Our pick: the TePe Original mixed pack, because it costs $8.99 for 8 color-coded sizes, is rated 4.3/5 from 13,364 ratings, and the two largest reviews we read rank interdental brushes first for gum inflammation (checked October 29, 2026). If a brush will not fit between your teeth, the Waterpik Aquarius at $79.95 is the one to buy.
Interdental brush or water flosser: who wins, line by line?
Brushing your teeth does not clean the sides where two teeth touch, so you need a second step. The two most popular are the interdental brush, a tiny bottle brush you slide between teeth, and the water flosser, which sends a pulsing jet of water along the gumline.
| Criterion | Interdental brush | Water flosser | Winner |
|---|---|---|---|
| Gum inflammation (studies) | Ranked 1st of 10 methods (Kotsakis 2018) | Ranked 2nd, just behind | Brush ✅ |
| Plaque (Cochrane) | May reduce plaque more than brushing alone (low certainty) | No reduction shown at 1, 3 or 6 months | Brush ✅ |
| Entry price (Oct 29, 2026) | $8.99 for 8 brushes (TePe mixed pack) | $35.98 (COSLUS C20) to $79.95 (Waterpik Aquarius) | Brush ✅ |
| Braces, implants, bridge | Possible where it fits; TePe markets brushes for braces and dental hardware | Dedicated tips (7 with the Aquarius) | Water flosser ✅ |
| Very tight teeth | Never force it: you need a size that slides in | The jet goes everywhere | Water flosser ✅ |
| Travel | Fits in a pouch; no water, no plug | Reservoir and charger (the C20 is cordless, USB) | Brush ✅ |
| Two-year cost (our math) | $44.95 to $116.87 depending on how often you replace | $35.98 to $79.95, tips not counted | Tie |
Studies: Cochrane review (2019) and the network meta-analysis by Kotsakis et al. (2018), detailed below. Prices checked on Amazon.com on October 29, 2026.
What do the studies and the ADA say?
Two syntheses of the research point the same way, and the American Dental Association (ADA) has reviewed one water flosser.
- The Cochrane review (35 trials) found that interdental brushes might reduce gum inflammation more than string floss at one and three months, and plaque more than brushing alone (low certainty). For water flossers it found a possible drop in gum inflammation at one month, with no effect shown at three or six months and no clear effect on plaque (very low to low certainty).
- The Kotsakis network meta-analysis (Journal of Periodontology, 2018: 22 trials, 10 methods) ranks interdental brushes first against gum inflammation (64.7% probability of being the best method), the water flosser second (27.4%), and floss and toothpicks last. The authors conclude the choice should fit each person’s situation.
- The ADA Seal page covers the Waterpik Countertop Family Water Flosser: the ADA found it safe and effective at removing plaque along the gumline and between teeth and at helping to prevent or reduce gingivitis when used as directed. Waterpik’s Amazon listing for the Aquarius cites that Seal.
In plain terms: both habits are good, the brush starts with a small measured lead, and the water flosser takes the lead where a brush fits badly.
Three budgets
Prices, ratings and stock checked on Amazon.com on October 29, 2026; each product has a buy button. Features come from each Amazon listing.
| Level | Product | Price (Oct 29, 2026) | Amazon rating | Buy |
|---|---|---|---|---|
| Cheapest that holds up · Our pick ✅ | TePe Original mixed pack (8 brushes, 8 sizes) | $8.99 | 4.3/5 (13,364 ratings) | Amazon |
| Best value (water flosser) | COSLUS C20 (cordless, 300 ml tank, IPX7) | $35.98 | 4.4/5 (54,868 ratings) | Amazon |
| Best quality (water flosser) | Waterpik Aquarius (10 settings, 7 tips, 90+ second reservoir) | $79.95 | 4.6/5 (158,671 ratings) | Amazon |
TePe Original mixed pack. Eight color-coded sizes, so you can find the exact size for each gap before you buy a pack of a single size. The listing says the brushes are made in Sweden and designed with dental professionals, and claims they remove “up to 40 percent more plaque than brushing alone”; that is a manufacturer figure we could not check. Sold by TePe Oral Health Care, Inc. and shipped by Amazon.
