TWO PAIRS OF DENTURES WANDERING AROUND A CAR BOOT SALE
MALE DENTURES
Look Aggie, here's a Max Bygraves record for 20p ,I'll have that.
FEMALE DENTURES
Bargain... and look Jim, The Best of Des O Conner, only 10p.
MALE DENTURES
Put it down Aggie, the thought of it's setting me teeth on edge.
But they ARE the teeth! Madness!
True..but they are mad denture folk!
If they are a pair of dentures going to a car boot sale then maybe they could buy a pair of gumless pensioners in the world of the cartoon.
I think you need to make what they do specific to them being dentures. I like Nigel's idea. I have done something similar with eyes.
Good ideas thanks. 
Also, I think that speech bubbles coming from dentures would look quite funny in a visual context.