The Philips Sonicare DiamondClean 9900 Prestige shows you areas you’ve missed
15.9.2026
Translation: Natalie McKay
Pictures: Anna Sandner
The DiamondClean 9900 Prestige shows you right on the handle which teeth you still need to brush and for how long. This makes your brushing routine more systematic, but it comes at a cost.
Brush for two minutes, spit and done. That’s how I used to brush my teeth. The Philips Sonicare DiamondClean 9900 Prestige aims to turn this rather humdrum routine into a live coaching session in your bathroom and help you achieve a more thorough clean by providing feedback as you brush. But this comes at a price. Depending on the offering, the high-tech sonic toothbrush will set you back between 350 and 590 euros/Swiss francs, including a charging glass and a travel case. That’s not to mention the ongoing costs. Philips recommends replacing the A3 brush head about every three months; two replacement heads cost around 22 euros/Swiss francs.
I spent several weeks testing to see whether the many features really improve my daily brushing routine or are mostly just expensive gimmicks. Philips provided me with a device for this purpose.
Luxury bathroom set
Inside the box, along with the handle, are a brush head, a charging glass with a charging dock and a travel case that charges via a USB-A cable with a Euro-8 plug. It looks as though Philips designed this toothbrush more for a display case than to be put next to my soap dispenser – it’s elegant and beautifully crafted. The handle fits comfortably in my hand and feels less bulky than I would’ve expected given its array of features.
I’m not such a fan of that fancy charging glass, though. I find the brush keeps tilting to one side in there, but it still charges just fine. That’s why I prefer to use the travel case at home. This meant the battery never ran out while I was testing the gadget. According to Philips, a full charge lasts up to 14 days with regular use.
The DiamondClean 9900 Prestige comes pre-charged and is ready to use right away, without a manual or app. The display and confirmation button guide you intuitively through the most important settings. So, for your basic morning routine, all you have to do is take it out of the box and press the power button.
Guided cleaning
At first glance, the high-tech brush does a great job. It cleans quietly. The soft Premium All-in-One brush head, which Philips calls «A3» for short, vibrates strongly enough to give a noticeable clean, but not so powerfully that my hand starts to tingle after two minutes. After the first brush in Clean mode, my teeth feel smooth and clean. For a toothbrush in this price range, though, that’s really the least I expect.
The DiamondClean 9900 Prestige offers five brushing modes and three intensity levels. The modes differ only in duration and intensity. For example, Deep Clean just runs one minute longer than Clean – but that’s the only difference. It’s somewhat annoying that the toothbrush turns off at the end of the selected mode, even if I haven’t finished brushing my whole mouth thoroughly. So after a while, I usually just choose the longer mode to begin with.
Segment by segment until the blue light comes on
I can adjust the settings right on the handle to choose whether I want feedback on coverage, scrubbing or pressure while I’m cleaning. First, the brush analyses my usual brushing routine based on duration, areas I’ve missed, pressure and scrubbing. My result leaves room for improvement. I clean a little too briefly and move on from certain areas too quickly. On the plus side, I don’t scrub too hard and, according to the brush, the pressure I apply is usually just right, though sometimes a little too light.
What interests me the most is the cleaning coverage. The light ring, accompanied by vibration and a beep, lets me know when I’ve brushed one of my twelve mouth segments for long enough. The light then changes from yellow to blue. Once I’ve completed all segments, the brush plays a short victory tune.
Cleaning with an app
To delve deeper into my toothbrushing routine and get the most out of my toothbrush, I finally decide to download the app. Pairing is a breeze. After that, the app requests location access and a Philips account. Philips explains that permission for approximate location is required to connect a Bluetooth device. According to the company, the app doesn’t use this permission to work out the user’s location and doesn’t store any location data. Still, it feels kind of strange to have to grant location permission for a toothbrush.
