The British Dental Association (BDA) has warned that using tooth whitening products used and supplied by a Belfast business owner is the "equivalent of brushing your teeth in bleach".
Samuel Irvine Madine, owner of the HD Smile Clinic on the Shankill Road, recently pleaded guilty to five charges at Belfast Magistrates' Court after a case was brought by Belfast City Council.
Four different products were seized over a period of time for testing. The seized products were found to contain sodium perborate, a banned substance which is carcinogenic.
Testing of the products revealed that all samples contained levels of hydrogen peroxide in excess of the permitted level of 0.1%, with one product being more than 300 times greater than this.
A spokesperson for the BDA told the BBC: "This man was convicted for levels of hydrogen peroxide higher than dentists are legally permitted to use.
"It's the equivalent of brushing your teeth in bleach.
"Such high levels of hydrogen peroxide are likely to cause irreparable harm to teeth and gums, including blisters and burns to the gum and damage to nerves and tooth enamel.
"This man's reckless disregard for his customer's health is confirmed by his use of sodium perborate, a carcinogenic substance which is banned across Europe."
Mr Madine was found to have breached Comestic Product Enforcement Regulations. He also pleaded guilty to failing to meet obligations of a distributor, including the required safety and labelling requirements.
He will be sentenced on June 4.