When deciding on whether a patient needs extractions as part of orthodontic treatment, I consider the following factors:
1) Space requirements
This refers to the amount of space needed to straighten the teeth. If the amount of crowding is severe, this means that more space will be needed.
If sufficient space cannot be created by other methods (slimming down the teeth by interproximal reduction or IPR, arch expansion and incisor proclination) then extractions may need to be considered.
Which tooth or teeth need to be extracted depends on other aspects of the case such as anchorage requirements, tooth size proportion and other factors discussed below.
2) Facial profile
This is equally important as space requirements when trying to decide if extractions are required. Since the upper front teeth support the upper lip, extractions may reduce the amount of lip support and change how your face appears in profile.
This may or may not be a desirable effect, depending on the individual.
3) Cephalometric measurements
Measurements of specific reference points and angles of an xray of your skull will reveal underlying skeletal proportions.
For adult patients there is very little or no growth potential left in the facial skeleton, so most non-surgical orthodontic treatment is aimed at camouflaging the underlying skeletal proportions.
Cephalometry is a useful tool when deciding on where any extractions should take place.
4) Patient preference
Many patients want to be treated without extractions because of the perceived benefits (shorter treatment time, unwilling to extract healthy intact teeth for the sake of orthodontics). I usually take patient preferences into account during treatment planning.
However, going the non-extraction route may sometimes make treatment more complicated and may not be suitable for every case.
If extractions are something that you feel strongly about, do bring this up during the pre-treatment discussion. There are always alternative treatment options available and I present multiple treatment plans (including non-extraction and extraction plans) so that my patient is fully informed.
Since there are some aspects of orthodontic treatment planning that are subjective, it is not uncommon for practitioners to have differ.
In certain borderline cases, it may be prudent to either have a predicted tooth setup done (this is usually done on a model of your teeth) or proceed without extractions first (therapeutic diagnosis).
When using a therapeutic diagnosis, extractions can be considered when the teeth have been straightened to a certain degree without much disruption to your treatment.