No feedback without data sharing
To receive personalised recommendations, I need to consent to the processing of my oral care data. Although the app initially offers «No, thanks» as an option, it won’t let me proceed without my consent. So, grudgingly, I agree. At least I can click away the Amazon brush head subscription that appears afterwards.
The app shows me metrics including brushing time, intensity, pressure, coverage and a more detailed mouth map. For example, if I’m brushing with coverage feedback and have the mouth map displayed, the app will alert me in real time if I’m pressing too hard or scrubbing too vigorously. I can also keep track of other oral care activities, such as flossing, using mouthwash or cleaning my tongue. Based on this data, I’m given suggestions for improvement.
Does the DiamondClean 9900 Prestige really do a better job?
After using the DiamondClean 9900 Prestige for a while, I’ve noticed that I’ve actually been brushing longer and more thoroughly – thanks to the brushing coverage display. Every beep that signals a colour change on the light ring feels like a little reward, so I wait patiently until I finally hear the victory tune.
I’ve also realised that I used to brush in a pretty haphazard way, which is probably why I’ve ended up neglecting certain areas. The feedback has helped me develop a consistent, more systematic approach. But the system also managed just fine when I did end up jumping back and forth between areas of my mouth. In my subjective self-test, it reliably indicated that the segments I had actually spent a sufficient amount of time on were covered.
Where the mouth map comes up short
Still, it’s not entirely reliable. The twelve sections of the mouth map are much bigger than the A3 brush head. But the brush only detects whether the brush head has been inside the segment for long enough. So a segment can be considered complete even though I haven’t brushed every single tooth in that area.
In my day-to-day testing, the DiamondClean 9900 Prestige has still noticeably improved my routine. However, I doubt that this actually results in objectively less plaque on my teeth or healthier gums, though I wouldn’t be able to tell anyway in a test like this.
The app – a nice extra, but not a must-have
I have to admit I only used the app for this test. It highlights weaknesses and has a lot to offer people who find statistics and tips motivating. In everyday life, though, I found it too much of a hassle to have my mobile phone with me while brushing, and I don’t want to permanently share my oral care data.
The handle does the job for me – coverage feedback, pressure alerts, modes and replacement reminders all work even without the app. If you just want to improve your routine, that alone will get you a long way.
After several weeks, what started out as a fun new gadget has, for me, become a reliable timekeeper more than anything else. I can (fortunately) easily do without the app, but I’ve grown fond of the prompts on the handle. They’re what provide the added value of the DiamondClean 9900 Prestige – and, at the same time, pose the question of whether this motivation is worth several hundred Swiss francs or euros to you.
In a nutshell
Premium toothbrush with real-time feedback
The DiamondClean 9900 Prestige cleans quietly, fits comfortably in my hand and leaves my mouth feeling clean. What makes this sonic toothbrush special is its real-time feedback. The display and light ring on the handle show you which areas of your mouth still need attention while you brush. You also get insights into pressure and brushing movements. It works for me – I clean for longer and more systematically, and take more time on areas that I would otherwise skip over quickly.
The app provides additional analysis, mouth maps and statistics, and uses this information to give you tips on how to brush better. If you use this data regularly and take motivation from it, you can see real value in it. To me, the DiamondClean 9900 Prestige is still a luxury product. The functions are well-designed, but they come with a high price tag.
Pro
- Toothbrush can be charged in the travel case and charging glass
- App offers detailed tracking, analysis and a mouth map
- Intuitive basic operation without the app
- High-quality finish and good handling
- Pressure and scrub detection
- Encourages longer and more systematic brushing
- Handy real-time feedback on brushing coverage provided at the handle itself
Contra
- Mouth map doesn’t recognise individual teeth
- App requires an account, location permission and data consent
- High price tag
Anna Sandner
Senior Editor
Anna.Sandner@galaxus.deScience editor and biologist. I love animals and am fascinated by plants, their abilities and everything you can do with them. That's why my favourite place is always the outdoors - somewhere in nature, preferably in my wild garden.
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