Functional Appliances vs Jaw Surgery: How Orthodontists Decide

When most people think about orthodontic treatment, they likely picture straightening teeth. But a truly harmonious smile is about more than just aligned teeth. It’s about how your upper and lower jaws meet and work together.

If you’re an adult with an overbite – or a parent whose child has been told they have a Class II malocclusion (where the top teeth bite well ahead of the bottom teeth) – you might be wondering about your options. For patients with a small lower jaw or significant jaw size discrepancy, the path forward isn’t always straightforward. Should you consider orthognathic (jaw) surgery, or can non-surgical orthodontic treatment do the job?

The decision between jaw surgery or braces with functional appliances is one that orthodontists navigate carefully. Your age, the severity of your case and your treatment goals all play a part in determining which route makes the most sense for you.

What are functional appliances?

Functional appliances are orthodontic devices that work with your body’s natural muscle forces to correct your bite. Think of them as gentle guides that encourage your lower jaw to shift into a better position by harnessing growth.

These clever devices come in different forms:

• Removable appliances like the Twin Block Braces, which use interlocking blocks to guide jaw position.
• Fixed functional appliances that stay bonded to your teeth throughout treatment.

Most are made of plastic and wire, and are designed to be worn consistently (especially the removable types).

The concept behind functional jaw orthodontics for young people – sometimes called dentofacial orthopaedics – is beautifully simple: Instead of waiting until your child is fully grown and needing surgery, we can encourage the jaws to grow in a more balanced way during adolescence.

Why adolescent timing is everything

Functional orthodontics works best when nature is already on your side. Orthodontic guidelines suggest that these orthodontic devices are most successful during the pubertal growth spurt – typically between ages 11 and 14 in boys, and 10 to 13 in girls.

During this window, a functional brace can harness the natural greater growth of the lower jaw compared to the upper jaw. By positioning the lower jaw forward consistently, these appliances help redirect jaw growth and improve your profile. For Class II correction in growing patients, this timing really matters.

Do functional appliances actually ‘grow’ the jaw?

You might hear claims that functional appliances can ‘grow’ your jaw significantly. The reality is a bit more nuanced.

Research tells us that while these devices are clinically effective for correcting overbites, the type of change they create isn’t always what you’d expect. Much of the correction is actually dentoalveolar – meaning it involves the tipping of the incisor teeth, and changes to the bone and gum tissue around them – rather than purely skeletal growth of the jaw itself.

While the occlusal correction (how your teeth fit together) tends to be stable at the end of treatment, there’s limited evidence for massive, permanent skeletal change when compared to untreated patients who simply grow naturally.

Are functional appliances still worth it?

Absolutely. Here’s why functional appliances may still be excellent choices:

1. They achieve stable dental and skeletal improvements for Class II malocclusion.
2. They work with natural jaw alignment processes during growth.
3. They help position teeth in their new position without surgery.
4. They’re particularly effective when used in the right patients at the right time.

The key is understanding that these orthodontic appliances harness and optimise natural growth rather than creating entirely new bone. For treatment with functional devices, the goal is guiding the underlying skeletal structures in a more favourable direction.

Orthognathic surgery: when braces aren’t enough

The jaw surgery route

Once you’ve reached 18 (or your growth is complete), functional appliances lose their effectiveness. For adults with significant jaw discrepancies – or teenagers with severe underbite or overbite issues – orthognathic surgery becomes the most reliable option for correcting the underlying skeletal base.

Orthognathic surgical procedures can include repositioning either jaw or performing bimaxillary surgery (operating on both jaws) to achieve the facial harmony that braces alone can’t deliver. This isn’t just about aesthetics, though, as surgery can permanently correct functional issues like difficulties with chewing, breathing or speech.

Typical braces and jaw surgery timeline

The process usually unfolds in three phases:

1. Pre-surgical orthodontics (12 to 18 months): Braces before jaw surgery align your teeth within each arch, even if it temporarily makes your bite look worse.
2. Surgery: Your oral surgeon repositions your jaws to the correct relationship.
3. Post-surgical orthodontics (six to 12 months): Fine-tuning the bite and ensuring everything settles properly.

By the end of this surgical treatment, your teeth are arranged differently, your facial profile is improved and your jaws work together in an improved functional relationship.

Comparing surgery to early intervention

Research published in The Angle Orthodontist compared outcomes between patients treated with functional appliances and those who underwent surgical correction as adults. Interestingly, similar dentoskeletal changes were achievable through both routes. However, the functional route is strictly for growing patients, while surgery remains the only option once growth plates have fused.

