Crack Tooth Syndrome

Crack tooth syndrome.

The diagnosis of the above condition and its management of the tooth is one of the most perplexing issue a dentist can often face with. Many a times it leads to serious contention between the patient either with his dentist or even the endodontist. That's the reason it has such a unique sounding name.

Simply put, the tooth structure has cracked and through this crack bacteria can reach the inner sanctum of the tooth. This results in an infection of the  pulpal tissue..The inflammation of the pulp causes severe pain and what we commonly call toothache. This pain is the most common reason why a patient seeks treatment. As we all know this pain does not come suddenly. Unlike severe trauma to teeth such as a big blow to the tooth, cracks must have started off as very fine failures in the tooth surface, With time and continuous abuse  these cracks will slowly enlarge and deepen  allowing the ingress of bacteria. At different stages of the  crack, the patient will feel varying degrees of pain. To make matters worse human beings have very different pain thresholds. So some can come in early and some come in late. The treatment rendered and the resultant outcome is highly dependent on the right diagnosis as to which stage the crack has occurred.

Rationale for treating a crack tooth.

Functions of teeth

Our teeth exist for many functions. These include chewing, speech and also facial profiles. This are all very important functions for human beings.

Chewing. Eating well is one of the great pleasures in life. The ability to chew food properly not only enhances the taste but also aid in its digestion. This gives us the nutrition we need for good health.

Speech. Without teeth or wearing loose dentures can cause speech difficulties and a source of embarrassment.

Facial profiles. Whenever teeth is lost the bone that is holding to the teeth is also lost. This results in the face losing its support and the person now looks much older than their age.

For all the above reasons patients would want  to keep their teeth for life.

Potential trauma from Extractions

Not all dental extractions go smoothly. Some can go terribly wrong. Pain from extractions and its associated complications are not only feared but definitely want to be avoided by the patient.

Inconvenience and costs of replacements

Any loss of teeth will result in many inconveniences for the patient. All forms of tooth replacement involves loss of time, in some cases further pain and definitely can be very costly . This can be in the form of dentures , bridges and implants. All these replacements have their own lifespan and thus sooner or later they will have to be replaced. That would result in even further loss of tooth. If a crack tooth is well treated it should be able to survive at least for another 10 years or more. It is a good way of buying time.

Timely treatment

As with any dental condition the earlier it is diagnosed and treated the better the survival rate of the tooth. At the early stages, the pulpal inflammation is reversible.If the patient has turned early and the dentist correctly diagnosed the condition, just a crown will be sufficient to protect the tooth. Once a toothache has occur a root canal treatment becomes necessary to stop the pain.

As the ageing population increases there is a proportional increase in the number of crack tooth.

Root canal treatment and its problems

The idea behind root canal treatment is very basic. The patient is having a toothache and wants the pain removed. The nerves in the tooth is inflamed and the technical term is pulpitis. There is a great buildup in pressure inside the pulp that causes this pain.  Hot drinks will precipitate severe pain. Worse of all when one lies down to sleep at night the ache seems to get worse and with the silence of the night this really becomes unbearable. All the painkillers does not seem to work or at best effective only for a short time.

To save the tooth from pain all you have to do is remove the nerves in the pulp cavity and the root canals. Then you seal up all these spaces so that bacteria cannot live in them and thus there will be no further infection. The tooth then is restored with a crown and become functional again.

This is easier said than done. It is a blind technique, that is you cannot see what you are cleaning more so than able to see where you are sealing. Till today not all endodontist can agree on the perfect technique. Even with the best results the longevity of a root treated tooth is significantly shortened.

Usually in severe pulpitis it is very difficult to achieve sufficient numbness to treat the tooth. So patient can be uncooperative. At this phase this is the bane of dentists who performs extractions. The patient will complain of severe pain during the extraction and in later life will have a dreaded fear of dentistry.

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Why do teeth crack?

There are many reasons for teeth to crack. The causes can work alone or in tandem.

Most dental schools suggests that the most frequent reason for a tooth to crack is due to abnormal function e.g. bruxism. Such patients gnash or bite  hard on the teeth resulting in severe wear and concomitant cracks. Generally most people are really normal.

