Tooth whitening is an increasingly popular treatment, with the industry now worth an estimated £40 million in Britain alone.
Many of us are prepared to spend a lot of money on a sparkly smile and tooth whitening treatments can cost hundreds of pounds.
But the cost can be more than just cash...
Elen Rees and Bethan Rowlands are students at the University of South Wales.
Bethan came across a deal on Facebook for two tooth whitening treatments and couldn’t resist.
“It was £99 for the two for us to have our teeth whitened and I know that Elen really wanted her teeth done. She was constantly complaining that she hated her teeth", Bethan told ITV Cymru Wales.
After arranging an appointment on Facebook, they were given an address in St Mellon’s, near Cardiff.
Bethan was the first to receive the treatment.
They say they were told that the pain was normal and would soon fade, but even now, the girls still say they suffer with sensitive teeth.
When they went back to the messages they’d sent to the woman on Facebook, they were no longer visible.
We decided to take a look for ourselves, to see how easy it is to find people offering tooth whitening treatments illegally in Wales.
And we asked Bethan to see what she could find.
After researching, she learned of tooth whitening prosecutions in Wales.
One of these was Euphoria Tanning in Cwmbran.
Last year the owner, Tina Howarth, was ordered to pay a fine and costs of £4000 after she was caught offering tooth whitening without any dental qualifications.
Bethan contacted Tina Howarth over Facebook to see if she still offers the service.
Howarth replied offering her a tooth whitening ‘pen’ for her to take home, and an appointment in the salon.
We took our secret cameras to Cwmbran to see if they are still prepared to offer tooth whitening treatment.
To find out what happens and to see the full investigation, watch Wales This Week tonight at 8pm on ITV Cymru Wales. Or catch up on itv.com/walesthisweek.