iO Series 9 (Oscillating, 7 modes, colour display) review 2027

What problem does the Oral-B iO Series 9 solve?

The Series 9 is aimed at people who want the coaching, not just the cleaning. Its app tracks all 16 zones in real time, and in our test the people using it improved measurably. That is the benefit the price buys: a brush that tells you where you missed and a magnetic charger plus a power-bank travel case that keep it ready. The cleaning itself is 88% plaque removal, tied for best in the test. The verdict is blunt about the rest: it cleans exactly as well as its $100 sibling, and that is the fact that decides it.

How did it score 8.9 out of 10?

Five criteria, 100 points available.

• Cleaning performance — 34 of 35. Plaque reduction measured with disclosing tablets across six testers, and along the gumline specifically.
• Comfort & pressure control — 18 of 20. Noise, vibration in the hand, pressure sensor behaviour, gentleness on gums.
• Battery & build — 13 of 15. Days per charge at two minutes twice a day, charger type, water resistance, travel case.
• Replacement head cost — 9 of 15. Price per head at the recommended three-month change, and availability of third-party heads.
• Modes & app — 15 of 15. Brushing modes, timers and pacers, and whether the app coaching changed our testers' coverage.

It lost points on value, and the head-cost criterion is where the deduction is largest.

Where the Series 9 stands out

Three measured results carry the review. Plaque removal came in at 88%, tied for best in the test. Battery life ran 14 days at two minutes twice a day. Heads cost about $8 each. The app tracks all 16 zones in real time and our testers improved measurably, which is the strongest thing that can be said for any coaching feature here. The magnetic charger and the power-bank travel case are practical additions, and the interactive colour display is the visible difference between this brush and everything below it.

How does the oscillating technology work?

Oscillating heads rotate back and forth in small arcs rather than sweeping side to side like a sonic brush. The motion is concentrated at the head, so the bristles work the tooth surface and the gumline directly. Oral-B pairs that with a magnetic drive in the iO line, which smooths the motion and reduces the vibration you feel in the handle. The Series 9 adds 3D tracking in the app: the brush reports its position and orientation, and the app maps that onto the 16 zones of your mouth so you can see which ones you have covered and which you have not.

Parts, build and what you get

The spec sheet is the full picture. Technology is oscillating. There are 7 modes. The pressure sensor is a light ring. Battery life in our test was 14 days. Replacement heads run 8 USD each. The app does 3D tracking. The brush carries the ADA Seal. Plaque reduction measured 88%. The charger is magnetic and the travel case doubles as a power bank, which is unusual at any price.

How it compares with the brushes we tested alongside it

Against the Sonicare DiamondClean 9000 (8.8, $230), the Series 9 is ahead on plaque removal, 88% against 85%, and ahead on modes, 7 against 4 modes × 3 intensities. It is behind on head cost, 8 USD against 10 USD, and both run 14 days. The DiamondClean has a charging travel case and smart head recognition; the Series 9 has the colour display and the power-bank case.

Against the iO Series 5 (8.6, $100), the Series 9 is level on the number that matters most: both measured 88% plaque removal. Both run 14 days, both use 8 USD heads, both carry the ADA Seal and both use the Oral-B app. The Series 5 has 5 modes and a light ring pressure sensor; the Series 9 has 7 modes, a colour display and 3D tracking. The Series 5 is the value case against it.

Against the Sonicare ProtectiveClean 6100 (8.4, $110), the Series 9 is ahead on plaque removal, 88% against 83%, and ahead on app support, which the 6100 does not have. Both run 14 days and both use 8 USD heads. The 6100 offers 3 modes × 3 intensities and a pressure sensor.

Where it falls short

Value is the loss. $300 buys the same cleaning as the $100 Series 5, and that is the whole argument against it. Heads are about $8 each, which is not the cheapest in the test. Seven modes is five more than anyone used, so most of the mode count is unused capacity. The app is excellent, but it is the reason to buy, not the cleaning.

Is $300 good value?

The price is $300. Heads cost 8 USD each at the recommended three-month change. For that money you get 88% plaque removal, 14 days of battery, a magnetic charger, a power-bank travel case, a colour display and the best app coaching in the test. The cleaning is identical to the $100 Series 5. If you will use the app, the premium buys something real; if you will not, it buys a nicer object.

Who should buy the Oral-B iO Series 9?

Gadget lovers who will use the app. That is the buyer this brush is for. If you want the coaching, the colour display and the travel case, the Series 9 delivers them with the same 88% clean as the cheaper iO. If you want the clean without the extras, the Series 5 does the same job for a third of the price.