1: What would make the spinners move? Car spinners use the rotation of the tires, but what would make the mouth ones work? Would you need to spin your head around for them to work?

2: Saliva or other mouth contents could jam the spinners.

Holographic illusions? Miniature internal devices?

Oh, like that... Maybe LED/OLED displays? Blinking grills? They just need power from somewhere...

I would think a perpetual smile would hurt after a bit, joking.

But not withstanding, if a removable dental insert were made to take advantage of the pinching action of the teeth, a spring could be wound to power the spinning device. As the person would talk, the spring would wind up in the cheek area. Not so much that you would look like a chipmunk with its cheeks full of nuts.



A small hearing aid battery could be put in the insert in the other cheek to provide miniature lighting.

Additionally, the spinning device would be in a clear bubble so you could see the spinning device without lips and saliva jamming the spinner.

If you don't like the idea of a windup spring, you could simply have a cable connection to a small magnet that wiped past the spinner as you talked. The spinner would then spin like a compass in the presence of a rapidly moving magnet.