In this article you will learn about true smile vs. fake smile. It is believed that the Duchenne smile is the only form of what one could call the "genuine" smile. The "Pan American smile," on the other hand is the smile expressed to show politeness.
A Japanese company named Omron has created a device that scans a person’s face, renders a 3D model of it and checks a few critical spots (mouth, eyes etc.) to evaluate if someone is smiling hard enough. Every smile gets a percentage from 0% to 100%, with 100% obviously being the perfect smile (see the picture below). The device, which consists of a small analogue video camera, a sensor unit and a piece of software, is only available in Japan at this point.