The treatment of Cracked Cusp Syndrome is fairly complex and you may not remember all of the details mentioned to you at the time of your visit. To help you remember we are giving you this brochure You should read every word of it so you are fully informed.

In the past, we have had problems when some patients have not been prepared for some eventualities, which can be time consuming and expensive. Therefore, in the interests of the best possible relations with our patients, avoiding problems before they happen, and the principle of being “fully informed”, we have prepared the following question and answer brochure for your consideration.

How does it happen ?

Cracked cusp syndrome is a very common problem, usually affecting teeth that are heavily filled. The decay and subsequent filling causes a weakening of the remaining tooth structure. Like all materials, teeth are subject to stress fatigue. After many bites on the tooth (stress cycles), a hairline fracture can develop, usually at the bottom of the cavity.If you are under a lot of stress, you may grind your teeth (usually at night). Almost every self employed person and executive will grind their teeth, so it is very common. Grinding causes a significant increase in the stress and strain on your premolars and molars, especially if you have worn down the canines and lost the protective effect they can give in sideways grinding jaw movements. You may benefit from either a removable nightguard, or some other permanent addition to your canines to increase “lift off” and thus protect the back teeth from lateral stress. You may also have unlucky tooth anatomy (genetic) or worn down fillings, where the “valleys” on top of the teeth are deep, not shallow. This puts a lot more lateral splitting forces on the cusps during chewing.

Why does it hurt to bite on ?

As the tooth flexes microscopically, the nerve is stimulated via tiny tube (tubules) which are situated in the dentine (the inner core of the tooth, below the enamel), which run down to the nerve.

Why does it sometimes hurt to be exposed to hot and cold ?

The nerve is aggravated by the crack and by the bacteria being pumped into it via the flexing action of chewing. It becomes inflamed by the bacteria. A classic symptom of nerve inflammation is hot and cold sensitivity.

If I do nothing - what eventually happens?

The nerve can be killed by the bacteria, leading to extreme sensitivity to hot and/or cold and a persistent ache in the tooth as it dies, usually of moderate to severe intensity. The infection in the nerve can then spread into the bone underneath, causing an abscess. This pain is usually severe, not effectively controlled by pain killers. The crack continues to slowly propagate (spread) like a crack in glass. Sometimes the crack goes off to the side and the fragment of tooth breaks off.Ê The crack can also go deep into the root and at times right into the nerve. Teeth can often go for months in a stable, yet inflamed condition. Sometimes they seem to get better, only to suddenly get worse. It is hard to predict the course of the untreated tooth, but usually it is a slow downhill slide as the crack deepens. It is not a good idea to leave it, because a small crack can be fixed, but a bigger one can lead to root canal treatment or extraction if you are unlucky.

What is the best way to treat CCS ?

Unless the crack is immobilised and splinted together the tooth is very likely to deteriorate. Although various methods have been employed in an attempt to stick the crack together, chewing forces are extremely powerful, and these “patch up” solutions are fairly unpredictable and ineffective. The only real solution is to bind the whole tooth together with a “cap or “crown” (same thing), so that any chewing force moves the tooth as a whole, rather than splitting it apart. The metal is coated with porcelain so that if it looks like a tooth.

What colour will this tooth be ?

Most people prefer a natural appearance, therefore a porcelain fused to metal crown is made in most cases. You can have gold if you prefer. Because most CCS teeth have large black amalgam fillings, a net improvement in appearance results, which is some small compensation for the time and expense involved. There are a new generation of strong, all porcelain crowns which are even better looking.

Are there any other advantages to a full crown ?

The crown is bonded over the entire tooth - this seals all the micro-cracks and the variety of sources of bacterial leakage coming from the joints in the patchwork of fillings typical in these teeth. The nerve is now given its best chance at recovery because it has been hermetically sealed and the crack has been immobilised - but not necessarily a complete immobilisation.

Can you guarantee that the nerve will recover ?

No! Despite the best treatment about 10% of CCS teeth have nerves that go on to die. The tooth can still move slightly within the bone and this slight movement can flex the crack from underneath despite the crown on top. Also, sometimes the existing bacterial damage is so substantial, and the damage to the nerve is so severe, the nerve goes on to die regardless. Early treatment is therefore recommended.

What will happen if the tooth does not recover ?

The nerve will die and an abscess will probably develop. Therefore, the nerve remnants should be removed and the inside of the tooth cleaned and sealed. This process is called Root Canal Therapy (RCT) or Endodontic Therapy. A small hole is made in the top of the crown (it can not be removed without risking breaking the tooth or crown) and access obtained to the nerve for cleaning. Later on the hole is filled in with a permanent, whiteplastic filling or porcelain inlay sealed to the tooth and the porcelain. It is a pity to have a hole in the crown,because it may weaken the crown slightly, but it is a quick and uncomplicated solution to the problem, with few long term problems. The white filling will match the crown reasonably well, but don't expect the white filling to be absolutely invisible against the top of the crown. For most people, it's not a problem. If the hole really worries you, a new crown can be made if you don't mind the additional expense. There is another option, and that is to cement the crown with a temporary cement, so that in the event of the nerve dying, the crown can be removed, and recemented later when the RCT is completed. This saves having a hole drilled in it, but comes with it's own set of problems - and you must decide if you are prepared to accept these. Firstly, if the crown is put on with temporary cement, it will come off one day. Depending on the type of cement and the retentive ability of the crown this could be six months to two years. Usually, 99% of the time, the crown will come off and you will notice it and retrieve it, so that all ends well. However, you may bite on it, break it or swallow it accidentally (unlikely, but it has happened, so you need to be advised of these possibilities before you make your decision, because you may be up for the cost of repair or a new crown. It may not be as expensive as the first one if you keep the rubber impression of your tooth preparation - ask your dentist.

After the crown falls out you can elect to have it re-cemented again with temporary cement or have it cemented permanently. If enough time has passed to decide with a fair degree of certainty that the nerve has survived, you may want to go permanent. Discuss this with your dentist, because the time needed to reach a reasonable safety zone varies from 3 months to three years.. Clinical judgement and many complex individual case factors need to be taken into account, and even despite the best efforts, some nerves go on to die after permanent cementing (sometimes years later). You should also note that the cost of making your crown includes cementing it once. If you elect to cement it with temporary cement, extra expense will be involved, especially if the jaw needs to be numbed. Ask your dentist about the cost, but expect it to be around a quarter of the cost of the crown, depending on many factors.

How successful is RCT ?

The actual root treatment is about 95% successful. However, where there is a crack in the tooth which is not completely immobilised, a further 10% of those root treated teeth will get continuing pain when the tooth is bitten on, or sometimes pushed from the side. This is due to the crack movement irritating the tissues around the tooth known as periodontal ligament. There is no treatment other than extraction for these rare cases. If you end up losing the tooth there are several options for treatment - an implant into the bone which supports a new tooth; a conventional bridge (caps on the teeth on either side of the gap, fused to a false tooth resting just above the gum); a Maryland bridge (like the conventional bridge but with special metal wings instead of crowns - but not universally applicable) or a partial denture. The advantages and disadvantages of each of these are discussed in other literature.

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