Gera Dental Access & Activity Index (GDAAI) — Methodology
Full reproducible formula behind the GDAAI, computed only from real NHS Digital data (Open Government Licence v3.0).
Index definition
Gera Dental Access & Activity Index (GDAAI) is a 0–100 integer score assigned to each of England's 42 Integrated Care Boards (ICBs). It is a direct min-max normalisation of the adult NHS dental access rate for that ICB as published in NHS Dental Statistics for England 2022-23, Table 3e (NHS Digital, OGL v3.0).
GDAAI = round( (adult_access_pct − 30.6397) / (53.6238 − 30.6397) × 100 )
- adult_access_pct = adults seen by an NHS dentist in the previous 24 months as a percentage of the ICB's adult population, as at 30 June 2023.
- MIN value = 30.6397% (Gloucestershire, lowest access in England) → GDAAI 0.
- MAX value = 53.6238% (South Yorkshire, highest access in England) → GDAAI 100.
- Values are rounded to the nearest integer.
- A score of 100 means the best adult NHS dental access in England; 0 means the lowest.
Source data
The underlying metric — adult patients seen as a % of the adult population — is taken directly from NHS Dental Statistics for England 2022-23 Annual Report, Table 3e: “Adult patients seen in the previous 24 months and child patients seen in the previous 12 months as a percentage of the population, by patient type and Integrated Care Board (ICB), as at 30 June 2023.”
- Published: 24 August 2023 by NHS Digital (now NHS BSA)
- Data file: dental_geographical_breakdown_22_23_v2.0.xlsx
- Licence: Open Government Licence v3.0 (OGL v3.0)
- Population denominators: ONS mid-year estimates as used by NHS Digital for the 2022-23 publication
Self-verification
Five ICB values were independently cross-checked against Table 3b (absolute patients seen) in the same publication:
| ICB | Table 3b adults seen | Adult population | Computed % | Table 3e % | Match |
|---|---|---|---|---|---|
| Bath & NE Somerset, Swindon and Wiltshire | 257,785 | 734,622 | 35.1% | 35.1% | Yes |
| Cheshire and Merseyside | 925,316 | 1,994,031 | 46.4% | 46.4% | Yes |
| Greater Manchester | 1,055,116 | 2,199,696 | 48.0% | 48.0% | Yes |
| South West London | 416,282 | 1,166,520 | 35.7% | 35.7% | Yes |
| West Yorkshire | 848,860 | 1,853,221 | 45.8% | 45.8% | Yes |
Update cadence
The GDAAI is re-computed annually when NHS BSA (formerly NHS Digital) publishes the next NHS Dental Statistics annual report, typically in August. From 2023-24, the publication moved from NHS Digital to NHS BSA at nhsbsa.nhs.uk. The MIN and MAX ICBs — and the national average — may change each year as access rates shift. When the min/max ICBs change, Gera publishes the updated constants here under a versioned update date.
Current version: computed from 2022-23 data (as at 30 June 2023), published 2026-06-20.
| ICB | Adult access rate | GDAAI |
|---|---|---|
| South Yorkshire (best) | 53.6% | 100 / 100 |
| Greater Manchester (best) | 48.0% | 75 / 100 |
| Coventry and Warwickshire (best) | 47.9% | 75 / 100 |
| Cheshire and Merseyside (best) | 46.4% | 68 / 100 |
| Black Country (best) | 46.1% | 67 / 100 |
| Gloucestershire (lowest) | 30.6% | 0 / 100 |
| Surrey Heartlands (lowest) | 32.5% | 8 / 100 |
| Cambridgeshire and Peterborough (lowest) | 33.5% | 13 / 100 |
| Kent and Medway (lowest) | 34.1% | 15 / 100 |
| North Central London (lowest) | 34.5% | 17 / 100 |
Why “patients seen” rather than “accepting new patients”?
NHS England does not publish a national, ICB-level dataset on the percentage of practices accepting new NHS patients; that information is collected locally and published in real time only via the NHS dentist-search service (nhs.uk). The “patients seen as a percentage of population” metric from NHS Dental Statistics is the authoritative, consistently defined, annually published, OGL-licensed measure that most directly captures access at area level. An ICB where only 30% of adults have been seen in 24 months is structurally under-served by NHS dentistry relative to one where 54% have been seen, regardless of how many individual practices currently have open lists.
Contains public sector information published by NHS Digital / NHS England and licensed under the Open Government Licence v3.0. Source: NHS Dental Statistics for England 2022-23 — Table 3e (Geographical Breakdown) (June 2023, published 24 August 2023).
Informational/educational only — not a substitute for professional medical advice; a clinician interprets results.