Malocclusion treatment: what works, when, and for whom

What dental occlusion is, and what makes it correct

Occlusion describes how the teeth on the mandible below meet the teeth on the maxilla above. In a bite that functions well, the outer surfaces of the upper teeth sit slightly outside the lower ones, which keeps the cheeks clear of the biting surfaces, and the arc formed by the inner surfaces of the lower teeth stays smaller than the upper arc, which keeps the tongue out of the way (Hennessy, 2026).

Orthodontists define an ideal bite by measurements rather than appearance: a Class I molar and canine relationship, an overjet of 1 to 2 mm, an overbite of a similar size, little or no crowding, and contacts spread across the full arch (Ghodasra & Brizuela, 2023). That spread matters, because the loads involved are substantial, in the region of 1,000 kilopascals across the molars and up to 1,700 kilopascals during night-time clenching (Hennessy, 2026). Carried by three or four teeth alone, those forces eventually wear them down or loosen them.

Very few people reach an ideal bite without treatment. A slight overlap, a rotated tooth or a small gap belongs to what clinicians call an acceptable occlusion, and it is not a condition.

How to recognise a malocclusion

A misaligned bite rarely announces itself through pain. It shows up in ordinary actions that become less comfortable, and the recognised list of signs is short: visibly irregular alignment, difficulty biting or chewing, repeated biting of the cheeks or tongue, a lisp or other speech difficulty, breathing through the mouth instead of the nose, and a change in the shape of the face, chin or lip line (Ghodasra & Brizuela, 2023).

Many people with a malocclusion notice nothing at all, which is why it is usually picked up at a routine check-up. A dentist assesses the bite by holding the cheeks clear with a tongue depressor and asking the patient to clench on the back teeth, because asking someone simply to bite often makes them close on their incisors and produces a false impression of a posterior discrepancy (Hennessy, 2026). A malocclusion can be identified as early as the first dental visit at around a year old, and picking it up early makes later treatment more straightforward.

Three clinicians may be involved. A general dentist spots the problem and refers, an orthodontist plans and delivers the treatment, and an oral and maxillofacial surgeon takes over when the discrepancy sits in the jawbones themselves.

The types of malocclusion

Two naming systems run in parallel and they describe different things. The older one, Angle’s classification, reads the position of the upper first molar against the lower first molar. It says where the overall discrepancy between the arches sits.

Angle class	What it describes
Class I	Molars meet correctly
Class II	Lower jaw sits back
Class III	Lower jaw sits forward

The share of each class is frequently misquoted. Among people who have a malocclusion, Class I accounts for around 60% of cases and is the most common molar relationship, Class II for around 32%, and Class III for the remainder (Ghodasra & Brizuela, 2023). These figures describe the population that already has a malocclusion, not all children or adolescents.

A Class I relationship means the molars interlock normally, which still leaves room for crowded incisors, displaced canines or a localised crossbite. Class II describes a mandible set back relative to the maxilla; its first division combines upper incisors tipped forward with a deep overbite, its second division has the upper central incisors tipped back towards the palate. Class III places the mandible ahead of the maxilla, so the lower teeth pass in front of the upper ones, and it is generally the hardest pattern to correct.

The second naming system describes the problem as it appears in the mouth, without assuming whether the cause is dental or skeletal. This is the vocabulary used in most consultations.

What you can see	Name of the problem
Upper front teeth stick out	Increased overjet
Lower teeth in front of upper	Underbite
Front teeth never meet	Open bite
Upper teeth hide the lower	Deep bite
Upper teeth bite inside	Crossbite
Teeth overlapping each other	Crowding
Gaps between the teeth	Spacing

Contrary to a claim that circulates widely, an underbite is not among the most common forms. Anterior crowding on a Class I base is the usual finding, and crowding becomes more frequent as the permanent dentition comes through (Lombardo et al., 2020).

