Short Answer: It means the root of your tooth is getting shorter, most likely because of your braces. There is no treatment, but further damage might be preventable.
Long Answer: Hold a pen vertically and stick it in jello. Now move it through the jello while keeping it perfectly vertical. That was easy, right? Now do the same exact thing, but this time put the pen in thick molasses. That took a lot more time and a lot more force to do, right? Also, you might notice that it took even more effort to keep the pen perfectly vertical as you passed it through he viscous material. Now imagine that the pen is a tooth and the thick molasses is the jaw bone. Braces apply forces to the top part of the tooth and it takes a lot of pressure to slowly move teeth through bone AND to also keep them vertically upright. If that pressure is excessive or applied for long periods of time, eventually your body will melt away the end of the root. In other words, your body knows that it’s easier to move a shorter pen through the bone than a longer one…so it makes it shorter. As your root gets shorter, this is known as external root resorption.
There are many factors involved in root resorption, but it seems to happen much more frequently in people that have braces for a long time (many years) and in cases where a lot of force is applied to the teeth (the amount of force can be tuned by the dentist). Also, some specific movements of teeth cause the problem to occur more than others (for example, pushing teeth deeper into bone causes the problem more than pulling teeth out to look taller). Specific teeth seem to be more prone to the problem than others, and the most commonly affected teeth are the front incisors. There are also genetic factors involved, which means one person gets severe root resorption and someone else getting identical treatment gets none. Even seemingly unrelated factors like alcoholism, asthma and allergies can predispose someone to more root resorption. The bottom line is if the roots get short enough, they may start to wiggle when you bite on them or when you press on them with your fingers. In more severe cases, the teeth can hurt. In a worst-case scenario, a severely affected tooth might need to be removed (but this is quite rare). It is important to note that even in mild cases, any amount of resorption does make the tooth more susceptible to problems over a lifetime than if it was never affected with this problem. This is why I repeat what I have stated in other blog posts: there is no such thing as a risk-free dental procedure and you should always insist on being fully informed about the risks, benefits and alternatives of the treatment you are undertaking.
PREVENTION / TREATMENT:
The easiest prevention is to avoid braces, which may not be an option for some. If you have chosen to get braces, it is recommended the dentist take x-rays periodically and throughout your treatment to make sure resorption is not occurring. If it is, your treatment can be ‘paused’ sometimes for several months, as your bone and teeth have time to recover. Studies show that taking pauses in treatment and reducing the amount of force applied to the teeth greatly reduces the risk of external root resorption. Some patients object, however, because it can significantly increase the time in braces overall. If resorption occurs rapidly and persists even after pausing treatment, the treatment may need to be stopped early altogether.
It is important to remember that not everyone who has braces gets external root resorption, but it is a risk. Once resorption occurs, there is no treatment to recover the lost part of the root. This makes the tooth more susceptible to gum disease and other problems over a lifetime. Ultimately, the tooth could be lost at an earlier age – an outcome everyone wants to avoid.