Caries is still the most frequent cause of weakening of tooth structure. To stop the caries from spreading and later affecting the health of the pulp , the cavity is cleansed and a filling is done.  Very often caries are detected very late and a lot of tooth structure has been destroyed. . Caries can spread like wildfire in dentine. Caries itself can transmit bacteria into the pulp with resultant pulpal inflammation. As the dentine is destroyed or weakened the enamel is unsupported and it will crack. Fillings cannot replace the manner in which dentine support enamel.

Increasingly patients come into the surgery free of caries and fillings also without any parafunction to the extent that the tooth is structurally untouched with just some sign of wear.

So what is the new cause of crack tooth.It is definitely the ageing process.

The ageing process and its effect on dentine.

If you ask most dentist what is the function of dentine , they will say it is a hard tissue that contains nerve tissue that is connected to the pulp. As such it acts as an early warning system to indicate that bacteria is penetrating into the pulp.  This reason does not make sense as if one looks back more than a hundred years ago when dentists do not exist , even if the dentine can warn you of a potential threat  there is no way one can find a dentist to solve it.

To solve this dilemma all we need is to look at the structure of dentine. Dentine is made up of tubules with a nerve in each tubule. One end of the tubule is at the pulp while the other ends at the enamel. Enamel is made up of prism like crystals and completely free of nerve tissue. It is like glass. The enamel sits on the dentine layer. The dentine tubule being connected to the pulp has also dentinal fluid. If you look at the way the whole system is set up then you can see the function of dentine. Tubular structures can flex and the dentinal fluid provide even greater flexibility to the system. Through this unique structural combination the dentine acts as a flexible support to the enamel enabling the enamel to function like hard glass but does not crack in the process.

As one grow older secondary dentine is deposited at the pulpal end of the tubule. In teeth where fillings have been done or severe wear is seen, a thick layer of secondary dentine is seen. This can  act as a barrier to irritants from reaching the pulp. Secondary dentine is an amorphous mass and as they are deposited they block the renewal of dentinal fluid from the pulp. Without this renewal of dentinal fluid the dentine layer loses its flexibility.

If we use the rational of ageing bamboo we can come out with the most likely cause of crack tooth. As we all know young bamboo is green in colour with great flexural strength. It has a lot of fluid in its structure. As bamboo aged, they dry up and turn brown. Brown bamboo cracks much more easily. If you apply this rationale to the dentine , we can deduce that when there is an absence of secondary dentine i.e in a young tooth or tooth that has not have any wear or damage, the enamel is well  supported by the dentine’s ability to flex to absorb all the stresses. As ageing progress or the tooth suffers from wear or injury, the secondary dentine formed now blocks the dentinal fluid from the pulp. The dentine now acts like brown bamboo and as it has lost its flexural strength , it no longer can support the forces acting on the enamel leading to cracks developing in the enamel.

To make things worst cracks do not just appear in the enamel. It extends into the dentine. These cracks then become the pathway for bacteria to reach the pulp causing inflammation and eventually pulpal death. Cracks now not only can exist in the coronal part of the tooth but propagates into the neck and eventually the root of the tooth. At this stage a split tooth is seen.

Is there any other natural factor that cause people to have a higher rate of crack-tooth?

It may come as  a surprise to you that the dental profession does not know that the jaw relationship plays a major role in crack teeth. Commonly human being’s teeth are classified into three relationship i.e how the upper jaw come to contact the lower jaw.

These are namely Class I, II and III.

People with Class II Division II jaws has the highest frequency of crack teeth. (I will dwell into it in another chapter)

Management of the crack tooth.

Once you can understand the anatomy of the tooth and nature’s way of using this anatomical setup, you can see there are varying stages of cracks developing in the tooth. At each of stage they not only present with different symptoms they also call for different methods of treatment with the resultant outcome. Ironically the diagnosis is not as simple as just detecting the extent of the crack.

Factors affecting the correct diagnosis of the stages of a cracked tooth

The patient’s experience of a cracked tooth.

