Dear Dr. Crapo,
About ten years ago I was hit head-on in a car accident. Thankfully I was only travelling about 20 km/h. My vehicle didn’t have an airbag and the impact drove my face into the steering wheel, breaking quite a number of teeth. As a result, all my upper teeth needed root canals and crowns. I lost my upper right molars and the rear teeth in my lower jaw had to be crowned. Miraculously my lower front teeth from eye tooth to eye tooth were not damaged at all; however in the last two years I’ve had some problems that now require attention. A lower bridge has unrepairable decay and a crown is loose – again – after three attempts to recement it. I thought crowns were supposed to last a lifetime and why did my bridge fail? I know ten years sounds like a long time but it seems like yesterday that I was recovering from the accident and then having all that dental work.
As I work with people in solving their dental needs, I run across this problem from time to time. Sometimes the cause that made your crown come loose and your bridge fail also loosens a tooth – to the point it falls out. In other cases, an individual might see fillings repeatedly “dislodged” in a short period of time after they’d been placed.
In every case the affected tooth is taking more force than it was when the crown/filling was first done. Though the reason for this extra force is a complex matter, your history provides some clues.
You stated that all your teeth received crowns except your lower front teeth. Over the past ten years your lower front teeth, which provide masticatory (chewing) guidance, have been subject to continual rubbing or friction against the porcelain crowns on your upper front teeth. I’m sure if you look closely at your natural lower teeth you will see wear. You may even see wear to the point that the edges of your lower teeth now show the underlying dentin (you will see it because it’s darker). Dentin supports the enamel of our teeth but when the enamel is worn away, the dentin (which is softer) wears even faster. Wear on your front teeth has changed the pressure placed on your back teeth. As the back teeth take on more stress, it does so unevenly and one or more teeth end up taking stress that is beyond their biologic stress limits. This leads to your problem and the others discussed above.
A thorough evaluation of this wear will lead to a solution that will both protect your lower front teeth and prevent excessive force on your back teeth – thus preventing future failures.
If we can help, we’d like to. Call 250-800-3647 for a free consultation.
This article was originally featured in the Victoria Times Colonist on October 25, 2015