--- title: "Bolton Discrepancy UK | Tooth Size Mismatch Explained (2026)" url: https://virtualconsultant.online/guides/bolton-discrepancy-orthodontics-uk description: "What Bolton analysis measures, what causes a discrepancy between upper and lower tooth sizes, how it affects orthodontic outcomes." updated: 2026-08-17T00:00:00Z publisher: Virtual Consultant Online --- Bolton Analysis Tooth Size IPR # Bolton Discrepancy: When Tooth Sizes Don't Match Orthodontic treatment moves teeth, but it cannot change their size. When the combined mesiodistal widths of the upper teeth and lower teeth are mismatched, the result — even after perfect alignment — may be a poor interdigitation, an incorrect overjet, or residual spacing. Bolton analysis quantifies this mismatch and allows the treatment plan to compensate before treatment begins. [Start Photo Assessment](https://virtualconsultant.online/evaluations/quote) [Compare Costs](https://virtualconsultant.online/costs) ## What Bolton analysis measures Bolton analysis, developed by Wayne Bolton in 1958, compares the sum of the mesiodistal (front-to-back) widths of upper and lower teeth to determine whether the two arches are proportionate. The anterior Bolton ratio compares the combined widths of the six upper front teeth (central incisors, lateral incisors, and canines) against the corresponding six lower teeth. The overall Bolton ratio compares the combined widths of the twelve upper teeth against the twelve lower teeth. Normal ratios are approximately 77.2% for the anterior comparison and 91.3% for the overall comparison. A value above or below these norms indicates a discrepancy — either the lower teeth are collectively too wide relative to the upper teeth, or the upper teeth are too wide relative to the lower. ## What causes a Bolton discrepancy The most common causes of clinically significant anterior Bolton discrepancy are peg-shaped or congenitally small upper lateral incisors, which reduce the upper anterior sum relative to the lower, and congenitally missing upper teeth (hypodontia), which similarly reduce the upper total. Oversized lower incisors — broad, wide lower front teeth relative to average — can also create a lower excess. Overall Bolton discrepancy can arise from extra-wide lower molars, impacted or missing teeth that alter the arch lengths, or simply genetic tooth size variation. A Bolton discrepancy does not mean anything is wrong with the teeth themselves — it is simply a measurement of proportionality between the two arches. ## How a Bolton discrepancy affects treatment outcomes If a Bolton discrepancy is not identified and planned for before treatment begins, the end result may be suboptimal despite technically well-aligned teeth. An anterior upper excess — too much upper tooth material — may prevent the overjet from being reduced to the correct amount, leaving the upper front teeth protruding slightly. An anterior lower excess — too much lower tooth material — may mean the lower front teeth cannot be fully retracted behind the upper teeth, leaving a reverse overjet tendency or poor interdigitation. Spacing may remain at the end of treatment that cannot be closed by moving teeth alone. Identifying the discrepancy in advance allows the clinician to factor in corrective procedures at the planning stage. ## Clinical solutions for Bolton discrepancy The available solutions depend on whether there is an excess in the upper or lower arch. Where there is a lower excess — too much lower tooth material relative to the upper — interproximal reduction (IPR) can be used to reduce the widths of the lower teeth by polishing small amounts of enamel from the contact points between teeth. This is most commonly applied to the lower front teeth. Where there is an upper deficit — teeth that are too small — the solutions involve building up the smaller teeth. Composite bonding can add width to peg-shaped lateral incisors or small upper front teeth. Porcelain veneers offer a more durable solution for the same purpose. Crowns may be appropriate where a tooth is structurally compromised. In cases with missing teeth, orthodontic space management followed by an implant, bridge, or partial denture may be required. ## When Bolton analysis is carried out Bolton analysis is typically performed during orthodontic treatment planning, either from study models (plaster casts or digital scans of the teeth) or from digital measurements taken on intraoral scan software. It is most relevant for cases involving anterior aesthetic work, cases where perfect occlusal interdigitation is a goal, and cases involving peg laterals, missing teeth, or unusually sized teeth. Not all orthodontists routinely perform a formal Bolton analysis for every case — mild discrepancies in straightforward cases