Cracked Tooth Syndrome

Why do teeth get cracks?
Cracked tooth 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, a hair line fracture can develop, usually at the bottom corner of the cavity.

Does grinding my teeth make it worse?
Yes, and grinding is a very common habit. Almost every person will at some time in their life grind their teeth – usually due to stress. Unknown to you, grinding at night causes a massive increase in stress and strain on your teeth. You may benefit from a night guard to protect the teeth from cracking.

Why does it hurt to bite?
As the tooth flexes microscopically, the nerve is stimulated. There are tiny fluid filled tubes (tubules) which are situated in the dentine (the inner core of the tooth, below enamel). These tubules run down to the nerve and as the tooth flexes microscopically, the crack opens and closes, sucking and pumping on these tubules, causing fluid to push and pull on the sensitive nerve.

Why is it sensitive sometimes to hot and cold?
The nerve is aggravated by the crack and by the bacteria being pumped into it via the tubules. It becomes inflamed because of toxins in the bacteria. A classic symptom of nerve inflammation is excessive sensitivity to hot and cold.

What is the best way to treat a cracked tooth?
Unless the crack is immobilized 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. The only real solution is to bind the whole tooth together with a cap or crown (same thing), so that chewing force moves the tooth as a whole, rather than splitting it apart.

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 typically in these teeth. The nerve is now given its best chance at recovery because it has been hermetically sealed and the crack is immobilized.

Can you guarantee that the nerve will recover?
No! Despite the best treatment about 10% of cracked 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. Sometimes the existing bacterial damage is so substantial, that the nerve goes on to die regardless of what we do. Early treatment is therefore recommended to minimize the size of the crack and the extent of bacterial invasion.

What will happen if the nerve does not recover?
The nerve will die and an abscess will probably develop. Therefore, the dead nerve remnants should be removed and the inside of the tooth cleaned and sealed. This process is called Root Canal Treatment (RCT). A small hole is made in the top of the crown and access obtained to the nerve for cleaning. Later on , the hole is filled in with a permanent , white plastic filling or porcelain inlay sealed to the tooth and the crown. It is a pity to have to put a hole in a crown, because it weakens the crown slightly, but it is a quick and uncomplicated solution to the problem.

Could the nerve in my tooth already be dead?
Yes. Cracks in teeth develop slowly and this can allow a slow ingress of bacteria into the nerve. As a result, the nerve can die in a manner that is less noticeable than usual. Nerves can become mildly sensitive to hot and cold, and then die, or they can die without noticeable symptoms or pain. Many patients have teeth which, unknown to them, have dead nerves.  Sometimes there are even dormant abscesses on these teeth and the patient still does not know.

Is it safe to leave a tooth with a dead nerve?
Sometimes you can get away with it for awhile, but unfortunately these teeth are like ticking time bombs. The low grade infection that is usually in them can suddenly flare up and cause pain, swelling and pus. It is best to treat it as soon as possible to minimize the size of bone destruction that occurs at the end of the root, where the infection comes out of the tooth and into the jaw.

You said before that a crown was needed in order to avoid the nerve dying. If my nerve is dead, do I still need a crown?
Yes, and even more so. You need a crown now to stop the existing crack (which was severe enough to kill the nerve), spreading down the brittle root. This is called vertical root fracture. These nasty occurrences result in an untreatable problem, and extraction of the whole tooth is required. Crowns are needed on “dead” teeth even more so than teeth with living nerves, because they become brittle and very prone to these unfortunate types of cracks. Regardless of how a nerve dies , crack or no crack, it is standard practice to put a crown on a tooth that has had root canal treatment because of the risk of this crack developing. If there is already a crack, then it would be unwise not to put the crown on it. Therefore, if you have a cracked tooth syndrome, be it in a tooth with a living nerve or a dead one, you need the protective wraparound effect of a crown, regardless.

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