Delixe: On the British teeth thing I think it's only partially to do with dental standards, it has more to do with the culture actors are raised in the respective countries. In the US people who want to be actors are usually groomed for the role at an early age. They look after themselves with various diets, they regularly go to gyms and appearance is almost as important as acting abilities. Just look at Ben Affleck. Teeth are important as one of the hallmarks of a good leading man is that winning smile with the little sparkle so they look after and craft their teeth just as fastidiously as they do their faces and hair.

British actors on the other hand usually learn acting in the theatre where the audience is not close enough to see an actors chops in any great detail. It's also seen as a benefit when the audience imagines an actor is the character and not the actor playing the role so you don't expect to see Nick Cage or Tom Cruise playing Hamlet. If you consider some of the best British actors like Pete Postlethwaite, Michael Caine, Patrick Stewart and Jim Broadbent then you will notice none of them have what American's consider an attractive mouth and most of this is due to the fact they all started on stage and not TV or Movies. Even David Tennant a favourite pin up of most SciFi fangirls looked to have a particularly grotty mouth when standing next to the immaculately dentured John Barrowman.