Overbite, Underbite, or Crossbite: What's the Difference — and What Should You Actually Do About It?
May 4th, 2026
By Dr. Ross Aronson, Board-Certified Orthodontist | Aronson Orthodontics | Waterbury & Southbury, CT
You've probably heard these words before — maybe from your dentist, maybe from a worried parent, maybe from a quick Google search that left you more confused than when you started.
Overbite. Underbite. Crossbite.
They sound clinical. They can feel alarming. And for most people, the next question is: Is this actually a problem? And if so, what do I do about it?
As a board-certified orthodontist treating patients of all ages in Waterbury and Southbury, CT, I've answered these questions thousands of times. Let me give you the clear, honest explanation you deserve — no jargon, no pressure.
First: What Is a "Bite Problem" Exactly?
Your bite — clinically called your occlusion — is simply how your upper and lower teeth meet when you close your mouth. In an ideal bite, the upper teeth fit slightly over the lower teeth, like a lid on a box. The back teeth mesh together evenly. Nothing shifts, grinds, or hits at an odd angle.
When that relationship is off — whether because of how the teeth grew in, how the jaws developed, or habits during childhood — we call it a malocclusion ("bad bite").
Here's the thing most people don't realize: the American Association of Orthodontists estimates that perfectly aligned bites are actually the exception, not the rule. Most people have some degree of malocclusion. That doesn't mean everyone needs treatment — but it does mean an evaluation is always worth having.
Let's break down the most common bite problems and what they mean for you or your child.
Overbite (Deep Bite)
What it is: An overbite occurs when the upper front teeth overlap the lower front teeth more than they should. A small amount of overlap — about 2 to 4 millimeters — is completely normal and actually necessary for function. When the overlap becomes excessive (sometimes called a deep bite), the lower teeth can be almost entirely hidden when the mouth closes.
What causes it: Most overbites are genetic. A lower jaw that's slightly underdeveloped, the disproportionate eruption of front teeth, or a skeletal imbalance between the jaws can all contribute. In some children, prolonged thumb sucking or pacifier use can worsen an existing overbite.
Why it matters: An untreated deep bite can cause the lower front teeth to bite into the roof of the mouth, leading to gum tissue damage. It can also create uneven tooth wear over time, increase the risk of chipping front teeth, and contribute to jaw discomfort or TMJ issues as an adult.
How it's treated: For children who are still growing, a deep bite often responds well to orthodontic appliances that can guide jaw development. For teens and adults, braces or Invisalign with precision attachments can correct the bite by moving teeth into their proper position. In very severe skeletal cases in adults, surgery may be recommended alongside orthodontics — but this is genuinely rare.
The bottom line: Overbites are one of the most common bite issues we treat, and they respond very well to treatment when caught at the right time.
Underbite
What it is: The opposite of an overbite. With an underbite, the lower jaw sits in front of the upper jaw, so the lower front teeth protrude past the upper front teeth when the mouth is closed. In mild cases, the teeth meet nearly edge-to-edge. In more pronounced cases, the lower jaw visibly juts forward, affecting the profile.
What causes it: Underbites are almost always skeletal in origin — meaning the problem is in the jaw, not just the teeth. An upper jaw that didn't grow enough, a lower jaw that grew too much, or both working together can create an underbite. Because of this, the timing of treatment matters enormously.
Why it matters: Underbites interfere with chewing and speech, create abnormal wear patterns on the teeth, and can place significant stress on the jaw joints. They rarely self-correct, and the longer they go untreated in a growing child, the more difficult — and expensive — the eventual correction becomes. Catching an underbite at age 7 or 8 versus age 15 can be the difference between an orthodontic appliance and orthognathic (jaw) surgery.
How it's treated: In young children (ages 7–10), growth modification appliances like a reverse-pull facemask can encourage the upper jaw to come forward and keep pace with the lower jaw. For adolescents in full braces, elastics and careful bite mechanics can often correct mild-to-moderate underbites. Significant skeletal underbites in adults may require a combination of braces and corrective jaw surgery.
The bottom line: Underbite is the bite problem where early treatment makes the biggest difference. If you notice your child's lower teeth sitting in front of the upper teeth — at any age — please don't wait for the next dental cleaning. Schedule an orthodontic evaluation now.
Crossbite
What it is: A crossbite happens when one or more upper teeth bite on the inside of the lower teeth, rather than the outside where they belong. It can occur in the front of the mouth (anterior crossbite) or in the back (posterior crossbite), or both.
Posterior crossbites often cause the lower jaw to shift to one side when closing — what we call a functional shift. This is a particularly important warning sign, because a jaw that habitually shifts to one side during every single bite can lead to asymmetric jaw growth over time if left unaddressed.
What causes it: Crossbites can be caused by a narrow upper arch (palate), teeth that erupted in an unusual position, or a combination of skeletal and dental factors. Like underbites, they're heavily influenced by genetics.
Why it matters: Beyond aesthetics, an untreated crossbite can cause:
- Asymmetric jaw growth in children
- Irregular tooth wear
- Gum recession on the affected teeth
- Jaw pain and TMJ problems
- Facial asymmetry that becomes more noticeable over time
How it's treated: For children, a palatal expander is often the most efficient solution for a posterior crossbite. This appliance gradually widens the upper arch over several months, creating room for the teeth to come into proper alignment. The results are remarkable — and best achieved while the growth plates in the palate are still active, typically before age 12 or 13. After that, expansion becomes significantly more difficult.
For single teeth in crossbite, braces or aligners can often reposition the individual tooth without an expander.
The bottom line: Like underbites, crossbites are better treated early. If you see your child's lower jaw shifting when they close their mouth, that functional shift is a meaningful clinical sign — not something to monitor indefinitely.
