Philips Sonicare DiamondClean Smart 9300 Review: a pricey toothbrush that actually cleans really well

I’ve been using the Philips Sonicare DiamondClean Smart 9300 (the black HX9903/15) for a few weeks now, twice a day, after coming from a basic Oral-B and an older Sonicare. I bought it fully aware that the price is on the painful side for a toothbrush, so I went into this kind of skeptical. I wanted to see if it actually does anything more than a regular electric brush, or if it’s just an app, a pretty glass, and some marketing.

In day-to-day use, the first thing I noticed is how my teeth feel right after brushing. With my old brush, they felt clean but still a bit rough between the teeth if I ran my tongue over them. With this one, the surface feels much smoother, like that feeling you get leaving the dentist after a cleaning, just a milder version. That was basically after the first evening, without changing toothpaste or anything else in my routine.

I also paid attention to the stuff that usually annoys me: noise, vibration in the hand, splatter around the sink, and battery. It’s quieter than my old Oral-B, the vibration in the handle is there but not crazy, and once you get used to holding it at the right angle, it doesn’t fling toothpaste everywhere. Battery life is honestly one of the main positives so far; I charged it once and then just forgot about it for weeks.

So, is it perfect? No. It’s expensive, the app is helpful at first but not something I’ll use forever, and the whole charging glass thing looks fancy but is a bit gimmicky in daily life. But if we talk just about cleaning performance and how my mouth feels, it’s clearly a step up from the cheaper models I’ve used. The big question is whether that step up is worth the money for you, and that’s where the rest of this review comes in.

Let’s talk straight: this toothbrush is expensive. You’re paying for the brand, the design, the smart features, and the accessories on top of the basic brushing function. If you only care about getting your teeth reasonably clean and you’re on a budget, a mid-range Sonicare or even a cheaper electric brush will already be a big step up from manual. So for a lot of people, this 9300 model is probably overkill.

Where it starts to make sense is if you’re the kind of person who: hates dental work, wants to keep gums in good shape, drinks a lot of coffee/tea/wine, and is actually willing to use the different modes and maybe the app at least at the beginning. The cleaning performance is strong, the battery is great, and the pressure sensor plus app can genuinely help improve your brushing habits. If that helps you avoid one or two expensive dentist procedures over the years, the price doesn’t look as bad.

On the downside, you have to factor in the ongoing cost of brush heads, the fact that the travel case doesn’t charge, and the potential durability issues some users reported. Also, a lot of the “smart” stuff is more like training wheels than something you’ll use for the next five years. After the novelty wears off, you’re basically left with a very good electric toothbrush that you mostly use on one or two modes.

So in terms of value, I’d say it’s good for people who are serious about oral care and have the budget, but not the best choice if you’re just curious about electric brushes or trying to save money. There are cheaper Sonicare models that share a lot of the same core technology without all the extras. This one is for someone who wants the nicer version and is okay paying for it, but it’s definitely not the only sensible option on the market.

The design is clearly meant to look premium. The black handle has a matte finish that feels good in the hand and doesn’t show fingerprints too badly. Buttons are simple: one power button and one mode/intensity button. There’s a small row of icons for modes and some LEDs for intensity and battery. Nothing flashy on the front, which I like. It doesn’t scream “tech gadget” too much, more like a slightly fancy bathroom tool.

One thing I noticed is the shape of the handle. It’s slim enough to grip easily, but the length and weight are a bit more than my older Sonicare. It’s not heavy to the point of being annoying, but if you have smaller hands, you’ll feel it more, especially during the longer Deep Clean+ mode. The balance is okay: the weight is in the handle, not the head, so it doesn’t feel top-heavy. When it’s standing on the charging stand, it looks stable and doesn’t wobble.

The light ring for the pressure sensor is at the bottom of the handle. When you press too hard, it flashes a kind of white/blue-ish light. It’s visible enough in a normal bathroom, but if your mirror is far from the sink or your lighting is very bright, you might not notice it right away at first. Personally, I learned to pay attention after it flashed a few times, then it just became a reminder in the background. It doesn’t buzz or cut power, which some people might actually prefer because it’s less intrusive.

