Here's a question we've gotten from a few doctors new to orthodontics:
I have a patient that is in the middle of treatment and I noticed that some of the teeth are mobile or feel loose. The patient did not have any periodontal problems before treatment and keeps their teeth clean. Should I stop treatment until the mobility goes away or should I not be concerned about this and continue with aligner treatment?
Dr. Mah responds:
Tooth mobility of ~1mm is relatively common during active tooth movement. The tooth socket is being remodeled to allow for the tooth's movement. During remodeling, it is slightly enlarged.
In addition, the periodontal ligament is undergoing tremendous remodeling in phases of resorption and reformation. During this time, it is not as taut and does not function as well, resulting in slight mobility.
Also, the supporting bone has a dense cortical border with trabecular bone in between. The significance of the trabecular bone is that it is not homogenous. Rather, its appearance is like "Swiss Cheese" with spaces between the supporting bone scaffolding. As a tooth is moved through bone, it will pass through the bone scaffolding and the spaces. In the latter, there may be more mobility.
Having said this, clinicians should be on the lookout for occlusal interferences, periodontal disease, endodontic problems, excessive root shortening and pathology during orthodontic tooth movement. Mobility of greater than 1mm should be further evaluated for any possibility of these other problems. Most commonly, excess mobility is due to occlusal interferences.