The majority of patients have no experience of a cracked tooth and thus is not aware that a tooth has cracked until they notice significant symptoms. If the dentist are not aware of the the signs and symptoms of crack tooth early sufferers are usually not treated.

Most people still associate dental sensitivity with caries or expose roots. Exposed roots is the culprit in modern society as there are plenty of advertisements by manufacturers of desensitising toothpastes highlighting their efficacy against such an irritation to one’s comfort.

In the average person there is always a certain degree of exposed roots. In people with chronic gum disease the surface area exposed is increased significantly. The roots of teeth have no enamel cover and the dentine tubules are exposed to the oral environment and its stimuli of temperature, touch and pH changes. Our modern diet can change from an ice cold drink to some very hot food. Food can be sweet, saltish, sour and bitter with its different pH. When it comes to brushing teeth some people brush too hard while others will use very abrasive toothpastes to the detriment of the exposed roots.

So people and dentists are usually fixated with these causes and overlook the initial cracks.

The symptoms associated with cracked tooth

These can be divided into early, intermediate and late symptoms.

Each patient has a different pain threshold, thus it is utmost importance that the patient’s story is correctly heard.

Early symptoms.

The first inkling of a crack tooth is when the patient comes into surgery usually on their routine dental  check up, complaining that there is occasional pain on biting. Some patient may even tell you that recently on biting something hard,  they had heard a crack sound in one of their teeth. Usually they cannot tell for sure which tooth is involved. To make matters worse the nature of the trigeminal nerve and its interpretation of the source of pain complicates the diagnosis of which tooth is involved.  A fair number of patients will point to the opposite or the next tooth as the source of pain. In the absence of clear cut pathology such as deep fillings, it is very difficult to confirm the cause.

X-ray films are of little help as the crack is usually at right angle to the x-ray beam and thus does not show up at all.

In some cases they don’t even mention of the pain but on examination one can see that the patient had avoided biting on the side. Only on detailed questioning will they tell of the symptoms. The pain is fleeting and once the patient avoids biting on that side, it no longer bothers the patient. The tooth is usually not affected by temperature changes.

Examination can reveal one or more cracks in one tooth or on its neighbouring teeth. Some of the cracks are fine and can  be seen only by refracted light.  This is useful as it can be use to differentiate between cuspal fracture or a midline fracture.  The tooth involved may not have any restorations but usually show some wear facets. When the patient is asked to bite on a woodstick, the location of the crack can often be confirmed.

X-ray usually is not helpful at this stage but is important to rule out any inter-dental caries that was not seen.

This is the stage where the best results are obtained. Since there is no response to temperature stimuli, the pulp is still healthy and when the tooth is restored properly  it will heal uneventfully.  However the x-ray film must also rule out that there is no periapical lesion which would indicate that the tooth is already non vital and so patient does not respond to temperature stimuli.

A crown is the treatment of choice in restoring the tooth. It is usually a difficult recommendation as the patient may be taken aback that a perfectly sound looking  tooth requires such an expensive treatment. To make matters worse  he make seek a second opinion in which the other dentist lacking experience may rule against your diagnosis. The age of the patient, presence of severe wear facets, a lone tooth and a class 2 division 2 bite  can guide you to push for the crown treatment.  When in doubt and when the patient show reluctance ,explain to the patient that if symptoms persist or gets worse, he should return for treatment.

Even at this very early stage, the dentist may recommend a crown without root treatment. Very soon after the crowned has been cemented the tooth becomes painful and needs a root canal treatment That highlights the difficulty in the right diagnosis.

The intermediate stage.

At this stage the patient has had suffered from pain on biting for some time. This can be a little as a few weeks or more than a year. Now the patient seeks treatment because he is bothered by the irritation when having cold drinks even though he has avoided chewing on the causative tooth. Frequently he may have consulted one or more dentists who could not find any pathology. The usual treatment they have received is an application of a desensitising paste and even a filling at the exposed root of the tooth. By now the causative tooth can be usually be pinpointed easily. When asked they probably cannot recall any episode of a crack sound on biting.

