🪥 Feno: $5M run rate building smart toothbrush

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An oral surgeon told me about a patient who nearly died from a tooth infection. That surgeon, Dr. Kenny Brown, just hit mid 7 figure annualized run rate selling a smart toothbrush that can help more people from avoiding life-threatening oral diseases.

He isn't your typical founder. He's still performing oral surgery three mornings a week while running Feno, the AI-powered oral health company that's raised $6M and is growing 40% month-over-month. 

I’ve written before about why I’m bullish on the oral health space, and today, I’m super excited to feature one of the budding stars in this space.

Continue reading to find out:

Dr. Kenny Brown's path to Feno started in the operating room. 

As an oral and maxillofacial surgeon who graduated from Stanford, Dr. Brown witnessed firsthand how tooth infections become brain abscesses and how dental issues turn life-threatening. Oral health also directly links to dementia, cancer, and heart disease.

Nevertheless, most people have poor dental hygiene: 

If oral health drives overall health, why do most people have gum disease? 

Dr. Brown realized people mostly fall short on time and technique. 

He set out to solve this problem with a smart U-shaped toothbrush called Feno that cleans your teeth perfectly in just 20 seconds.

Instead of going solo on this project, Dr. Brown partnered with Share Ventures, a venture studio founded by MoviePass co-founder Hamet Watt. 

The studio focuses on human performance and leveraging technology to support it. Dr. Brown knew that creating significant impact requires a team, especially for hardware where the complexity spans manufacturing, regulatory, supply chain, and go-to-market challenges.

The built-in investor network led directly to Bold Capital Partners, True Ventures, and Upfront Ventures for the eventual $6M seed round. 

Dr. Brown took two and a half years to get to a product he felt comfortable bringing to market. 

It was intentional. 

There was already a graveyard of failed U-shaped toothbrushes, and Dr. Brown knew he didn’t have many shots on goal. Most people’s first reaction was, ‘I’ve seen this before—it doesn’t work.’

He had to build a product that’s different, not incrementally better. 

To understand the landscape, Dr. Brown bought every U-shaped toothbrush on the market and ran them through a detailed evaluation framework, testing for efficacy, comfort, coverage, and user experience.

Rather than treating other teams as rivals, he looked for collaboration. The breakthrough came when he found an early-stage company with technology that wasn’t effective in its current form but had the strongest foundation. The original plan was to license portion of the tech. Instead, the strong fit led Dr. Brown to bring both the technology and the team in-house.

He then rounded out the team with specialists: an aligner expert who knew how teeth move and fit together, a physicist to design optimal cleaning action and pressure distribution, and a manufacturing expert to ensure the product could be built at scale.

1/ Year one: Proof of concept

This stage was about proof, not polish. The team built a crude Smarthandle to test full movement patterns, oversized and ugly by design. 

They ran mouthpiece experiments to balance comfort and coverage, measured plaque removal, and wrote an algorithm to optimize where and how the brush made contact. 

10+ 3D-printed prototypes went through the lab to validate efficacy and removal rates.

2/ Year two: Building a product for consumers

The focus shifted from “does it work” to “will a consumer actually use it.” 

The team locked the core approach, slimmed the hardware into a form factor people would want on their sink, and made it manufacturable. They created molds, set up vendors, and brought a first production line online so units could be built with consistent quality.

3/ Year three: Validation and launch

The final stretch was about pressure-testing. 

They made small test runs of 100+ units to confirm yields and reliability. Three to six months before launch, they ran a quiet pre-launch to gauge demand and collect feedback. Manuals, how-to videos, and support flows were created so the product would feel complete on day one. 

Prototypes went to a tight group of early users, and the team shipped a small initial batch, then ramped as they learned from real-world usage, bugs, and hardware tweaks.

Dr. Brown knew building a toothbrush that could stand apart wasn’t just about design. Manufacturing, inventory, and regulation would make or break the product.

1/ Manufacturing: Engage early

Most first-time founders wait too long to think about manufacturing. Dr. Brown did the opposite: he began outreach as early as Year 1. 

He scoured blogs, forums, and industry chatter to build a list of reputable consumer electronics factories. 

Then he called them directly with the following 4 questions:

They surfaced which partners could iterate with him versus those only set up for mass production. 

