Philips Sonicare DiamondClean Smart 9300 Review: a high-end brush that cleans great but costs a lot

I’ve been using the Philips Sonicare DiamondClean Smart 9300 for a few weeks now, and I’ll be honest: it’s a toothbrush that takes itself very seriously. There’s an app, multiple brush heads, a light ring, several modes, intensities, a charging glass…the whole package. At the end of the day though, the real question is simple: does it clean better than a basic electric brush, and is it worth the price?

I switched to this model from an older Sonicare and a cheap Oral‑B I keep for travel. So I had something to compare it to right away. The first surprise was how strong the vibration feels on the default setting, even though the bristles are soft. After the first use, my teeth really did feel smoother than with the cheaper brush, especially around the gumline and between teeth.

The “smart” side (app, pressure sensor, brush head detection) sounded like a gimmick at first, but I actually ended up using some of it. The pressure warning light in particular is handy if, like me, you tend to scrub too hard. The app is more of a bonus than a necessity: nice to have for tracking and coaching, but I wouldn’t buy the brush just for that.

Overall, this is clearly a premium product: it looks good, the battery lasts a long time, and the cleaning is strong. But it’s also expensive, and reading some of the Amazon reviews about the top rod going loose made me a bit cautious about long‑term durability. So my take is: good tool if you’re serious about oral care and can swallow the price, but not some magic gadget that replaces regular dentist visits and flossing.

Let’s talk about the awkward part: the price. This is not a cheap toothbrush. You’re paying for the brand, the smart features, multiple brush heads, and the premium design. Does it clean better than a $30 basic electric brush? Yes, in my experience, the cleaning is stronger, the gum care is better, and the guidance helps. But is it three or four times better? That’s harder to justify. For someone with already decent teeth who brushes well with a cheaper brush, the difference might not feel huge.

Where it starts to make sense is if you struggle with plaque, gum issues, or motivation. If the app and sensors push you to brush longer, use less pressure, and hit all areas properly, you might avoid some dentist bills. One Amazon reviewer mentioned they don’t floss regularly and still have very little build‑up, according to their dentist. I wouldn’t use that as an excuse to skip flossing, but it shows the brush can help if your routine isn’t perfect.

On the downside, replacement heads are not cheap, especially the premium ones included here. Over a couple of years, the total cost (brush + heads) adds up. And if you’re unlucky and hit the top‑rod looseness issue mentioned in the 1‑star review, and your local Philips support is limited, you’re going to be very annoyed at how much you paid. So there is some risk there in terms of long‑term value.

In short, I’d say the value is good but not amazing if you actually use the features and care about your oral health. If you’re just going to use it like a basic electric brush and ignore the app and modes, you’re probably overpaying. There are cheaper Sonicare models that clean very well without all the extras. This one makes more sense for people who like tech, want strong cleaning, and are ready to invest a bit more in their mouth than average.

Design‑wise, this is clearly not a cheap plastic toothbrush. The white finish looks clean, the handle is slim, and it doesn’t scream “medical device” on the sink. It’s more like a minimal gadget vibe. The surface has a slightly matte feel, which is good because it doesn’t get slippery with water and toothpaste. After a few weeks of use, it hasn’t yellowed or picked up stains, which is always a risk with white products in the bathroom.

The button layout is simple: one power button and one mode button below. You get a small row of icons to show which mode you’re on, plus three little dots for intensity. You don’t get a big screen or anything like that, which I actually prefer. In daily use, you just press power and brush; you only mess with modes or intensity when you want to change something. The light ring at the bottom for pressure feedback is visible enough without being a mini disco on your counter.

The charging glass is a bit of a love/hate thing. Functionally, it works: you drop the brush in and it charges inductively. It looks a bit fancy, but it takes up more space than a simple stand and collects water and toothpaste drips at the bottom. Thankfully, they also include a small charging stand, and I ended up preferring that day‑to‑day. The brush sits upright, the footprint is smaller, and cleaning around it is easier.