My only real concern with the design is the internal rod that connects to the brush head. There are a few user reviews complaining that this part became loose and wobbly after a few months. Mine is still solid for now, but I did check specifically because of those comments. If this part fails, the whole brush is basically done. So while the design looks good and feels nice, there is a bit of doubt in the back of my mind about long-term durability of that moving part, especially at this price point.

Battery life is one of the things that impressed me the most. Using it twice a day on mainly Clean mode with medium intensity, I went a bit over two weeks before the battery indicator dropped low enough to worry about charging. Some people say it lasts even longer depending on mode and intensity, and I can believe it. Compared to my old brush that needed a charge every 5–7 days, this one is clearly better. It’s nice not having to think about it all the time.

Charging options are a bit of a mixed bag. You get the charging glass with a base and a separate compact stand. The stand is what I ended up using daily because it takes less space and looks cleaner on the sink. You just drop the handle on it, and it stands upright. The glass charger looks fancy, and yes, you can use the glass for rinsing if you want, but realistically it just eats up counter space. Functionally, both charge the brush fine, so it’s more about what fits your bathroom setup.

The main downside for me is the travel case. It’s sturdy and protects the brush well, but it doesn’t charge the handle. For this price range, I expected at least a USB charging case. If you go on a short trip (like a week), the battery will probably last and you won’t care. But for longer trips, you either bring the stand and wall charger or switch to a manual brush. It’s not the end of the world, but it does feel like a corner cut on a premium product.

On the plus side, the brush doesn’t stay hot or do anything weird while charging, and the battery indicator is clear enough: you’ve got a simple LED that tells you roughly how full it is. No app needed just to know when to charge. Overall, the battery performance is very good, the charging options are fine, but the lack of a charging travel case is a bit disappointing at this price.

Comfort-wise, the brush is pretty solid but not perfect. The bristles on the included heads are on the softer side, which I appreciated. I have slightly sensitive gums, and on the default medium intensity, the first couple of brushes felt a bit strong but not painful. After two or three days, my mouth got used to it, and now I can use even the higher intensity on Clean mode without feeling sore. If you’re used to a manual brush, you probably want to start on the lowest intensity with Gum Health mode until you get used to the sensation.

The sonic vibration is very different from a rotating brush like Oral-B. It’s more of a high-frequency buzz than a mechanical scrubbing. At first, it tickles the lips and tongue a bit if you’re not careful, and it can cause some extra foam and drool if you leave your mouth too wide open. After a week, I adjusted my technique: mouth more closed, slower movements, and just letting the brush glide along the gum line. Once you figure that out, it’s much more comfortable and less messy.

In the hand, the handle’s matte texture has good grip even when wet. It doesn’t slip, and the buttons are easy to press without having to look. The only small downside is that the longer Deep Clean+ mode (3+ minutes) can make your hand and wrist feel a bit tired if you’re gripping too tightly. That’s more about user habit though; if you lighten your grip and let the brush do the work, it’s fine. The weight is acceptable for daily use, just not super light.

Noise level is another comfort factor. This Sonicare is quieter than my old Oral-B rotating brush. It’s still not silent, but the sound is a higher pitch hum rather than a loud grinding noise. If you brush while someone is sleeping in the next room, this is less likely to bother them. Overall, from a comfort point of view, it’s good: soft enough on gums, manageable vibrations, and no weird sharp edges or awkward grip problems. Just expect a short adjustment period if you’re new to sonic brushes.

In the first weeks, the build quality feels solid: no creaks, no loose parts, the finish looks well done, and the buttons respond properly. The handle feels like it can take normal bathroom abuse: a bit of water, toothpaste spills, being knocked over once in a while. I haven’t dropped it hard on tile yet (and I’m not going to do that on purpose), but it doesn’t feel fragile in the hand. The brush heads click on firmly and don’t wobble on my unit.

That said, I did read the negative reviews mentioning the internal metal rod becoming loose after about six months, making the head wobbly and basically killing the brush. That’s not something you can see or test right away, but it’s a known weak point on some Sonicare models. So far, on mine, the rod is tight and there’s no play when I try to move the head side to side. I do handle it with care: I don’t force the head on and off, and I avoid twisting it too aggressively. Still, at this price, I shouldn’t have to baby it that much.

