Cracked teeth are a pest. They can be sore to bite on, and sensitive to hot and cold. They seem to have little timers inside that count down so they break on Christmas Eve, on Friday night before a long weekend, on the way to the airport for your around-the-world trip. Finding a crack in a tooth before it starts to cause problems is the ideal situation, so you can deal with it before it becomes urgent.
There are two main ways teeth can become cracked. Acute trauma, like copping a thrown tee-ball bat to the face (something I had the displeasure of experiencing as an 11 year old). Or, more commonly from the chronic trauma of clenching or grinding your teeth, (something that I still do to this day). A tooth that already has decay or an existing restoration, (filling), is at a higher risk of cracking, as it is already weakened.
Cracks can be detected by your dentist using a few techniques. Some cracks are easily visible, especially if your dentist uses magnifying loupes for examinations. If a crack has been present for a while, it may start to become stained so it's visible to the naked eye. A bright light shone through the tooth can show up less visible cracks, this process is called transillumination. The classic way to detect a crack is using a bite stick. Your dentist will have you bite down on a specially designed plastic stick, placing it on different parts of the tooth. If a particular spot is very painful to bite on, (or painful on releasing your bite), there is likely a crack which is being opened and closed by the bite pressure.
The reason to fix a sensitive or painful cracked tooth is obvious - to alleviate the discomfort. But what if your dentist finds a crack in a tooth that still feels fine? If it's just a fine hairline crack on the surface, it may not need any treatment at all. Fixing a more significant crack will reduce the risk of the tooth breaking, and prevent infection from getting into the tooth via the crack. Being proactive about fixing a cracked tooth can have a big impact on the outcome. Cracks in teeth are like a chip in your car windscreen - they never get smaller, but rather propagate and get bigger with time. So, fixing it earlier means fixing a smaller crack.
The other reason to jump straight on it is that cracked teeth sometimes break in ways that are hard to fix. Your dentist can remove the cracked part of a tooth in a very controlled way, preserving as much of the remaining tooth as possible. If you bite on something hard and your tooth breaks off below the gum line, it's a lot more difficult to fix.
With the festive eating season upon us, you need to trust that your teeth are in good working order. A great dentist will always have a plan in place for his/her regular patients who need urgent care at awkward times. It's best though if you never have to find out!