Just as important were the red flags:

💡 Dr Brown’s advice: start with smaller, nimble manufacturers. They’re often more flexible, cost-effective, and willing to co-develop with you. Going straight to a behemoth like Foxconn is tempting, but it can trap you in rigid systems that kill iteration speed.

2/ Inventory: Keep it lean and flexible

In the first 6–12 months after launch, his team carried just one to two months of inventory, just enough to meet demand but not so much that they were locked in.

As sales scaled, they moved to two or three months of inventory but with a key twist: order manufacturing parts ahead of time while delaying final assembly until the last moment. This allowed them to fix bugs and ship updated versions quickly without sitting on obsolete units.

💡 Dr Brown’s advice: Inventory is capital. Every extra unit sitting on a shelf is money you can’t use elsewhere. Keep it tight early, adapt fast, and only scale when the data says it’s safe.

3/ Regulation: Treat compliance as part of design

Dr. Brown also baked compliance into the process from the very beginning, to avoid late-stage regulatory bottlenecks.

As a toothbrush, his product was classified as Class I, 510(k)-exempt, meaning it required FDA registration but not lengthy approvals. The annual cost was around $9–10K, but the bigger challenge was ensuring full compliance with industry standards across manufacturing and distribution.

💡 Dr Brown’s advice: Do a deep dive early to understand what rules apply to your category. Choose a manufacturer already aligned with those standards. If you leave compliance until the end, you risk delays, redesigns, or even blocked launches.

Dr. Brown leveraged investor Peter Diamandis's longevity and health community for initial validation. 

He showed up at Diamandis's conferences as a vendor and featured company. Those events were intimate gatherings of health optimization enthusiasts, biohackers, and longevity-focused individuals who were already spending significant money on health technology.

The audience was primed for innovative solutions and willing to pay premium prices for products that delivered real benefits.

He acquired first 50 customers from those events. More importantly, Dr. Brown got immediate feedback on product-market fit, pricing sensitivity, and user experience. These early customers became advocates and provided testimonials that shaped future marketing.

Dr. Brown ran extensive landing page A/B tests to determine which value propositions resonated fastest with potential customers. 

The winning value proposition was convenience: the 20-second brush, not the health benefits. People understood the health benefits intellectually yet were motivated by time savings emotionally.

This insight shaped their early advertising strategy on Meta. Convenience became the primary hook, with health benefits as supporting evidence rather than the lead message.

In addition to Meta ads, long-form content became essential for reaching beyond early adopters. Dr. Brown understood that for most people, brushing is an afterthought. Long-form formats gave him space to explain why oral health matters and tie it to broader health outcomes people already cared about.

He started with small podcast appearances, using them as practice grounds to refine his story: the oral-systemic health connection, his journey from surgeon to entrepreneur, and the technology behind Feno.

As his messaging sharpened, he scaled to larger, sponsored shows in health, wellness, and entrepreneurship, reaching more targeted audiences.

The company is growing at high double digits month-over-month inching towards $5M annualized run rate, hitting an inflection point where organic word-of-mouth and viral content are driving growth. 

This shift has lowered CAC while increasing AOV, with sales now split between D2C and Amazon. While D2C remains the core, Amazon has quickly become a major channel with strong organic traction. Growth is fueled by content—viral videos, authentic reviews, and customer referrals—working hand in hand with performance marketing.

1/ Do unglamorous research. Before building anything, Dr. Brown bought every U-shaped toothbrush on the market and tore them down. That upfront work showed him exactly why others failed and where the opportunity was.

2/ Build a cross-disciplinary team. Solving oral health at scale required more than dentists. Dr. Brown recruited an aligner expert, a physicist, and a manufacturing specialist to ensure the product worked, felt good, and could be built reliably.

3/ Use long-form to build trust. U-shaped toothbrushes carried skepticism, so Dr. Brown leaned into podcasts, interviews, and educational content to explain the science and connect oral health to broader outcomes. Long-form content gave him the runway to change minds.

4/ Start manufacturing and compliance early. Dr. Brown engaged factories in Year 1 and treated regulation as part of design, not an afterthought. That early work prevented late-stage surprises that kill most hardware startups.

5/ Go where your product resonates. His first 50 customers came from longevity and biohacking circles already primed to pay for health tech. Starting in the right community gave him traction, feedback, and social proof.

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See you next Tuesday,

Leo

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