Overbite: When the Upper Teeth Cover the Lower Too Much
For adults unsure what an overbite is: how it differs from overjet, how it is measured, when it matters and evidence on correction. Overbite is the vertical overlap of the front teeth. A deep bite may lead to wear and potentially gum damage, the British Orthodontic Society (BOS) says. If your bite injures your gums, show a dentist.
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Clinically reviewed by Dr Ibraheem Ijaz, dentist · GDC 301711
Medical disclaimer: This page is for general information only. It does not replace an examination or treatment by a dentist.
Dr Ibraheem Ijaz, principal dentist, reviewed this page. He is a General Dental Practitioner: BDS, BSc (Hons), MSc (Leeds), PG Dip Implant Dentistry, PG Cert Restorative and Aesthetic Dentistry.
What is the difference between overbite and overjet?
Overbite is the vertical overlap of the upper front teeth over the lower ones; overjet is the horizontal distance between them.
An increased overbite is a deep bite: BOS describes upper teeth covering the lower teeth too much. Our page on protruding front teeth covers increased overjet.
Elsewhere, the US site MedlinePlus calls Class 2 malocclusion, where the upper jaw and teeth severely overlap the bottom jaw and teeth, overbite, and the NHS uses it for upper and lower jaws that do not meet properly. Here it means the vertical measure, and in most headings an increased one.
| Overbite | Overjet | |
|---|---|---|
| Direction | Up and down | Front to back |
| Average in normal development, adult teeth, UK guide | One third to one half of the lower incisor covered | 2 to 4 mm |
| Linked concern | BOS: a deep bite may lead to wear and potentially gum damage | 2015 review of 54 studies across ages: large overjet, about double the odds of front-tooth injury |
How is an overbite measured?
An overbite is measured by the share of the lower front teeth covered, or in millimetres.
A 2014 UK restorative review calls it deep when the overlap exceeds half the lower incisor height.
The Index of Orthodontic Treatment Need, used for adult teeth in an NHS England guide, grades overbite and overjet differently: a deep overbite complete to the gum or palate with no trauma is grade 3, borderline need; an increased and complete overbite with trauma is grade 4, need treatment. Increased overjet reaches grade 5 at over 9 mm.
When does an overbite matter?
For most patients, the risk of harm from a slight deep bite is probably minimal, a 2012 systematic review's authors say.
Where a deep bite impinges on the palate, they add, there is the potential for trauma and damage to the palatal tissues.
Is a deep overbite linked to tooth wear and gum or palatal trauma?
It may be. BOS says the lower teeth biting into the back of the upper teeth may lead to wear and potentially damage to the gums.
A study of casts from 51 people at 15 and 27 concluded that increasing age, incisal wear, vertical overbite and incisal occlusion were clinical predictors of central incisor wear in adolescents. Over 12 years, overbite and overjet diminished and biting-edge wear increased. Its summary reports predictors, not a cause, with no direction for overbite.
The 2014 UK review says problems associated with a deep overbite can include soft tissue trauma, lack of space between the arches and tooth wear.
If your bite injures your gum or palate, or your teeth look worn, show a dentist. Our page on teeth that are wearing down covers that condition.
To ask about orthodontic treatment, book online or call 0114 288 2121.
Is an overbite linked to jaw joint problems?
A 2017 systematic review of 25 adult studies found results quite consistent towards a lack of clinically relevant association between jaw joint disorders and occlusion.
Its summary notes some possible quality shortcomings, names two bite features of almost forty as associated with temporomandibular disorder (TMD) in most single-variable patient analyses, says association does not imply cause, and does not mention deep overbite. A 1993 comparison of 147 symptom-free controls with five TMD groups listed deep overbite among features that did not contribute, though occlusion's contribution was not zero. The NHS lists an uneven bite among causes of TMD, without saying whether that includes an overbite.
