--- title: "What Is an IOTN Score? IOTN Explained UK | NHS Braces Eligibility" url: https://virtualconsultant.online/guides/iotn-score-explained-uk description: "What an IOTN score means in the UK: Dental Health grades 1–5, the Aesthetic Component, the NHS braces threshold and options if you are borderline." updated: 2026-09-19T00:00:00Z publisher: Virtual Consultant Online --- IOTN NHS Eligibility Orthodontic Assessment # What Is an IOTN Score? IOTN Explained UK The Index of Orthodontic Treatment Need (IOTN) is the clinical tool used across the UK to decide whether a patient qualifies for NHS orthodontic treatment. Understanding how it works helps patients and parents navigate the referral process with realistic expectations. [Start Photo Assessment](https://virtualconsultant.online/evaluations/quote) [Check NHS Eligibility](https://virtualconsultant.online/about/do-i-qualify-for-nhs-treatment) ## What is the IOTN? The Index of Orthodontic Treatment Need was developed at the University of Manchester in the late 1980s and has been used by the NHS as its primary eligibility tool ever since. It provides a standardised framework for clinicians to assess how much a patient's dental misalignment affects their dental health and aesthetics, and therefore whether treatment is justified at public expense. IOTN has two separate components — the Dental Health Component (DHC) and the Aesthetic Component (AC) — with the DHC as the main measure and the AC deciding borderline grade 3 cases. The index is not used to design treatment; it is used purely to determine whether NHS funding applies. Private treatment is available regardless of IOTN grade. ## Dental Health Component (DHC) grades 1 to 5 The DHC uses a five-point scale, with each grade defined by specific measured features. Grade 1 means no treatment need: only minor irregularities. Grade 2 means little need, such as an overjet of 3.5 to 6 mm with lips that close comfortably, or teeth displaced by 1 to 2 mm. Grade 3 means moderate, borderline need, such as an overjet of 3.5 to 6 mm with lips that do not close, a reverse overjet of 1 to 3.5 mm, or teeth displaced by 2 to 4 mm. Grade 4 means great need, including an overjet over 6 mm up to 9 mm, teeth displaced by more than 4 mm, a deep bite that damages the gum, or less extensive missing teeth. Grade 5 means very great need, including an overjet over 9 mm, teeth prevented from erupting (such as impacted canines), extensive hypodontia, and cleft lip and palate. Grades 4 and 5 qualify for NHS treatment; grade 3 qualifies only with an Aesthetic Component of 6 or more, which is what the shorthand 3.6 means. ## How the IOTN score is measured The clinician examines the teeth and measures overjet (how far the upper front teeth sit ahead of the lower) and overbite (how much they overlap vertically), checks for crowding and how much space is missing, and looks for crossbites, open bites, rotations, and missing, extra or impacted teeth. The DHC grade is set by the single most severe feature found, not an average, so one significant finding such as a large overjet or an impacted canine can place a case in grade 4 or 5 even if everything else is mild. The Aesthetic Component is then scored by matching the front teeth to the ten-photograph scale. The whole assessment takes a few minutes within a normal examination. ## Aesthetic Component (AC) scale 1 to 10 The AC uses a set of ten standardised photographs of dental arrangements ranked from 1 (most attractive) to 10 (least attractive). The clinician compares the patient's smile to this scale and assigns a score. Scores of 1 to 4 indicate no or slight treatment need. Scores of 5 to 7 indicate moderate treatment need. Scores of 8 to 10 indicate a great treatment need. The AC matters for NHS eligibility only in grade 3 cases: a DHC grade 3 combined with an AC of 6 or more qualifies. A high AC score on its own does not qualify a patient whose DHC is grade 1 or 2. ## NHS eligibility threshold The standard NHS threshold is IOTN DHC grade 3.6 or above: a DHC grade of 4 or 5, or a DHC grade 3 with an Aesthetic Component of 6 or more. Grade 3 cases with an AC below 6, and all grade 1 and 2 cases, do not qualify. In practice the DHC is weighted so that certain features automatically trigger the grade ceiling: a large overjet, impacted permanent teeth, traumatic overbite, and hypodontia are among the features that push a case to Grades 4 or 5. Eligibility applies to under-18s referred through normal NHS channels, and treatment must start before the patient turns 18. Eligible under-18s pay nothing. Adults are very rarely eligible for NHS orthodontics except under specific clinical exceptions such as jaw surgery cases or those with certain developmental conditions. ## Who assesses the IOTN? The IOTN is assessed by a qualified dental professional, most commonly a specialist orthodontist or an orthodontic therapist working under one. General dental practitioners can also carry out an IOTN assessment when referring a patient to an orthodontic service. In NHS settings, the referring GDP usually provides an initial IOTN estimate, and the orthodontist carries out a formal assessment at