Dental & oral health

Overbite and Overjet Are Not the Same Thing

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The two words get used interchangeably in everyday conversation, but a dentist or orthodontist treats them as separate measurements because they point to different problems and sometimes different fixes. Overjet is the one people usually mean by "buck teeth" — forward projection. Overbite is the one behind a "deep bite," where the lower front teeth disappear almost entirely behind the uppers when the mouth closes.

Last updated: July 2026

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What's the actual difference between overbite and overjet?

Overbite is a vertical measurement: it describes how much the upper front teeth overlap the lower front teeth top-to-bottom when the back teeth are closed together. Overjet is a horizontal measurement: it describes how far the upper front teeth extend forward, toward the lips, past the lower front teeth. Overbite is up-and-down overlap; overjet is front-to-back projection — a mouth can have one without much of the other. Both are present to some degree in nearly every bite; a small amount of vertical overlap and forward projection is simply how upper and lower front teeth are supposed to meet. What varies is degree, and it's the degree — not the presence — that a dentist evaluates when deciding whether either one needs attention.

Why the two words get confused

Both overbite and overjet fall under the broader category of malocclusion, the general term for teeth or jaws that don't align the way a typical bite does, and both are usually assessed at the same exam using the same front teeth as the reference points. That overlap in language and in the teeth being measured is why the words get swapped in everyday conversation — someone describing a child's protruding front teeth will often call it an overbite, even though "buck teeth" is more precisely an overjet. Orthodontic treatment planning depends on getting this distinction right, since correcting a vertical overlap and correcting a horizontal projection can call for different mechanics, even when both problems are visible in the same mouth. Overbite, overjet, crossbite, and underbite are the main types of malocclusion a dentist sorts a bite into before deciding whether treatment is worth pursuing.

What causes an overjet

Overjet most often develops from a mismatch between upper and lower jaw size or position — an upper jaw that grows forward relative to the lower one, or a lower jaw that grows less than expected. Prolonged thumb-sucking, pacifier use past the age when front teeth are erupting, or a resting tongue-thrust habit can also push the upper front teeth forward over time, which is why pediatric dentists watch those habits closely in young children. Genetics plays a large role in the underlying jaw-size mismatch itself, independent of any habit, which is part of why overjet can run in families even when no one in the family sucked their thumb.

What causes an overbite

A deep overbite tends to come from how the back teeth erupted and how much the jaw grew vertically rather than from a habit — if the back teeth don't erupt to a height that keeps the jaw open enough, the front teeth end up overlapping more than they otherwise would. Missing back teeth, teeth that wore down unevenly, or a jaw growth pattern that favored width over height can all contribute. Because the cause is largely structural rather than behavioral, an overbite is less often something a parent could have prevented by stopping a habit, unlike some cases of overjet.

Why the distinction changes treatment

Correcting overjet usually means moving teeth — or in growing children, gently guiding jaw growth — front-to-back, which is what devices like headgear or certain elastic configurations in braces are built to do. Correcting a deep overbite usually means creating vertical space, sometimes with a bite plate or by adjusting how the back teeth meet, so the front teeth have room to come down into a shallower overlap instead of staying buried behind the uppers. Anyone comparing options after a diagnosis benefits from understanding the types of braces available, since not every appliance is built to correct both directions equally well, and an orthodontist typically picks mechanics based on which measurement — overlap or projection — is driving the visible problem.

Does it matter beyond appearance?

Both can matter for reasons beyond how a smile looks. A pronounced overjet leaves the upper front teeth more exposed — a fall, a sports impact, or a bike accident meets those teeth first, so a bigger horizontal projection is associated with a higher risk of dental trauma to the front teeth. A deep overbite can, in some people, let the lower front teeth bite into the roof of the mouth or the gum tissue behind the upper teeth, which irritates that tissue over time. Neither is automatically a problem severe enough to need correction — plenty of people carry a mild version of either for life without incident — which is why the decision to treat rests on an in-person exam rather than on how the bite looks in a photo.

What about the jaw joint?

