Last updated: April 2026 By Dr. Nicole Wax, DDS, MS (Orthodontics)
You’ve probably heard the word “overbite” thrown around — maybe at a checkup, maybe from a friend, maybe while staring at your child’s smile in a school photo. But almost everyone has an overbite. The real question is: how much is too much?
Here’s the clarity most articles skip. An overbite is a specific, measurable thing. A 2 to 4 millimeter vertical overlap between your upper and lower front teeth is completely normal — it’s actually what your teeth are supposed to do. Problems start when that overlap stretches significantly beyond that range.
This walks through what an overbite is, how to tell whether yours (or your child’s) is within normal, what causes it, and what treatment looks like at different ages.
What Is an Overbite? A Simple Definition
An overbite is how much your upper front teeth vertically overlap your lower front teeth when your mouth is closed. It’s a normal part of how teeth fit together — the upper teeth should cover about 2 to 4 millimeters (roughly 30% of the height) of your lower front teeth. When that overlap is significantly greater, orthodontists classify it as a “deep bite” or severe overbite, and it may need treatment.
In short: everyone has an overbite. Not everyone has a problem.
Normal Overbite vs an Overbite That Needs Treatment
This is the measurement piece most articles skip. Here’s what orthodontists actually look at:
Normal overbite:
- 2 to 4 millimeters of vertical overlap
- Upper teeth cover about 30% of the lower front teeth
- Lower teeth lightly touch the back of the upper teeth when biting
Severe overbite (deep bite):
- 5 millimeters or more of vertical overlap
- Upper teeth cover more than 50% of the lower front teeth
- Lower teeth may strike the roof of the mouth when biting down
The 30% benchmark comes from decades of orthodontic research and is broadly accepted in both the dental and orthodontic literature. It’s also what we teach at orthodontic residency programs.
Here’s what matters more than the number: whether the overbite is causing functional problems. A deep bite can wear down the lower front teeth over time, strain the jaw joints, contribute to headaches, and in severe cases cause the lower teeth to bite into the gum tissue behind the upper front teeth. Those are the cases where treatment moves from optional to recommended.
For kids and teens, the calculus is different. We often treat overbites earlier — while the jaw is still growing — because it’s significantly easier to guide bone growth than to move it later. An overbite that would need surgery at 25 might be correctable with braces or an appliance at 10.
Overbite vs Overjet: The Terms Almost Everyone Confuses
This is the single most mixed-up pair of words in orthodontics. Even dentists use them interchangeably sometimes, which doesn’t help. Here’s the distinction:
| Term | What It Measures | Example |
|---|---|---|
| Overbite | Vertical overlap (up and down) | How much the upper teeth cover the lower teeth when biting down |
| Overjet | Horizontal overlap (front to back) | How far the upper teeth stick out in front of the lower teeth |
| Underbite | Opposite of overjet — lower teeth in front of upper | Lower front teeth sit outside upper teeth when closed |
| Crossbite | Upper teeth behind lower teeth on one or both sides | Can be front or side; usually a jaw-width issue |
| Open bite | Gap when front teeth don’t touch at all | Upper and lower front teeth don’t meet when closed |
When most people say “my kid has an overbite,” they often mean overjet (“buck teeth” protrusion). Or they have both at once, since the two often appear together.
Overjet specifics: according to the Cleveland Clinic, a horizontal gap of more than 2 millimeters is considered overjet. Anything over 8 to 10 millimeters is severe and may require jaw surgery along with braces.
We sort out which you actually have at the free consultation. It matters because the treatment is different.
What Causes an Overbite?
Overbites fall into two broad categories, each with different causes.
Dental overbite happens when the teeth themselves are positioned wrong while the jaw structure is normal. Common causes:
- Missing lower back teeth (the upper teeth over-erupt into the gap)
- Late adult tooth loss in adults
- Thumb-sucking past age 4 or 5
- Long-term pacifier use
- Tongue thrusting when swallowing
- Nail biting or chewing on objects
Skeletal overbite happens when the jaw bones themselves are mismatched. Usually the lower jaw is smaller or positioned further back than it should be. Primary causes:
- Genetics (the most common factor by far)
- Jaw growth patterns during childhood
- Early injury affecting jaw development
For most kids we see, the cause is a combination — a genetic tendency toward a small lower jaw, made worse by a thumb habit that kept the upper teeth pushed forward. Both can be addressed. Skeletal cases are easier to fix while the jaw is still growing, which is one of the reasons the American Association of Orthodontists recommends an orthodontic screening by age 7.
