The teeth on the right weren’t real, fakes worn over his real ones for the part, the actor in real life had excellent teeth and was famously immaculately dressed and in contrast with that character.
On BBC comedy videos we buy here in the US there's usually a short promo for "BBC America" which is a cable channel here which shows various BBC shows (like Top Gear).It's a cartoon featuring the Queen talking about Britain.At one point you see a character in a dentist's chair with the most horrible teeth imaginable and as you see him the Queen's saying in the background "they say one's dentistry is diabolical...looks fine to me".
I looked for it on youtube but can't find it...it's really funny.