stop them spreading and to stop pieces of the tooth breaking away.

Below is an example of some cracks around an old metal filling.

Cracked tooth

Below is an example of a lost piece of tooth from around an old metal filling. This can be a consequence of leaving cracks in teeth.

Cracked tooth

It is also very important that your dentist looks into the cause behind your cracked or fractured tooth. It may just be a single tooth problem due to a large filling that has rendered a particular tooth structurally weak. However, it may be that the cause is due to abnormally high forces due to problems with your bite. It could also be that you have a clenching or grinding issue, known as bruxism. This could require some preventive steps to be taken to ensure no other teeth are damaged in the future.


The following video is helpful to visualise the effects of a cracked tooth.


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