Overbite and Underbite Treatment UK
Overbite, underbite, and open bite each need a different treatment approach — from braces alone for mild dental cases, to functional appliances during growth, to jaw surgery for significant skeletal discrepancies in adults. Both bite types affect function (chewing, speech) and appearance and are among the most common reasons UK patients are referred for orthodontic treatment. This guide covers all three major bite problems in detail.
What Do Overbite, Underbite and Open Bite Mean?
| Term | What It Means | Also Known As | Angle Class |
|---|---|---|---|
| Deep overbite | Upper front teeth overlap lower front teeth by >3–4 mm vertically | Deep bite, increased overbite | Class II div 2 commonly |
| Overjet | Upper front teeth protrude horizontally in front of lower teeth | Buck teeth, increased overjet | Class II div 1 commonly |
| Underbite | Lower front teeth sit in front of upper front teeth | Reverse bite, prognathism | Class III |
| Open bite | Upper and lower teeth do not meet when mouth is closed | Anterior / posterior open bite | Varies |
| Crossbite | Upper teeth sit inside lower teeth on one or both sides | Buccal / lingual crossbite | Varies |
How Is a Deep Overbite (Class II) Treated?
A deep overbite is when the upper front teeth overlap the lower front teeth vertically by more than 3–4 mm — or more than one-third of the lower tooth's height. In severe cases, the lower teeth may bite into the roof of the mouth (palate).
Overbite severity
| Severity | Overlap | Impact | Treatment Indication |
|---|---|---|---|
| Mild | 3–4 mm / up to 25% coverage | Minimal — mainly cosmetic | May not require treatment |
| Moderate | 4–6 mm / 25–50% coverage | Some tooth wear; moderate aesthetic concern | Orthodontics with bite-opening mechanics |
| Severe | 6–8 mm / 50–75% coverage | Significant wear; lower teeth may contact palate | Orthodontics ± functional appliance in growing patients |
| Complete (impinging) | >8 mm / >75% or biting into palate | Palatal trauma, severe wear, TMJ risk | Orthodontics + possible surgery in adults |
Treatment options for deep overbite
Fixed braces with bite turbos — small pads bonded to upper back teeth to prevent the bite from locking; the most reliable method for opening a deep bite.
Clear aligners with bite ramps — effective for mild to moderate deep bites; less predictable for severe cases.
Functional appliances (e.g., Twin Block) — used in growing patients (typically 10–14) to modify jaw growth and reduce the skeletal contribution to the overbite.
Intrusion archwires — specialised wires that intrude the back teeth upward to open the bite vertically.
Orthognathic surgery — for adults with a significant skeletal component that orthodontics cannot fully correct.
How Is an Underbite (Class III) Treated?
An underbite occurs when the lower front teeth sit in front of the upper front teeth. The cause may be dental (teeth tipping) or skeletal (jaw size difference) — and the cause determines the treatment.
Dental vs skeletal underbite
| Type | Cause | Who Is Affected | Can Braces Alone Fix It? |
|---|---|---|---|
| Dental underbite | Upper or lower teeth are tipped in the wrong direction | Any age; relatively uncommon | Yes — often correctable with braces alone |
| Skeletal underbite (mild) | Mild lower jaw excess or upper jaw deficiency | Often familial; may appear in childhood | Partially — camouflage orthodontics can mask mild cases |
| Skeletal underbite (moderate–severe) | Significant jaw size or position difference | More common in certain ethnic groups; also random | No — jaw surgery typically required in adults |
Treatment options for underbite
Reverse-pull facemask (protraction headgear) — used in children under 10–12 to protract the upper jaw before mid-face sutures fuse.
Fixed braces (camouflage) — suitable for mild skeletal and dental underbite; tips teeth to create an acceptable bite without correcting jaw positions.
Functional appliances — used during the growth phase to encourage upper jaw growth or limit lower jaw growth.
Orthognathic surgery in adults — upper jaw advancement (Le Fort I osteotomy), lower jaw setback (BSSO), or both. NHS patients must be fully grown (18+ for girls, 20+ for boys).
Distraction osteogenesis — used in very severe cases where the jaw must be moved more than standard surgery allows.
What Causes an Open Bite and How Is It Fixed?
An open bite occurs when the upper and lower teeth do not meet when the mouth is closed. It is most common at the front (anterior open bite) and is frequently associated with thumb-sucking, tongue thrust, or skeletal facial pattern.
Dental open bite: often caused by habits (thumb-sucking, tongue thrust). If habits stop early enough, some correction can occur naturally in children.
Skeletal open bite: caused by vertical facial growth pattern; more complex to treat and often requires jaw surgery in adults.
Clear aligners with vertical elastics have shown some success in mild anterior open bites.
In growing patients, habit-breaking appliances (tongue cribs, spurs) combined with braces can be effective.
Relapse rate after open bite treatment is higher than for most other malocclusions — long-term retention is essential.
When Is Jaw Surgery (Orthognathic Surgery) Needed?
Orthodontics alone can only tip and move teeth — it cannot move the jaws. For skeletal discrepancies above a certain threshold, jaw surgery is the only way to achieve a correct bite.
| Condition | Surgery Needed? | Notes |
|---|---|---|
| Mild dental overbite | No |
Fixed braces or aligners sufficient |
| Moderate skeletal overbite | Rarely |
Functional appliance if growing; camouflage for adults |
| Severe skeletal overbite in adult | Sometimes |
Depends on patient priorities and degree |
| Mild dental underbite | No |
Braces alone can camouflage |
| Moderate skeletal underbite in adult | Often |
Surgery gives best functional and aesthetic outcome |
| Severe skeletal underbite in adult | Yes |
Orthognathic surgery required for functional correction |
| Skeletal open bite in adult | Often |
High relapse with orthodontics alone |
Does the NHS Cover Overbite and Underbite Treatment?
NHS orthodontic treatment uses the Index of Orthodontic Treatment Need (IOTN). Severe overbite and underbite cases typically qualify for children under 18.
| Condition | Typical IOTN Grade | NHS Eligibility |
|---|---|---|
| Increased overjet >6 mm | Grade 4 | NHS eligible (children under 18) |
| Reverse overjet (underbite) | Grade 4–5 depending on severity | NHS eligible |
| Deep overbite with palatal trauma | Grade 4–5 | NHS eligible |
| Open bite >4 mm | Grade 4 | NHS eligible in significant cases |
| Combined with jaw surgery referral | Grade 5 | NHS eligible — referred by orthodontist to OMFS |
Can Clear Aligners Fix an Overbite or Underbite?
Clear aligners have improved significantly and can manage mild to moderate bite problems, but they have important limitations:
Mild to moderate overbites: Invisalign Mandibular Advancement can reduce overjet and overbite simultaneously in growing patients.
Moderate dental underbites: some success with aligners and Class III elastics, but results are less predictable than fixed braces.
Severe skeletal cases: aligners cannot move the jaw — surgery is still required regardless of aligner brand.
Open bite: vertical forces with aligners and elastics can help mild anterior open bites; skeletal cases need surgery.
Relapse risk: bite corrections with aligners require strict long-term retainer use — vertical and horizontal changes are among the most relapse-prone movements.