Where a malocclusion comes from

In the great majority of cases the cause is not identifiable. Only 8% of malocclusions have a known origin; the remaining 92% arise from a mix of genetic and environmental influences that no examination can separate for an individual patient (Ghodasra & Brizuela, 2023).

The commonest mechanism is a mismatch between the size of the jaws and the size of the teeth. A narrow maxilla, or teeth that are simply too large for the space available, produces crowding without anything being wrong on either side (Hennessy, 2026). Tooth size and jaw size are inherited independently of each other, which explains why a malocclusion can appear in a family where nobody else has one.

The remaining causes are more specific. Prolonged thumb or dummy sucking, and tongue thrusting against the front teeth, gradually push the upper incisors forward. A permanent tooth lost and not replaced allows the neighbouring teeth to tip into the gap while the opposing tooth drifts down into the space; a bridge, a partial denture or a dental implant prevents that movement. Losing a baby tooth early has the same effect in a child, by removing the space the permanent tooth needed to erupt into. Impacted teeth that never reach the arch, facial trauma and congenital conditions such as cleft palate complete the list.

What makes a malocclusion worse

A bite deteriorates slowly, and several years can pass between the initial trigger and any noticeable difficulty. That delay is the reason for monitoring during growth instead of waiting for a complaint.

Four situations are genuinely documented. Non-nutritive sucking habits carried on past the age of three or four, which progressively deform the upper arch. Chronic mouth breathing, often linked to nasal obstruction or enlarged adenoids, which alters tongue posture and palatal development. Unreplaced extractions, as described above. And oral hygiene during treatment itself: brushing badly around fixed appliances demineralises the enamel and brings on decay and gum inflammation, which is why the NHS advises interdental cleaning under the brackets every day and warns against sugary food throughout treatment (NHS, 2026).

Prominent upper incisors deserve separate mention, because they take the impact in a fall or a collision. The Cochrane review by Batista et al. (2018) quantified this: 30% of children in the late-treatment group sustained a new incisor injury, against 19% of those treated early. Wearing a mouthguard for contact sport follows the same logic.

Several factors repeated in consumer articles have no support behind them. Chewing gum, sleeping on one side, eating food that is considered too hard and nail biting have never been established as causes or aggravators of malocclusion. Gum is discouraged during orthodontic treatment for a purely mechanical reason, because it gets stuck in the appliance (NHS, 2026).

What malocclusion actually causes, and what it does not

This is where published sources diverge most sharply from what is commonly asserted online.

The established effects

The first consequences are functional and aesthetic. A marked malocclusion hampers chewing, distorts certain sounds, wears down the surfaces that carry the load alone, and changes facial balance. These are the primary reasons a malocclusion is corrected, ahead of any general health argument (Hennessy, 2026).

The psychological impact is measurable. The meta-analysis by Alrashed and Alqerban (2021) found that adolescents with the most severe forms report the poorest oral-health-related quality of life, with the size of the effect varying by age and cultural setting.

The link with gum health exists but is weaker than usually stated. The meta-analysis by Szyszka-Sommerfeld et al. (2026) found an association between certain malocclusions, namely crowding and Class II or Class III molar relationships, and higher odds of gingivitis before the age of 18. The authors grade that certainty as very low and state that no causal relationship can be inferred from it. The MSD Manual applies the same caution to the expected benefit: treatment can, in some cases, increase resistance to caries and periodontal disease by making realigned teeth easier to clean (Hennessy, 2026).

Sleep is a separate question. Craniofacial disharmony is a recognised risk factor for obstructive sleep apnoea, and the meta-analysis by Neelapu et al. (2017) identified an increased anterior lower facial height, a lower hyoid bone position and a reduced pharyngeal airway space in affected adults. That is not the same as saying a malocclusion causes apnoea: the features involved are skeletal proportions, not the alignment of the teeth.

