I’ve been told by dentists and dental hygienists for the better part of my life that I could do a better job of flossing my teeth. It took an interview with a startup founder and the chance to try a unique product for me to finally consider a real change in habits.
“You’re not alone,” said Brynn MacLennan. “Most people do not floss at all, and those that do mostly do it incorrectly. And that’s why we invented our product.”
MacLennan is co-founder and CEO of Slate, a Spokane, Wash.-based maker of an electric flosser.
MacLennan has a background as a product designer, and her co-founder and ex-husband Danny Snyder just happens to be a dentist and would-be inventor.
They started working on Slate in 2019, got a patent in 2020, launched a Kickstarter in 2021, and started selling product in November 2022. In 2023, they made $1 million in sales.
Slate, which previously raised $800,000 in seed funding, recently raised another $1.75 million in a second seed round, according to an SEC filing.
MacLennan said when she and Snyder first built Slate, they sent 500 to hygienists and 200 to dentists. They heard back from 95% of them who said they’d recommend the flosser to their patients, and 74% who said it was better than any tool on the market at stimulating the gums.
“When I got that data, I was like, ‘OK we can invest our energy in this,” said MacLennan, a mother of five who now runs the startup on her own.
The device looks and handles like an electric toothbrush, similar to Sonicare. The floss head at the top vibrates at three different speeds and features what Slate calls “Gum Sweeps.”
“That’s what makes our product better than anything else,” MacLennan said of the Sweeps. “These little triangles are what dentists would call an ‘interdental brush’ or ‘gum brush.’ We call them Gum Sweeps because they’re a new design, and we invented them, and this is what’s patented on our product.”
The little triangles on either end of the floss are designed to go where your gums and teeth touch, and sonic vibrations from the flosser massage your gums and disrupt plaque.
I use a Sonicare and have been using string floss and pick-style floss to varying degrees of success for years. I get dinged by my hygienist during cleanings every six months, and each time I leave I resolve to do a better job of staying on top of flossing.
After an initial test drive, the Slate flosser is certainly easier to use than wrapping string around my fingers. I could feel the Gum Sweeps working their way between the base of my teeth and vibrating against the gum line. It didn’t hurt, and I didn’t bleed the way I sometimes do after traditional flossing. Although, I might be bleeding because I’m not flossing regularly enough.
Slate recommends that the floss heads — available in a variety of colors — be changed every week. The reverse side of the head also doubles as a tongue scraper, apparently to remove even more bacteria. My teenager uses a tongue scraper, which means someone on TikTok has decided tongue scrapers are a thing now.
I took the flosser with me to my six-month dental checkup to show it off to my hygienist and get her opinion about whether such a device is worthwhile.
Kendra Cedana has been cleaning teeth for four years. She hadn’t previously seen or used a Slate flosser, but admitted that the device looked “cool” and that that can sometimes be all it takes for people to get into habits they may otherwise avoid.
Cedana watched how I used the flosser and then took her own turn using it on my teeth.
“The vibration is stimulating the gum, but it’s not dislodging any of the plaque,” Cedana said. “You have to still do the physical work of scrub, scrub, scrub.”
Cedana demonstrated with a regular piece of string floss the technique that she would normally use, and it involved six distinct moves that cleaned the sides of my teeth as well as below the gum line.
“Overall, I think manual, traditional flossing is going to be more effective,” Cedana said. “I would say [the Slate flosser] is better than nothing, because at least something’s getting through to the contact spot where the teeth come together, where cavities really start.”
We agreed that a humanoid robot powered by AI that comes to my bathroom every night — armed with regular old floss — is something that Cedana should invent.
Along with her hardware ambitions, MacLennan would love to innovate some software functions into the flosser, including the ability to communicate applicable data with high-tech wearables such as the Apple Watch or Oura Ring.
The Slate flosser retails for $119 and a box of 20 floss heads is $25, available direct-to-consumer, on Amazon, and through some dental offices. A three-pack of Oral-B Glide Deep Clean Cool Mint Dental Floss is $10 at Walmart.
MacLennan said the price of her device, manufactured at factories in China, Taiwan and the Philippines, is likely to go up soon due to President Trump’s tariff policies.
She also added that the product should be coming to a “popular retailer” soon, thanks to a deal that’s in the works with a company she could not yet name.