The NHS says TMD is not usually serious and generally gets better on its own. Ask for an urgent GP appointment or get help from 111 now if you are unable to eat or drink, have clicking, popping or grinding noises when you move your jaw, have difficulty opening your mouth fully or your jaw is locking, have pain around your jaw, ear or at the side of your head, have frequent, severe headaches, have pain or tenderness at the side of your head or on the scalp, or have vision problems, such as double vision or loss of vision in one or both eyes.
These can be signs of a serious problem that needs urgent treatment. You can call 111 or get help from 111 online.
Has Class II division 2 treatment in children been trialled?
Not by late 2017. A 2018 Cochrane review of Class II division 2 treatment in children found no randomised or controlled clinical trials, so no trial evidence to recommend or discourage any type of orthodontic treatment for it. A 2025 UK randomised trial followed, in 38 people aged 9 to 16 with this bite.
Class II division 2 means upper front teeth tilted toward the roof of the mouth with an increased overbite.
How is an overbite corrected in adults?
Management options depend very much on the situation and symptoms, says the 2014 UK restorative review, whose summary names no age group.
They may range from a simple removable appliance or splint and non-surgical gum treatment to combined orthodontic, jaw surgery and restorative care.
Bite opening means orthodontic treatment that reduces the overlap; see how teeth move for the biology.
A 2026 review of randomised adult trials of anterior intrusion techniques found six, generally small, four in people also with a gummy smile, and its text rates certainty low to very low, its table low. None reported stability after treatment, and it said evidence does not allow definitive clinical recommendations.
The 2012 review of 26 studies, mostly case series of adolescents with fixed appliances, gives mean overbite as 5.3 mm before treatment, 2.6 mm after and 3.4 mm long term. It says most of the correction appears stable, with retainers possibly still in use, but evidence quality is not high, some studies selected successful cases, and individuals can relapse significantly.
Initial severity appeared related to long-term overbite, though difficult to isolate from other factors. One of its two age comparisons, in small subgroups, suggested adolescent treatment was slightly more stable. The other reported similar stability; the review's table, for two extraction groups, shows 30 adults losing 82% of a 1.1 mm correction by 4.1 years and 44 adolescents 53% of a 1.5 mm correction by 6.6 years.
Who is orthodontic treatment at Deepcar Dental Care for?
Orthodontic treatment at Deepcar Dental Care is for adults only.
See orthodontics at Deepcar Dental Care for the treatments offered.
Frequently asked questions
How common is a deep bite?
About one in five, on one global estimate. A 2018 review of population studies, counting more than 2.5 mm as deep, averaged 21.98% for adult teeth, ranging from 2.2% to 56% by study. Increased overjet, over 3 mm, averaged 20.14%.
Can an overbite change with age?
It can go either way. Of 20 people with a deep overbite at 8, all but one untreated, 16 could be assessed at 65: nine decreased, five increased, two stable. They averaged 3.4 missing teeth against 1.6 in a normal-bite group; all rated their oral health good or excellent. Four had varying mucosal indentations with the overbite.
Can a deep overbite make crowns or other restorations harder?
It can. A 2014 UK restorative review says lack of space between the arches can present significant challenges, and careful planning is essential. A 2024 review of 10 case reports, in adults with Class II division 2 and severe wear, recommended a multidisciplinary team approach, and said its results should be interpreted with caution.
How long does correcting an overbite take?
Often 1 or 2 years for adult orthodontic treatment generally, the British Orthodontic Society says. That is to get the teeth to bite better, and it may take longer for more difficult problems. For fixed braces, the NHS says 1 to 2 years.
Can an overbite affect speech?
MedlinePlus lists speech difficulties, including lisp, as a rare symptom of malocclusion generally. In 115 patients aged 8 to 36 seeking orthodontic evaluation, with overbite among the traits examined, an open bite over 2 mm was the key factor underlying speech sound errors. Errors were likelier with more severe malocclusion; the study's summary names no deep bite result.
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