What the literature does not support

The belief that malocclusion causes temporomandibular joint disorders shaped clinical practice for decades. It no longer holds. The systematic review by Manfredini et al. (2017) examined 25 clinical studies and around forty occlusal features, and concluded that there is no clinically relevant association between occlusion and these disorders. A single variable emerged from the multivariable analyses, and the authors note that the relationship may run the other way, with the contact interference being the result of the joint disorder instead of its cause. Their recommendation is unambiguous: abandon that framework in clinical practice.

The postural theory fares no better. Manfredini et al. (2012) concluded that no predictable relationship has been demonstrated between occlusal features and postural ones, and that joint pain shows no detectable link to measurable abnormalities of that kind. Posturographic platforms, surface electromyography and kinesiography, often presented as justification for these assessments, are not supported by the literature.

Costen’s syndrome, described in 1934 and still cited today, belongs to the same inheritance. The symptoms attributed to it, dizziness, tinnitus and neck pain, are real in the people who report them, but tracing them back to the bite means relying on a model that association studies have set aside. The same applies to chronic fatigue, tendinitis, digestive complaints and palpitations, all listed by some sources as consequences of a misaligned bite. Nothing establishes that, and directing a patient towards occlusal treatment on that basis delays a useful search for the actual cause.

Malocclusion treatment options

The assessment that comes first

Clinical examination gives the first reading; imaging supplies the rest. A panoramic radiograph shows the full set of teeth, how many there are and how far each has erupted. The lateral cephalogram, specific to orthodontics, captures a side view of the face and measures where the jawbones actually sit relative to each other, which is what separates a dental problem from a skeletal one. Cone-beam computed tomography adds a three-dimensional reconstruction of the face, along with a view of the airway and the joint, when the case justifies it (Ghodasra & Brizuela, 2023). Impressions or intraoral scans complete the record and provide the baseline for comparison.

Everything that follows is decided here: the type of appliance, whether extractions are needed, whether surgery is involved, and the timescale quoted.

The appliances and procedures

Palatal expansion addresses a narrow palate, crowding and crossbites. The device pushes the two maxillary bones apart at the midline suture, gaining a millimetre or less per activation. It only works while that suture remains unfused, which restricts it to childhood and adolescence.

Fixed braces remain the reference treatment. Brackets bonded to each tooth and an archwire apply a light continuous force that gradually remodels the alveolar bone around the roots, moving the whole tooth including the root in all three dimensions. Ceramic and lingual versions answer an aesthetic preference without changing the mechanics. Fixed metal braces are the type most commonly fitted on the NHS, worn for one to two years, with an adjustment appointment every six to eight weeks (NHS, 2026).

Clear aligners are a series of removable trays that move the teeth in stages, by around 0.3 mm per tray, each worn for roughly two weeks (Hennessy, 2026). Invisalign is the best known brand in this category, and our assessment of aligner treatment abroad explains why it travels poorly, but several manufacturers offer the same principle. The documented trade-off is clear: Ke et al. (2019) found a significantly shorter treatment time than with fixed braces, alongside weaker control of final occlusal contacts, of root torque and of retention. Aligners also depend on being worn 20 to 22 hours a day, which no clinician can check.

Extractions of permanent teeth, usually first premolars, release the space an arch cannot otherwise provide. Selective occlusal adjustment is a narrow, targeted procedure aimed at contacts that meet prematurely, restorations included. It repositions nothing and is not a substitute for orthodontics.

Orthognathic surgery applies when the discrepancy between the jawbones exceeds what tooth movement can compensate for. It is carried out after growth has finished, under general anaesthetic, and involves cutting and repositioning all or part of the maxilla or the mandible. An orthodontic phase almost always precedes and follows it.

Restorative work, meaning dental crowns and onlays, belongs to a different logic. It builds up a collapsed occlusal surface, replaces a missing tooth or rebuilds a broken-down one. It does not correct a malposition.

