In orthodontics, non-coincident midlines are about more than just aesthetics. They can indicate orthodontic complexity for a number of reasons including previous extractions, severe crowding, facial asymmetry, among others.
Because of this, it is helpful to figure out with your patient whether midline correction is important to them, as it may mean that treatment is extended or that clear aligners are not the best tool for the job.
You should check whether midline symmetry along these dimensions is a ‘must-have’ for patients.
If they are not willing to compromise and want a guarantee that their midlines will be coincident this patient is probably best referred to a specialist orthodontist who may need to used fixed appliances to achieve this.
Many patients won’t have thought about midlines before, and won’t mind a small discrepancy.
In that sense, having an initial conversation is part of the consent process, and you should document the patient’s response in your submission, and in the 32Co patient materials, if you choose to use those.
If you work with a Specialist on your case it is likely they will warn you of any changes to the midline in their advice.
You may worry about making patients feel self-conscious by asking questions about symmetry (this is similar to discussing black triangles).
However, setting expectations early will avoid problems down the line if the patient feels they have not achieved the results they are looking for- particularly if they’ve never thought about midlines before.
Various studies have shown that the majority of people in studied populations have a minor maxillary and mandibular dental discrepancy.
One study (link) suggests the midline may be placed in precision with facial midline or at a slight variance from the facial midline (not > 2 mm) with no loss in natural appearance.
This has implications for not just orthodontics but all restorative work; midlines don’t have to be perfectly coincident to look natural.
Midlines is a big topic in clear aligners, keep an eye out for future content on midline improvement and correction, and using midlines for diagnosis and assessing complexity.