Jennifer Lunt, 22, told the New Zealand Herald she wanted a Hollywood smile ahead of her wedding and decided to buy an over-the-counter kit to do it herself.
However, what she did not know was that the slightly darkened tooth was actually infected, something a dentist would have spotted straight away if she had opted for teeth whitening in a surgery.
"I needed a root canal and a white composite filling to cover the discoloured tooth," Ms Lunt revealed.
She urged other people to beware and warned that the packaging on DIY kits is no substitute for proper dental advice.
Last month, Miriam Stoppard pointed out to the Mirror that even though teeth whitening kits used by professionals do contain sodium bicarbonate and hydrogen peroxide, dentists know what they are doing with the substances.