the first appointment. It is the orthodontist's assessment that determines eligibility, not the GDP's referral opinion. Self-referral to NHS orthodontics is not available in England and Wales; a GDP referral is required for most patients. ## What happens if the IOTN score is too low? If the formal IOTN assessment finds a score below the NHS threshold, the patient is discharged from the NHS waiting list and private treatment becomes the only funded option. The orthodontist should explain the result and what features contributed to the score. Patients who are borderline — particularly at the upper end of Grade 3 — may be reassessed at a later date if eruption of permanent teeth changes the clinical picture. It is also worth noting that an IOTN assessment is not a refusal of treatment; it is a statement that the NHS does not fund treatment at that level of need. Private orthodontic treatment can address mild to moderate malocclusion that does not reach the NHS threshold. ## Private treatment if your IOTN score is below the threshold Private orthodontics has no IOTN requirement: a clinician assesses your case on its own merits. Many teenagers and adults with grade 2 or 3 crowding, spacing or mild bite problems still benefit from treatment. Typical UK private fees are £1,500 to £3,500 for metal braces, £2,000 to £4,500 for ceramic braces, £4,000 to £8,000 for lingual braces, £2,500 to £5,500 for Invisalign, and £1,500 to £5,500 for supervised clear aligners. Clear aligners are a common choice for mild grade 2 to 3 cases that do not need complex bite correction, and most practices offer payment plans. ## Limitations of IOTN IOTN was designed in the late 1980s and has been criticised in the research literature for several reasons. The aesthetic component relies on photographs of smiles that do not reflect modern dental aesthetics and may not capture the full psychological impact of dental appearance on individual patients. The DHC does not adequately capture functional problems such as TMJ symptoms or speech difficulties that may be genuinely related to the malocclusion. The index also does not account for the patient quality of life impact, which can be significant even in mild cases. Despite its limitations, IOTN remains the standard tool because it provides consistent, evidence-based, comparable assessments across a very large and variable NHS system. ## Devolved nation variation IOTN thresholds and NHS orthodontic provision vary across the four UK nations. In Scotland, NHS orthodontics is administered through the Scottish Dental Service and IOTN thresholds are broadly similar to England, though local health board variation exists. In Wales, the NHS Wales threshold broadly mirrors England. In Northern Ireland, the Health and Social Care system uses IOTN but commissioning decisions are made regionally. It is always worth checking with a local orthodontic service or GP dental practice to understand the threshold that applies in your area, as eligibility can differ meaningfully between postcodes and commissioning regions. ## Useful related pages [How to Find an NHS Orthodontist UK](https://virtualconsultant.online/guides/how-to-find-nhs-orthodontist-uk) [NHS Treatment Bands Explained](https://virtualconsultant.online/guides/nhs-treatment-bands-orthodontics-uk) [NHS Orthodontic Waiting List UK](https://virtualconsultant.online/guides/nhs-orthodontic-waiting-list) [Orthodontic Second Opinion UK](https://virtualconsultant.online/guides/second-opinion-orthodontist-uk) [NHS Braces Eligibility Checker](https://virtualconsultant.online/about/do-i-qualify-for-nhs-treatment) [NHS vs Private Braces UK](https://virtualconsultant.online/guides/nhs-vs-private-braces) [How to Get NHS Braces](https://virtualconsultant.online/guides/how-to-get-nhs-braces) [NHS Braces Cost UK](https://virtualconsultant.online/costs/nhs-braces-cost) [Braces for Teenagers UK](https://virtualconsultant.online/treatments/braces-for-teenagers) [Teeth Straightening Cost UK](https://virtualconsultant.online/guides/teeth-straightening-cost-uk) IOTN scoring is carried out by a qualified dental professional after a clinical examination. Scores estimated online or from photographs are indicative only; NHS eligibility is decided by the orthodontic provider at assessment. ### 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 an IOTN score? IOTN stands for Index of Orthodontic Treatment Need. It is a two-part clinical scoring system used in the UK to determine whether a patient qualifies for NHS-funded orthodontic treatment. The Dental Health Component (DHC) grades dental features from 1 to 5 based on their health implications, while the Aesthetic Component (AC) rates dental appearance on a scale of 1 to 10. A DHC grade of 4 or 5, or a grade 3 with an AC of 6 or more, meets the NHS threshold. What IOTN score do I need for NHS orthodontic treatment? The standard NHS threshold is IOTN DHC grade 3.6 or above. In practice that means a Dental Health Component grade of 4 or 5, which qualifies on its own, or a grade 3 combined with an Aesthetic Component score of 6 or more. A grade 3 with an AC below 6 does not qualify, and nor do grades 1 and 2, whatever