One can see the crack clearly. However in some cases it can be masked by amalgam or other restorations. In non restored teeth the amount of stains in the crack can give one the degree of severity and duration of the crack. As mentioned earlier the crack is the path of bacteria ingression. Darkly stained cracks would indicate that the crack has been around for a long time. Refracted light will show an obvious crack even in the absence of stains. The most important observation is if both mesial and distal cracks are seen, then the condition is fairly advanced.  The tooth should be immediately restored. X-rays is taken to rule out any other pathology. In some cases one can see that the pulp is shrunk from the crack area. This is due to the deposition of secondary dentine.

This is a troublesome stage of affairs. If the patient’s history point to an early appearance of the symptoms to cold, no root treatment is recommended. If they have a long history of sensitiveness and if you can see some fillings around the cervical part of the tooth, it is best to complete the root treatment prior to the restoration. Some patients may resist a root treatment. They may have heard that root canal treatment is painful and maybe they would not like to put with additional cost. Such patients must be informed that the need for root treatment later. The bad news is some patients may come back complaining of pulpitis soon after you have restored the tooth. Also it is imperative you rule out the presence of other crack teeth. The prognosis is now guarded.  Due to the difficulty in pinpointing the extent of the crack, it is advisable to inform the patient that the whole treatment may fail many years down the road as cracks reaching the root can progress further down resulting in abscesses even with no obvious split in the root.

The Late stage.

This is the most obvious stage. The tooth is a hot tooth and is giving the patient a lot of pain. The diagnosis is very easy and the patient usually reacts even with a slight tap. Patient will complain of severe pain when having a hot drink. Most of the time they will also tell you that cold drinks relieve the pain. Now all you need is to rule out if the pain is a result of a crack tooth or due to a deep restoration. With a crack tooth the information the patient receives is very important as at this stage the crack may have gone so far down the the crown that it has reach the root of the tooth.

The following observations are very important.

Visual  and physical examination.

At this stage the crack is clearly seen. It is  mesio-distal in nature or involves two sides of a cusp. Some are stained deeply. When you run a probe across the crack it catches the tip. If you can place the probe tip into the crack, the tooth is best extracted. The tooth maybe be slightly mobile which is indicative of some sort of abscess. Do check for any gingival pockets as it may show up an endo-perio lesion. This only occurs in molars as only one of the root is already necrotic but the other roots may still have some nerve tissue.

The tooth may or may not show any mobility.  Mobility is usually a bad sign.

X-ray will show up many issues. An enlarged periodontal space is not a good sign. This is an indication that the crack has reached the root of the tooth.

Management of the crack tooth at the late stage

In the absence of any of the above negative issues, a root treatment must be instituted immediately. Previously it was advocated that a band be placed around the tooth to prevent it from splitting up. However placing a smooth fitting band is extremely difficult. Many a times it may result in more aggravation of the patient. It is easier to grind the tooth completely out of occlusion and use a composite as a temporary restoration. If the tooth actually cracks during the interim period it may be a blessing in disguise.

Then it should be extracted immediately.

Many problems associated with treatment arise at this stage. This is all due to the difficulty of diagnosing if the crack has reached the root. Sometimes when using a tool called apex locator, when it gives a funny reading you can conclude the crack tooth is beyond redemption.

When root canal treatment is completed and the tooth absent from any symptoms it is best to crown the tooth immediately.

It is obvious that the patient is cautioned that the tooth has a high possibility of it being extracted if all fails.

The end stage of the crack tooth.

Failure of the whole treatment can come anytime. Those that come very early i.e less than a year is always a point of contention between the patient and the dentist. This due to the high cost and amount of time already expended. Even at the very early stage, the dentist may have recommended a crown without root treatment. Very soon after the crowned has been cemented the tooth becomes painful and needs a root canal treatment Whose fault is it?

Sometimes there can a be swelling of the gums or an abscess. Other times it just presents with a very small swelling followed by what we called a sinus tract. X-ray will show changes to the bone on the side of one of the roots.

This is the end stage and the tooth should be extracted.