How We Fix Overbites by Age
Treatment depends on age, severity, and whether the problem is skeletal or dental. Here’s the general framework:
Kids ages 7 to 10 (Phase 1 treatment): At this age, the jaw is still growing, and we can influence how it grows. For skeletal overbites, we might use a palate expander or a functional appliance that encourages the lower jaw forward. For dental issues, we sometimes use limited braces on just the front teeth. Phase 1 is usually 9 to 18 months. Not every child needs it — in fact, most don’t — but for the ones who do, it can prevent jaw surgery years later.
Teens ages 11 to 17 (Phase 2 treatment): Once most permanent teeth are in, we move to full braces or Invisalign Teen. For most dental overbites, braces with elastics (small rubber bands) are highly effective. Invisalign Teen with attachments and elastics works well for mild to moderate cases. Treatment is typically 18 to 24 months.
Adults: Adult teeth still respond to orthodontics — the jaw just doesn’t grow anymore. Braces and Invisalign both work for mild to moderate overbites in adults. Severe skeletal overbites in adults may require jaw surgery combined with braces, but most cases we see don’t. The earlier an adult starts, the easier the process. Treatment is typically 18 to 30 months.
At Wax Ortho, braces and Invisalign cost the same. You choose based on the treatment that’s right for the case, not the price tag.
One thing worth naming directly: mild overbites often don’t need treatment at all. If the overlap is in a normal range and there’s no functional or cosmetic concern, we say so. We’re not looking for reasons to treat — we’re looking for reasons why treatment would help.
When to Schedule an Evaluation
Schedule a free orthodontic evaluation if:
- Your child is age 7 and hasn’t been seen yet (this is the AAO’s universal recommendation)
- You notice your child’s upper front teeth significantly overlapping the lower ones
- Your child’s lower front teeth seem to be hitting the roof of their mouth
- Your child complains about jaw soreness, headaches, or difficulty biting
- You as an adult have a bite that’s worsening over time
- You have worn front teeth, chipping, or TMJ pain possibly linked to your bite
A consult doesn’t commit you to anything. If your child doesn’t need treatment, we’ll say so and put them on our monitoring schedule. If treatment would help, we’ll walk through the options and costs. Either way, you’ll leave with a plan.
Frequently Asked Questions
How can I tell if my overbite is severe?
Look in a mirror and bite down naturally. If your upper teeth cover more than half of your lower front teeth, or if the lower teeth are hitting your gums, your overbite is likely beyond normal range. A 2 to 4 millimeter overlap is typical; over 5 millimeters is usually classified as severe. An orthodontist can measure exactly during a consult.
Can an overbite fix itself?
Typically, no. Mild overbites sometimes improve slightly as permanent teeth come in during childhood, but significant overbites rarely self-correct. They tend to stay the same or worsen over time, especially without treatment.
Does an overbite cause health problems?
A normal overbite is healthy and functional. A severe overbite can cause tooth wear, jaw joint strain (TMJ issues), difficulty chewing properly, and damage to gum tissue. It can also affect the long-term stability of the lower front teeth.
Can Invisalign fix an overbite?
Yes — for mild to moderate overbites. Invisalign paired with attachments and elastics can correct most common overbite patterns. Severe skeletal overbites may need braces or a combined approach. A free consult will tell you which category your case falls into.
Is there a difference between overbite and deep bite?
They’re often used interchangeably. “Deep bite” is the orthodontic term for an overbite that’s more severe than normal — typically more than 5 millimeters of vertical overlap. All deep bites are overbites, but not all overbites are deep bites.
The Bottom Line
Most overbites are normal and need nothing more than regular dental checkups. Severe overbites — those beyond about 5 millimeters of vertical overlap — often benefit from treatment, especially while kids are still growing.
If you’re not sure which category describes your (or your child’s) bite, a free orthodontic evaluation gives you a definitive answer. No commitment, no pressure, and if no treatment is needed, we’ll tell you.
Book a free consult at Linden, Highland, or Flushing. We’ll measure, explain, and help you decide.
About the Author
Dr. Nicole Wax, DDS, MS is a board-trained orthodontic specialist and founder of Dr. Wax Orthodontics. She holds a DDS from The Ohio State University and a Master’s in Orthodontics from the University of Detroit Mercy, where she completed advanced training in growth modification and bite correction. Since 2014, she’s treated thousands of overbite cases across kids, teens, and adults at her Linden, Highland, and Flushing offices.