Overbite vs Underbite: What’s the Difference and How to Fix Them?

Bite problems are one of the most common reasons people seek orthodontic treatment – but the terminology can be confusing. Overbite, underbite, crossbite, open bite – what does it all actually mean, and does it really matter if your bite isn’t perfect?

The short answer is yes, it can matter quite a lot. Here’s a clear explanation of the difference between overbites and underbites, why they’re worth treating, and what orthodontic options are available to fix them.

What Is an Overbite?

An overbite – sometimes called a deep bite – occurs when the upper front teeth overlap the lower front teeth vertically by more than is considered normal. A small degree of overlap is completely normal and expected. Problems arise when that overlap is excessive.

In a significant overbite, the upper teeth may cover a large portion of the lower teeth when biting, or in more pronounced cases, the lower teeth may bite into the roof of the mouth.

What Causes an Overbite?

Overbites can be caused by a combination of genetics, jaw development, and habits. Common contributing factors include:

• Jaw size discrepancies – the upper jaw sits too far forward relative to the lower jaw
• Prolonged thumb sucking or dummy use in early childhood
• Tooth size and positioning

Problems Associated With an Overbite

Left untreated, a significant overbite can lead to:

• Excessive wear on the lower front teeth
• Jaw pain and discomfort, particularly with chewing
• Increased risk of trauma to the front teeth (which are more exposed)
• Speech difficulties in some cases
• Aesthetic concerns – overbites can affect the overall profile and appearance of the face

What Is an Underbite?

An underbite – sometimes called a Class III bite – is the opposite of an overbite. It occurs when the lower teeth sit in front of the upper teeth when the mouth is closed. In some cases this affects only a few teeth; in others, the entire lower jaw sits forward of the upper.

Underbites are less common than overbites, but they tend to be more noticeable and often have a more significant functional impact.

What Causes an Underbite?

Underbites are often hereditary. They can result from:

• Lower jaw overgrowth or upper jaw undergrowth
• Genetics – underbites often run in families
• Certain childhood habits that affect jaw development

Problems Associated With an Underbite

An untreated underbite can cause:

• Difficulty biting and chewing food effectively
• Accelerated wear on the front teeth
• Jaw pain and joint stress (TMJ issues)
• Speech problems, including difficulties with certain sounds
• Self-consciousness about facial profile and smile appearance

Overbite vs Underbite: Key Differences

While both involve the upper and lower jaws not aligning correctly, the direction of the problem is opposite:

• Overbite – upper jaw or teeth protrude forward or downward over the lower.
• Underbite – lower jaw or teeth sit in front of the upper.

Both can range from mild (requiring minor correction) to significant (requiring more involved treatment). Both are also worth treating – not just for cosmetic reasons, but for the functional and long-term health benefits of a properly aligned bite.

Can Overbites and Underbites Be Fixed?

Yes – both can be treated effectively with orthodontic treatment, though the approach varies depending on the severity of the case and the age of the patient.

Treatment During Childhood and Adolescence

When bite issues are identified early – ideally during the jaw growth years – there are more options available and treatment is often more straightforward. For children and teens, treatment may include:

• Braces – fixed braces remain one of the most effective tools for correcting bite issues, often used with elastics to help shift jaw position. 
• Functional appliances – removable or fixed appliances that help guide jaw development in younger patients whose jaws are still growing. 
• Invisalign Teen – clear aligners can be used to address some bite issues in teenagers, sometimes in combination with other techniques.

Treatment in Adults

Adults can absolutely be treated for overbites and underbites, though the options depend on the severity. For mild to moderate cases:

• Braces – highly effective for repositioning teeth and improving bite alignment in adult patients.
• Invisalign – can address many bite issues in adults, sometimes with the addition of elastics or other attachments. 

For more severe cases where skeletal jaw discrepancy is significant – particularly pronounced underbites – a combination of orthodontic treatment and orthognathic (jaw) surgery may be recommended. This is relatively uncommon but produces excellent outcomes when indicated.

Your orthodontist will assess your bite thoroughly and recommend the most appropriate treatment pathway for your individual situation.

Compare braces and Invisalign for bite correction: ethosorthodontics.com.au/blog/braces-vs-invisalign-which-is-best/

See patient results: ethosorthodontics.com.au/your-ethos-experience/before-and-afters/

How Long Does Bite Correction Take?

Treatment time varies significantly depending on the type and severity of the bite issue, the treatment used, and the age of the patient. As a general guide:

• Mild bite issues in children may resolve within 12 to 18 months
• Moderate cases in teens typically take 18 to 24 months
• More complex adult cases may take 24 months or longer

Your orthodontist will give you a personalised estimate at your initial consultation, based on what they find during your assessment.

Get Your Bite Assessed at Ethos Orthodontics

If you’re concerned about your bite – whether it’s an overbite, underbite, or something else – the best next step is a proper orthodontic assessment. Bite issues don’t fix themselves, and in many cases they become more complex (and more costly to treat) over time.

At Ethos Orthodontics, our specialist orthodontists assess bite issues every day across our 13 Queensland clinics. Your first consultation takes around an hour, and gives you a clear picture of what’s happening and what your options are.

👉 Book your consultation at ethosorthodontics.com.au/contact-us/

Frequently Asked Questions

What is the difference between an overbite and an underbite?

An overbite is when the upper front teeth overlap the lower teeth excessively. An underbite is the opposite – where the lower teeth sit in front of the upper teeth when biting. Both are bite misalignments that can be corrected with orthodontic treatment.

Can an overbite or underbite fix itself?

No. Bite issues don’t self-correct and typically become more complex to treat over time if left untreated. Early assessment and treatment – particularly while the jaw is still growing – generally produces the best results.

Is it painful to correct an overbite or underbite?

Orthodontic treatment for bite correction is not painful in the way many people expect. Some mild soreness when braces or appliances are first fitted or adjusted is normal, but this settles quickly and is manageable with over-the-counter pain relief.

Can Invisalign fix an overbite or underbite?

Invisalign can treat many overbites and some underbites, particularly mild to moderate cases. For more significant bite discrepancies, braces or a combination approach may be more appropriate. Your orthodontist will advise based on your individual assessment.

At what age should bite problems be treated?

Early assessment around age 8 to 10 is recommended. Treatment timing depends on the type and severity of the issue – some bite problems are best addressed during jaw growth, while others can wait until more permanent teeth have come through.

Will I need jaw surgery for an overbite or underbite?

Most overbites and many underbites can be corrected with orthodontic treatment alone. Surgery is typically only considered for very severe skeletal discrepancies that cannot be fully addressed with braces or aligners. Your orthodontist will discuss all options clearly at your consultation.