--- title: "Malocclusion UK: Types, Causes, Treatment" url: https://virtualconsultant.online/guides/malocclusion-uk description: "Malocclusion means a bad bite — Angle's Class I, II and III system classifies it, and treatment depends on type, severity and whether growth remains." updated: 2026-08-09T00:00:00Z publisher: Virtual Consultant Online --- Malocclusion Bite Problems Classification # Malocclusion — Types, Causes and Treatment Malocclusion means a bad bite: the upper and lower teeth do not fit together correctly when the jaws close, and it is the core clinical concept behind almost every orthodontic treatment plan. Fewer than 30 percent of people have a clinically perfect bite, so some degree of malocclusion is the norm rather than the exception. This guide explains Angle's Class I, II and III classification, what causes malocclusion, when it actually needs treatment, and which options suit each type. [Start Photo Assessment](https://virtualconsultant.online/evaluations/quote) [Compare Costs](https://virtualconsultant.online/costs) ## What is malocclusion? Malocclusion is the clinical term for misalignment between upper and lower teeth when the jaws are closed. Normal — or Class I — occlusion involves specific molar and incisor relationships where the teeth fit together in a balanced, functional way. Any deviation from this in any direction constitutes a malocclusion. Fewer than 30% of people have a clinically perfect occlusion; the remainder have some degree of malocclusion, ranging from mild crowding with no functional impact to severe skeletal discrepancies affecting eating, speech, and facial appearance. ## Angle's Classification The most widely used classification system was developed by Edward Angle in the late 19th century and remains the clinical standard. Class I describes a normal molar relationship where the upper and lower first molars align correctly, but crowding, spacing, or rotations may still be present — the most common finding. Class II Division 1 describes upper front teeth that protrude forward with an increased overjet, often associated with an underdeveloped lower jaw — commonly called buck teeth. Class II Division 2 describes upper incisors that are retroclined (tipped backwards) producing a deep overbite; this subtype has an association with TMJ problems. Class III describes a lower jaw that protrudes ahead of the upper, or an underdeveloped upper jaw, resulting in an underbite or anterior crossbite. ## Causes of malocclusion Genetics account for the majority of malocclusion — jaw size, tooth size, and their relationship are largely inherited traits. Developmental factors also play a role: early loss of baby teeth allows adjacent teeth to drift, and impacted permanent teeth can cause crowding or displacement. Habits during childhood — prolonged thumb sucking, dummy use beyond age 3 to 4, and mouth breathing — can influence jaw development and tooth position. Jaw injuries during growth can alter development. Missing teeth cause adjacent teeth to drift over time. Bolton discrepancy — a mismatch between the combined size of upper and lower teeth — can cause crowding or spacing that cannot be fully resolved without additional treatment. ## Does malocclusion always need treatment? No. Many people have mild malocclusion that causes no functional problems and requires no treatment. Treatment is typically recommended when there is difficulty eating or speaking, risk of tooth damage such as lower incisors biting into the gum behind the upper front teeth, a significant aesthetic concern affecting quality of life, or where the IOTN score meets the threshold for NHS treatment for eligible under-18s. Mild crowding that does not affect function, bite, or oral hygiene does not need to be treated unless the patient wishes it for cosmetic reasons. ## Treatment options by malocclusion type Class I crowding or spacing is typically treated with fixed braces or clear aligners, with extractions where crowding is severe. Class II Division 1 in growing patients responds well to functional appliances such as twin blocks or Herbst appliances that guide jaw growth, followed by fixed braces. In non-growing adults with a skeletal component, orthognathic (jaw) surgery combined with orthodontics may be required for the best outcome. Class II Division 2 requires fixed braces to correct the deep overbite and retroclination. Class III malocclusion with a dental cause can often be treated with braces alone; skeletal Class III in adults who have stopped growing usually requires orthognathic surgery combined with orthodontic preparation and finishing. ## Useful related pages [Overjet vs Overbite](https://virtualconsultant.online/guides/overjet-vs-overbite-uk) [Overbite