If you're happy and you know it, don't clap your hands. Smile. The smile is a sign of friendliness recognised throughout the world. A smile says we come in peace. But many people refuse to smile. Why? Because they're embarrassed about the state of their teeth.
America - land of the (true or false) smile - knows this only too well. But even we tight-lipped Brits are becoming increasingly interested in keeping our mouths open for other than medical reasons. In pursuit of this dental dream, 100,000 people a year in the UK are having their teeth whitened.
I am one of them. The 18th century anatomist Baron Georges Cuvier said: "Show me your teeth and I will tell you who you are." To my dentist, Dr Mohammed Omer, my open mouth is an open book. The brown blotches on the enamel, which I'd presumed were pay back for excessive caffeine consumption, he immediately identifies as the result of antibiotic staining. One of my top front teeth is probably dead, due to a sprung train window smashing up in to my jaw 10 years ago; that, too, is brown. My molars are ground down, due, Omer suspects, to grinding at night. My fillings demonstrate an early addiction to dolly mixtures. If I were brutally murdered, you wouldn't need any of my DNA to find out almost everything about me. You could just use my dental records.
The very same people, including myself, who wag a censorious finger at those who indulge in liposuction and face lifts, are lining up to have our smiles straightened or whitened. The mouth is the one place where it's acceptable to spend a lot of money on medically unnecessary, invasive techniques.
As a child with braces, I hated saying "cheese!" for the camera. But as a grown up, I want to be able to express open-mouthed joy like Julia Roberts. Omer holds my happiness in his surgically gloved hands. It is not a risk-free process. In a few cases, the high concentrate of chemicals used in whitening can make your teeth painfully sensitive, especially if you have a build up of plaque and your gums are damaged. Omer is cautious about whose incisors he tackles, but admits many dentists aren't. "There's a lot of very aggressive marketing, and it's a bit of a carte blanche," he says, intending no pun.
On his advice, I opt for the less risky method, applying a weaker bleaching gel over a period of weeks at home. Two trays like gum shields, filled with a rubbery substance whose main constituent is kelp, are placed in my mouth and imprints taken of my upper and lower jaw. It is a revolting experience, like having a huge ball of plasticine stuffed into your mouth and then being told to relax. At this stage, cosmetic dental treatment seems far more indulgent than liposuction.
The whitening process - applying the gel - commences next week. Until then, I'll keep my mouth shut.