I was at the library today, and found a book that’s all about smiles, called Smile! The Ultimate Guide to Achieving Smile Beauty.
In fact, the Introduction chapter title is: What’s In A Smile? Naturally, I had to check it out.
It’s written by a dentist to the celebrities, who created a teeth whitening system call GoSMILE. I just scanned the chapter on teeth-whitening, and it’s fairly neutral; at least the info was consistent with what I’ve gathered so far on teeth-whitening. So my guess is that it has some helpful info in it; not just a marketing ploy.
I’ll read more and get back to you. Here’s a fun fact from page 2 of the book:
“FACT: It takes nearly three times the number of muscles to frown as it does to smile. Frowning requires forty-three, while smiling asks only seventeen to help out. Stop working so hard!”