Treating Underbites: What You Need to Know About Class III Malocclusion

Treating Underbites: What You Need to Know About Class III Malocclusion

3 July 2025

An underbite, what orthodontists call a Class III malocclusion, is one of the most complex bite issues we treat in orthodontics. Treating underbite involves addressing when the lower teeth sit ahead of the upper teeth, either due to the position of the teeth, the jaws, or both. But not all underbites are the same, and neither are the treatment options.

In this blog, I’ll break down what causes an underbite, the difference between dental and skeletal types, common myths about early treatment, and the real options available, both surgical and non-surgical.

What Is a Class III Malocclusion?

A Class III malocclusion (underbite) happens when the lower jaw (mandible) sits forward relative to the upper jaw (maxilla). This can be:

• Dental in nature: where the teeth themselves are positioned in a way that creates the underbite.
• Skeletal in nature: where the underlying bone structure causes the problem, most commonly, the upper jaw is too small, or the lower jaw is too large.

Skeletal underbites are largely influenced by genetics. If one or both parents had an underbite, there’s a higher chance their child will too.

The Role of Genetics and Early Development

Underbite features often begin to show at a young age, sometimes as early as 5 or 6. Understandably, many parents are eager to intervene early to try to “correct the problem before it gets worse.”

But here’s the important truth: Early treatment does not guarantee avoiding jaw surgery in the future.

This is a common misconception. In fact, some clinicians overstate the benefits of early treatment and promise outcomes that simply aren’t supported by long-term evidence. A true skeletal underbite driven by genetics will almost always continue to develop, regardless of how early treatment starts.

That said, early intervention can be helpful in mild to moderate cases, especially when the discrepancy isn’t too severe. In these cases, results can be stable. However, it’s worth noting that these same cases could also be corrected later in life using non-surgical orthodontics.

So When Is Surgery Needed?

The best way to determine whether jaw surgery is needed is to assess the facial profile, not just the teeth.

• If the patient’s face looks balanced and acceptable in both the front and side views, it’s likely that the bite can be corrected without surgery.
• But if the face shows signs of significant maxillary (upper jaw) deficiency, such as a flat midface or sunken upper lip, then surgery may be the best option to restore both facial aesthetics and proper function.

The Biritsh Orthodontic Society has a very helpful infomation page about jaw surgery, click here to view.

How Are Underbites Treated?

Almost every Class III case benefits from some form of expansion. That’s because in many underbite cases, the upper jaw is not just short in length, it’s also narrow in width.

Common Treatment Methods:

• Expansion appliances: To widen the upper jaw.
• Facemask therapy: This device aims to pull the upper jaw forward. However, in my clinical practice, I rarely use it. Why?
  1. Compliance: Expecting any one to wear a facemask daily, even at home, is often unrealistic today.
  2. Effectiveness: Research shows that most of the benefits come from the expander attached to the facemask, not the facemask itself. The forward movement achieved is often just a few millimetres, and even that is difficult to measure reliably.
• TADs (mini-screws): A more modern and patient-friendly option. These have largely replaced facemasks in my practice. TADs help anchor the appliance and move the teeth or jaw more predictably without relying on patient compliance.

Non-Surgical Options in Teenagers and Adults

In cases where surgery is not necessary, we can still treat the underbite using combinations such as:

• Expansion and protraction with elastics
• Expansion plus extraction of lower premolars
• Expansion and removal of lower wisdom teeth and the use of TADs to adjust the bite and rotate the occlusal plane

The best appliance depends on the severity and nature of the case:

• Traditional fixed braces: Reliable and widely used.
• Clear aligners: A discreet option for certain cases.
• Lingual braces: These sit behind the teeth and offer superior precision, especially useful in complex Class III cases where the upper arch is constricted or the lower front teeth are tilted backwards. Because they are custom-made for each patient, they allow for excellent control in difficult movements.

Final Thoughts

If you or your child has an underbite, the most important first step is a comprehensive orthodontic assessment. Every case is different, and the right treatment depends on the exact nature of the problem, both in the teeth and the facial structure.

The idea that early treatment alone can prevent surgery in all underbite cases is simply not true. It depends on the type and severity of the Class III malocclusion. If someone tells you otherwise, they may be overselling the benefits for reasons that aren’t entirely clinical.

If you’d like an honest, expert opinion on how best to treat your underbite, I’m happy to help. Feel free to get in touch to book a consultation.