Invisalign clear aligners have been used by millions of patients for orthodontic treatment.

SmileDirectClub, which produces at-home invisible teeth alignment products, has raised a new round of funding from investors that values the company above $3 billion, three people with knowledge of the matter said.

The round of fundraising was led by private-equity firm Clayton, Dubilier & Rice, said the people, who asked not to be named because the process is still private.

That price tag is almost 11 times the $275 million valuation SmileDirectClub obtained in its last fundraising two years ago, although this is the first time SmileDirectClub has accepted ample amounts of outside, institutional capital.

An investor group led by Clayton, Dubilier & Rice, that also includes Kleiner Perkins and Spark Capital, invested $380 million in this round at a valuation of $3.2 billion, one of the people said.

A spokesman for Clayton Dubilier declined to comment. Kleiner and Spark weren't immediately available. A representative from SmileDirect declined to comment.

SmileDirectClub, based in Nashville, Tenn., provides a direct-to-consumer option for teeth-straightening. The company, which has had more than 300,000 customers, first sends an "impression kit" to take a mold of its clients' teeth. The 3D impression is then reviewed by a licensed dentist or orthodontist, who will create a treatment plan that lasts six months, on average, according to the company's website.

SmileDirectClub will then send the aligners and once the treatment is completed, customers can purchase a set of retainers for $99. The entire process costs less than $2,000 on average, which can be less than half that of a traditional teeth-straightening process. SmileDirectClub's business is profitable, one of the people said.

The startup competes directly with Invisalign, whose parent company, Align Technology acquired a 17 percent stake in SmileDirectClub in 2016. It did not participate in the current fundraising round, one of the people said. Align Technology, which trades with a $26 billion market cap, slipped 4.6 percent midday Tuesday.

While SmileDirectClub conducts much of its business via e-commerce, the company has about 150 retail locations, where customers can go in for their consultation and set up their treatment plan in person.

Co-founders Jordan Katzman and his friend Alex Fenkell first met at summer camp at age 13 and founded the company in 2014.

The two were initially seeded by Katzman's father, David Katzman. SmileDirectClub was initially self-funded through David Katzman's venture fund, Camelot Venture Group, which invested in 1-800-Contacts and Quicken Loans. Katzman had previously served as the vice chairman of the Cleveland Cavaliers basketball team. David Katzman currently serves as the chief executive officer of SmileDirectClub.

JPMorgan served as the sole placement agent for the deal, three people said. JPMorgan declined to comment.