Burst is a DTC company—that’s direct-to-consumer, similar to how makeup company Glossier and luggage company Away are eschewing traditional retail channels and selling their stuff through their own websites. Burst is also a subscription business. If you buy the $70 Burst Sonic Toothbrush, which offers charcoal-infused bristles, a built-in timer, and 33,000 sonic vibrations per minute, then you’re automatically enrolled into a recurring delivery of $6 replacement brush heads every 90 days. (The company says you can opt out of the subscription program at any time.)

And then there’s a Burst Ambassador program, which pays people who promote the products. Stewart says that around $.25 of every dollar in sales goes into a profit-sharing pool. The company claims around 25,000 ambassadors across the US, all of them dentists or dental hygienists. Nearly 10,000 of them are part of a Facebook group for all things Burst ambassador-related. I requested access, but at the time of publication, hadn’t been accepted. Most of the public Burst-related posts I found online—on Facebook, YouTube, Pinterest, and on ADentalTip.com—offered the $70 Sonic toothbrush for $30 off.

Stewart says the company uses a “proprietary algorithm” to determine how much these people get paid. There’s a variety of things that ambassadors can do to promote Burst, whether on social media or through “IRL” recommendations, all of which add up to a profit-sharing percentage. She calls it a kind of “direct referral 2.0.”

You wouldn’t be wrong to think this sounds a little like a multilevel marketing company, the kind that pays commissions to people who acquire and distribute products on the company’s behalf. These can quickly devolve into pyramid schemes, defined by the US Federal Trade Commission as businesses that promise consumers or investors “large profits based primarily on recruiting others to join their program” and push for “inventory loading,” which forces recruits to buy more products upfront than they could ever feasibly sell.

Whether or not the Burst ambassadors are encouraged to purchase inventory is a matter of who you ask. Initially, a dental office buys one Burst toothbrush at a reduced cost of $20, and then, upon the successful first sale of a Burst toothbrush, the dental office receives a refund for that $20. One spokeswoman tells me that there is no inventory or product that ambassadors must buy for retail purposes, while another spokeswoman followed up to say that “ambassadors do not ever buy bulk inventory — all sales are made via their promo code online on our website.” However, a Burst webpage for the company’s Office Sales and Gift Program says dental offices can receive discounts on brushes and oral care products when they’re purchased in bulk.

Stewart and Khayat say Burst is not a multilevel marketing company, that they borrowed things they liked from direct selling companies and implemented some of those tactics. (“WE ARE NOT AN MLM,” their website states, in all caps.) Larry Cheng, a partner at Volition Capital and an investor in Burst, also insists it’s not a multilevel marketing model. “The dental offices don’t really take inventory. It’s probably closer to an affiliate model. You don’t get paid on recruits and their sales,” he says. “It’s more gamified.”

Burst’s latest oral care product, the one the company shipped to me, is floss. This is not just any floss. It’s expanding, charcoal-coated, mint-and-eucalyptus flavored, antimicrobial floss. Like the toothbrush, it is subscription-based. It is also supposedly eco-friendly. You pay $13 upfront for the floss and dispenser, and after that, receive a new floss refill bobbin every 90 days for $7. The idea is that you reuse the plastic dispenser. Floss has never been so involved before.