The other durability topic is the warranty and support. On paper, Philips offers a warranty, but one reviewer pointed out a real problem: if you’re outside the US and you bought a US unit, getting it serviced can be a pain or even impossible because they only ship within the USA. So if you’re buying this while traveling or importing it, keep that in mind. A premium toothbrush that fails after six months and can’t be serviced is basically an expensive mistake.

Brush heads themselves are fine, but they are not cheap. You’re supposed to replace them every three months. If you stick to official Philips heads, the yearly cost adds up quickly, especially if more than one person is using Sonicare in the house. So while the handle seems well-built for now, the combination of possible rod issues, limited service logistics in some regions, and the cost of heads makes me a bit cautious about calling this thing truly durable. It’s okay so far, but I wouldn’t call it bombproof, especially considering the price tag.

This is where the DiamondClean Smart 9300 actually justifies itself a bit. In daily use, the cleaning performance is clearly better than my older mid-range Sonicare and definitely better than a manual brush. After about a week, I noticed less plaque build-up along the gum line, especially on the back molars where I usually struggle. When I ran my tongue over the teeth, they felt smoother for longer during the day, not just right after brushing. I didn’t change toothpaste or diet, so I’m putting that down to the brush doing a more thorough job.

The different modes are not just marketing labels; they actually feel different. Clean is the standard two-minute routine that gets everything decently done. White+ runs longer and focuses a bit more on the front surfaces; after several days using it in the evening, I did notice some surface stains from coffee and tea fading slightly. It’s not like a professional whitening treatment, but my teeth looked a bit brighter in the mirror. Gum Health is gentler and adds extra time around the gum line, which is good if your gums bleed easily. Deep Clean+ is the most intense and longest; I use it when my mouth feels particularly gross, like after a day of snacking or traveling.

The app tries to help by showing you which zones you missed and if you’re scrubbing too much. At the beginning, it actually pointed out that I was rushing the inner surfaces and brushing too hard on one side. After a few days of following its tips, I improved those habits. After that, the app became less important; I don’t need a phone every time I brush. So in terms of performance, the app is a good training tool for a week or two, then it’s mostly optional.

One practical detail: the 62,000 “movements per minute” sounds like a big number, but in reality, it just means it vibrates a lot and pushes fluid between the teeth. I still wouldn’t skip flossing completely, but I’ll be honest: on the days I got lazy with floss, my teeth still felt reasonably clean with this brush. For someone who hates flossing, this might help reduce the damage, though it’s not a magic fix. Overall, as a cleaning tool, it does its job very well, better than cheaper brushes I’ve used, but how much that matters depends on how serious you are about oral care.

Out of the box, the DiamondClean Smart 9300 feels like one of those products where they tried to justify the price with accessories. You get the handle, two brush heads (A3 Premium All-in-One and C3 Premium Plaque Control), a charging glass with a base, a separate small charging stand, and a hard travel case. No extra charger in the case, just the case itself. The whole setup looks more like something you’d leave on display in a bathroom than a basic hygiene tool.

In practice, here’s how I ended up using it: the small stand is what I use daily because it takes less space and keeps the handle straight up. The glass charger looks cool but is bulky, and I honestly don’t need a dedicated glass just for my toothbrush. The travel case is decent: it protects the handle and two heads, but since it doesn’t charge, you still have to bring the charger for long trips. For a toothbrush at this price, a charging case would have made more sense, especially if you travel a lot.

The handle has four modes: Clean, White+, Gum Health, and Deep Clean+. You switch with a simple button, nothing complicated. Three intensity levels are controlled separately, so you can run, for example, Gum Health on low or Clean on high. The pressure sensor is a light ring near the bottom that flashes when you’re pressing too hard. It’s visible enough that you notice it, but it doesn’t beep or do anything dramatic.

The app connects through Bluetooth. Setup is pretty straightforward: install the Philips Sonicare app, hold the brush near your phone, and it pairs. The app then tries to track where you’re brushing in your mouth, gives you a map, and nags you about missed areas. It’s useful for the first week or two to fix bad habits, but I can already tell it’s not something I’ll open every single day. Overall, the package is full-featured, but in real life I mainly use: one mode, one intensity, the basic stand, and I forget the rest most days.