I was recently asked to be an expert witness against another orthodontist in my community that had “caused” some root shortening (root resorption) in one of his patients. Could something that orthodontist did actually have caused the roots to get shorter? How serious is root resorption? Can it be prevented or treated?
Braces work by creating little cramps or “Charlie Horses” around each tooth. The enzymes that are summoned by orthodontic forces cause old bone to dissolve where there is pressure and new bone to be formed where there is a void. These responses are normal and are the basis for orthodontic tooth movement. Research has shown that tooth movement causes at least small changes in the shape and length of the roots in ALL patients. In 98% however, these changes are undetectable with the naked eye.
In 1-2% of patients, however, obvious root shortening occurs during routine orthodontic treatment. These patients are just more genetically susceptible to root resorption. I have even noticed that root shortening runs in families (after noticing resorption in two children from the same family I looked at the mom’s records and found the same thing). This genetic predisposition is important and should be communicated to your orthodontist if you are aware that it has been noticed in your family.
Are there things an orthodontist can do to cause or prevent root resorption? Some have theorized that root resorption happens if the teeth are moved too quickly or too slowly. Teeth that are moved too quickly may be subject to too much force they say. However, in my cases where I’ve seen resorption I’ve used exactly the same amount of force for exactly the same amount of time as everyone else. Braces that are on longer logically have more time to cause a problem. Having said that, I’ve seen transfer cases that have had braces on for more than 5 years with no signs of root change. There really is neither documented cause of nor protocol to follow to prevent this shortening.
So what can be done about root shortening during treatment? About the only thing we can do as orthodontists is monitor our patients during treatment using routine x-rays. These should be taken at least annually as long as the braces are on. If root shortening is noticed, it should be pointed out and discussed with the patient and their family. Depending upon the amount of shortening, treatment may be continued as normal, the treatment time shortened (stopping after spaces close for example), or the braces immediately removed. It is generally believed however that a tooth can lose up to half of its root length and never have a problem. In my 21 years of private practice, not a single tooth has been lost to root resorption.
My answer to the prosecuting attorney trying to sue my competitor was this. “Root resorption is a normal consequence of orthodontic treatment. I’ll bet [the doctor] can produce hundreds of cases he’s treated exactly the same way without incident. As long as he took annual x-rays to monitor the presence and amount of shortening, I think he’s done everything he possibly could to give his patient good treatment. I don’t think you have a case.” I never heard from him again. Be sure you allow your orthodontist to take x-rays on a regular basis to monitor your progress and screen for problems during treatment. Ask him to specifically look for root shortening if he doesn’t bring it up himself.