When someone asks us which electric toothbrush to buy, we give the same answer every time: the Oral-B iO9. It is the only toothbrush we sell, and that was a deliberate choice by the practising dentists behind Onyx. Here is our case for it, the toothpaste we pair it with and what it costs.
Our verdict
Buy it. The iO9 does the two things we most want a toothbrush to do at home: it tells you, while you are brushing, when you are pressing too hard, and it keeps you going for the full two minutes. Around that it adds seven cleaning modes, a colour display, app coaching when you want it and a charging travel case. Nothing else we looked at puts all of that in one handle for the money.
The Black Onyx edition is £164.99 at Onyx, against Oral-B's £500 list price. See the iO9 Black Onyx, or get it with a year of heads and a toothpaste in our £180 Complete Care Bundle.
Why our dentists chose the iO9
It tells you when you are pressing too hard
Brushing too hard is the habit we see most, and it is stubborn because it feels thorough. The Oral Health Foundation warns that it can damage teeth and gums. The iO9 has a ring of light at the top of the handle that shows, as you brush, whether your pressure is too hard, too soft or just right. You correct it mid-stroke instead of hearing about it at your next check-up, and you may be surprised how often it lights up in the first week.
Seven modes, so it suits your mouth
Smart Adapt, Daily Clean, Sensitive, Whitening, Gum Care, Intense Clean and Tongue Clean. Sensitive is the one we suggest if your teeth or gums are tender, and Smart Adapt, according to Oral-B, adjusts rotation and pressure to the way you brush in real time. Most people settle on a favourite, but the choice is what keeps the brush comfortable on the days your mouth is not in a Daily Clean mood.
A colour display that keeps you on track
The display on the handle counts you through the two minutes, tracks your pressure and battery, and tells you when the head needs changing. It puts the information where you are already looking, which is most of the trick of building a habit.
App coaching, when you want it
Pair the iO9 with the Oral-B app and it tracks your brushing time and coverage, so you can see the areas you keep missing, and it syncs brushing time with Apple Health. It is optional: the pressure light, timer, display and modes all work with your phone in another room.
Ready to travel
In the box are the handle, one brush head, a charging travel case, a magnetic charger and a hygienic brush-head holder. Oral-B quotes a full charge in about three hours, and with the charging case there is one thing to pack instead of a charger and a pouch.
Why the iO9 rather than a cheaper iO
We looked across the whole iO range before choosing. The iO2 and iO3 have three modes and no display, and the iO2 only warns you when you press too hard. The iO5 and iO6 stop at five modes, have no colour display and take 12 to 18 hours to charge. The iO9 brings all seven modes, the colour display, the three-hour magnetic charger and the charging travel case together. The iO10 above it has the same seven modes and adds a charger that shows your brushing feedback, for well over £100 more. The iO9 is where the features stop being extras and start earning their keep. Our guide to every Oral-B model sets out what each one gives up, and our iO9 vs iO10 comparison covers the one above it.
The toothpaste we pair it with: Biorepair Plus
A brush this good deserves a toothpaste with a reason behind it. Ours is Biorepair Plus: fluoride-free and built on microRepair®, Biorepair's zinc-substituted hydroxyapatite. Hydroxyapatite is the mineral tooth enamel is mostly made of, so rather than bringing a different chemistry to your teeth, the toothpaste supplies the mineral they are built from.
The evidence is better than most people expect. A 2023 meta-analysis of 44 trials found hydroxyapatite reduced tooth sensitivity significantly more than placebo and more than fluoride. For decay, randomised trials in adults and in children found a hydroxyapatite toothpaste no worse than a fluoride one. Those trials used a different brand's formula; we chose Biorepair because it publishes its concentrations, and they are high.
Choose Total Protection (20% microRepair®) for everyday care, or Sensitive Teeth (24%) if cold drinks make you wince; with the iO9's Sensitive mode and pressure light, that is the routine we suggest for sensitive teeth. Both are £6.99, and our hydroxyapatite guide goes through the research in full.
Before you buy
The iO9 takes Oral-B iO heads only; heads for older Pro, Vitality, Smart and Genius brushes will not fit. Oral-B recommends a new head every three months, so our genuine iO Ultimate Clean four-pack at £20 is a year's supply for one person, and you can subscribe and save 10%. Our iO heads guide has the detail, and every pack of iO replacement heads we sell is genuine Oral-B.
And the honest bit: no brush does the brushing for you. Two minutes, twice a day, every surface. The iO9 simply makes that much easier to get right, which is exactly why we chose it.
The bundle: brush, heads and toothpaste for £180
Our Complete Care Bundle puts the iO9 Black Onyx, the four-pack of iO Ultimate Clean heads and a Biorepair Plus toothpaste (Sensitive Teeth or Total Protection) in one order, and delivery is free.
| Item | Onyx price |
|---|---|
| Oral-B iO9 Black Onyx | £164.99 |
| iO Ultimate Clean heads, black four-pack | £20 |
| Biorepair Plus toothpaste | £6.99 |
| Bought separately | £191.98 |
| Complete Care Bundle | £180.00, saving £11.98 |
Why buy it from Onyx
Everything at Onyx is chosen by practising dentists, and the iO9 is the brush we built the shop around. We sell it for £164.99 against Oral-B's £500 list price. Order before 4pm and it is dispatched the same day by Royal Mail Tracked 24; delivery is free on orders from £50; anything unopened can come back within 30 days; and if you have a question before or after you buy, ask us and one of our dentists will reply.
Buy the Oral-B iO9 Black Onyx, £164.99
Get the Complete Care Bundle, £180
Sources
- Oral-B UK: iO9 Black Onyx (modes, pressure sensor, display, app, charging, box contents) and the iO range, checked 29 September 2026.
- Oral Health Foundation: electric toothbrushes.
- Limeback, Enax and Meyer, Biomimetics (2023): hydroxyapatite and tooth sensitivity, a meta-analysis of 44 trials.
- Paszynska and colleagues: adults, Frontiers in Public Health (2023) and children, Scientific Reports (2021).
- Biorepair: microRepair® concentrations.
- Onyx product prices and delivery and returns, checked 27 October 2026.