Who knew that Morgan Freeman once appeared in a TV commercial for Listerine, the mouthwash that allegedly powers through your mouth eliminating 97 per cent of the germs left after brushing?

Countless actors have paid their rent by making terrible adverts before making it in the movies. Meg Ryan did toothpaste long before cosmetically inflating her lips up to the size of Texas to hide that perfect Colgate smile. Yet one of several oddities about the young Freeman's 1973 proselytising of mouthwash is that he has such bad teeth. He has said that he regrets not sorting his gnashers out when young, because that way he would have picked up more romantic roles than the institutionalised lifer, Brooks in The Shawshank Redemption.

The ad itself is peculiar enough, in that Morgan explains that anything tasting so vile must be doing a bit of good. Whether this high-risk commercial strategy was any more successful than John Major's 1997 election slogan – "Yes it hurt. Yes it worked" – is not known.

Weirder still is the level of oral-hygiene confusion that seemed to plague Freeman. Two years earlier he appeared in an advert for the cigarette brand Long And Black. "We have come so far in the last 20 years," declared the scion of slaves while clad in the garb of Huggy Bear the jive dude. "Granddaddy did good, Daddy did better. We marched a long way ... Stay black, stay strong, stay black and long ... That's some good nicotine!" Too good to be scourged from the tooth enamel by twice daily blasts of stain-removing Listerine, apparently.

Then Freeman changed his thinking on the black pride front, advocating that the only way to end the discord is to stop talking about racial differences. "I am going to stop calling you a white man," he once told a 60 Minutes interviewer, "and I'm going to ask you to stop calling me a black man."

If the Seventies was as productive a decade for Freeman on the advertising front as for the makers of Blaxpoitation movies, his screen career now seems to be coming full circle, with a new generation of Britons knowing him only through those More Than Freeman TV commercials. If he is tempted to complain about the abuse of his gloriously distinctive voice for profit, he has missed that boat by some 40 years.