Showing too many teeth can spoil a winning smile

Smiling too widely can be a social handicap. The most effective smiles hit a “sweet spot” that is not too wide and avoids excessive tooth exposure, say scientists.

Researchers tested the reactions of 802 volunteers to computer-generated 3D faces. Each facial expression was altered by varying mouth angle, teeth visibility and the breadth of smiles, as well as their symmetry.

Dr Nathaniel Helwig of the University of Minnesota said: “These findings have broad applications in a variety of areas, such as facial reanimation surgery, rehabilitation, computer graphics, and psychology.”