The travel case is rigid and feels sturdy enough to protect the brush in a bag. However, it doesn’t charge the brush, which at this price point feels slightly cheap, especially when some older DiamondClean models had charging cases. That said, the battery life is long enough that for short trips, I didn’t bother bringing the charger anyway. Overall, the design is pretty solid: good grip, clean look, and buttons that make sense, even if some pieces (like the glass) feel more like show than real utility.

On the battery side, this brush is honestly pretty solid. I charged it fully when I got it, then used it twice a day on a mix of Clean and Deep Clean+ modes. It easily went more than two weeks before I started worrying about the battery. One Amazon user said the battery “lasts FOREVER”; that’s obviously exaggerated, but for a toothbrush, it’s clearly on the long side. You’re not stuck charging it every few days, which is nice.

The charging options are a bit unusual. You can either drop the handle into the glass that sits on a base, or you can use the smaller stand. Both charge the brush inductively, so you don’t plug anything directly into the handle. In practice, I ended up leaving the small stand on the sink and the glass in a drawer. The glass looks nice, but it takes more space and collects residue at the bottom, while the stand is compact and easy to wipe.

One thing that annoyed some people (and I get it) is that the travel case does not charge the brush. At this price point, a charging case would have made sense. For short trips, it’s not a big deal because the battery lasts long enough. For longer travel, you either bring the charger or accept that at some point, you may need to switch to a manual brush. Personally, I can live with that, but if you travel all the time, it’s something to keep in mind.

The battery indicator is basic but fine: small LEDs tell you roughly how much charge is left. It doesn’t give you an exact percentage, but I never ended up with a dead brush out of nowhere. As long as you drop it on the stand every week or so, you’ll probably never think about the battery. Overall, no big complaints here: it charges reliably, the battery lasts a long time, and you’re not fighting with cables every few days.

Comfort is where I was a bit cautious at first. The brush uses Sonicare’s 62,000 movements per minute thing, and you can feel it. On the highest intensity, the first time I turned it on, it felt quite strong, almost borderline ticklish around the lips and nose. After two or three days though, I got used to it and actually started to like the higher intensity on Deep Clean+. If you’re new to sonic brushes, I’d start on the lowest intensity and move up once you’re comfortable.

The brush heads are soft, which helps a lot. I didn’t get any gum bleeding, even when I stayed a bit too long on the same spot. The Gum Health mode is noticeably gentler, with a slower pattern and less aggressive vibration, which is good if you have sensitive gums or inflamed areas. The head shape is fairly standard Sonicare – a bit long and narrow – so reaching the back molars is okay, but you do have to angle the head properly.

The pressure sensor is actually useful for comfort. I realized I was pushing way more than needed. When the ring lights up, it’s a good reminder to let the brush do the work. After a week, I noticed I was pressing less, and brushing felt more comfortable overall. I also stopped getting that slight gum soreness I sometimes had with my old brush when I went too hard.

In the hand, the handle is light enough and nicely balanced. I never felt like it was heavy or tiring to hold, even during the longer Deep Clean+ cycles. Noise level is reasonable: it’s not quiet, but it’s not a loud rattling sound like some oscillating brushes. If you share a small bathroom, someone will hear it, but it’s not obnoxious. Overall, comfort is pretty good once you dial in the right intensity and mode for your mouth; out of the box on max power, it can feel a bit intense for beginners.

Performance here is more than just clean teeth; it’s about how the features work together: timers, sensors, app, and modes. The brush has the usual 2‑minute timer with 30‑second quadrant alerts. That alone helps a lot with consistency. The vibration pause every 30 seconds is clear enough to feel, and it nudges you to move to the next section. With my old brush, I often under‑brushed some areas; here, I actually hit all four quadrants more evenly.

The Philips Sonicare app is better than I expected but not life‑changing. It shows a mouth map and tries to track where you’re brushing in real time. It’s not perfect – sometimes it thinks you’re on the wrong side – but it’s good enough to make you aware of neglected areas. I liked the reminders for problem zones you can flag in the app; I set a note on a molar where food often gets stuck, and it did help me remember to slow down there. After the first week though, I wasn’t opening the app for every brushing session. For me, it’s useful mainly at the beginning to build good habits.

