No evidence that orthodontic extractions damage facial profiles.
Early last year I wrote several posts on the effect of orthodontic extractions on facial profile. Since then, this interesting systematic review has provided us with more useful information.
We are all aware of the issues concerned with the need to extract teeth as part of orthodontic treatment. There currently appears to be a trend towards providing more non-extraction treatment. I am certainly surprised to see orthodontists suggest non-extraction treatment for cases with severe crowding. Some people even refer to extraction as “the removal of body parts” or “amputation”! But maybe they need to get out a bit more?
I feel that this systematic review goes some way to providing information that may help resolve our dilemma.
Lared et al
The Journal of the American Dental Association, Volume 148, Issue 1.
A team from Brazil carried out this review. Importantly, no member of this group was an orthodontist, so I thought that author bias was reduced. The Journal of the American Dental Association published this paper. This is a high quality journal.
What did they ask?
They did a systematic review to find out if there were any differences in facial aesthetics between patients who had received orthodontic treatment with and without the extraction of four premolars. They also looked at the duration of treatment and whether any cephalometric measurements could help with the extraction/non-extraction decision.
What did they do?
They did standard well executed systematic review. The PICO was;
Participants: Patients who received orthodontic treatment
Intervention: Extraction of four premolars.
Control: Treatment without extractions.
Outcomes: Aesthetic perception of profile, cephalometric measurements, treatment time.
Study design: Clinical trials and observational studies.
They selected only RCTs and cohort studies. They evaluated risk of bias with the Cochrane tool for the RCTs and a variant of the Newcastle-Ottawa tool for observational cohort studies.
What did they find?
After the usual filters, they found one RCT and five retrospective cohort studies.
The studies had three important outcomes;
- Aesthetic change measured by rating panels.
- Change in soft tissue morphology; measured by several metrics
- Duration of treatment.
I will look at these findings more closely;
They found that the lay panels preferred the profiles of the patients who had extractions.
They found that in patients who had extractions there was retraction of the lips. When they looked at at these measurements more closely they found that extraction retracted the nasolabial angle by 1.4° and without extractions increased it by 3°.
Duration of treatment
Duration of treatment was 7.8 months (95% CI 3.2 – 12.3) longer than none extraction treatment.
Finally, and importantly, when they looked at risk of bias. They classified the RCT as high risk and I felt that the retrospective cohorts were at moderate risk.
Overall they concluded;
- There was no real differences between the changes in facial profile following orthodontic treatment with and without extractions in terms of aesthetic outcome.
- If a patient had lip protrusion then premolar extractions were beneficial.
- The duration of treatment was longer for extraction patients.
What did I think?
I thought that this was a good and well carried out systematic review. When I interpreted the results I took the following factors into consideration
- The studies were done on “borderline” cases. This is a logical step as we all know that some cases are clearly non extraction and others are clearly extraction (most of the time)
- I thought it was very important that they considered studies that evaluated laypersons perceptions. This results in greater generality of the findings and conclusions.
- I was disappointed to find that the RCT was at high risk of bias. Furthermore, they included retrospective studies and this introduces a degree of selection bias (even though the Newcastle- Ottawa scale rated these studies as being of low/moderate risk of bias). When I bear this in mind I can only conclude that any recommendations on treatment, from this review, are of low/moderate strength.
- As I discussed in my post last week on the interpretation of negative findings. We can only conclude that there is no evidence of a difference in facial profile changes from extraction and non-extraction treatments.
When I wrote about extractions in my previous posts, my overall conclusion was that extractions are necessary as part of orthodontic care. We should not be afraid of taking this decision. It is also important for us to remember that it is not only the decision to extract that influences the facial profile, the most important influence is likely to be our skill and use of mechanics. This is part of the art of being an orthodontist. As a result, we should not fall into the trap of believing that extractions do harm and adopt non-extraction philosophies too readily.
It is always useful to consider how the results of a study can influence our practice. When we look at the findings of this paper, we need to remember that the cases in the review were “borderline” extraction. As a result, I can conclude that there are minimal differences in the effect of extractions on borderline cases (this agrees with the studies by Lysle Johnston). This means that when I see a patient with moderate crowding, I am more likely to do non-extraction treatment, because I prefer not to extract teeth. When there is mild crowding, I will go non-extraction. In cases of severe crowding, I am more likely to extract. This is not rocket science!
Furthermore, we all know that non-extraction treatment is easy. I cannot help feeling that people promote non-extraction treatment for all cases, as part of a new philosophy or paradigm change, because it is so straightforward. I think that we need to be more cautious. If we extrapolate some of the findings from this review to the decision to to treat patients with severe crowding on a non-extraction basis, it appears that we could make the profile too protrusive by non-critical expansion.
We can all procline teeth and expand arches to put roots through the alveolar bone and create patients with rictus smiles. In this respect, this review is good, timely and relevant to today’s trend to ignore evidence and follow the paths laid out by the non-extraction gurus, pedlars and quick fix salesman.
Let’s have a good and civil discussion!
Emeritus Professor of Orthodontics, University of Manchester, UK.