Whichever route is taken, retention is not optional. The remodelled bone takes months to settle, and teeth drift back towards their original positions without something holding them. A wire bonded behind the teeth or a removable retainer takes over, worn full-time at first and then at night, for two to three years (Hennessy, 2026). In adults, with no further bone growth, retention is often kept up for considerably longer.

When to treat

Timing is the most heavily studied question in this field, and the answer runs against intuition.

For prominent upper front teeth, the Class II pattern, the Cochrane review by Batista et al. (2018) compared early two-phase treatment at seven to eleven years old with a single course in adolescence. Once both groups had finished, no difference remained in final overjet or in the relative position of the jaws. The benefit of treating early lies elsewhere, in the reduction of incisor trauma described above. Starting sooner does not produce a better final result; it protects the teeth in the meantime.

For prominent lower front teeth, the Class III pattern, the Cochrane review by Owens et al. (2024) pooled 29 randomised trials covering 1,169 children aged five to thirteen. Non-surgical treatment, most often a facemask combined with rapid maxillary expansion, produced a substantial improvement in overjet of around 5 mm on average, at a moderate level of certainty. The authors note that only one trial followed patients into the long term, which leaves the durability of the result into adulthood unresolved.

Adults can still be treated, but teeth move more slowly once growth and bone maturation are complete and bone density is lower. Cases that combine a skeletal discrepancy with a request for full correction fall to the orthodontic and surgical route together.

Malocclusion treatment: before and after

The photographs below show Body Expert patients before and after their dental treatment. They document prosthetic smile rehabilitations, carried out with dental veneers or crowns, not orthodontic corrections.

The distinction matters when choosing. A prosthetic rehabilitation covers the visible surface of the teeth and transforms the appearance of alignment within a few appointments. It does not move roots and does not change the relationship between the jaws, so a skeletal discrepancy remains exactly what it was behind the new crowns. It also requires the teeth concerned to be prepared, which makes it irreversible. Orthodontics does the opposite, moving teeth through bone over months or years. The two are sometimes combined, alignment first and reconstruction afterwards, when teeth are also broken down or missing.

How long treatment takes, and NHS eligibility in the UK

Most courses of orthodontic treatment run for one to two years, with retention on top, and the length depends on the severity of the case, the space available in the arch and the overall health of the teeth and gums.

NHS coverage is narrower than it is often described. Braces are usually free on the NHS only for people under 18 who have a clinical problem with their teeth. A dentist refers the child to an orthodontist, who examines the teeth and jaws, takes radiographs, photographs or scans, and decides whether the case qualifies, based on how the teeth are affecting day-to-day life such as eating and cleaning. Waiting lists for that assessment can be long. If the case does not qualify, the alternatives are other dental treatments or private care. Anyone aged 18 or over normally pays for braces privately, and the cost varies with the complexity of the case and the type of appliance chosen (NHS, 2026).

That gap in adult funding is what leads some patients to look at dental treatment abroad. The reasoning works for procedures that can be completed within a single trip. It fits orthodontics poorly, because aligners and braces depend on regular in-person reviews spread across one to two years and on retention monitored well beyond that. A skeletal discrepancy corrected surgically, a prosthetic rehabilitation or the replacement of missing teeth are a different matter, and the page covering dental care in Turkey sets out what each of those involves.

Frequently asked questions

Can a malocclusion correct itself?
No. Unassisted tooth movement tends to make things worse, particularly after a tooth has been lost and not replaced. Some irregularities in the baby teeth resolve as the permanent dentition comes through, but that applies to a growing child and is not seen in adults.

Does a malocclusion that causes no trouble need treating?
Not necessarily. The indication rests on functional difficulty, on the size of the discrepancy and on the effect on oral health, not on the distance from an ideal bite that few people have. Mild crowding without symptoms can simply be monitored.

Can clear aligners replace fixed braces?
Yes, for mild to moderate cases that need no extractions, once growth is complete. Beyond that, fixed braces retain the advantage in controlling roots and final contacts (Ke et al., 2019). The initial assessment settles it.