COSLUS C20. A cordless, USB-rechargeable water flosser with a 300 ml tank and an IPX7 waterproof rating, according to its listing. Sold by a third-party seller and shipped by Amazon.
Waterpik Aquarius. The most-reviewed water flosser here (158,671 ratings), with 10 pressure settings, 7 tips, a 22 oz removable reservoir, 90+ seconds of flossing and a 3-year limited warranty, per its listing. Sold and shipped by Amazon.
Brushes or water flosser: which costs less over two years?
By crossing today’s Amazon.com prices with the published studies, one point stands out that none of these sources makes on its own: the price advantage of brushes melts away over time, because brushes wear out and get rebought.
- There is no official replacement rule. Published advice ranges from every few days to several weeks; the only shared sign is bristles that spread apart. We worked out two rhythms.
- One brush a week: 104 brushes in two years is 13 packs of 8 at $8.99, or $116.87, more than the Waterpik Aquarius ($79.95).
- One brush every 21 days: 35 brushes is 5 packs, or $44.95, close to the price of the COSLUS C20 ($35.98).
- The study gap is small. In the Kotsakis analysis the average drop in the gingival index is 0.23 for brushes against 0.19 for a water flosser, while the comfort gap can be large for anyone with braces. The right choice is the one you will do every day.
Which one for your mouth?
- Open spaces between teeth, no braces: interdental brushes in the right size. Start with the TePe mixed pack; most mouths need two or three sizes.
- Braces, implants, crowns or a bridge: a water flosser with dedicated tips, such as the Waterpik Aquarius, plus brushes where they fit. For the full Waterpik story, read our guide Are water flossers worth it?
- Very tight teeth: if even the smallest brush needs force, don’t force it; a water flosser or string floss takes over.
- You drop small habits quickly: the water flosser is easier to keep up daily.
- Who should skip it? If you already clean between your teeth every day and your dentist is happy with your gums, keep your routine. If your gums bleed for weeks or hurt, talk to your dentist first.
- Next to the basics: a good toothbrush comes first; see our Oral-B iO 9 vs iO 7 comparison.
1. We read the published reviews first, then the listings. 2. We check today’s price, rating and number of ratings. 3. We work out the two-year cost, not just the sticker price.
Frequently asked questions
Are interdental brushes better than a water flosser?
In the studies we read, interdental brushes have a small lead against gum inflammation: the Kotsakis network meta-analysis ranks them first of 10 methods and water flossers second. The Cochrane review says brushes might also reduce plaque more than brushing alone, with low certainty.
Can a water flosser replace brushing my teeth?
No. A water flosser or interdental brush goes with your toothbrush, not instead of it. Brushing cleans the surfaces of your teeth; these tools clean between them.
How often should I replace interdental brushes?
There is no official rule. Published advice ranges from every few days to several weeks, and the shared sign is bristles that spread apart. At $8.99 for 8, replacing one every 21 days costs about $44.95 over two years, and one a week about $116.87.
Does the ADA recommend the Waterpik Aquarius?
The ADA’s Seal page covers the Waterpik Countertop Family Water Flosser, which it found safe and effective at removing plaque along the gumline and between teeth and at helping to prevent or reduce gingivitis, when used as directed. Waterpik’s listing for the Aquarius cites that Seal.
What if my teeth are too tight for a brush?
Don’t force one. A water flosser or string floss takes over where the smallest brush does not fit; ask your dentist which size suits each gap.
Our verdict
Our pick: the TePe Original mixed pack, because it costs $8.99 for 8 color-coded sizes, is rated 4.3/5 from 13,364 ratings, and interdental brushes rank first against gum inflammation in the largest reviews we read (checked October 29, 2026). Braces, implants or tight teeth? Take the Waterpik Aquarius at $79.95, or the cordless COSLUS C20 at $35.98 for travel. See all of our recommended beauty devices.
- Cochrane — Home use of devices for cleaning between the teeth to prevent and control gum diseases and tooth decay (35 trials)
- Kotsakis et al., Journal of Periodontology (2018) — A network meta-analysis of interproximal oral hygiene methods
- American Dental Association — Waterpik Countertop Family Water Flosser (Seal of Acceptance)










