CHARLOTTE, N.C. -- Teeth whitening is more popular than ever.

"I think a lot more people are getting it now. It's more affordable,” said Dr. Regina Henderson.

She showed Eyewitness News the process she uses to whiten patients' teeth and remove stains, a process she's legally allowed to do because she's a licensed dentist.

North Carolina law spells out exactly what constitutes the practice of dentistry. Among other things, it requires a person who "removes stains, accretions or deposits from human teeth" to be licensed.

But during a six-week Eyewitness News investigation, reporter Jim Bradley found companies offering to whiten teeth without licensed dentists.

Eyewitness News made several visits to teeth-whitening kiosks at Concord Mills and at Carolina Place Mall in Pineville. Both kiosks are independently-owned BleachBright franchises that sell a whitening gel in a mouthpiece, which customers apply to their teeth at the kiosk, along with a special light.

What does all that do? At Carolina Place, several employees repeatedly said their products do indeed remove stains.

“It opens the pores in your teeth and it bleaches your teeth and it takes all the stains off,” one said.

“So it actually removes the stains. It's not just a cover-up?” the undercover Eyewitness News producer asked.

“No! It doesn't cover up. It removes,” an employee said.

At Concord Mills, employees gave the same claims.

“It doesn't just cover up; it removes the stains?” the producer asked.

“No, it removes the stains,” the worker said.

Dr. Alec Parker, head of North Carolina's Dental Society, said the businesses are removing stains through a chemical means and he believes they are practicing dentistry. But, he said, he's most concerned that they aren't regulated by the state.

"I feel like they should either stop or they should be under some type of regulation where the public has some idea as to how this is being delivered, what kind of training they have," Parker said.

At Concord Mills, the Eyewitness News producer asked about the difference between the product and the one a dentist uses, since it cost $120 at the mall and much more at the dentist. The employee said it’s the same.

"So you're saying you get the same exact thing as the dentist for a lot less money?" the producer asked.

"Faster, safer," the kiosk worker said.

Parker said it’s not the same procedure though.

“And 'safer', I don't understand how they can make the statement that without any training they can provide a safer service than someone who's been to dental school,” he said.

The Eyewitness News producer asked, “What if something goes wrong?”

That same kiosk employee at Concord Mills said that wasn't possible.

"There's really not a way for it to go wrong," he said.

On another visit to the same location, a different employee wasn't sure.

“If you were to have any problems?” the producer asked.

“If you have any problems, I can give you the number to my manager and you can call her,” the employee said.

“I would come back here, or go see my dentist, or do you know?” the producer asked.

“I really don't know. I mean, I can ask,” the worker said.

Parker said that’s a big problem.

“One of the questions I would have had was, “Well, what's the manager going to do? Does he or she have a relationship with a dentist who's agreed to handle any problems? And if so, who's going to pay for that?” Parker said.

During Eyewitness News’ visits, two Channel 9 employees used the teeth whitening product. Both had to sign a consent form, which asked, among other things, whether they're allergic to carbamide, peroxide or glycerin. Neither employee had any problems resulting from the procedure.

North Carolina's Board of Dental Examiners has had a complaint, however, from a man who claims to have had complications after visiting a BleachBright kiosk in Raleigh. BleachBright is disputing that claim.

But what about the things Eyewitness News witnessed in its investigation?

The company said employees at BleachBright kiosks are not practicing dentistry, insisting they're selling customers an over-the-counter product to use themselves. He likened it to the whitening strips sold at drugstores.

As far as claims that the procedure is safer than at the dentist, BleachBright CEI C.W. Baudot said, "That's not so."

He said a dentist is "certainly the safest."

He also said as a result of Eyewitness News’ investigation, the company will retrain employees at all 440 BleachBright locations across the country, saying some of them "need a little more guidance."

Parker said even more needs to be done.

“I truly believe that they need some oversight,“ he said. "We ask that people who provide cosmetic services like hair care and nail care be regulated and have some kind of training."

Since Eyewitness News contacted BleachBright, the company sent a letter to franchises insisting that proper procedure be followed and reminding employees that their function is only to sell this product and explain how customers can whiten their own teeth.

Also, BleachBright's owner told Eyewitness News those kiosks will start using new packaging that lets customers perform more of the whitening process themselves.

The state dental society said if you do use one of these businesses, ask about sanitation because many of the kiosks don't have running water, ask how much experience and training the employees have and ask what to do if you have problems or complications.

RAW VIDEO: What Customers Should Look For To Get Teeth Whitened At Mall