To Crown or Not to Crown

To crown or not to crown… that is the question.

One of the more common negative dental experiences that I have seen on the rise in adolescents and adults is cracking the crown on one’s tooth. Usually a bicuspid… sometimes a molar. If it’s due to trauma, it’s one or more anterior teeth.

Cracking a tooth can occur due to several situations:

Grinding and Clenching

Grinding and clenching at night has decreased in recent times due to the unlimited sources of night guards and the subsequent drop in prices. While I was at a conference last year, they discussed that a new group of clenchers has been on the rise… the under-35-year-old daytime clenchers. Seems being on the computer for six to eight hours a day can cause the accumulation of stress and the clenching need to release it from the body. These individuals find themselves wearing some form of polymer protective appliance for their teeth nearly 23 hours a day! Phew!

Trauma

The second most popular tooth-fracturing event is trauma, either from car, truck, bike, or quad. It is relatively low in incidence, but does increase in warmer weather.

Chewing on Ill-Advised Foods or Objects

The number one cause is chewing on stuff we shouldn’t. Be it nails, something of the metal variety, unpopped popcorn kernels, or the most popular tooth cracker… ice chewing! Ice freezes the surface of the enamel, which has very similar properties to glass, and then we bite down and the ice cleaves off or fractures the enamel cusp tips of the involved teeth. Usually the tooth’s chewing surface has been weakened by being undermined with a filling, making it vulnerable to fracture. This is due to the basic physics of the fragility of artificial material to support natural enamel, which is naturally supported by soft compressive dentin. The most vulnerable tooth to fracture is one that has undergone endodontic therapy or, in other words, had a root canal. This is due to the fact that once the tooth has had a root canal it slowly dries out from the inside out.

So back to the question at hand - to crown or not to crown?

One word - yes!

There should be a state or national law, paid for by insurance companies, that if you get a root canal, you must crown the involved tooth within four-six months once the tooth has been deemed to be symptom free. Cash comes into play here. You just spent a chunk of change, over 1000 dollars, for a root canal. It feels great and now you have to spend over another 1000 dollars for a crown? Yep! The reason… it’s pure physics. A crown covers the entire tooth above the gum line and when pressure is placed upon it, as in chewing, the forces are evenly dissipated across the entire surface of the tooth, with no pressure points to cause a fracture. Even more, today’s porcelains or hybrid polymer glasses used in crown construction are stronger than the original enamel.

What if you elect not to get a crown?

Let’s say, for argumentative sake, you don’t get a crown after your root canal. Finishing your soda or adult beverage, you feel the last of the ice slide down the glass and bump your lips. Just like a knock at the door, you open, let it in, and start chewing. All of a sudden, you get that feeling in the pit of your stomach - this may have been a very expensive beverage! And the best part of today may already have occurred!

How a tooth fractures is random, but also physics-driven.

If you are lucky, only a single cusp tip fractures off or is cleaved off. Remember, enamel is like glass and breaks along fault lines or paths of least resistance. In the example above, if the ice really got a chance to lower the surface temperature of the enamel, the fracture goes further and deeper and is more random. If the fracture goes really bad, then it goes vertical and below the gum line. Once below the gum line, the remaining part of the tooth is non-treatable due to uneven margins below the line of sight. Now, the fractured piece and any other pieces have to be extracted, leaving a gaping hole! Where in the mouth this occurs usually determines how fast and by what prosthesis the hole is filled with. One’s choices range from a removable partial… to a fixed multi-unit bridge… or one’s best bet - a standalone implant.

I get a couple adults a year who come in after fracturing a tooth and having it extracted, hoping with braces we can close the newly formed gap. Depending on the location, sometimes we can move another tooth into the space. But if the tooth has been missing longer than six months, the bone has probably shrunk to where braces won’t work.

“An ounce of prevention is worth a pound of cure.”

Ben Franklin’s sage advice rings true today. A crown after a root canal will be 1/5 to 1/4 the price of any of the later-developing options once you fracture a tooth and have it removed! But the best prevention is to listen to what your mother told you over and over - “Don’t put things in your mouth that don’t belong there and only chew on food.”

Now go out and have the best summer ever! You’ve earned it!

- Dr. P