and Underbite Treatment](https://virtualconsultant.online/guides/overbite-underbite-treatment-uk) [Crowded Teeth Treatment UK](https://virtualconsultant.online/guides/crowded-teeth-treatment-uk) [Types of Braces UK](https://virtualconsultant.online/guides/types-of-braces-uk) [Jaw Surgery and Orthodontics](https://virtualconsultant.online/guides/jaw-surgery-orthodontics-uk) [Genetics and Malocclusion UK](https://virtualconsultant.online/guides/genetics-malocclusion-orthodontics-uk) [Top 10 Reasons Teeth Become Crooked or Shift](https://virtualconsultant.online/guides/top-10-reasons-teeth-become-crooked-or-shift-uk) This guide is for general information only. It is not a diagnosis, treatment plan, or substitute for advice from a registered dentist or orthodontist. ### Compare next steps [Orthodontist Near Me](https://virtualconsultant.online/locations/orthodontic-treatment-near-me) [Clear Aligners Near Me](https://virtualconsultant.online/treatments/clear-aligners-near-me) [Invisalign Near Me](https://virtualconsultant.online/locations/invisalign-provider-near-me) [Browse Locations](https://virtualconsultant.online/locations) ### Ready for a clearer starting point? Upload guided photos and receive an indication of likely treatment options and pricing before booking appointments. [Get an Online Quote](https://virtualconsultant.online/evaluations/quote) ### Frequently Asked Questions What is the most common type of malocclusion? Class I crowding is the most common finding — the molar relationship is normal but the teeth are crowded, rotated, or spaced. Class II Division 1, the overjet or protruding front teeth type, affects around 15 to 20% of the UK population. Is malocclusion genetic? Genetics account for most of it. Jaw size, tooth size, and the relationship between the two are largely inherited, which is why crowding, a receding chin, or a prominent lower jaw so often run in families. A child can inherit a small jaw from one parent and larger teeth from the other, and the mismatch shows up as crowding. Environment modifies the inherited pattern rather than creating it: prolonged thumb sucking or dummy use beyond about age three or four, mouth breathing, early loss of baby teeth allowing neighbouring teeth to drift, and jaw injuries during growth can all shift the outcome. Because the skeletal component is inherited, some adult malocclusions need jaw surgery rather than tooth movement alone. Can malocclusion cause jaw pain? Yes. Class II Division 2 with a deep overbite and skeletal Class III malocclusion in particular are associated with TMJ (temporomandibular joint) symptoms in some patients. Addressing the underlying malocclusion through orthodontics or surgery can reduce these symptoms, though the relationship between occlusion and TMJ pain is complex. What IOTN score does malocclusion give? This depends on the type and severity. IOTN grades 1 and 2 indicate little or no treatment need. Grade 3 is borderline; grade 4 and 5 indicate definite treatment need. A large overjet, traumatic overbite, impacted teeth, and severe crowding all contribute to higher IOTN grades that qualify for NHS treatment in eligible under-18s. Can malocclusion affect speech? Yes. Open bite, severe Class III, and pronounced Class II Division 1 can all affect speech — causing lisping, difficulty with certain consonants, or altered tongue position. Treatment can improve speech function, though long-standing compensatory patterns may need separate speech therapy input. Can malocclusion get worse if left untreated? It can, particularly in growing children where an underlying skeletal discrepancy continues to develop with the jaws, and in adults where habits such as teeth grinding, gum disease, or tooth loss allow existing malocclusion to gradually worsen over time. Mild malocclusion causing no functional problems often stays stable, but a clinician should assess whether your specific case is likely to progress before deciding that no treatment is needed. Explore your options Quick links Not sure where to start? Use these quick links to explore orthodontic treatments, typical costs, and helpful guides that explain what different options involve. 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Upload guided photos and get a tailored recommendation for your teeth and bite. [Start Photo Assessment](https://virtualconsultant.online/evaluations/quote) [Find an Orthodontist](https://virtualconsultant.online/locations) Citation details Title Malocclusion UK: Types, Causes, Treatment Publisher Virtual Consultant Online Published 2024-06-01 Updated 2026-08-09 URL [https://staging.virtualconsultant.online/guides/malocclusion-uk](https://staging.virtualconsultant.online/guides/malocclusion-uk)