Short answer: small clinical studies on retainers and aligners found that an active cleaning step (tablet, brush, or both) beats rinsing with water alone, and brushing plus a cleaning solution produced the best surfaces in two separate studies. A 2025 randomised trial went further and found denture-cleansing tablets, while leaving aligners looking clearest, actually damaged the surface with frequent use. Plain colourant-free soap was the safest daily option. The bigger practical differences between tablets and liquid are persulfate allergy warnings (listed as a contraindication on RetainerBrite's own instructions), cost over time, and the nightly faff: a 250ml bottle of Blakmint liquid (£14) runs up to 5 months reused over 6-day batches, while tablets are a fresh sachet every single night.
Blakmint's own liquid cleaner was tested under ASTM E2315, the standard lab method for measuring bacterial reduction on dental appliances, at a 20-minute soak, not a number invented for the label.
Tablets vs liquid, side by side
| What matters | Tablets | Blakmint liquid |
|---|---|---|
| Typical cost | around £6 to £7 a month (e.g. a 54-tablet pack at £12.39 used daily) | From £2.80/month (£14 bottle, up to 5 months reused) |
| Soak time | 10 to 15 minutes, most brands | 5 to 20 minutes routine, one overnight soak max |
| Persulfate free | No. RetainerBrite's own instructions list persulfate allergy as a contraindication | Yes |
| Surface safety with frequent use | A 2025 trial found denture tablets can visibly damage aligner surfaces over repeated use | No abrasive or oxidising agents |
| Daily waste | One foil sachet opened and binned per day | One bottle, solution reused up to 6 days |
| Taste, per a verified buyer | "Tasted of chlorine" | "So much better" (same reviewer, same mouth) |
Tablet pricing: Kukident 54-tablet pack, £12.39. Review quote: verified Amazon buyer, via Blakmint's product listing.
Soaking is only half the job
A small 2015 study using electron microscopy on aligners found that tablet plus brushing produced the cleanest surfaces, with brushing alone close behind. Water alone was the clear loser in a separate bioluminometer study on retainer wearers. The soak helps, but the brush does a lot of the actual work, same as it does for your teeth.
Liquid handles the soak step without the unwrapping, fizzing or waiting. You soak it, you brush it if it needs it, you're done.
The finding worth knowing about frequent tablet use
A 2025 randomised trial tested five different cleaning agents against aligner colour and surface over two weeks of wear. Plain, colourant-free soap came out safest with the least overall effect. Cleaning crystals and whitening toothpaste caused the most visible change, and a denture-cleansing tablet left aligners looking clearest of all, while visibly damaging the surface, enough that the study's authors advised against using one frequently. Clear doesn't always mean undamaged; sometimes it just means freshly scrubbed.
The allergy warning that's on the box
RetainerBrite's own manufacturer instructions list persulfate allergy as a contraindication, not a vague warning, a reason not to use the product. Most wearers never notice a thing. Some get gum tenderness, a rash, or a reaction they'll spend weeks blaming on toothpaste, stress, or a new pillowcase before anyone thinks to check the tablet.
Blakmint's liquid is persulfate free, which doesn't make it magic. It just removes one specific, documented allergen from a routine you're doing every single night.
What it actually costs you, every month, forever
A 54-tablet pack like Kukident runs £12.39 and lasts about 54 days used daily, roughly £6.88 a month, for as long as you wear a retainer.
A 250ml bottle of Blakmint is £14 and, mixed at the 10% solution and reused across 6-day batches, stretches to 5 months. That's as little as £2.80 a month, with no sachets piling up in the bathroom bin.
Can it go in an ultrasonic cleaner?
There's a clinical trial currently running that pairs an ultrasonic cleaner with a tablet as one of its test arms, which tells you the research community isn't totally sure yet either. What Blakmint can say is narrower and tested: the liquid is stated as compatible with ultrasonic retainer cleaners, because it was actually run through one before that claim went on the label.
What we actually tested, not just claimed
We ran the liquid cleaner through ASTM E2315, the lab standard for measuring bacterial reduction on an appliance surface, against a mixed inoculum of four real bacteria strains: Pseudomonas aeruginosa, E coli, Staphylococcus aureus and E hirae. At a 20-minute soak, the result was a 99.99% reduction for the sample tested. That's the same number printed on the bottle, not a rounder one for this page.
One verified buyer on Amazon said it plainer than any lab report: "The liquid solution is so much better than the standard cleaning one I was given initially that tasted of chlorine." Nobody paid them to say that.
If the nightly routine has worn thin, the Blakmint liquid retainer cleaner is £14 for up to 5 months of use, persulfate free, ultrasonic-safe, and recommended by orthodontists we work with.
Frequently asked
-
Does brushing my retainer even matter if I'm already soaking it?
Yes. In the aligner studies above, tablet-plus-brushing beat tablet alone, and brushing alone nearly matched it. The soak and the brush are doing different jobs; skipping the brush leaves work undone. -
How long can I soak overnight, and is that safe?
Blakmint's own instructions call for 5 to 20 minutes for routine cleaning, with an occasional overnight soak when needed, never more than one overnight period before rinsing thoroughly and inspecting the appliance again. -
Is persulfate actually dangerous?
Not for most wearers, but it's listed as a contraindication on RetainerBrite's own instructions for use, not just a generic warning label. If you've had an unexplained gum or skin reaction after using tablets, persulfate is worth ruling out. -
Can I reuse the liquid solution, or is it one soak and bin it?
Keep the same mixed solution for up to 6 days in a clean, sealed container. Ideally replace it every 2 to 3 days, sooner if it looks cloudy or dirty. -
Will a cleaner fix retainer smell on its own?
Mostly, but not completely. The clinical studies above found the best results came from combining a cleaning step with brushing, not from either alone.
Where this leaves you
The research doesn't crown one format the outright winner, but it does say the soak is only half the job, brushing is the other half, persulfate is a real documented allergen, and frequent tablet use carries a surface-damage trade-off most people never hear about. Past that, it's cost and nightly faff, and now you've got real numbers for both.
Want the full academic picture, references and all? Read How Should You Clean Your Aligners and Retainers? What the Studies Actually Show for the peer-reviewed deep dive this post draws from. For the general daily routine, wire and clear retainers both, see How to Clean Retainers. Dentures, mouth guards or clip in veneers instead? Read Why Liquid Beats Tablets, or Dirty Aligners & Retainers for what happens when cleaning gets skipped altogether.