the AC score. Treatment must also start before the patient turns 18, and eligible under-18s pay nothing. If your child is borderline, a later reassessment as more adult teeth come through can change the grade. Who measures my IOTN score? The formal IOTN assessment is carried out by a specialist orthodontist or an orthodontic therapist at an NHS orthodontic appointment. Your general dentist (GDP) will usually provide an initial estimate when referring you, but the orthodontist's assessment is the definitive one. You cannot self-refer for NHS orthodontics in England and Wales; you need a referral from your dentist. Can I appeal if my IOTN score is below the threshold? There is no formal appeals process for IOTN assessments within NHS orthodontics in most areas. However, if circumstances change — for example, if additional teeth erupt and worsen crowding — a new referral from your dentist may result in a higher score at a future assessment. If you believe the assessment was incorrectly carried out, you can request a second opinion from another orthodontist, though this will typically be at private cost unless your dentist refers you again. Does IOTN apply to adults? IOTN was primarily designed for children and adolescents, and NHS orthodontic treatment for adults is very limited in England. Adults are generally not eligible for NHS orthodontics based on IOTN alone. Exceptions exist for patients requiring jaw surgery (orthognathic treatment) where orthodontics is a clinical component of surgical planning, and for patients with certain developmental conditions. Adults seeking orthodontic treatment for cosmetic or functional reasons will almost always need to self-fund through private care. What is the aesthetic component of IOTN? IOTN has two parts, and the aesthetic component is the second of them. It is a scale of ten photographs of front teeth, arranged from the most to the least attractive alignment, and the clinician matches the patient's teeth to the closest image. It exists because the dental health component alone measures function and long-term risk, and does not capture appearance, which is often what brings someone for assessment. In England, an aesthetic component of 6 or more can qualify a patient for NHS treatment when their dental health component is grade 3, where that grade alone would not. Does my IOTN score affect private orthodontic treatment? No. Private orthodontic treatment has no IOTN threshold, so anyone can access it regardless of their score. A private orthodontist assesses suitability on clinical need, the outcome you want and your dental health, not on whether a grade meets NHS funding rules. Patients who score grade 1, 2 or a grade 3 with a low aesthetic score, and adults who are not eligible for NHS orthodontics at all, can still have private treatment and achieve meaningful improvements to their smile and bite. A photo-based assessment can give an indicative view of options and cost first. Is the IOTN score checked again after the NHS waiting list? Yes. NHS orthodontic waiting lists vary widely by area, from months to several years, and the IOTN is reassessed by the NHS orthodontist when the patient reaches the top of the list and is seen for assessment. If the teeth have changed since referral, for example because more adult teeth have erupted, the grade may go up or down, which can affect whether treatment is accepted. Time on the waiting list is time before the assessment appointment, not before braces are fitted, so it is worth asking your dentist to refer as soon as a problem is noticed. 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. Whether you're researching braces or clear aligners, comparing pricing, or just getting a feel for what comes next, you can browse at your own pace and come back when you're ready to request a quote. Explore [Get Quote](https://virtualconsultant.online/evaluations/quote) [Costs](https://virtualconsultant.online/costs) [Browse Treatments](https://virtualconsultant.online/treatments) [Teeth Straightening](https://virtualconsultant.online/treatments/teeth-straightening) [Browse Problems](https://virtualconsultant.online/problems) [Locations](https://virtualconsultant.online/locations) [Near Me](https://virtualconsultant.online/locations/orthodontic-treatment-near-me) [NHS Eligibility Checker](https://virtualconsultant.online/about/do-i-qualify-for-nhs-treatment) [IOTN Score Checker](https://virtualconsultant.online/about/iotn-score-checker) [How To Take Orthodontic Photos](https://virtualconsultant.online/about/process/how-to-take-orthodontic-photos) [Online Orthodontist](https://virtualconsultant.online/guides/online-orthodontist-uk) [Research Papers](https://virtualconsultant.online/research) [Social Channels](https://virtualconsultant.online/social) ## Ready for a personalised answer? 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 What Is an IOTN Score? IOTN Explained UK | NHS Braces Eligibility Publisher Virtual Consultant Online Published 2026-05-28 Updated 2026-09-19 URL [https://staging.virtualconsultant.online/guides/iotn-score-explained-uk](https://staging.virtualconsultant.online/guides/iotn-score-explained-uk)