Sooner or later, teeth with compromised structural integrity because of large existing silver fillings almost always develop cracks.  A careful inspection with the intra-oral camera of your existing fillings may reveal one or more cracks that deserve careful attention.  (Click on this link to learn more: Silver Fillings).

Our normal chewing pattern is not straight up and down like a hinge, but rather is an "envelope of motion." This means we put a lot of sideways pressure on the cusps of the back teeth!.  This can create stress on the cusps and cause micro-fractures (or cracks) at the base of your fillings.  (Click on this link to learn more: Conservative Care).

Grinding your teeth (generally unconsciously at night), eating hard candies, or chewing on ice can put a tremendous amount of stress on teeth.  Thermal expansion and contraction of a filling within a tooth can, over time, contribute to the fracture of adjacent tooth structure.

Why does it sometimes hurt to bite on a tooth with a crack in it?

As the cusp of the tooth flexes, the nerve within is stimulated.  Generally, after the stress is eliminated, the cusp returns to its normal position and the paid goes away.  We learn very quickly to avoid hard chewing on teeth with cracks in them!

Why is my tooth sometimes sensitive to hot and cold?

As bacteria penetrate the crack, they release toxins that stimulate the nerve within the tooth.  Abnormal sensitivity to hot and cold are classic symptoms of nerve inflammation caused by cracks in teeth.

What will happen if I do nothing about the crack in my tooth?  

Just like the crack in an auto windshield, a crack in your tooth will continue to grow. Sometimes the crack veers off to the side, and a fragment of tooth breaks off.  But the crack could also go deep into the root right to the nerve.  Chronically inflamed nerves within teeth sometimes seem to get better, only suddenly to get worse.  It is hard to predict how an untreated tooth will feel, but it is usually a slow downhill slide as the crack worsens.

What is the best way to treat "cracked tooth syndrome?" 

Because most cracked teeth have large black amalgam fillings, the best course of action is to remove the filling along with any recurrent decay, remove the areas of the crown that have been compromised by the cracks, and prepare the tooth for a full-coverage porcelain crown.  The crown is bonded over the entire tooth, sealing all the cracks and the variety of sources of bacterial leakage coming from the joints in the patchwork of fillings typically found in these teeth.  The nerve is now given its best chance of recovery because it has been hermetically sealed, and the crack has been stabilized.  (Click on this link to learn more: Same Day Crowns).

Despite the best treatment, some cracked teeth that have been restored with crowns have nerves that eventually die.  Slight movement of the tooth can continue to flex the crack from underneath despite the crown on top. Sometimes, the bacterial damage is so substantial that the nerve goes on to die regardless of what is done to protect it.  Early treatment is therefore recommended to minimize the size of the crack and the extent of bacterial invasion within the tooth.

What will happen if the nerve doesn't recover? 

An abscess will probably develop.  Clinical judgment and many complex individual case factors need to be considered, and even despite the best efforts, the nerves within some teeth go on to die months or years after permanent cementation of a crown.  In these cases, an evaluation will be made to determine the feasibility of treating the tooth with a root canal.  (Click on this link to learn more: Laser Assisted Root Canals).

Cracks in the teeth can develop slowly, allowing a gradual penetration of bacteria into the nerve.  As a result, the nerve can die in a way that is less noticeable than usual.  Even mild sensitivity to hot and cold can indicate irreversible inflammation of a nerve, or nerves can die without any symptoms or discomfort.

These teeth are often like ticking time bombs.  A low-grade infection can suddenly flare up and cause significant symptoms.  (Click on this link to learn more: The Fires Within).

Even more so.  Teeth that no longer have a vital pup (a nerve and blood supply) become surprisingly brittle and very prone to continuing fracture.  These teeth, in particular, need the wrap-around protection that a crown provides.

What is the bottom line? 

Teeth that have been diagnosed with cracks, and especially those that are already creating symptoms or that have visible evidence of bacterial penetration, should be protected with crowns.  It is much easier and less expensive to treat teeth this way, before more serious and potentially devastating problems occur.  (Click on these links to learn more: Same Day Crowns, Single Visit Crowns, Old Silver Fillings, and Cosmetic Dentistry).