Dark side to teeth whitening

Gleaming white celebrity smiles and TV makeover shows are encouraging a surge of tooth-whitening, but dentists warn that do-it-yourself kits can cause serious mouth trouble.

Some in the New Zealand tooth whitening industry say increasing numbers of people are having their teeth bleached or doing it themselves in a bid to beam like Catherine Zeta-Jones, Kate Beckinsale or Britney Spears, who have helped popularise the treatments.

In the United States the industry has swelled nearly 500 per cent since 2000 to be worth an estimated US$2 billion ($2.83 billion).

The costs can range from $20 for a paint-on home treatment to around $1000 for light-activated gel applied in a dentist's chair. For around $500 to $600 dentists will custom-make thin, close-fitting, plastic trays for use at home with a smear of bleach gel.

But it is the $40 DIY treatments using loose-fitting mouth-guard-like trays and gel purchased from pharmacists that are causing particular concern to dentists, who sometimes have to repair the results.

Papakura prosthodontist Dr John Bell said serious complications were rare but he has seen a handful.

Some needed a root filling after a tooth with a hole was inadvertently killed by home peroxide treatment.

Others hurt their jaw joints by using the trays overnight - not recommended - which could require slight grinding of teeth to adjust the bite.

"Appearance medicine is a growing field, and it has sometimes been driven, I feel, for the wrong reasons.

"People think white teeth will make them look younger. In my view it just makes things look a bit false."

Teeth-whitening - his practice offers it - should be the "icing on the cake" after attending to basic oral health and straightening.

Dental Association executive director Dr David Crum said people considering bleaching should first have a dental check for cavities, exposed root surfaces or anything that could lead to damage.

"It surprises me anybody would want to put bleach in their mouth in those [over-the-counter] trays, particularly if you haven't had your teeth checked first."

But Intercare, the New Zealand distributor of DIY tray kit Plus+White, which recommended on its packet the product should be used for a maximum 15 minutes at a time, said the treatment was safe.

"Ours is a soft foam mouth guard. I can't see that being a problem leaving it in your mouth too long," said sales and marketing manager Russell Shillingford.

Sales were increasing rapidly, he said.

The Dental Practice in Botany Downs offers a light-activated peroxide gel process and take-home trays and gel for around $1000. It is called Zoom and was taught to its dentists by Dr Bill Dorfman, the dentist for the American TV show Extreme Makeover, which promotes cosmetic surgery.

Dental Practice spokeswoman Natalie Haynes said demand was rising, especially among men, because people wanted a "better smile".

"People are very aware of having a beautiful smile. It just doesn't make sense that you look after your hair, you look after your nails and have a shoddy smile."
Consumer magazine, after assessing tooth-whitening products, recommended professional tooth cleaning, using whitening toothpaste and reducing use of tooth stainers such as tea and tobacco. Deep stains needed a dentist's help.

Bleaching does not work for everyone, for instance those whose teeth were stained in childhood by a particular antibiotic.

Teeth whitening: the options

* Top of the line: Light-activated gel applied in a dentist's chair (around $1000)

* Middle range: Custom-made plastic trays for use at home with a smear of bleach gel ($500 to $600)

* Bargain basement: Paint-on-at-home treatment ($20) or a DIY version of the trays and gel method ($40)