What About Open Bite?
An open bite is when the upper and lower front teeth don't meet at all when the mouth closes, leaving a visible gap. This is most commonly caused by prolonged thumb sucking, pacifier use, or tongue thrust habits. Open bites can also result from uneven jaw growth.
They can affect speech (creating a lisp), make biting into food difficult, and place extra pressure on the back teeth. Treatment depends on whether the habit driving the open bite has resolved and on the patient's age — early intervention during growth is far more predictable than treatment in adulthood.
The Bigger Picture: Bite Problems and Long-Term Health
One of the most important things I try to communicate to parents and patients is that bite issues aren't just cosmetic. Yes, a well-aligned smile looks great. But bite problems, when left untreated, can contribute to:
- Accelerated tooth wear — when teeth don't meet correctly, the ones that do bear all the grinding pressure
- Chipping and fractures — especially with deep bites and crossbites where teeth hit at odd angles
- Gum recession — teeth in crossbite often have reduced bone support on one side
- TMJ pain and jaw dysfunction — abnormal bite mechanics stress the jaw joints over years
- Sleep and airway concerns — jaw positioning affects the airway, especially in growing children
This is why we look at far more than just tooth alignment during an orthodontic evaluation. We look at how the jaw moves, how the teeth meet in every position, and how everything fits together as a whole.
Should I Be Concerned About My Child? What About Myself?
Here are the signs worth paying attention to:
In children:
- Lower teeth sit in front of upper teeth (underbite)
- Jaw shifts to one side when closing (crossbite with functional shift)
- Large gap between upper and lower front teeth when at rest (open bite)
- Mouth breathing, snoring, or difficulty chewing
- Teeth look very crowded or very spaced
- Baby teeth falling out unusually early or late
In teens and adults:
- Jaw pain, clicking, or tenderness
- Worn-down, chipped, or notched edges on front teeth
- Teeth that have shifted noticeably since braces (especially if retainer wear lapsed)
- A bite that feels "off" or like certain teeth hit harder than others
- Difficulty chewing comfortably
You don't need to self-diagnose. That's exactly what we're here for.
How Dr. Aronson Evaluates a Bite
At Aronson Orthodontics, every consultation starts with a thorough clinical examination. For patients where we need more detailed information, we use digital X-rays and 3D imaging to evaluate not just the teeth, but the underlying jaw structure, the relationship between the upper and lower jaws, and how everything works together functionally.
You'll receive a clear, honest explanation of exactly what we see — what's significant, what we'd monitor over time, and what, if anything, we'd recommend addressing. We don't push treatment for treatment's sake. If I look at your child and tell you we should wait and reassess in a year, that's what I genuinely believe is in their best interest.
And if treatment is indicated, we design a plan around your life — not just around the clinical ideal. We understand busy school schedules, athletic seasons, work commitments, and family budgets.
"Can't This Wait Until All the Permanent Teeth Come In?"
This is one of the most common questions I hear from parents — and it's a completely reasonable one.
The honest answer is: it depends on the problem.
For most bite issues, yes, we can wait and do comprehensive treatment once the permanent teeth have erupted. But for a subset of problems — underbites, significant crossbites with jaw shifting, and severe narrow arches — waiting until the permanent teeth come in means missing a window that genuinely makes a difference. The treatment that takes three months at age nine might require surgery at age twenty-two.
The American Association of Orthodontists recommends a first orthodontic evaluation by age seven — not because every child needs treatment at seven, but because that's when a trained orthodontist can spot the problems that are time-sensitive to address.
If your child hasn't had that first evaluation yet, it's a simple, no-pressure appointment. We just want to look.
Frequently Asked Questions
Can adults get their bite corrected? Absolutely. Adult bite correction with braces or Invisalign is very effective, though it may take a bit longer than in growing patients since the bone is no longer malleable. Many adults are surprised by how significantly correcting the bite improves not just aesthetics, but comfort, chewing function, and even jaw tension.
How long does bite correction take? It depends entirely on the type and severity of the problem, and the patient's age. Many cases are completed in 12–24 months. Complex skeletal cases can take longer, particularly if appliances or multi-phase treatment is involved. We'll give you a realistic timeline at your consultation — not an optimistic one designed to get you started.
Does insurance cover bite correction? In most cases, yes — orthodontic insurance benefits apply to bite correction just as they do to alignment treatment. We're in-network with Cigna and work with all major PPO dental insurance plans. We also offer flexible payment plans with 0% APR financing to make treatment accessible for every family.
Is Invisalign able to fix bite problems? Invisalign has become very capable for bite correction over the past decade, and for mild-to-moderate overbites and crossbites, it's often an excellent option. More complex bite issues — particularly severe skeletal underbites — typically require braces for optimal control. The right choice depends on your specific bite, and Dr. Aronson will give you an honest recommendation based on what will produce the best result for you, not on which option is easier or more popular.
What happens if a bite problem is left untreated? Most bite problems don't cause immediate pain or dramatic consequences — which is why many people live with them for years or decades. But over time, the cumulative effects of abnormal wear, asymmetric jaw function, and stress on the joint do add up. Addressing a bite problem proactively is almost always easier, faster, and less expensive than treating the downstream consequences.
Take the Next Step
If you've been reading this post and nodding along — recognizing something in your child's bite, or perhaps in your own — the best next step is simply to come in and let us take a look.
There's no obligation, no pressure, and no fee. Aronson Orthodontics offers complimentary consultations for new patients of all ages at both our Waterbury and Southbury offices.
We'll tell you exactly what we see. We'll explain what it means. And we'll give you the information you need to make a confident, informed decision about next steps — on your timeline, not ours.
Schedule Your Free Consultation →
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