One partner compared the colour of my teeth to a Mexican washroom hand towel. No longer

If my reception at the "Culture Wars" conference is anything to go by, my three weeks on Colgate Platinum are already bearing fruit. I was initially put off the new whitening toothpastes when I trotted down to Safeway one morning for my customary semi-skimmed and Farmhouse Crusty. I casually picked up a tube of Rembrandt and found myself being asked for £9.90 at the checkout. Had I accidentally chosen milk from a prize-winning herd of organic cows or a loaf containing flour milled that morning from wheat grown on the slopes of Mount Ararat? No, the assistant explained, it was the toothpaste. "This one is £7.50 because of the special whitening."

At such moments one's implicit trust in the operations of the market falters. In much the same way that one goes through life with the effortless assumption that Art Tatum has the cultural edge on Mrs Mills, so one assumes that in terms of price toothpaste will always rest comfortably somewhere between a litre of Highland Spring and a three-pack of mini pork pies. If my checkout assistant was to be believed then all of a sudden toothpaste had spiralled out of control, completely lost touch with its economic moorings and was now, at £7.50 a tube, presumptuously placing itself on the same footing as two fillet steaks.

So it was immensely gratifying to discover three weeks ago during a visit to my local Boots that Colgate was attempting to restore some sort of sanity to the market with a whitening toothpaste barely three times more expensive than a normal tube. Colgate Platinum had another claim on my attention. According to the packet, laboratory tests had proved it to be far better at removing stains than the leading American whitening toothpaste. A two-colour histogram labelled "Stain Removal Index" showed Colgate Platinum at 9.1, whereas its leading rival could only muster a derisory 5.8.

As soon as I got my tube back home I began the recommended regime: two vigorous brushings every day.

Nothing at all happened in the first fortnight. Even though I regularly inspected my teeth, they showed no sign at all of changing from their customary hue, a streaky grey which my partner once unflatteringly referred to as the colour of a hand towel in a Mexican washroom. But round about the middle of last week, I glanced in the mirror and saw a real difference. Even though on the Stain Removal Index I'd probably barely reached 5.8, I was sufficiently pleased by the new colour of my teeth to attempt a smile. It was, frankly, fairly dazzling.

I've now taken my new smile to several public functions. It was difficult to give it much of an outing last Thursday at the Hampstead Humanist Workshop on "Funerals Without God", but down at the Riverside Studio over the weekend I put it to such good use during the intervals between the excellent debates on cultural elitism that one woman mistook me for Melvyn Bragg, and an elderly male delegate wondered why I'd mentioned Jacob Bronowski during my comments on the dumbing down of television when I was clearly too young ever to have seen him.

I realise there's an element of narcissism in all this. As so many of the weekend's debates reminded me, there are more important matters in the world than one's body image. But my Catholic upbringing still ensures that whiteness of any sort has a powerful symbolic value. And now I've sorted out my teeth it might finally be time to turn to another long overdue hygienic task: the removal of several decades of serious stain from my immortal soul.