We sell this toothbrush, so treat this review with appropriate suspicion and hold us to the evidence. What follows is the assessment we would give a patient who asked across the chair: which features genuinely change how well you clean your teeth, which are pleasant but not important, and who would be better off spending less. If you want the marketing version, Oral-B's own page does it better than we could.
What it is
The Oral-B iO9 sits at the top of Oral-B's iO range. The Black Onyx Special Edition is the same technology in a black finish with a charging travel case. Oral-B's stated headline features are an interactive colour display, a visible pressure guide, multiple cleaning modes, a fast magnetic charger that Oral-B says reaches a full charge in around three hours, and optional Bluetooth connection to the Oral-B app for coaching and position tracking.
It uses Oral-B's iO magnetic drive with the round brush head the company has built its range around. Oral-B describes the combination of iO micro-vibrations and the round head as delivering a professional-clean feeling — that is the manufacturer's wording and we pass it on as such rather than as our own claim.
At Onyx it is £169.99 against Oral-B's official £500 RRP. To be straight with you about what that number means: £500 is the manufacturer's list price, and this model is discounted widely. Across the UK market in 2026 we have seen it between roughly £149 and £209. Our price is competitive within that range. It is not a £330 saving in any practical sense, and we would rather tell you that than let the compare-at figure imply it.
The features that genuinely matter
Pressure feedback — the reason to buy it
If you take one thing from this review, take this. The single most common technique fault we see is brushing too hard, and it is remarkably persistent because it feels productive. Over years, heavy brushing contributes to enamel wear and gum recession — which is one of the standard routes to exposed dentine and cold sensitivity.
The iO9's pressure guide shows visibly when your pressure is too hard, too soft or just right. Unlike a buzz or a beep you can learn to ignore, it is a persistent visual signal, and it is honest. Most people who use it for a fortnight discover they had been pressing considerably harder than they thought.
This is a real behaviour-change tool, and it is the feature we would not give up.
The two-minute timer
Unglamorous and effective. NHS guidance is to brush twice a day for about two minutes, and almost everyone who is not timing themselves brushes for less. The iO9 has a built-in two-minute timer and displays progress, so the target stops being a guess.
The colour display
The display shows timing, pressure, battery and brush-head reminders. The brush-head reminder is the quietly useful one, because it removes a decision from your memory — and Oral-B recommends replacing the head every three months, or sooner if bristles fray.
The features that are pleasant rather than important
App coaching and position tracking
Connect over Bluetooth and the Oral-B app offers coaching and position tracking, showing where you have and have not brushed. Genuinely interesting, and useful for a week or two as a diagnostic — most people find they consistently neglect the same area, typically the inner surfaces of the lower back teeth.
In our experience, very few adults keep using the app long-term. That is fine. Use it for a fortnight to find your blind spots, then let it go. Importantly, the toothbrush works completely normally without it: the display and timer are on the toothbrush itself. Do not buy this expecting to use the app daily, and do not avoid it because you would not.
Multiple cleaning modes
The iO9 offers several cleaning modes. Most people find one they like in the first week and never change it again. Modes are a reasonable thing to have and a poor reason to spend more.
The Black Onyx finish and travel case
It is a good-looking object and the charging travel case is practical if you travel often. This is aesthetics and convenience, honestly labelled. It does not clean your teeth better than the same technology in white.
The honest downsides
It is expensive. £169.99 is a lot for a toothbrush, and no amount of feature discussion changes that.
Replacement heads are an ongoing cost. iO heads only fit iO toothbrushes. Budget around £23.99 a year for a four pack of iO Ultimate Clean heads, or £21.59 on subscription. That is roughly 7p a day, but it is a commitment you are signing up to.
It is not compatible with your old heads. If you are coming from an Oral-B Pro, Vitality, Smart, Genius or Pulsonic, your existing heads will not fit. This catches people out regularly.
NHS guidance does not say you need one. This is the most important caveat and we are going to state it clearly: NHS guidance says "It doesn't matter whether you use an electric or manual toothbrush", provided you clean all the surfaces thoroughly with toothpaste. A manual brush used well beats a premium electric brush used badly, every time.
Who should buy it, and who should not
Worth it if
- You know or suspect you brush too hard, or you have wear or recession
- You have sensitivity and want to stop making it worse with technique
- You reliably brush for well under two minutes
- You want feedback rather than guesswork, and you will act on it
- You will keep it for years — spread over five years, the daily cost is small
Buy something cheaper if
- Your technique is already good and your check-ups are clean
- You want the aesthetics more than the feedback
- Budget is tight — a mid-range electric toothbrush with a timer and a pressure sensor covers the two features that matter most
- You will not change heads on schedule. A worn head on a premium toothbrush cleans worse than a fresh head on a basic one
That last point is the one we would emphasise most. The heads matter more than the toothbrush. If your budget stretches to either a premium toothbrush or a year of on-time head changes, choose the head changes.
How to get the most out of it
Let the toothbrush do the work — guide it along the gum margin rather than scrubbing. Watch the pressure indicator for the first two weeks until light pressure becomes automatic. Change the head every three months, or sooner if the bristles fray or the indicator bristles fade from blue to white. Clean between your teeth daily, which no toothbrush of any price does for you. And spit rather than rinse after brushing, so your toothpaste stays where it is useful.
Our care guide covers all of that in sequence, with the toothpaste side included.
The verdict
The iO9 Black Onyx is a very good electric toothbrush whose real value is the pressure feedback and the timer, not the app or the modes. If those two features would change how you brush — and for a great many people they would — it earns its price. If your technique is already sound, you are buying a nicer object rather than better cleaning, and that is a legitimate choice as long as you make it knowingly.
If it is right for you
The Oral-B iO9 Black Onyx is £169.99 with Royal Mail Tracked 24 delivery, free over £50. If you are starting from scratch, the Onyx Complete Care Bundle adds the iO Ultimate Clean 4 pack and a Biorepair Plus toothpaste for £190 — a year of head changes and your toothpaste sorted in one order, saving £10.97 against the individual total of £200.97.