Can a misaligned bite cause migraines or tinnitus?
Association studies find no clinically relevant link between occlusion and temporomandibular joint disorders (Manfredini et al., 2017), nor between occlusion and body posture (Manfredini et al., 2012). Symptoms of this kind call for their own medical investigation instead of occlusal treatment.

How long is a retainer needed?
Two to three years of night-time wear is common after the initial full-time period, and adults frequently keep a retainer for far longer because the bone no longer remodels in the same way.

Sources

Alrashed, M., & Alqerban, A. (2021). The relationship between malocclusion and oral health-related quality of life among adolescents: A systematic literature review and meta-analysis. European Journal of Orthodontics, 43(2), 173-183. https://doi.org/10.1093/ejo/cjaa051

Batista, K. B., Thiruvenkatachari, B., Harrison, J. E., & O’Brien, K. D. (2018). Orthodontic treatment for prominent upper front teeth (Class II malocclusion) in children and adolescents. Cochrane Database of Systematic Reviews, 3, CD003452. https://doi.org/10.1002/14651858.CD003452.pub4

Ghodasra, R., & Brizuela, M. (2023). Orthodontics, malocclusion. StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK592395/

Hennessy, B. J. (2026). Malocclusion. MSD Manual, Professional Version. Retrieved 14 September 2026. Read the entry

Ke, Y., Zhu, Y., & Zhu, M. (2019). A comparison of treatment effectiveness between clear aligner and fixed appliance therapies. BMC Oral Health, 19(1), 24. https://doi.org/10.1186/s12903-018-0695-z

Lombardo, G., Vena, F., Negri, P., Pagano, S., Barilotti, C., Paglia, L., Colombo, S., Orso, M., & Cianetti, S. (2020). Worldwide prevalence of malocclusion in the different stages of dentition: A systematic review and meta-analysis. European Journal of Paediatric Dentistry, 21(2), 115-122. https://doi.org/10.23804/ejpd.2020.21.02.05

Manfredini, D., Castroflorio, T., Perinetti, G., & Guarda-Nardini, L. (2012). Dental occlusion, body posture and temporomandibular disorders: Where we are now and where we are heading for. Journal of Oral Rehabilitation, 39(6), 463-471. https://doi.org/10.1111/j.1365-2842.2012.02291.x

Manfredini, D., Lombardo, L., & Siciliani, G. (2017). Temporomandibular disorders and dental occlusion. A systematic review of association studies: End of an era? Journal of Oral Rehabilitation, 44(11), 908-923. https://doi.org/10.1111/joor.12531

Neelapu, B. C., Kharbanda, O. P., Sardana, H. K., Balachandran, R., Sardana, V., Kapoor, P., Gupta, A., & Vasamsetti, S. (2017). Craniofacial and upper airway morphology in adult obstructive sleep apnea patients: A systematic review and meta-analysis of cephalometric studies. Sleep Medicine Reviews, 31, 79-90. https://doi.org/10.1016/j.smrv.2016.01.007

NHS. (2026). Braces. Retrieved 14 September 2026. Read the page

Owens, D., Watkinson, S., Harrison, J. E., Turner, S., & Worthington, H. V. (2024). Orthodontic treatment for prominent lower front teeth (Class III malocclusion) in children. Cochrane Database of Systematic Reviews, 4, CD003451. https://doi.org/10.1002/14651858.CD003451.pub3

Szyszka-Sommerfeld, L., Machoy-Rakoczy, M., Belova, A., Lipski, M., Schuster, L., Dammaschke, T., Budzyńska, A., Świtała, J., Warcholak-Grzeszewska, A., Woźniak, K., Armogida, N. G., Spagnuolo, G., Stratul, S. I., & Boariu, M. (2026). The relationship between malocclusion and periodontal health in children and adolescents: A systematic review and meta-analysis. Journal of Clinical Medicine, 15(3), 1155. https://doi.org/10.3390/jcm15031155