The clinical pathway: how orthodontists decide

So how do orthodontic specialists determine whether functional appliances vs surgery is right for you or your child? The decision comes down to several key factors.

Age and growth potential

First and foremost, is there any remaining growth? For adolescents still in their growth spurt, functional orthodontics offers a window of opportunity to correct the overbite without surgery. But orthodontists and their patients must be realistic: Once you’re past that growth phase, we’re working with fixed skeletal structures.

Severity of the discrepancy

Mild to moderate Class II cases (typically up to 6-7mm of overjet) often respond beautifully to functional appliances. But when the discrepancy is more severe, or when there’s significant asymmetry, surgery provides more predictable, stable results.

Your orthodontist will use cephalometric analysis – specialised X-rays that measure the position of your jaw muscles, bones and teeth – to determine whether functional appliances can be used to avoid jaw surgery in your specific case.

Patient compliance

Note that removable appliances only work when they’re in your mouth during treatment. The Twin Block Braces, for instance, need to be worn 22+ hours per day to be effective. If compliance is a concern, fixed functional appliances or jaw surgery might be more reliable paths.

Your treatment goals

Some patients prioritise avoiding surgery at all costs. Others want the most comprehensive correction possible. Your treatment plan should reflect your personal goals, balanced with what’s clinically achievable and stable long-term.

Alternative approaches: fixed functionals and camouflage

Modern fixed functional appliances

Between removable blocks and major surgery lies an interesting middle ground. Modern functional appliances (like the Herbst) are bonded directly to your teeth, eliminating the compliance issue. These fixed devices can guide the lower jaw forward more consistently because they’re working 24/7, not just when the patient remembers to wear them.

Orthodontic camouflage: masking vs correcting

Another option worth mentioning is orthodontic camouflage. This approach uses braces to make your upper and lower teeth fit together better without actually moving your jaws. Sometimes this involves extracting a premolar to create space and allow the front teeth to move back.

While camouflage can create a functional bite, it won’t change your chin profile or facial proportions. It’s essentially masking the skeletal discrepancy with dental compensation. For some patients with borderline cases, this compromise between teeth and jaw positioning works brilliantly. For others, it leaves underlying issues unaddressed.

The treatment time for camouflage is typically shorter than combined surgical treatment, though it does require keeping permanent teeth in one arch properly aligned with an opposing arch that hasn’t been surgically repositioned.

Making the right choice for your smile

Whether you end up with a functional brace, aligners or orthognathic surgery, the ultimate goal remains the same: a stable, healthy bite that lasts a lifetime. Your orthodontist’s decision between these approaches comes down to safety, stability and aesthetics.

At Hampstead Orthodontic Practice, we take the time to assess each patient individually. We’ll discuss whether you’re a candidate for growth modification, whether surgical options make more sense, or whether there’s a middle path that achieves your goals.

Ready to explore your options? Book a FREE consultation with our team to discuss a personalised treatment plan that’s right for you.

FAQs

Can functional appliances avoid jaw surgery?

Yes, but only if you’re still growing. Functional appliances work best during the adolescent growth spurt (ages 10-14), when they can guide your jaw development and correct mild to moderate bite issues. Once you’ve finished growing, these devices lose their effectiveness, and surgery becomes the most reliable option for significant jaw discrepancies.

When is jaw surgery necessary for an overbite?

Surgery is typically necessary when you’ve finished growing and have a severe overbite (usually over 6-7mm) that can’t be corrected with braces alone. It’s also the go-to option for adults with significant jaw size differences, facial asymmetry, or functional problems like difficulty chewing or breathing. If orthodontic camouflage won’t achieve stable results, surgery offers the most predictable outcome.

What’s the timeline for braces before jaw surgery?

The full process typically takes two or three years. You’ll wear braces for 12-18 months before surgery to align your teeth within each arch. After your jaw surgery, you’ll continue with braces for another six months to a year to fine-tune your bite. Your orthodontist coordinates closely with your oral surgeon throughout this journey.

Do functional appliances actually grow the jaw?

Not quite in the way you might think. Research shows that functional appliances guide jaw growth and create stable bite correction, but much of the improvement comes from repositioning teeth and the surrounding bone rather than creating massive amounts of new jawbone. They work with your natural growth patterns to optimise jaw alignment during adolescence.

How do orthodontists choose between functional appliances and surgery?

The decision comes down to four main factors: your age and remaining growth potential, the severity of your jaw discrepancy, whether you can consistently wear removable appliances, and your personal treatment goals. Your orthodontist will use specialised X-rays to measure your jaw position and create a treatment plan that balances what’s clinically achievable with what you’re hoping to accomplish.