Can Braces or Orthodontics Fix Facial Asymmetry?

Verdict: only a clinic can, and only partly. Orthodontics moves teeth and, in a child, can influence how the jaw grows. In an adult it can fix a crooked dental midline and a crossbite, which changes the smile and sometimes where the lower jaw rests. It does not move the chin on the bone, and there is no trial showing it corrects facial asymmetry.

The question every orthodontist gets weekly

"My teeth are straight now, why is my face still crooked?" One commenter on an aligner forum put it plainly: this question comes up every week. The answer is that there are three different things that can be off centre, and braces reach only one of them cleanly.

• The dental midline: the line between your two front teeth. Braces move this.
• The functional shift: where the lower jaw slides when the teeth meet. Fixing a crossbite can remove this.
• The skeletal midline: where the chin sits on the mandible. Braces do not move this in an adult.

If your chin sits 4 mm to the left, straightening the teeth will make the smile symmetrical inside a face that is still 4 mm to the left. That is a real improvement. It is not the one most people were hoping for.

Where orthodontics genuinely helps: the growing face

A unilateral posterior crossbite makes the lower jaw slide sideways on closing to find tooth contact. It is common: a worldwide systematic review found posterior crossbite in about 9% of children and adolescents. In children around age 8 with this shift, the condyle (the jaw joint head) was already asymmetric, index 10.7% versus 4.2% in controls, and 3D scans of 78 crossbite children against 156 controls put the resulting asymmetry in the lower third of the face.

Correct the crossbite early and the sideways slide stops, and the jaw is free to grow without that daily push. This is the strongest case for orthodontics as an asymmetry treatment, and it is a case about children. There is still no randomised trial showing that correcting it prevents adult facial asymmetry; the mechanism is solid, the long-term proof is missing.

Even in children, the power of appliances over bone is smaller than people assume. A Cochrane review of 27 trials in 1,251 children found that starting functional appliances early rather than later changed the final jaw relationship by 0.02 degrees on average. Teeth move readily. Bone, even growing bone, moves a little.

The adult case

In an adult, the skeleton is set. Braces or aligners can align the dental midline, level a tilted bite plane and correct a crossbite. If a functional shift was pulling the jaw to one side on closing, removing it can let the jaw rest a few millimetres more centred, and the chin comes with it. That is the most an adult can expect from orthodontics alone, and it is worth having.

A quick self-check: open slightly, then close very slowly onto your back teeth while watching your chin in the mirror. If it slides sideways in the last millimetre, you have a functional shift, and that part is treatable. If it closes straight down and the chin is still off centre, the offset is skeletal.

For skeletal asymmetry, the clinic route is orthognathic surgery: repositioning the jaw itself, usually with orthodontics before and after. That is a surgical decision with its own assessment, and this article is not the place to make it. Talk to an orthodontist or a maxillofacial surgeon, and ask them to show you which of the three midlines is off on your own records.

The part nobody mentions at the consultation

Straightened teeth do not stay straight on their own. The University of Washington post-retention series, following patients for decades, found that crowding kept returning long after treatment; in 31 four-premolar-extraction cases followed for 20 years after retention, only about 10% still had clinically acceptable alignment. No pre-treatment variable predicted who would hold. In a 37-year follow-up of 41 treated patients, the mild-crowding group went from 3.31 mm before treatment to 0.58 mm after to 3.67 mm at the end, worse than before they started.

In one survey, about 40% of patients were not wearing their retainer as instructed, and nightly wear dropped the longer it had been since the braces came off. If the dental midline is the part of your asymmetry that braces fixed, the retainer is the part of the treatment that keeps it fixed.

What to measure before you decide

The symmetry tool reads chin offset from the facial midline in millimetres, along with eye, brow and mouth-corner differences. A chin offset under 6 mm is below the point at which ordinary observers notice it. Where the asymmetry is, and how much of it is chin versus mouth corner, is worth knowing before a consultation, because it is the difference between a straightforward orthodontic case and a surgical one.

Sources

• Alhammadi MS, Halboub E, Fayed MS, et al. Global distribution of malocclusion traits: A systematic review. Dental Press Journal of Orthodontics, 2018. PubMed 30672991 — worldwide review of mixed and permanent dentitions; posterior crossbite affected 9.39% of the pooled sample.
• Tortarolo A, Rotolo R, Nucci L, et al. Condylar Asymmetry in Children with Unilateral Posterior Crossbite Malocclusion: A Comparative Cross-Sectional Study. Children (Basel), 2022. PubMed 36421221 — 33 children with a one-sided crossbite against 33 matched controls; condylar asymmetry index 10.7% versus 4.2%.
• Primozic J, Perinetti G, Richmond S, et al. Three-dimensional evaluation of facial asymmetry in association with unilateral functional crossbite in the primary, early, and late mixed dentition phases. The Angle Orthodontist, 2013. PubMed 22889202 — 3D laser face scans of 78 children with a crossbite and 156 without; the crossbite group was more asymmetric, most of all in the lower face.
• Batista KB, Thiruvenkatachari B, Harrison JE, et al. Orthodontic treatment for prominent upper front teeth (Class II malocclusion) in children and adolescents. Cochrane Database of Systematic Reviews, 2018. PubMed 29534303 — 27 randomised trials with 1,251 participants; early functional-appliance treatment versus later treatment made almost no difference to the final skeletal jaw relationship (ANB mean difference −0.02°).
• Little RM. Stability and relapse of mandibular anterior alignment: University of Washington studies. Seminars in Orthodontics, 1999. PubMed 10860071 — summary of more than 800 post-retention records; lower front crowding keeps returning into the 20-to-40 age range and no pre-treatment variable predicts who relapses.
• Little RM, Riedel RA, Artun J. An evaluation of changes in mandibular anterior alignment from 10 to 20 years postretention. American Journal of Orthodontics and Dentofacial Orthopedics, 1988. PubMed 3163221 — 31 four-premolar-extraction cases; crowding kept increasing and only 10% still had clinically acceptable alignment 20 years after retention.
• Gambardela-Tkacz CM, Alcaraz G, Cotrin P, et al. Incisor irregularity and dental arch dimensions changes in subjects with different severity of anterior crowding: a 37-year follow-up. Progress in Orthodontics, 2023. PubMed 36935470 — 41 treated patients followed for 37 years; in the mild-crowding group lower incisor irregularity went from 3.31 mm to 0.58 mm after treatment and back to 3.67 mm.
• Lim ME, Dhaliwal JS, Wahab SWHA, et al. A survey of patient compliance with removable orthodontic retainer wear in Brunei Darussalam. BDJ Open, 2023. PubMed 36869042 — survey of 364 patients after fixed braces; about 40% were not wearing their retainer as instructed, and nightly wear fell the longer it had been since treatment.
• Wang TT, Wessels L, Hussain G, et al. Discriminative Thresholds in Facial Asymmetry: A Review of the Literature. Aesthetic Surgery Journal, 2017. PubMed 28200081 — systematic review of perception studies; asymmetry starts to be noticed at about 2 mm for the eyelids, 3 mm for the mouth corners, 3.5 mm for the brows, 4 mm for the nose tip and 6 mm for the chin.