Short answer: the Oral-B iO9 takes heads labelled Oral-B iO, and nothing else. Heads for Oral-B's older Pro, Vitality, Smart and Genius brushes use a different fitting and will not go on. The head our dentists chose, and the one we stock, is the genuine Oral-B iO Ultimate Clean in black: £20 for a four-pack, a year of fresh heads for one person, or £18 with subscribe and save 10%. Every pack in our Oral-B iO replacement heads range is genuine Oral-B.
Which heads fit an iO9?
| Head range | Fits an iO9? | What Oral-B designed it for |
|---|---|---|
| iO Ultimate Clean | Yes | Everyday deep clean (the head we stock) |
| iO Gentle Care | Yes | Extra-soft bristles for a gentler feel |
| iO Radiant White | Yes | Surface-stain removal |
| Pro, Smart, Genius or Vitality heads | No | Oral-B's earlier handle range |
Oral-B's UK replacement-head guide confirms the fit: iO handles take iO heads only. When you shop, look for the words “Oral-B iO” on the pack itself. A listing that just says “compatible with Oral-B” tells you nothing about the fit, or about who made it.
iO or classic: which Oral-B replacement heads do you need?
Check the handle. If it is an iO, from the iO2 to the iO10, it takes iO heads, and those are the only Oral-B replacement heads we stock, because the iO9 is the brush we recommend. If it is a Pro, Vitality, Smart or Genius, it takes Oral-B's classic round heads, such as CrossAction, and those will not fit an iO. If you are about to buy heads for an older classic brush, it is the moment to move up instead: our guide to every Oral-B model shows what the older brushes give up, and the £180 Complete Care Bundle puts the iO9 Black Onyx together with a year of genuine iO heads and a Biorepair Plus toothpaste, dispatched the same day if you order before 4pm.
Why we chose iO Ultimate Clean
Oral-B made Ultimate Clean as its everyday deep-clean iO head: a round head with tufted bristles angled at 16 degrees to reach around each tooth. That is exactly what the iO9 is built to drive. You guide the round head slowly from tooth to tooth, and the pressure light tells you when to ease off. Blue indicator bristles fade towards white when a new head is due, so the head tells you itself.
We chose the black four-pack to match the Black Onyx handle, and it is the same pack that goes into our Complete Care Bundles. If your gums are tender, keep the same head and switch the iO9 to its Sensitive mode for a gentler clean.
Why genuine matters
Search for iO heads online and you will find multipacks at a fraction of the price, some sold as “compatible”, some dressed up as the real thing. We would not put either in anyone's mouth, and there is a good reason. When City of London Police seized 3,000 counterfeit electric toothbrush heads in 2023, they warned that fakes are often made in unsanitary conditions from substandard materials, and that the head can detach and become a choking hazard.
Oral-B designs its heads for specific handle ranges, and for an iO9 that means a pack clearly labelled Oral-B iO. Every four-pack we sell is exactly that: genuine Oral-B iO Ultimate Clean.
How many heads do you need?
Oral-B recommends a new head every three months, or sooner if the bristles splay. That makes the arithmetic simple.
| Who is brushing | Four-packs a year | One-off price | With subscribe and save 10% |
|---|---|---|---|
| One person | One, every 12 months | £20 a year | £18 a year |
| Two people | Two, one every 6 months | £40 a year | £36 a year |
Our head replacement guide explains the signs a head has had its day, whatever the calendar says.
Subscribe and save 10%
The easiest way never to brush with a tired head is to let the next pack turn up on its own. Choose subscribe and save on the four-pack's product page and it arrives every 12 months for one person, or every six months for two, at £18 instead of £20. The spare is in the cupboard before you need it.
Buying the brush as well?
If you are buying the iO9 Black Onyx (£164.99) now, our £180 Complete Care Bundle adds this four-pack and a Biorepair Plus fluoride-free toothpaste. Bought separately at Onyx those three come to £191.98, so the bundle saves £11.98, and delivery is free. Our iO9 review explains why our dentists chose the brush.
Why buy your heads from Onyx
Every head we sell is genuine Oral-B iO Ultimate Clean, chosen by practising dentists to go with the brush we recommend. Order before 4pm and it is dispatched the same day by Royal Mail Tracked 24; delivery is free on orders from £50; unopened packs can come back within 30 days; and if you are not sure a head will fit your brush, ask us and one of our dentists will reply.
Shop the genuine iO Ultimate Clean four-pack, £20
Sources
- Oral-B UK: replacement brush heads, for compatibility, head types and replacement timing.
- Oral-B UK: iO Ultimate Clean heads, black, for the angled and indicator bristles.
- City of London Police (May 2023): police seize £45,000 worth of counterfeit toothbrush heads.
- Onyx product pages, subscription options and delivery and returns page, checked 30 September 2026.