Temporomandibular disorders, TMDs, are a group of more than 30 different conditions that cause pain or dysfunction in the jaw joint and surrounding muscles, and they remain an active area of research 1. Some people with a pronounced overbite or overjet also report jaw joint symptoms, which leads to a common assumption that the bite is the cause — but the relationship between bite alignment and TMJ symptoms specifically is complex and not something the evidence supports treating as a simple cause-and-effect. A jaw joint evaluation, separate from the bite assessment, is the more reliable way to sort out whether jaw pain is related to the bite at all.

Why an in-person diagnosis matters, especially for at-home correction

Moving teeth changes forces throughout the whole bite, not just at the tooth being moved, which is why professional supervision matters even for what looks like a small overjet or overbite adjustment. Direct-to-consumer aligner kits marketed for gap-closing or minor bite correction, used without an in-person exam, have been linked to reported harms in the FDA's adverse-event database, including new tooth mobility, newly created open bites, gum recession, and pain 2. That doesn't mean every aligner brand is unsafe — many are dispensed with in-person dentist or orthodontist oversight built into the process — it means the risk shows up specifically when tooth movement happens without anyone examining the mouth first. A dentist checking overbite or overjet in person can also catch a jaw-size mismatch or a habit driving the problem, neither of which shows up in a photo submitted for a remote fit.

Common questions

Yes. Overjet measures forward projection and overbite measures vertical overlap, and either can be pronounced while the other stays close to typical. Someone with protruding upper front teeth but a shallow bite has a significant overjet with minimal overbite — the two are scored independently at a dental exam.

No. A mild overbite that isn't causing tissue irritation, uneven wear, or bite dysfunction often doesn't need treatment at all. Braces or other correction usually become worth considering when the overlap is severe enough to affect chewing, cause the lower teeth to contact gum tissue, or wear teeth down unevenly.

Adults can and regularly do correct overjet, though the approach differs from childhood treatment. Growing children can sometimes have jaw growth guided into a better relationship, which isn't possible once growth is complete — adult treatment relies on moving teeth rather than jaws, usually with braces or aligners under an orthodontist's supervision.

No. A crossbite describes teeth that are misaligned side-to-side, where an upper tooth sits inside rather than outside its corresponding lower tooth, rather than the front-to-back or up-down relationship overjet and overbite describe. It's a different type of malocclusion that can occur alongside either or independently.

Both play a role, and it varies by which one is present. Jaw size and shape are largely inherited, which drives a lot of overjet and most overbite cases. Habits like prolonged thumb-sucking or pacifier use mainly affect overjet, by pushing already-erupting front teeth forward, and matter less for overbite, which is driven more by how the back teeth erupted.

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When a bite issue becomes a dental injury

  • —A front tooth that's chipped, loosened, or knocked out after a fall or impact — more likely when the upper front teeth already project forward
  • —Jaw pain that comes with the jaw catching, locking, or being unable to open fully
  • —Lower front teeth consistently biting into gum tissue behind the upper teeth, causing sores that don't heal
  • —Uneven, accelerated wear on specific teeth that's changed noticeably over months

A permanent front tooth that's been knocked loose or knocked out needs a dentist the same day — that's an urgent dental visit. Heavy bleeding that won't stop or a suspected jaw fracture after a significant impact is an emergency-room matter.

This article is general information, not a diagnosis. Only a dentist or orthodontist can examine a bite directly and determine whether an overbite or overjet needs treatment.

References

  1. 1.National Institute of Dental and Craniofacial Research (2024). Temporomandibular Disorders. NIDCR (NIH). link ✓That TMDs are a group of more than 30 conditions causing pain or dysfunction in the jaw joint and muscles, and that TMD is an active area of NIH research.
  2. 2.Kunkel T, et al. (2023). Adverse Events Related to Direct-To-Consumer Sequential Aligners - A Study of the MAUDE Database. PubMed Central (peer-reviewed study). link ✓That FDA MAUDE adverse-event reports for direct-to-consumer sequential aligners include tooth mobility, newly created open bite, gum recession, and pain.

2 sources, numbered by first appearance. General health information, not medical advice. AI-assisted editorial content — every citation independently verified. Editorial policy

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