The pressure sensor and scrubbing feedback are more relevant in daily use. If you scrub back and forth too much, the app nags you, and the light ring warns you about pressure. I actually changed my technique because of that: more gentle guiding motions, less aggressive scrubbing. My gums definitely appreciated the change. For someone who tends to overdo it, this is a practical feature, not a toy.

One thing to mention from the Amazon reviews: some people report the top rod becoming loose after a few months, which basically ruins the brush. I haven’t had that issue yet, but seeing that complaint more than once makes me a bit cautious. At this price, I’d expect rock‑solid reliability. Philips usually has decent customer service, but if you’re outside the US, the warranty process might be annoying, as one reviewer pointed out. Overall, performance is strong on the cleaning and guidance side, but there’s a question mark on long‑term robustness based on those user reports.

In the box you get the DiamondClean Smart 9300 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 travel case. No extra fancy stuff beyond that, but it’s enough to get started and test the different brushing modes properly. The model I used is the white HX9903/05.

The brush has 4 modes: Clean (standard daily), White+ (for stains), Gum Health, and Deep Clean+. On top of that, there are 3 intensity levels. In practice, I mostly used Clean and Deep Clean+; the White+ is a bit longer and focuses more on the front surfaces, and Gum Health is gentler and slower. The modes are switched via a single button, which is simple enough even half asleep in the morning.

The handle has a light ring near the bottom that acts as a pressure sensor indicator. If you press too hard, it lights up and the brush slightly reduces intensity. That’s not just a gimmick; I triggered it quite a few times the first days and had to adjust my grip. The brush heads also have a small chip inside, so the handle can detect them and select an appropriate mode automatically. For example, the A3 head tends to default to a more thorough clean.

The other big point is the Philips Sonicare app. You pair the brush via Bluetooth and it tracks your sessions: duration, coverage, pressure, and even areas you often miss. You can also flag problem zones (like a sensitive molar) so the app reminds you to spend a bit more time there. It’s not essential, but for someone who likes stats and reminders, it’s actually decent. Overall, the presentation is clearly high‑end: lots of features, but still usable without needing to read a 30‑page manual.

This is the part that matters: how well does it clean compared to a manual brush or a cheaper electric one. In daily use, I’d say the cleaning performance is clearly above average. After a normal 2‑minute Clean mode session, my teeth feel smoother than with my basic Oral‑B. When I switch to Deep Clean+ (which runs a bit longer), the feeling is close to that “just got back from the dentist” smoothness, especially along the gumline.

The plaque removal claims (up to 20x more plaque vs manual) are marketing numbers I can’t measure at home, but what I can say is this: after about a week, that fuzzy film you sometimes feel at the back of your lower front teeth between cleanings was much less noticeable. I also have a couple of tight spots where food tends to get stuck; with this brush and some floss, those areas stayed cleaner between meals. It doesn’t replace floss, but it does help push water and toothpaste between the teeth.

For stain removal, I drink coffee and tea daily. I had some light yellowing near the edges before switching to this brush. After about 10–14 days using White+ a few times a week plus Deep Clean+, I noticed a small but real improvement. Not a Hollywood smile, but those light surface stains faded a bit. One Amazon reviewer said their teeth looked whiter after the first use; I wouldn’t go that far, but there is a visible effect over a couple of weeks if you’re consistent.

As for gum health, I had some sensitivity in one area and occasional minor bleeding with my old brush when I went too rough. Using Gum Health mode around that area and letting the pressure sensor guide me, the bleeding basically stopped after a few days. Obviously, that’s just my case, but it lines up with the idea that the sonic motion is effective without needing brute force. Overall, in terms of raw cleaning, this brush is very solid. It won’t fix crooked teeth or deep tartar, but for daily plaque and light stains, it does its job very well.