Teeth crack for various reasons: pressure of biting, decay (new or old), or the “wedging” effect of old, non-bonded fillings, among others. (Please follow below.)
In this example, when the top and bottom teeth come together in normal chewing, the pressure on impact is transmitted, through the old filling that receives the cusp, to the left half of the remaining tooth. Because teeth are actually soft on the inside, this “wedging” effect causes the tooth to “give” at its place of least resistance.
Not only does a small crack start at the base of the filling, but the filling itself opens up at the top, allowing more uncleanable bacteria to get in, and forming a new cavity. There are now two problems, and they are both headed for the nerve!
Then, with more time, the complete fracture happens, usually when you least expect it. Now you are left with a broken tooth, an exposed nerve, pain and a more expensive treatment to save the tooth, or even a surgical extraction.
Now the GOOD NEWS..this can be prevented!!!
If you are diagnosed with cracked teeth, and you should choose to prevent a tooth problem rather than to react to one, you can help stop this cycle of problems.
By placing a crown over the tooth, the pressure caused by biting is now distributed equally, and eliminates this point of resistance, keeping the tooth healthy, and you happy.
Better yet, if cracked tooth syndrome is caught early enough, you may even just need to replace an old filling, with one which pulls the cusps together (bonding), not push them apart (fracturing).