Cracked Tooth Syndrome

In this section, we will cover:

What is cracked tooth syndrome?
How is it caused?
How is it diagnosed?
How is it treated?
How successful is treatment?

What is it?

Cracked tooth syndrome is a condition where there is a hairline fracture running through the tooth but no part of the tooth has broken off, i.e. an incomplete crack.

There will usually be sharp pain on biting and when having cold food/drink. It is difficult to pinpoint the exact tooth causing the symptoms. Pain is usually felt when biting on the tooth as the two parts of the tooth either side of the crack "flex" and move apart very slightly.

Cracked teeth are more common in a tooth with a large filling or if you grind/clench your teeth.

A cracked tooth is different to a chipped tooth (or tooth fracture) in which a part of the tooth completely breaks off.

How is it caused?

Cracked teeth are usually caused by:

Excessive force on healthy or restored teeth
This is more commonly seen in people who grind their teeth. This habit is called "Bruxism". Many people clench or grind their teeth when they are asleep so are unaware of this habit. Often it will be picked up by the dentist who may see signs in the mouth such as tooth wear, indentations in the sides of the tongue or raised ridges on the insides of the cheeks; or it may be picked up by a partner who can hear it at night.
Normal biting forces on root treated teeth, especially back teeth without a crown/onlay.
Normal biting forces on teeth with large fillings.

How is it diagnosed?

Diagnosing a cracked tooth is challenging as there is often not much to see in the mouth or on an xray. It is important to mention any symptoms to your dentist as this will encourage further investigation.

While it is occasionally possible to see a crack on a routine examination, more often than not your dentist will require the help of some extra tools and tests to diagnose a cracked tooth. Some of these include:

Magnification or "loupes" (special type of glasses with a small microscope attached to the lens)
Transillumination; this is the use of a blue light which is shone through the tooth. A crack will stop the blue light from shining through the tooth
Bite tests; this is essentially a piece of plastic/cotton roll/wood which is placed on the cusp (pointy part) of each tooth that you bite down on. If pain is felt on biting down on a particular cusp, it may indicate a crack involving this part of the tooth.
Periodontal probing; this is the use of a ball-ended (blunt) probe in the gap between the tooth and gum (known as a "pocket"). If there is a single deep pocket (i.e. the probe goes much deeper below the gum than everywhere else around the tooth), this indicates a fracture going down the root of the tooth. These teeth have a hopeless prognosis
Radiographs (xrays); although rare, xrays can sometimes show a crack in the tooth or bone loss around a tooth with a long standing root fracture
Copper/orthodontic band; if the pain goes away whilst the band is wrapped around the tooth and comes back once removed, there is probably a crack in the tooth
Removal of existing filling; this may reveal a crack underneath the filling. Your dentist may decide to investigate this crack to see how deep it goes
Sometimes you'll need to see a specialist endodontist for further investigation

How is it treated?

Cracked teeth are notoriously difficult to manage as there is no universally accepted treatment protocol. However, it is generally accepted that the aim of treatment is to keep the two parts of the tooth on either side of the crack together.

For a vital tooth (a tooth where the nerve is still alive), there are numerous treatment options. These include:

Direct bonded restoration (composite filling)
This is a filling placed by your dentist which is "glued" or bonded to the tooth surface. Depending on the extent of the crack, the dentist may place a small filling within the tooth or cover the whole biting surface of the tooth in an attempt to prevent the crack from becoming larger.
Indirect restoration - onlays and crowns
These cover the whole biting surface of the tooth and hold the tooth together. This is a more complex treatment which requires two visits as the restoration is made by a laboratory. Your dentist will file down the tooth and take a mould (or impression) of your top and bottom teeth so the laboratory technician can make a restoration which fits your mouth almost perfectly. After a couple of weeks at your second appointment, your dentist can fit the restoration onto your tooth.

If the crack involves the nerve, then the tooth will need either a root canal treatment or extraction. It is important to note that if the crack runs through the nerve and beyond, the prognosis of the tooth (how long the tooth will last) is poor. If the crack runs through the root of the tooth, it will need extraction as the prognosis is hopeless.

If you grind your teeth, you may benefit from a mouthguard to wear at night. This reduces the risk of damaging other teeth.

If you have any teeth with large fillings or root canal treatments without an onlay/crown, your dentist may suggest you have an onlay/crown on these to protect them from breaking.

How successful is treatment?

There is an 80% success rate over 6 years for painful cracked teeth (short-lived pain, pain on biting) treated with a dental crown, without the need for root canal treatment.

20%, or 1 in 5, of painful cracked teeth will eventually require root canal treatment or extraction. This will usually become necessary within 6 months after a dental crown is placed.