The Mistakes I See Often
Extraction or non-extraction: the decision is a diagnosis, not a preference. Dr Geoffrey Hall, Specialist Orthodontist, The OrthoED Institute.
The sentence I hear most often is this. “The patient does not want extractions, so I am not extracting.”
That sentence collapses two different things into one. Whether a case needs extractions is a diagnostic finding. Whether the patient proceeds is a consent decision. The first is ours to make, the second is theirs, and treating them as the same question is how cases go wrong.
Three categories, not two
Every case sits in one of three groups: clear-cut extraction, clear-cut non-extraction, and borderline.
Only the borderline group is a genuine discussion. In the other two the diagnosis has already answered the question. Treating a clear extraction case as a therapeutic trial is not a compromise. It is a decision to add up to a year of treatment and a measurable risk of root resorption, in exchange for an outcome you already knew you would not reach.
What actually drives the decision
Six factors, weighed together:
- Amount of crowding
- Facial profile type
- Lip position
- Position of the upper and lower anterior teeth
- Anterior overbite
- Skeletal vertical dimension
The vertical dimension is the one most often left out, and it is the one that determines what your mechanics will do to the bite.
The principle that ties them together
Crowding pushes teeth forward and opens the bite. Retracting teeth into space deepens the bite and retroclines the anterior teeth.
So a patient with bimaxillary protrusion, a dolichofacial pattern and minimal overbite will procline further and open further as crowding increases. A patient with spacing and an existing deep bite will see that bite deepen further as the anterior teeth are retracted.
From that follows the governing rule of space closure: the bite must be opened before the anterior teeth are retracted. Not during. Before.
Which appliance, and why it matters here
Opening the bite is difficult with aligners. It is more achievable with fixed appliances using a deep-bite setup and bite turbos.
Which raises the question I am asked constantly: should extraction cases be treated with aligners at all?
Torque control is the problem. To torque a root you need force applied at the gingival margin, which is the most flexible part of the aligner. The force system the case requires is precisely the one the appliance is least able to deliver. Root control is difficult with aligners, and it is not straightforward with fixed appliances either. Add the difficulty of opening the bite, which every space closure case demands, and the answer becomes a matter of careful case selection rather than enthusiasm for the appliance.
The conversation worth having
None of this means extracting against a patient’s wishes. It means telling them the truth: this is what your case requires, this is what happens if we do not do it, and this is the decision that is yours to make.
I have written separately that extractions do not flatten faces, poor planning flattens faces. The same holds here. The appliance does not make the diagnosis, and neither does the patient.
