Meet the 30-year-old cofounders of SmileDirectClub, Jordan Katzman and Alex Fenkell, who just became 2 of the youngest billionaires in the US

The two became close friends, according to SmileDirectClub's website. Both wore traditional metal braces at the time.

Katzman and Fenkell came up with the idea for SmileDirectClub while later reminiscing about their childhood years and wondering if they could find a less embarrassing and cheaper way to straighten teeth, according to SmileDirectClub's website.

Before SmileDirectClub, Katzman and Fenkell launched a car detailing business and another that developed a software company that allowed online shoppers to build a single shopping list pulled from multiple websites, according to Inc.

"It took Jordan and I years to find the right idea and you have to be willing to fail a few times beforehand to succeed," Fenkell told the Michigan Fashion Media Summit, an event that SmileDirectClub sponsored. "It's important to not get hung up on just one idea, you need to be willing to move forward and pivot when something isn't working."

The pair secured funding from the investment firm Camelot Venture Group, which is run by Katzman's father, David Katzman, according to Forbes.

Their goal was to revolutionize the teeth-straightening industry as Crest Whitestrips revolutionized the teeth-whitening industry by allowing people to whiten their teeth at home, Fenkell told Inc.

They originally named the business SmileCareClub, according to Inc.

David Katzman told the cofounders to build a website for the new business to see if there was any interest from potential customers, according to the Nashville Business Journal. So many people visited the site that it crashed within days.

David Katzman, 59, is also SmileDirectClub's largest shareholder. As of a Forbes article from September 3, he was expected to have an estimated net worth of $2 billion after the company's IPO.

Katzman had experience with direct-to-consumer businesses after investing in 1-800-CONTACTS and Quicken Loans through Camelot, according to SmileDirectClub's website. Katzman held positions at Home Depot, the Cleveland Cavaliers, and wall decal company Fathead before SmileDirectClub, according to the Nashville Business Journal.

Katzman's uncle, Steven Katzman, is SmileDirectClub's chief operating officer. Between Jordan, David, and Steven, the Katzman family will control 65% of votes within the company, CNBC reported.

Katzman runs SmileDirectClub's IT department while Fenkell heads up marketing, Inc. reported.

SmileDirectClub had an ill-fated partnership with Invisalign maker Align Technology. It ended in a lawsuit that forced Invisalign to close all of its stores, according to Inc.

The company has also faced substantial opposition from dentists and orthodontists who say that straightening your teeth without an in-person consultation with a medical professional can do more harm than good, The Detroit Free Press reported.

SmileDirectClub said in a press release that the company is "a target of a well-funded lobbying and public relations effort by the American Association of Orthodontics, the largest orthodontist industry group, which is seeking to shut down pioneers of innovative, affordable teledentistry services."

"If industry lobbyists have their way, millions of Americans will be denied access to a healthy smile through teledentistry," Fenkell said in a 2017 statement. "It's important that we stand up for those who, without SmileDirectClub, would not have access to an affordable new smile."

"Whenever you disrupt something, there's going to be some friction. It just takes some time to muscle through the first year of the business, to show the results, and we believe we've done that," Fenkell told Inc.

SmileDirectClub has even filed lawsuits against its detractors, including the Georgia and Alabama dental boards, according to the Nashville Business Journal.

If SmileDirectClub loses its lawsuits against the state dental boards, the company could be forced to overhaul its business model to include closer oversight of patients by dentists, according to the Nashville Business Journal.

"We would have to assess if that became the case," Fenkell told the Nashville Business Journal. "We just believe so strongly in what we're doing ... I just can't see that."

Katzman will hold a stake valued at $1.6 billion and Fenkell's stake will be worth $1.5 billion, according to Forbes. Each owns close to a quarter of SmileDirectClub's Class B shares.

Other young American billionaires include Stripe cofounders Patrick and John Collison (30 and 29 respectively), Snapchat founder Evan Spiegel (29), and social media mogul Kylie Jenner (22), according to Forbes.

Read more: How Kylie Jenner became the world's youngest self-made billionaire, from starring in a reality TV show at age 9 to running a $900 million cosmetics empire at 21