may have minimal clinical impact — but for complex cases or those combining orthodontics with restorative work, it is an important step. ## Bolton discrepancy and combined orthodontic and restorative treatment The clearest clinical application of Bolton analysis is in planning combined orthodontic and restorative cases. For a patient with peg-shaped upper lateral incisors, for example, the orthodontist and restorative dentist should agree in advance on the intended final width of the built-up lateral incisors. The orthodontist then spaces the upper arch accordingly during treatment, leaving the correct amount of space adjacent to each lateral for the dentist to fill with composite or a veneer. Without this coordination, the orthodontist may close space that the dentist needs, or leave space that is the wrong shape for the intended restoration. Bolton analysis provides the quantitative basis for this planning conversation. ## Useful related pages [IPR Interproximal Reduction UK](https://virtualconsultant.online/guides/ipr-interproximal-reduction-uk) [Composite Bonding After Braces UK](https://virtualconsultant.online/guides/composite-bonding-after-braces-uk) [Orthodontics for Missing Teeth UK](https://virtualconsultant.online/guides/orthodontics-missing-teeth-uk) [Malocclusion UK](https://virtualconsultant.online/guides/malocclusion-uk) [Orthodontic Treatment Plan](https://virtualconsultant.online/guides/orthodontic-treatment-plan) 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 a Bolton discrepancy in simple terms? It means the upper and lower teeth are not the same collective size relative to each other. If the lower front teeth are wider than expected for the size of the upper front teeth, there is a lower excess discrepancy. If the upper front teeth are smaller than expected, there is an upper deficit. Either way, teeth that are perfectly aligned may still not meet correctly if the discrepancy is not addressed. Will my orthodontist tell me if I have a Bolton discrepancy? A thorough orthodontic assessment should identify a significant Bolton discrepancy, particularly when the presentation includes peg-shaped or missing lateral incisors, unusually wide lower incisors, or where the patient has high aesthetic expectations. If you are concerned, you can ask your orthodontist directly whether a tooth size analysis has been carried out. Can IPR fix a Bolton discrepancy? IPR can address a lower excess discrepancy by reducing the width of the lower teeth. It is most commonly used on the lower incisors. The amount of enamel that can safely be removed is limited — usually 0.2 to 0.5 mm per contact point — so IPR is most suitable for mild to moderate discrepancies. Severe discrepancies may require a combination of IPR and restorative build-up. Can a Bolton discrepancy cause an overjet? Yes. If the upper arch has less tooth material than expected relative to the lower arch (an upper deficit), it may be difficult to achieve a normal overjet. Similarly, if the upper arch has too much material (a lower deficit), the upper teeth may protrude. Bolton discrepancy is one of several factors that determine whether a normal overjet can be achieved through orthodontics alone. Is Bolton analysis done for clear aligner treatment? Yes. Digital intraoral scan software used in clear aligner treatment planning (such as ClinCheck for Invisalign) typically includes or allows for tooth width measurements. Identifying a Bolton discrepancy before finalising the aligner plan helps ensure that the digital outcome is realistic and that any IPR or restorative work is incorporated into the plan. Does having a Bolton discrepancy mean I need surgery? Not usually. A Bolton discrepancy is a tooth size issue, not a jaw size issue. It is managed within the dental arch through IPR or restorative build-up. Orthognathic surgery addresses skeletal jaw discrepancies and is not typically indicated for Bolton discrepancy alone. How common is a significant Bolton discrepancy? Minor tooth size variation is extremely common and has little clinical impact. Clinically significant anterior Bolton discrepancy — typically defined as more than 2 mm deviation from the norm — is present in around 5 to 10% of orthodontic patients to a degree that warrants treatment planning attention. Peg-shaped lateral incisors, which are a particularly common presentation, affect approximately 1 to 2% of the population. 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 Bolton Discrepancy UK | Tooth Size Mismatch Explained (2026) Publisher Virtual Consultant Online Published 2024-06-01 Updated 2026-08-17 URL [https://staging.virtualconsultant.online/guides/bolton-discrepancy-orthodontics-uk](https://staging.virtualconsultant.online/guides/bolton-discrepancy-orthodontics-uk)