The formula for a beautiful smile

What’s in a beautiful smile?

According to science, and history, symmetry might be the answer.

“From ancient Greece and Italy of Renaissance, symmetry and parallelism were considered significant for the perception of attractiveness,” said Vasiliki Koidou, D.D.S., dental fellow in the School of Dentistry’s Department of Surgical Sciences.

A recent study Koidou published in the Journal of Prosthetic Dentistry further explored that idea by studying the aesthetic of celebrity smiles – and what’s deemed “attractive.”

Koidou’s team identified people widely considered to have superior smiles using popular Google searches. They compared 94 smiles of celebrities – like Halle Berry, Julia Roberts, Harrison Ford and George Clooney – with 97 smiles of dental students, serving as the control.

The group of celebrities was a convenient group since the pictures are on public display and the authors did not have to use raters to define attractiveness and form the experimental group. Koidou said that would introduce questions on what the criteria for rating attractiveness would be.

The authors also accounted for head rotation. A test on mannequins found that head angulation of 10 degrees or less did not affect the measurements, and therefore, researchers only studied photos of celebrities smiling with a head rotation less than that.

Those individuals with more “attractive” smiles tended to have a smaller angulation between the line connecting the pupils in the eyes (interpupillary line), and the canines in teeth (inter-canine line). This difference was statistically significant. A smaller angulation thus depicts a closer paralellism between the eyes and the smile.

That ties in to the symmetry and parallelism we see in art, Koidou said.

“Beauty is definitely revealed in nature through symmetry. Our study concludes that parallelism may be important for the perceived attractiveness but still the mechanisms of interpretation of attractiveness or symmetry or parallelism are not completely understood. In this context, minor adjustments of dental or facial elements may not significantly impact attractiveness,” Koidou said.

Moving forward, her team will also look into other parameters that may be at play in the perceived attractiveness, such as the application of the golden proportion

While beauty is fairly relative, and comes in all forms, shapes and sizes, Koidou’s team says their findings show there is no perfect formula.

“Aesthetic dental work isn’t always the answer,” Koidou said. “In our experiment, the majority of the more attractive smiles revolved around elements of facial symmetry, not just the teeth.”
University of Minnesota, Twin Cities