Orthodontics: to extract, or not to extract

This month, Saba Qureshi explores the longstanding debate around whether or not to extract teeth during orthodontic treatment.

Before all the avid Shakespeare enthusiasts come for me, I realise that’s not the phrase, but humour me this one time while I explore the age-old orthodontic argument of ‘extraction versus non-extraction’ therapy.

Since the introduction of braces, professional opinion on this matter has shifted from one extreme to another, and it remains a hotly-debated topic to this day.

So, why is it so controversial?

Well, mainly because many claim extraction treatment has a potentially negative impact on the facial profile, while others are concerned that non-extraction treatment does not impart post-treatment stability – and so the battle continues…

Let’s examine the argument in more detail:

Extraction concerns

The main concerns with respect to orthodontic extractions are as follows:

Facial profile – those who oppose orthodontic extractions claim that removal of premolars results in a concave facial profile, lacking in lip support, which is deemed unattractive
Buccal corridors – some clincians believe that extracting maxillary premolars causes narrowing of the maxilla, resulting in broader buccal corridors
Temporomandibular joint disorder (TMD) – it has purported that one of the side effects of premolar extractions is TMD
Airway dimensions – concerns have been expressed that premolar extractions can lead to a decrease in airway dimensions.

However, much of the literature does not support the above claims…

Are these concerns valid?

Studies comparing orthodontic extraction and non-extraction cases with respect to arch width have found small differences which are not statistically significant.

With respect to the soft tissue effects of extractions on the facial profile, the results are rather unsurprising. It is reported that, in the case of a convex profile with an acute nasolabial angle, extractions may provide some soft-tissue benefits. But where an obtuse nasolabial angle is present, extractions may have a deleterious effect.

It has also been stated that the facial profile flattening during treatment and long-term follow-up is primarily due to maturational changes, rather than as a result of orthodontic extractions. It all comes down to careful treatment planning of each individual case, taking into account dental and facial aspects of a patients malocclusion.

Where cases have been carefully planned, it has been demonstrated that even dental professionals cannot detect whether or not orthodontic extractions were performed based just on the facial profile.

Buccal corridors resulting from constricted arch widths are not a usual outcome of extraction treatment either when correct planning has been implemented.

And finally, there is no evidence to suggest a significant variation in condylar positions before and after extraction therapy which could lead to TMD.

Orthodontic expansion methods

Expansion has been used to correct posterior crossbites since 1860, making it one of the oldest means of creating space within the dental arches.

It can be divided into three categories:

Slow maxillary expansion (SME) uses lighter forces for a longer period of time to expand the maxillary arch by dentoalveolar changes. Slow expansion has been found to promote greater post-expansion stability, if given an adequate retention period. It delivers a constant physiologic force until the required expansion is obtained. SME produces more stable results when the maxillary arch is expanded slowly at a rate of 0.5-1 mm per week. The most common SME devices used in the UK are the quadhelix and the Damon system
Rapid rapid maxillary expansion (RME) involves the separation of midpalatal suture and movement of the maxillary shelves away from each other, producing skeletal expansion. Advocates of rapid maxillary expansion believe that it results in minimum dental movement (tipping) and maximum skeletal movement. An increase in maxillary arch width of up to 10mm can be achieved by RME with a rate of expansion around 0.2-0.5mm per day. RME appliances tend to be be tooth-borne (eg Hyrax appliance) or tooth and tissue borne (eg Haas appliance)
Surgically assisted rapid palatal expansion (SARPE) reduces the resistance of the closed midpalatal suture to correct maxillary constriction in skeletally mature adults by surgically separating the maxillary sutures. The following have been reported in the literature as indications for SARPE, all applying to a skeletally mature patient with a constricted maxillary arch. It is recommended for adult patients who require more than 5mm transverse expansion. The rate of expansion produced is in the region of 0.5-1 mm per day.

Non-extraction concerns

Now let’s look at the main concerns with respect to non-extraction expansion treatments:

Stability – Some worry about a lack of post-treatment stability in non-extraction cases
Impaction – Without orthodontic extractions, some claim that there is a greater chance of third molar impaction
Dehiscence – Complications of expansion include the risks of creating a dehiscence as a result of overexpansion.

Again, the literature offers conflicting opinions with respect to post-expansion stability and impaction, depending on which article you read. Clearly, there is scope for further research here.

As to the risk of dehiscence, planning individual cases carefully should avoid this.

Public perceptions

It is safe to say that there has been a steady reduction in the popularity of orthodontic extractions over time. In my opinion, this is driven not only by the clinical preferences of individual orthodontists, but public opinion regarding extractions.

Patients and parents are often concerned about having teeth removed because they are worried about:

Painful extractions
Aesthetics of extraction spaces initially
Removal of healthy permanent teeth
Damage to their facial aesthetics
Narrowing of the smile
Extraction spaces not closing fully.

These fears have become amplified by ‘horror’ stories shared freely on social media by influencers.

At the risk of sounding my age, the only influence I would like our patients to be under is that of well-informed clinical decisions.

Considerations

Occasionally, I will implement a ‘therapeutic diagnosis’ for borderline cases who I start non-extraction, with an understanding that extractions may need to be undertaken after initial alignment has taken place.

But this, of course, comes with increased treatment duration and perhaps round-tripping of teeth, so it must be carefully considered.

Ultimately, the decision of whether to prescribe orthodontic extractions should be made on an individual basis following a thorough assessment of the amount of crowding and space requirements, the size of the overjet, torque requirements and facial aesthetics.

Catch up on previous Straight to the Point columns:

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