Exclusive: Bristle polishes off $3M seed for oral health

With plans to debut the first at-home saliva test for oral health, startup Bristle has landed a $3 million seed round, CEO Danny Grannick tells Axios exclusively.

Why it matters: Bristle's offering combines three up-and-coming digital health subsectors — at-home diagnostics, which has blossomed amid COVID, oral health and consumer microbiome testing.

Deal details: Initialized Capital led the round with support from Y Combinator and 23andMe CEO Anne Wojcicki.

The backstory: Grannick and co-founder Brian Maurer, both veterans of genomics giant Illumina, came up with the idea for Bristle while attending a pitch competition full of gut microbiome startups.

• At the time, Maurer was dreading an upcoming dental appointment.
• "With the backdrop of these gut microbiome companies pitching and my friend complaining about this dental visit, it dawned on us that we’d never seen anyone leveraging microbiome science for oral health," says Grannick.

How it works: Bristle offers an at-home test designed to assess the oral microbiome, the combination of fungi and bacteria thought to be linked with conditions including gum inflammation, bad breath and tooth decay.

• Users swab the inside of their cheeks for the saliva-based test and send back their samples for processing.
• They are then paired up virtually with an oral hygienist who offers tips on behavior changes aimed at boosting their oral health.
• The test alone costs $119; users can subscribe and get tests every three months for $99 per test or every 6 months for $109 per test.

Between the lines: Research on the oral microbiome is still early, Grannick admits. Additionally, some scientists question whether a saliva-based test can provide a complete picture of teeth and gum microbes, as opposed to microbes on the tongue and cheeks.

• "Saliva does contain bacteria from all over the mouth, but most of the bacteria in saliva come from the tongue and cheeks," says Jessica Mark Welch, a microbial ecologist at the Marine Biological Laboratory in Woods Hole, Massachusetts.

The links between specific bacteria and specific diseases aren't super strong yet, meaning that for most bacteria:

• "It's too early to say whether the presence of those bacteria in your saliva says anything about your susceptibility to cavities or gum disease," Welch says.

What they're saying: Because the science is early, it's the right time for Bristle to start building the research around the oral microbiome.

• "A lot of the research in the past has looked only at a handful of bacteria," Grannick says. "The power behind our test is we can look at all these new types, and derive new insights about the links between those bacteria and various conditions. We want to build the research base."
• "What [Bristle is] doing now is the tip of the iceberg," says Initialized Capital partner Parul Singh. "There's so much potential for the science that comes out of this."

What's next: Although Bristle is starting DTC, the company is exploring the potential to add B2B lines of business.

• "We want people to have access to our tests wherever they are," says Grannick, "and that necessarily means developing B2B models and working with dentists and hygienists and self-insured employers."